i have learned some new layout ideas from several threads, Marty Marts Tornado built, but has a small problem (http://www.diystompboxes.com/smfforum/index.php?topic=54903.0), guidelines for laying out high gain circuits? (http://www.diystompboxes.com/smfforum/index.php?topic=55062.0), and PCB layout tips for high gain FET circuits? (http://www.diystompboxes.com/smfforum/index.php?topic=52406.msg395822#msg395822). there are probably other places where the ideas found there are explained, and references to them are welcome. what really brought the ideas home for me was applying them to a particular case. so here is another application, dr. boogey, where folks have had some difficulty taming the circuit.
i am hoping to learn more/better by having this layout critiqued here. and i hope others will learn, too.
what you see below is my attempt to apply of 4 principles: (1) a simple signal path, (2) +9v trace next to a ground trace, (3) star grounding, and (4) grounded guard traces. i learned them from a bunch of folks, including Basicaudio, MartyMart, puretube, and R.G.
the signal path is marked off in darkish blue. i hope that you can followi it going up the left side, down the middle, and back up the right side. i tried to avoid twisting back and forth in tight little zigzags, something that often happens if i am just trying to get a tight layout because of the way components get lined up in rows. what you see is piece-wise linear. still there are a couple of tight spots. the upper left-hand corner where the gain pot hooks up and the upper right-hand corner where the tone section hooks up. i am guessing that these are o.k. any thoughts?
the +9v rail is marked in red. several different ground regions are marked in two shades of green. notice that i have ground on either side of the +9v rail, wherever it goes.
star-grounding, as i understand it, brings several branches of ground together at the ground lead of the big supply filter cap, C14 in this layout. i have taken sections separated by coupling caps and connected their grounds indivdually to the location of C12 (roughly speaking). the input section has its own branch (the light green patch on the lower left. gain and Q2 have the next dark green patch, and so on. using the coupling caps as demarcations was my idea. is there a better approach?
finally, you will see that ground fill or traces also surround most of the signal path.
after comment, i will revise this and post it as a new dr. boogey layout. the schematic is the same one as for my most recent dr. boogey layout: schematic (http://gaussmarkov.com/layouts/drboo/schem.png). here is the layout:
(http://i41.photobucket.com/albums/e270/gaussmarkov/Forum%20Posts/boogcolourpcb.png)
Quote from: gaussmarkov on March 10, 2007, 05:12:54 PM
ii am hoping to learn more/better by having this layout critiqued here. and i hope others will learn, too.
What a great idea! I wish more of this went on. It's easier to learn from practical examples, and a better layout for this popular circuit would be a great help to all.
Quote
still there are a couple of tight spots. the upper left-hand corner where the gain pot hooks up and the upper right-hand corner where the tone section hooks up. i am guessing that these are o.k. any thoughts?
Well, I'm no expert, but I'll blab away anyways....
You've used vertical (standing) resistors throughout, yet there's still a fair bit of empty space on the board. It could probably be shrunk a lot further. But that's not important right now.
C14, the PS filter cap, looks to be falling off the layout. R2 is pretty close to the edge too. May cause mechanical problems. Oh, and how about some mounting holes?
I wish R5 was closer to Q2's gate. The blue signal wire from Q2 goes through C18 and C5 before hooking up with R5. This wire is very high impedence and sensitive, so I'd try to get R5 closer. The other Q's gate resistors are tucked up against the JFETs except for Q1. Q1 doesn't have a series gate resistor, just R1 for bias. I'd put a little resistance in series with it to help C17 work properly, a la fetzer valve.
The presence network, R15/C13, carries strong HF content and is awfully close to Q2's gate. Even worse, the presence pot is right up against the gain pot. It might help a lot if the knobs were re-ordered: gain, bass, mid, treble, presence, volume? The bass pot is less likely to leak to it's neighbours. Good that you gave the gain pot it's own ground.
I'm personally dubious of the +9 rail for everything. My preference is... battery though a small series resistor, cap to ground, protection diode to ground, and we have +9 for Q5, Q4 and Q3. Another series resistor and cap to ground from that rail, and we have the rail for Q1/Q2. Is this pointless?
Quote
using the coupling caps as demarcations was my idea. is there a better approach?
Seems reasonable to me. Q1 and Q2 are in opposite phase, so hopefully anything they do to the gnd and power rails will cancel somewhat. Same for Q3, Q4 and the follower Q5, which is the same phase as Q4.
Just as an aside from this topic I have to say gm your website has gone from excellent to Outstanding!
Nice work indeed.
BTW, I had thought about taking on this circuit and making a layout for it as a "fun" project but, it truly frightened me too much! :icon_lol:
Very nice Gauss, I like this open layout ideas thread.
There should be a 68K resistor before the gate of Q1 as Ardric mentioned (pretty sure it's on the original schematic) what this does is work in conjunction with C17 to guards against RF pick up and also creates the Miller Capacitance for the FETs that tube have by nature. Sets a similar capacitance curve...rolls of some of the super high frequencies.
R5 could be closer, just a matter of shuffling around C5 and C18. Maybe moving C15 and moving the left side of the board closer as well. The only thing that would really get too close are the first two trimmers and that's not a big deal.
The Cap and resistor that are off the board a little are no big deal. The board won't stop at the trace anyway.
The presence and Eq components are a bit close to Q2. This gets into the "Linear" layout area that we want to strive for. The EQ section is at the end of the line and is sensitive anyway. Lots of gain here. Wrapping it around to an earlier Stage (Q2) is "oscillationville".
I would try to swing those components to the right and you'll probably have the widen the board a bit to get it to work.
Maybe lowering the Last trimmer and laying out the pots so the presence is just before the volume. That way you don't have to put the presence components all the way over to the top left and close to the earlier stages.
In marshal amps this is the place they go anyway. The presence control in amps comes off the Output transformer and is the last thing in the line. Lots of gain and current here.
The point about a small series resistor and adding another cap and resistor to power Q1 and 2 sounds good. More capacitance is fine and the resistor would be more along the lines of RC filters in amps.
Adding theprotection Diode is aways good as well.
I pretty much go along with all of Ardric's post don't I ?
Looks like a good start. Just shuffle around the EQ section to get away from the input stages and were close...
John
thank you all! i will give this another crack tomorrow. regarding the 68K resistor on Q1, i missed that somehow. it isn't on the schematic that i found here and that i worked from: http://geocities.com/electrictabs/dr.boogey.png. can someone point me to the right version? or perhaps there is a thread where that got added?
again, thanks! i'm sure that others are learning from this as well. and we'll get a better dr. boogie layout out of it to boot. who says nothing gets done by committee? :icon_cool:
cheers, gm :icon_biggrin:
Quote from: gaussmarkov on March 11, 2007, 12:30:40 AM
regarding the 68K resistor on Q1, i missed that somehow. it isn't on the schematic that i found here and that i worked from: http://geocities.com/electrictabs/dr.boogey.png. can someone point me to the right version? or perhaps there is a thread where that got added?
I just finished a hissy but otherwise well behaved Dr Boogey and there is no 68k anywhere in it??
After reading all the DB threads I could find, I'm under the impression the "Miller Cap" was achieved solely by adding the 220pf cap between the transistors gate and drain. I was planning on adding this using Gaussmarkov's schematic as a guide. So, is there more to adding Miller Caps than just a cap?
Yes please, someone post a link to the thread where this comes to light.
Nice work on your layout.
Why did you not connect the two ground traces just to the left of C1?
I see a jumper that does the same. Whats the reason for it not to be connected?
I guess I just added the 68K myself, sorry about that....I think on the layout it's a jumper. It help with the miller effect to set a roll off in conjuction with the 220pf from gate to source.
This explains it: http://www.aikenamps.com/ look under tech info > advanced > miller capacitance Also see the grid/gate resistor article
Pushtone: Gaussmarkov is using satrt grounding on this layout. Each section is connected to the central grounding point. This was each section gets a clean ground reference. This way dirty or poluted ground areas do not impart noise to sensitive areas. Also explaind in the above link.
John
Quote from: Pushtone on March 11, 2007, 12:59:51 AM
...I'm under the impression the "Miller Cap" was achieved solely by adding the 220pf cap between the transistors gate and drain. ...
That would be 2-3pF from gate to drain, or approximating this with a 220pF cap from gate to source.
The parasitic loss is multiplied by the gain when you go from gate to drain.
The 220pF G-S "Miller-Caps" do help with getting a more amp-like sound rather than sounding like just another pedal.
Quote from: Basicaudio on March 11, 2007, 01:26:18 AM
I guess I just added the 68K myself, sorry about that....I think on the layout it's a jumper. It help with the miller effect to set a roll off in conjuction with the 220pf from gate to source.
...
Yep, I did the same thing and that's what I thought too. I also added input/ouput coupling caps - along with a rev-volt protecting diode - it's something I try to always do.
Quote from: mojotron on March 11, 2007, 03:33:32 AM
Quote from: Basicaudio on March 11, 2007, 01:26:18 AM
I guess I just added the 68K myself, sorry about that....I think on the layout it's a jumper. It help with the miller effect to set a roll off in conjuction with the 220pf from gate to source.
...
Yep, I did the same thing and that's what I thought too. I also added input/ouput coupling caps - along with a rev-volt protecting diode - it's something I try to always do.
Yup +1 on all that, also I think that I stuck a 33k or 47k where the 68k is being used, a bit like the fetzer valve
input choice.
MM
Just a little suggestion for avoiding the beast from screaming..and what about pcb mounting jacks?
Quote from: Pushtone on March 11, 2007, 12:59:51 AM
After reading all the DB threads I could find, I'm under the impression the "Miller Cap" was achieved solely by adding the 220pf cap between the transistors gate and drain. I was planning on adding this using Gaussmarkov's schematic as a guide. So, is there more to adding Miller Caps than just a cap?
the miller caps are in there. :icon_wink: i did catch that part of the wave. :icon_biggrin:
Quote from: Basicaudio on March 11, 2007, 01:26:18 AM
I guess I just added the 68K myself, sorry about that....I think on the layout it's a jumper. It help with the miller effect to set a roll off in conjuction with the 220pf from gate to source.
This explains it: http://www.aikenamps.com/ look under tech info > advanced > miller capacitance Also see the grid/gate resistor article
Thanks John for explaining that.
I see the jumper you speak of in Buck's layout.
I'll socket it and try different values after I add the Miller caps.
Thanks for posting the Aikenamps link, I think thats the second time you pointed to it in reference to the DB.
Made more sence this read through.
And thanks Mojotron for correcting my error. Gate to Source on the Miller cap, got it. Thanks
I took the liberty to scale your layout. I wanted to see what enclosure it fits in.
I matched the trimer pads to scale it but didn't look if the right value caps would fit.
I'm I close?
(http://www3.telus.net/public/david65/pedal-pics/1590BB-DrB-GussmarkovL.gif)
1590BB bottom outline shown.
If so...
Its a super nice fit in a 1590BB sideways. Plenty of room for the battery and FS.
Nice work! Its still about the size of Bucks layout I'm using, maybe even a little smaller.
Looks like a good fit but sure tight on the pots. Not sure if those are scaled 100% accurate but They are touching in the mock up there. Too tight for my comfort. Hopefully they are actually smaller so there is a little slop room in between.
Did you make that Hammond template pushtone or was that a data sheet thing from hammond?
John
the layout is on a .1" grid. 25 x 16. i cannot tell whether your scaled version is bigger or smaller, pushtone. waddya think?
i just finished a revised version, same size and i will post it shortly. i think my original layout was 22 x 16, so i haven't added many columns. everything fit on the last one, caps and all. i use the datasheets to make my component outlines and so far those have been reliable. :icon_biggrin:
new schem and new layout. i hope i incorporated all of the suggestions. there are now two +9v rails, both with RC filters. the polarity reversal diode is there. i moved all the tone section to the upper right-hand corner--is it too tight? and the presence pot is beside the bass pot now. i left bass, mids, treble in the original order because flipped over they are in the order one expects. i suppose that one does not have to put all of the pots in a straigth row. and if necessary the presence pot could be shielded.
also R5 is now much closer to Q2's gate. will that do? it could be closer still, no problem.
everyone, thanks for the help. please feel free to critique this version also. as soon as it passes consensus, i will post all files: eagle, graphics, and pdf project file.
(http://i41.photobucket.com/albums/e270/gaussmarkov/Forum%20Posts/perf-3.png)
(http://i41.photobucket.com/albums/e270/gaussmarkov/Forum%20Posts/schem-3.png)
Looks like a winner Gauss
One thing that I do is to have the pots layed out like this:
Looking at the finished pedal with the shafts face up in two rows of three knobs each.
Volume Presence Gain
Treble Middle Bass
This way you can have the volume directly above the "out" pad on the board, the gain pot above the gain pot pads and the treble mid and bass controls in a row on the bottom with short wires . This is good because the treble wiring is right next to the gain wiring otherwise. Which is like having the end of the circuit next to the input of the circuit and will cause oscillation. I use shielded wire from the gain to the board and from board in/out and in/out jack to the switch. Some people have had success without doing that but better safe than sorry.
John
Quote from: Basicaudio on March 11, 2007, 10:23:13 PM
Looks like a good fit but sure tight on the pots. Not sure if those are scaled 100% accurate but They are touching in the mock up there. Too tight for my comfort. Hopefully they are actually smaller so there is a little slop room in between.
Did you make that Hammond template pushtone or was that a data sheet thing from hammond?
John
Basicaudio, thats the pdf from www.hammondmfg.com, scaled and edited in Adobe Illustrator.
The scale was just for the layout part. I know six 16mm pots will fit cause I just did it for a "Bucksears" version.
I took Buck's layout literally and put all six pots in a row even though I would have preferred a different order to the controls.
I was expecting your (Gussmarkov) layout to be bigger, ya know with more space between parts and all.
I was expecting a 1790NS size enclosure would be required. Like what Basic posted in the Pictures thread the other day.
It's great that you kept it small. You got skills Guss! I'm blown away that you totally moved the PRESENCE pot to the other side so quickly.
Your schematic is just what this project needed.
Documentation of the evolved Dr Boogey. For the little pepole.
Thanks in advance Gussmarkov!
I would be honored to build on your (finalized) layout.
Then I could make a direct comparison between Electrictabs original schematic and Bucks original layout (just finished) with your improved schematic and layout.
And I'll be able to do it in the same enclosure with the same parts layout to boot!
Ok, cool. I didn't mean to say that the scaling was wrong.
Just that I didn't know how close it was as pictured verses in real life.
I admire being able to get tolerances that close.
I er on the side of larger enclosures so I have some room to work.
Thanks for all the work again here gauss and to those who gave their input.
Here's a different pic of mine with the two row spacing.
(http://www.mrdwab.com/john/DBredongreen.jpg)
1790NS size box in Red Texture powdercoat from Pedal Parts Plus
John
i guess we're virtually ready to issue this layout. i think i will take the letters "gm" off of this one and replace them with "diy" to indicate corporate authorship. :icon_wink:
one final question: i am pretty sure we can take out 2 columns and make this layout 23 x 16. is it worth it? the 2 big islands of ground fill on the left and right would each lose a column. would this significantly change the functioning of the circuit?
cheers, gm
Quote from: Nashtir on March 11, 2007, 06:49:58 AM
Just a little suggestion for avoiding the beast from screaming..and what about pcb mounting jacks?
I agree. And maybe pcb mounting pots, also? To eliminate all that crossing wires that leads into "oscillation city" :-X
A little room for the battery and for the switch, it's enough, I believe.
Quote from: Victor on March 13, 2007, 08:56:46 AM
Quote from: Nashtir on March 11, 2007, 06:49:58 AM
Just a little suggestion for avoiding the beast from screaming..and what about pcb mounting jacks?
I agree. And maybe pcb mounting pots, also? To eliminate all that crossing wires that leads into "oscillation city" :-X
A little room for the battery and for the switch, it's enough, I believe.
builds with the pcb mounted jacks and pots are very cool. i wonder if such designs shouldn't be left to each builder, because the way things fit in the enclosure varies so much from person to person? because i post the eagle files for these layouts, it is possible for anyone to load them in the eagle layout editor and make such adjustments without having to lay the whole circuit out again. so i am going to pass on these suggestions, though i am sympathetic. :icon_cool:
also, any thoughts about replacing the trimmers with sockets for fixed resistors? i suggest this for two reasons: (1) trimmers are space hogs and (2) trimmers are noisy. with sockets for the drain resistors, you can still adjust until you get the right values. this seems like something worth considering for all of these high gain circuits.
fwiw, here is a smaller (23 x 16) layout (0.1" grid). there are some incidental improvements in this version. the potential problem that i see is that the treble signal is getting close to the bypass cap for Q2. at least that's not the primary signal path. and there's still some space.
(http://i41.photobucket.com/albums/e270/gaussmarkov/Forum%20Posts/perf-4.png)
After all the headache with the trimmers on the tornado I think I'm converted to fixed resistors for good now! I just tack on a pot, measure the voltage and then put in a close valued resistor. Depends on the circuit but the next high gainer I build will be "fixed resistored".
Either that or buy better Trimers ($$$)
John
gaussmarkov - what value for c20? 47uf? thank you.
Both Caps at the power supply should be 100uf. It's not totally necesary but gauss is trying to build a bullet proof version here.
Gaussmarkov
Seems like the revisions are set for now. I wouln't mind seeing the larger of the two PCBs used but I don't know if it's an issue. The space between Q2 and Q5/Q6 looks a little close to me. It's all so confusing isn't it!
I need to build another so when you decide just let me know when you get a chance to post the Transfer patern.
Thanks for the work again!
John
Quote from: Basicaudio on March 14, 2007, 03:56:50 PM
Both Caps at the power supply should be 100uf. It's not totally necesary but gauss is trying to build a bullet proof version here.
exactly. thanks, john! :icon_cool:
Quote from: Basicaudio on March 14, 2007, 03:56:50 PM
Seems like the revisions are set for now. I wouln't mind seeing the larger of the two PCBs used but I don't know if it's an issue. The space between Q2 and Q5/Q6 looks a little close to me. It's all so confusing isn't it!
I need to build another so when you decide just let me know when you get a chance to post the Transfer patern.
i just posted the new version: dr. boogey (http://gaussmarkov.net/index.php?page=layouts#drboo). this is the smaller layout, because i ended up moving the tone pots around as you suggested much earlier and this gave me a chance to move a cap and introduce a guard trace. john, if you want the other version after all, please let me know.
everyone: coupling caps are in this version, too. this required quite a bit of rejuggling to stay inside 23 x 16. and it led to the new pot order.
man i hope this is an improvement, gm :icon_biggrin:
:o Great work. Thanks!
This newest version looks good. In moving around the parts It looks better to my eyes.
Some things I did to mine and I like the ways it sounds. Quiet and squeal free with all 201s
20pf replaced with 120pf
Shielded wire from in/out jacks to switch and from switch to in and out of board. If you have very short leads and they are routed out of the way and kept from the tone controls the shielding won't be necesary.
I used a 500K log pot for the gain control on one out of control build. Still had all the gain but not of the oscillation.
220pf caps across gate and source for Q1, Q2 and Q4.
Thanks gauss!!
John
Hi again, and sorry about the delay.
The last March 14th version seems to have introduced a new problem. C21, the new input coupling cap, prevents R1 from biasing Q1's gate. It won't work as drawn unless C21 is replaced by a jumper, or by adding another 1M from the C21/R19 junction to gnd for bias. R1's purpose is then to prevent the opposite side of C21 from floating, DC-wise, to prevent clicks and pops.
Personally, I've had good luck omitting an input cap with ROG's JFET simulations. None of my guitars or pedals seem to have a problem with it so far. I guess best would be to put the extra cap and resistor on the layout, but make their use optional.
Regarding the power supply, I was thinking more like the +9 end of R17 would connect to the R16/C20/VB node. That means Q1 and Q2's power goes through R16, C20, R17 and C14, filtered twice. I'm still hoping someone will chime in with reasons for or against this approach, since it's used by the actual amps but rarely seen in pedals. Maybe if the R's and C's are sized appropriately we can get a little tube rectifier sag simulation going on too.
I'd move C15 on the schematic from Q2's drain to the power supply drawing, parallel to C14. That's really what it's doing. It would also be nice to connect common gnd nodes on the schematic together with wires before bringing them to a gnd symbol, so what's common with what before returning to the star gnd is seen at a glance.
We've got a few grounds to account for... the circuit gnd, the input jack gnd, the output jack gnd, and the box/shield gnd. Where's the star when it's all boxed up? Is it the input jack sleeve? Perhaps a couple extra gnd pads on the board would be nice to have available if needed. Heck, we could also leave room for a LED dropping resistor for those so inclined. It would be wired to PWR before the filter resistors, then to a pad to the wire to the LED's anode, so pulling the other end to gnd lights it.
Lastly, I can't help frowning at the 1MA volume pot on the output. The whole 5-knob tonestack/volume output deal, actually. I wonder if at least one of those tonestack knobs could be replaced with preset resistors to free box space. I'd also prefer a buffered output of some kind, post volume control. But there's a lot of people happy with the original, so it's only fair I give it a shot.
I've got a bag of J201's sorted out and ready to go. I'm looking forward to getting a new build underway. Thanks to everyone for contributing.
Some good points Ardric
The 1M pot at the end is a bit foolish. In the amp version it's fine because at that point the impedance is still high and being fedd to two more stages, (phase inverter and the output tubes) I brought this up in another thread but yeah.... The Volume pot should be 100Klog. This lowers the ompedance signifinantly and pwdal after the DB won't load down the tone. I tried a delay after the DB and it was super muddy. 100k has plenty of volume.
The input cap does need a pulldown resistor at both sides of the cap to work and keep the first FET biased correctly.
Putting the resistors bettween the power supply fileter caps may work but the 9v supply is so small anyway.
Smoothing the last bit or posible ripple out of the 9V is pretty common with a small resistor and a large cap. 1000uf sometimes.
Putting the resistor between the caps may work as well but I think Gaussmarkov was trying to balance out the power distribution so the later stages had a clean source of ground and power.
C15 is a curious one because in the amp version the cap is localized because of the r/c filters. But in the pedal veersion here the cap may as well just be across +9v and ground anywhere in the circuit as the power supply is the same all through the circuit. Nothing gained by putting it close to Q2.
The grounding is a goos point. We've come up with a fairly elaborate star grounding system but we've left out a big part of the grounding circuit. input/output and chassis ground. Since most input/output grounds are connected to ground at the chassis I guess thats a little bit of a mute point but the star system is dependant on a single point to the chassis and localizes grounding point with one connection to ground at the star. Maybe we should just make a couple more pads at the main star point on the board and wire jack grounds there?
What kind of buffer are you thinking Ardric? The Source follower Q4 lowers the impedance....
John
ardic, thanks for those comments. :icon_biggrin:
i have made a critical change and accomodated two others. first, the needed 1M resistor to ground is in place for proper grounding biasing. second, i have reconfigured the power supply section so that VA gets filtered twice. third, i have placed extra pads on the ground rail.
i will make the schem clearer later. those are all helpful suggestions and, honestly, it had not yet dawned on me to make the star-grounding approach clear on the schematic.
as ardic said, it seems reasonable to leave the rest as is, given the general happiness with the dr. boogey. that said, i think additional discussion would be great. i'm just getting this off again so that those who want to go ahead this weekend and try the version we have can do so. everything is posted in the same place as above: http://gaussmarkov.net/index.php?page=layouts#drboo (http://gaussmarkov.net/index.php?page=layouts#drboo)
over and out, gm
Quote from: Basicaudio on March 16, 2007, 07:26:40 PM
I brought this up in another thread but yeah.... The Volume pot should be 100Klog. This lowers the ompedance signifinantly and pwdal after the DB won't load down the tone. I tried a delay after the DB and it was super muddy. 100k has plenty of volume.
Read that thread. Makes perfect sence.
I was planning and referencing your post in a DB build report.
Thanks, a very good tip for the DB.
Didn't you also use 500k instead of 1meg on the gain?
Thats another tip I went with based on the exsisting DB threads.
PLENTY of gain!
I even used linear pots on the Mastr and gain and it works good.
The taper dosent seem to matter too much with this one. Smooth response across the dial.
I used a 500K gain pot for my first one which was a little out of control at first. But then I built a second one for a friend and used all the stock values at first and was prepaired to be blown away with squeal but it was well behaved and not a peep of noise or oscillation.
I guess my wrestling with the first one forever got my layout issues worked out and got lucky... or just had a good combonation of j201s....
I've been using 100k linear pots for the volume and tacking on a 25K resistor from the wiper to ground to simulate an audio taper. Really, for the output volume the taper isn't a big deal, you set it so it sounds right.... taper shmaper!
For the gain control that's interesting that you got a nice sweep with the liner because even with the audio pots I get a bit of a gain jump right off the bat. Barely cracked open it gets a good OD sound but then a hair later it's "for those about to rock!" Maybe a linear taper 1M pot with a 330K or even 470K across wiper and ground it would get some mid drive levels and then ramp up pretty good to the high octane stuff.
John
Quote from: Basicaudio on March 17, 2007, 01:06:22 AM
you set it so it sounds right.... taper shmaper!
John
LOL, we need more of that attitude in general around here.
I can get some low gain sounds out of it. At least low gain for a DB.
Which is super crunchy but without the violin sustain of the higher setting.
I guess the 500k GAIN pot is helping that along some.
It IS funny how the low gain stuff it pretty crunchy just not as sustained. Pretty much the same tone just a bit thinner but with the same crunchy edge. I do like how the sound isn't squishy or rubbery sounding at all though. Reducing or omitting the bypass cap on the gain control will give you more low end meat to the low gain settings.
One thing that I wonder about is the third stage and the 3.9K source bypass resistor. In the Dual Rec amp the value is 39K! which is called a "cold clipping" stage as it biases the stage super "cold" and with asymetrical clipping in spades. I wonder why the DB uses 3.9K as oppossed to the 39K of the original? One of those things I've been meaning to try out. Can't just be a typo they (electrictabs) went with....
John
Great work Gauss - looking V good :D
I can also recommend the 100k vol pot, I use whar ever I have around, log/lin
250k with a 220k across it - you name it !
John, I spotted the 3k9/39k thing a while ago when making one and I did try it.
This sets up the bias VERY differently and it lost a lot of gain that way, it did "work"
and may be a closer approximation to the real deal !!
It would certainly syop any gain/howl problems :D
MM.
Quote from: MartyMart on March 17, 2007, 05:46:54 AM
...
This sets up the bias VERY differently and it lost a lot of gain that way, it did "work"
and may be a closer approximation to the real deal !!
It would certainly syop any gain/howl problems :D
...
I tried that too and got the same result, the tone was kind of thin and uninspiring. That change did not affect my squeal issues on my first build (that was a really troubled build anyway - too many experiments killed the thing) - I went back to the 3.9k value.
Quote from: Basicaudio on March 17, 2007, 02:15:30 AM
...
just a bit thinner but with the same crunchy edge.
...
.
I tried bumping up the values of the "Miller Caps" (270pF, 330pF) and the tone got less thin without reducing the high-end too much, but the 220pF values worked better with my gear.
Hmmm ok. so it thinned the sound out to have the 39k in there? Did you notice a change in the clipping or asymetry?
Can you comment on it more Marty?
Running through a '73 Twin Reveb ("blackfaced') The DB to me is a bit bright and I run the treble about 12 oclock, Mid at about 9 or 10, bass full up or a bit less, and the presence about 12 o clock. The twin is a bright amp though. (bright switch off of course).
Maybe I'll try the higher miller caps or even a snubber cap across one of the later stages trimmers. .001 or so...
John
Quote from: Basicaudio on March 17, 2007, 04:54:00 PM
Hmmm ok. so it thinned the sound out to have the 39k in there? Did you notice a change in the clipping or asymetry?
Can you comment on it more Marty?
Thinking back 18 months to a "sound" is tough !
It just seemed to have less gain and was a bit of a pig to bias, couldnt get it under 6v if I remember
right ?
I dropped the idea after 10 mins and went back to 3k9 or perhaps 4k7 - seem to have LOTS of those !!
I dont often go for all "exact" values - whatever I have will useually do :D
May be worth experimenting, in a 9v stomp version perhaps the 39k would work better at 12k or so
for this stage.
Like ROG's Thor - they were aiming for a "true" amp response and not "flat out rediculous" like the
T-chief was ! - so they made some adjustments to allow for this
MM
Just etched and drilled your layout.
Very compact fit in a BB. Nice work.
(http://www3.telus.net/public/david65/pedal-pics/DrBoogiePCB-low.jpg)
As soon as I populate the kids into their beds I'm gonna populate this.
I forgot to leave space on one side for a mounting hole Dam. :icon_redface: :icon_redface:
It will be supported on one side.
The pads are on the smallish side. I would think a drill press mandatory to dill this one without lifting a pad or two.
More pad matierial would be nice but not mandatory.
Thanks again.
Thanks Marty. I would assume if it the 39K made a big difference in a good way you would have mentioned it before... Has been a while.
Pushtone. I fattened up the whole boards trace in Photoshop, "Minimize" in "other" in the filters section.
I like big pads as well. Haven't populated the board yet.
Looks pretty roomy in there.
John
Nice layout! :icon_biggrin:
I'm working on some mods for me (making pcb-mounted pots), but I still have some questions:
- Between Q4 and Q5, there's no coupling cap, should I put one there, to prevent some DC coming from previous to the next stages? Is it necessary?
- And what about a Miller cap on Q5?
If someone had already built the circuit using this layout, please post your impressions about it. :)
Q5 is a source follower. Basically lowwers the impedance and buffers the Tone controls a bit. No need for a miller cap there as it is not a gain stage and has little gain. No need for a coupling cap their either.
I breadboarded the circuit yeaterday and found that the big place the miller cap make a difference is Q2 and to a lesser degree Q4. Q1 still should have one but if you want to cut some fizz I'd put a 220 or more pf in Q2. I also bumped up the pf to 120 in Q2 for the 20pf to ground.
I used 220pf Gate to Source and 120pf gate to ground.
Start by building it stock and then modify it if need be.
John
sorry i'm a bit late in this thread...but has the layout been verified? and have the noise issues been resolved? sorry it's pretty crazy and i can't read through the whole thread.
Seems like pushtone is close to finishing this layout...
Other than that I'm not sure anyone had built on it.
The noise issue has to do with layout of the pots mostly.
There are many threads about the Dr boogie, this one being shorter than some.
If you read the whole thread here and use this layout here you should be good.
John
It would be cool if at the (temporary) end of all of this that we put together a list of the changes made from Electrictabs' version to Gaussmarkov's.
I haven't had any noise issues, so I'm probably going to stick with my board that has additional pads for 'miller caps' and see how they sound.
I might build the newer/enhanced DB later.
- Buck
Has anyone got a tonestack-less layout? I want to experiment a little.
Thanks!
There are only 5-6 parts in the tone stack. Just leave out those parts.
Leave of everything after Q4 and add a cap to the drain of Q4. 1uf should be fine.
The tone stackless build sounds pretty good still.
Just bit louder and more mids and highs asuming you compare it to the regular version with the knobs set at half way up.
John
Cool, thanks. I have built the full version and I really like it. Now I want to experiment with some different stacks- maybe just a single 1 knob control... we'll see.
Didnt GM have a layout for the stackless version on his site? Looks like its gone now. :icon_cry:
Take a look at Jack Orman's "Presence" control. It's a big muff style tone control with High pass, Low pass and A mid control. 2 knobs.
AMZ link above. It's in the Lab Notebook section...
John
folks,
something just occurred to me and so i am breaking my temporary vow of silence to pass this on. :icon_wink:
when i added the input coupling capacitor and then the biasing resistor per ardic's comments, i kept the biasing resistor at 1M and made the pull down resistor a standard 1M. this isn't quite right. these two resistors in parallel, ignoring the coupling capacitor (which is reasonable), make for a combined resistance of 500K. to get the biasing right, i suggest increasing both to 2M.
somebody, check me on this.
all the best, gm
gm,
I believe that in JFET's DC analisys, the standart autopolarization model leaves the anti-pop resistor out of the "equation", because the input cap is a open circuit in DC. Considering this, we need Rg (1M or greater) to show that Ig equals zero. In AC, the input cap is a short circuit for a center frequency, so the input impedance of the circuit will be the anti-pop resistor in parallel with Rg. And your suggestion of using both 2M2 resistors seems nice, but I'm getting worried about any kind roll-off effect in freq. at input caused by that associaton of R's and the input cap........ :icon_confused:
Interesting, a vow eh? :icon_wink:
Anyway,
Q1 biased just fine for me.
It's Q2 thats is giving me biasing problems. It's behaving strangely.
And I kinda painted myself into a corner too.
I wanted to get rid of the trimers for the least noise.
I soldered jumpers from the PCB to a breadboard with four trimers.
Note that I don't have any pots connected yet. I didn't think that would matter.
(http://www3.telus.net/public/david65/pedal-pics/DrBoogiePCB-Trimers.jpg)
All the transistors biased fine with the breadboard trimers. A sweep of 0-8.5v. No problem getting 4.5 on any of them.
I metered the impedance of each trimer and soldered a resistor of that value into the PCB trimer location.
I bridged the trimer at pins two and three with the resistor. I kept trimer for Q1.
Q2 didn't do so well in the translation from trimer to resistor.
When the circuit powers up I get 8.5V on the Drain of Q2. But 4.5V everywhere else.
If I touch the Gate of Q2 for a moment with the meter probe, then go back to the drain it meters 4.5V.
Same thing if I touch the output of R5, drain drops from 8.5 to around 4.5
It's stable at 4.5V until the power is cycled off and on, whereby it goes back to 8.5V.
If I hold the meter probe on the drain of Q2 and tap the gate with a metal tool I can get it to bounce around.
8.5V to 3.3V to 6.7V to 2.5V.
I'm going to put a trimer here too I guess, darn one was enough. :icon_sad:
I've reheated all the solder joints. Anything else I should test for?
Did the same thing happen when the trimmer was hook up?
The Resistor is just holding a resistance like the trimmer so the problem should be the same for either one. I would suspect the trimmer if that was the case but I a fixed resisistor should be fine and has less to go wrong.
Did you try another FET? That would be my first guess as a problem. They are all over the place sometimes.
The source resistor will change the bias as a second guess. But again I don't know why the resistor whould change unless its a solder joint or solder bridge.
We're rootin' for ya!
John
Quote from: Victor on March 19, 2007, 09:16:18 PM
gm,
I believe that in JFET's DC analisys, the standart autopolarization model leaves the anti-pop resistor out of the "equation", because the input cap is a open circuit in DC. Considering this, we need Rg (1M or greater) to show that Ig equals zero. In AC, the input cap is a short circuit for a center frequency, so the input impedance of the circuit will be the anti-pop resistor in parallel with Rg. And your suggestion of using both 2M2 resistors seems nice, but I'm getting worried about any kind roll-off effect in freq. at input caused by that associaton of R's and the input cap........ :icon_confused:
ack. i was thinking AC analysis. don't we assume, when we leave off the coupling cap that the ac signal is coming in with no dc offset? aren't we just adding the cap for insurance? the input resistor to ground is setting input impedance, no? for the usual coupling cap values, i was thinking of C1 as a short so that we are going from the original 1M resistor (when there was no coupling cap) to 2 parallel 1M resistors (with the coupling cap and its pulldown resistor). but, again, that's for AC. waddya think?
Quote from: Pushtone on March 19, 2007, 10:34:27 PM
Interesting, a vow eh? :icon_wink:
yeah, i'm supposed to be "working." :icon_biggrin: no fun until the job is done. don't tell anyone you talked to me, k? :icon_cool: :icon_cool:
keep up the good work y'all, gm
Quote from: Basicaudio on March 19, 2007, 11:38:43 PM
Did the same thing happen when the trimmer was hook up?
No, it worked like a charm with the four breadboard trimers. 4.5V all around.
They all wanted a 33k resistor to bias at 4.5V
Quote from: Basicaudio on March 19, 2007, 11:38:43 PM
Did you try another FET? That would be my first guess as a problem.
Yeah a couple. And I can take the transistor in Q1 thats fine, pop it in Q2 and same result.
Weird that touching the gate will drop it by half?
Putting the trimer in now... back in ten.
This layout is tight!. Needs smallest capacitors for all values.
The Xicon sub miniature greenies are good ones. That's what I had.
Box caps, especially the ones with the short legs, might be a problem with this build.
The greenies can pack tighter and don't have to be seated all the way down to the board.
(http://www3.telus.net/public/david65/pedal-pics/DrBoogiePCB--caps.jpg)
Quote from: gaussmarkov on March 19, 2007, 11:44:04 PM
Quote from: Victor on March 19, 2007, 09:16:18 PM
gm,
I believe that in JFET's DC analisys, the standart autopolarization model leaves the anti-pop resistor out of the "equation", because the input cap is a open circuit in DC. Considering this, we need Rg (1M or greater) to show that Ig equals zero. In AC, the input cap is a short circuit for a center frequency, so the input impedance of the circuit will be the anti-pop resistor in parallel with Rg. And your suggestion of using both 2M2 resistors seems nice, but I'm getting worried about any kind roll-off effect in freq. at input caused by that associaton of R's and the input cap........ :icon_confused:
ack. i was thinking AC analysis. don't we assume, when we leave off the coupling cap that the ac signal is coming in with no dc offset? aren't we just adding the cap for insurance? the input resistor to ground is setting input impedance, no? for the usual coupling cap values, i was thinking of C1 as a short so that we are going from the original 1M resistor (when there was no coupling cap) to 2 parallel 1M resistors (with the coupling cap and its pulldown resistor). but, again, that's for AC. waddya think?
Quote from: Pushtone on March 19, 2007, 10:34:27 PM
Interesting, a vow eh? :icon_wink:
yeah, i'm supposed to be "working." :icon_biggrin: no fun until the job is done. don't tell anyone you talked to me, k? :icon_cool: :icon_cool:
keep up the good work y'all, gm
Adding the input cap for insurance, makes sense, yes.....
And you are also right about the input impedance. Your AC analisys is correct, I believe. :)
In DC, only Rg is considered, but it'll only leads to Vgs and Id math (also Vds, but not that important, I think).
Quote from: Pushtone on March 20, 2007, 12:15:08 AM
Putting the trimer in now... back in ten.
Nope, didn't work. Same flakey biasing on Q2 even with a trimer.
Checking for hairline cracks in traces. Covering traces in solder. Going to bed.
Goodnite!
Quote from: Basicaudio on March 19, 2007, 05:53:38 PM
There are only 5-6 parts in the tone stack. Just leave out those parts.
Leave of everything after Q4 and add a cap to the drain of Q4. 1uf should be fine.
The tone stackless build sounds pretty good still.
Just bit louder and more mids and highs asuming you compare it to the regular version with the knobs set at half way up.
John
OK I'm digging in and want to make sure I do this correctly... where Q4 connects to Q5 (q4's D to q5's S) I would add a 1uf cap. Does that cap go to ground or does it go in-line and continue my path to either a volume pot or whichever EQ I put in place?
Thanks for the help!
In line off the drain and onto the next section/output vol pot.
I'm going to change my mind slightly and tell you to just go off the Q5 output with a 1uf cap inline into either another alternate tone stack or a volume pot.
Keeping Q5 is a good thing as it will drop the impedance an help keep the output stable when/if you add effects after the DB.
John
OK... so keep Q5- will that effect the gain any?
Q5 doesn't add any gain. It just lowers the impedance. This is good for the tone stack and for the whole impedance of the output section.
Lower is better. When you add another effect the impedance of the next effect will be high (most likely) which is good.
Generally, High impedance in, low impedance out is what you want so you don't load down the input of each succesive pedal.
John
> Lower is better. When you add another effect the impedance of the next effect will be high (most likely) which is good.
The output impedance of the dr boogie is pretty high really and some effects will have an effect. Plugging into a sound card will hard a large effect on the tone.
If you ask me, given the Q5 buffer is there, the whole circuit following Q5 should be scaled down in impedance. A factor of 10 should sill be ok but I suspect you don't need to go that far. There might be some reluctance to do this since it results in different tone control part values that the standard circuits but that's only a human thing - electronics says scaling works fine.
Another option is to add another buffer after the tone control/volume control but you probably don't need to go that far.
Interesting George. So you mean scaling down the cap and pot values in the tone stack?
I use a 100K for the volume pot now.
John
> So you mean scaling down the cap and pot values in the tone stack?
Yes. A scaling down by a factor of 10 would be:
Slope Resistor: was 47k now 4k7
Treble Cap: was 680p now 6n8
Mid Cap: was 22n now 220n
Bass Cap was 22n now 220n
Treble Pot: was 250k now 25k
Mid Pot: was 25k now 2k5
Bass Pot: was 1M now 100k
Volume Pot was 1M now 100k
Presence Resistor was 22k now 2k2
Presence Pot was 100K now 10k
Presence Cap was 3n now 30n
A 2k5 pot might be harder to find but you could go for say a scaling factor of 5 instead of 10 in the example.
Quite a few commecial amps use scaled versions of the tone stack - mainly to keep noise down.
> I use a 100K for the volume pot now.
If you *only* change the volume pot, then the volume pot significantly loads the tone control. When this is done there is quite a change in the frequency response and the "gain"of that circuit is 4 to 10dB lower. As a rough comment it pushes all the frequencies up because the R in f=1/(2piRC) is smaller. By changing the pot to 100k it essentially loads down the circuit from the start. What the scaling tries to achieve is to keep the original response and make it immune to loads placed on the output. You don't want to scale to too lower impedance either because then it will start loading the buffer stage.
Quote from: Pushtone on March 19, 2007, 10:34:27 PM
It's Q2 thats is giving me biasing problems. It's behaving strangely.
Pushtone, do you have the gain pot in circuit? Because the Boogey uses the DC path through the pot to bias Q2. No gain pot, no bias.
Betcha your drain problem on Q2 is because the gate is floating up. You could also try adding an additional 1M or 2M2 from gate to ground, just to be sure.
George
Thanks for the info. More evolution going on!
For the odd pots it would be simple to put a resistor across the outside lugs of a pot to get the correct value. All the odd value pots are linear anyway except for the treble pot. Maybe a 50k linear pot with a reisistor across the outer lugs to get the rough resistance and a reisistor from wiper to lug 1 to get the right taper.
Ardric/pushtone
That make sence about the gate floating without the pot in circuit.
I bet if you hook up the gain control it's bias right up!
John
Quote from: Ardric on March 22, 2007, 07:51:44 PM
Quote from: Pushtone on March 19, 2007, 10:34:27 PM
It's Q2 thats is giving me biasing problems. It's behaving strangely.
Pushtone, do you have the gain pot in circuit? Because the Boogey uses the DC path through the pot to bias Q2. No gain pot, no bias.
Betcha your drain problem on Q2 is because the gate is floating up. You could also try adding an additional 1M or 2M2 from gate to ground, just to be sure.
Yep, right on. Biases fine with the GAIN pot soldered in. Silly me.
I see the DC path through the GAIN pot now. C4 was throwing me.
Thanks Ardric.
So the PCB build is seems to be working fine. I've put a 1k tone thru it.
Think I'll skip the test rig and just box it up.
The layout is a pleasure in the order of the pots and the I/O pads on one side.
Thank Gussmarkov, can't wait to compare this to my finished, un-modded Bucksears layout version.
Pushtone,
Any squeals coming out from the new "beast"?
I'm just waiting to see some comparative review of both layouts on this, so I can start my 2ยฐ Boogey assured that will work just fine.. ;D
I've decaled the box and I'm just waiting for the clear coat to dry enough to handle.
No squeals, but I only listened with the audio probe at a few random points around Q1 and 2 with only the gain pot connected.
I'll be finishing it up and I'm worried I won't keep the star ground intact.
To keep the integrity of the star ground Gussmarkov has set up I'll be bringing EIGHT leads to the output jack ground.
Wow.
I can cut that down to five if I solder together all the shields from the I/O cables into one drain wire to output jack ground.
But still, FIVE.
PCB ground
Input jack ground
DC ground
Switch ground
I/O cable shields (x4)
I don't know if I can ward off temptation to bond to the input jack ground too, in addition to the output.
Because of the side I chose to put the footswitch, the input jack is closer to some things.
I'm also concered about George's comment about the 100K VOLUME pot. I may use the 1M for this build. My other one is very - ultra sonic.
I'm finished with the build. Fired up great.
100% No squeals at all, even with all unshielded wire, even with all controls maxed.
Congratulations Gussmarkov!
One tiny, itsy bitsy thing. The MID pot works in reverse. :icon_question: :icon_rolleyes: :icon_question: :icon_redface:
Full clock wise is max cut and full counter clock wise is max boost. I'll tripple check it again.
All other controls work fine and similar to my Bucksears build.
Here are the specs.
All J201's
I used all the exact values except for:
MID pot - used 25kB
TREBLE pot - used 250kA.
I used trimers to bias Q1 and Q2 . The other transistors I used fixed resistors.
Still playing with the bias but I'm liking 7.8V on Q1 and 4.4V on Q2.
.05uF for an input cap and .1uf for an output cap.
Are these values OK?
I had to use electrolytics for the 1uf caps C1 and C6
How bad is that? Is it worth ordering in some small 1uF film caps?
All grounds go to the output jack sleeve lug.
Controls on both layouts respond basically the same.
Gain control works better with the 1M pot than with the 500k.
SO it's working but it sounds a lot better than my version on Buck's layout with the 100k VOLUME pot.
I think George has a good point about scaling the values for the 100k pot.
The one with the 100K VOLUME pot has more high end content and an almost ultrasonic component.
I think I have to replace the 100K VOLUME pot I used on Bucks layout with the stock 1M.
I bet both layouts will sound the same then.
Is there another way to deal with the output impedance of a 1M pot? A buffer following?
The layout is great! No squeals, except for the MID pot no debugging, (it IS working, just backwards).
My input wire is on the left. The out from the VOLUME pot to the switch and switch to jack are on the right.
(http://www3.telus.net/public/david65/pedal-pics/DrBoogie-Guss-insides-.jpg)
Bigger version of insides picture
http://www3.telus.net/public/david65/pedal-pics/DrBoogie-Guss-insidesB-.jpg (http://www3.telus.net/public/david65/pedal-pics/DrBoogie-Guss-insidesB-.jpg)
http://www3.telus.net/public/david65/pedal-pics/DrBoogie-Guss-insides2-.jpg (http://www3.telus.net/public/david65/pedal-pics/DrBoogie-Guss-insides2-.jpg)
http://www3.telus.net/public/david65/pedal-pics/DrBoogie-Guss-PCB.jpg (http://www3.telus.net/public/david65/pedal-pics/DrBoogie-Guss-PCB.jpg)
http://www3.telus.net/public/david65/pedal-pics/DrBoogie-Guss-topNK.jpg (http://www3.telus.net/public/david65/pedal-pics/DrBoogie-Guss-topNK.jpg)
Thank Electritabs for releasing this over-the-top distortion project.
Thanks Bucksears for the first layout that started the buzz.
Thanks Gussmarkov for your huge refinement effort.
thanx guys for the improvements on this circuit. Iยดm looking forward to rebuild mine with this new layout since the other one i've built from gringo's, is quite "trippy"! ;)
What if moving the volume control BEFORE the last FET? all the low impedance we get with this buffer is brought up again with the 1M pot, so i think it will keep the output impedance real low, with little o no change on sound...
Looking good pushtone! Thanks for posting your results. The 1M volume and stock tone stack values work fine if you just use the DB alone. The impedance is high which is far less that optimal but it will work. The problem is if you run anything after the DB you run into a good bit of loading and the tone goes downhill, sucks the high end out of the DB. We'll have to try Georges tone stack scaling and 100k volume pot.
Dschwartz
Putting the Volume before the last fet would requitre putting the tone stack before it as well. They are both High impedance circuits.
Adding another buffer would work but then it gets even more complex...
The way I see it Q5 lowers the impedance that aloows the tone stack (which is high impedance) to work better. The after the tone stack the impedance is high which feeds into the 1M volume pot. So if we lower the tone stacks impedance as George outlined we can use a lower volume pot and retain a low impedance....
John
but isnยดt the tonestack already before Q5??
maybe scaling the tonestack and moving the volume control between the tonestack and q5 could improve the impedence issue....
Q5 is before the tonestack and volume.
Scaling the tonestack is the cure it would seem.
If you scale the tonestack then there is no need to move the volume (100K).
Q1-Q4 is high impedance
Q5 lowers the impedance as not to load the tone stack (which is high)
Seems like Q5 (low imp) into a scaled tone stack (low imp) and a 100K volume pot would keep things low imp and not load down pedals or the amp down the line.
John
Pushtone,
Your impression sounds complete, very detailed. Thank you, I will proceed in building mine now. :icon_lol:
I did some simulations on TSC using George's theory about scaling TS components on 100k vol pot's use. Found some interesting values, and a similar curve. I'll try those values on mine, hoping that all works fine as it says on paper (screen). :)
But I have two new questions:
1) Did somebody measure Vgs e Idss of their J201 used on Dr. Boogey? I'm going to do that, and also try to unveal the "magic" happening on paper caused by their different values......
2) Is there any way to implement a Road King switch mod, like Raw/Vintage/Modern switch? I was thinking of using it to change between Q1's source cap values in order to get those sonic variations......... Raw would be standart cap, Vintage equals no cap, and Modern would be a bigger cap, but I don't have any Mesa Road King sound references, so I'm a bit confused........ can someone enlighten me about this (if it is worth the "pain", how does it sound in the real amp, etc..)?
The Source bypass cap and resistor will make a difference is gain and tone. No cap will have less gain (which can be a good thing) as well as less treble. 1uf is a treble boosting cap as used here. Boosting the treble/cutting bass is how these high gain amps get a nice crinch sound without getting "farty" or "flubby" in the low end. Changing the resistance will change the bias a little depending on how far you change from the original value. More drain voltage will yeild a cleaner sound which can sound nice with the DB.
You can solder a couple wires to the source resistance points on the board and experiment with different resistance and capacitance.
I would think you could get some nice lower gain sounds without the some of the 1uf bypass caps.
John
Troubleshooting the backwards MID pot wasn't so hard.
I noticed Buck's MID and BASS pot wiring was a little different.
I reversed the MID pot so that lug-3 on MID went to lug-1 on BASS.
Works better now.
Gussmarkov, I used your March 14 2007 project file. Backwards MID pot wiring.
Simple to fix, just reverse lugs-1 and 3 on MID pot. Most folks will figure it out on their own.
I did and I'm no electronics wiz.
Sounds good on almost every amp I tried so far EXCEPT for a new 2005 Fender Twin. I think it's a reissue version??
Could not get a good tone out. I wonder if the Twin didn't like the high output impedance?
But the sound was all high-end, hissy and brittle, not darker.
This same amp didn't like my other "Buck" Dr Boogey either.
Same result - ultra sonic high end, brittle, unpleasant.
The Twin sounds great clean. I was disappointed.
Here's a kicker, I had several of my new distortion builds "on demo" and
several players agreed the Thunderchief sounded best (with the same Fender Twin) !
Go figure.
I also remembering someone asking if these "amp" pedals can be used as a regular preamp and patched into the amp's effects return.
I tried it and I get MORE THAN ENOUGH gain to drive the power amp section of my combo. The sound through the return was warmer, and less noisy.
The tone controls worked well to shape the sound, better in fact that thru the amp's preamp.
Bass response was the same as thru the preamp. In combination with the TREBLE control and the Presence on the amp I am able to control the high end from dark to sparkly.
I find I set the TREBLE control low around 9 o'clock when plugging into the amps input preamp.
But when connected to the effects return the TREBLE control is much warmer when turned past 12 o'clock.
The sound is more open, less harsh and generally better than when passed thru the amp's input preamp.
Tried it with the ROG English Channel too. Same deal. It sounds better.
I only have one solid state amp with an effects loop to test with but I'm going to say yes, they can be used as preamps to drive power amps.
Instead of messing with the tone stack why not just add to the layout a simple buffer /switchable?/ after the TS like the one found in Randall's preamp?
Adding a buffer after the TS sounds practical. Maybe just another source follower?
John
I've made some improvements over the gm's layout. Added output buffer, mid pot wiring corrected and made connections "board-pots" as simple as possible. My board looks a little diferent. Here it is:
http://rapidshare.com/files/23212138/gm_layoutDr._Boogey_mid_pot_corrected_added_output_buffer.rar.html
I'm not sure about the output cap position (before or after Q6)...... ???
My express pcb throws an error trying to open the files...
can you make a pdf or image file please?
I could not get to the file either. I can host it for you if you want. just email me.
A schematic would be good as well as the layout. I know Gauss will amend his layout as well when he gets back here.
John
Quote from: dschwartz on March 28, 2007, 02:15:24 PM
My express pcb throws an error trying to open the files...
can you make a pdf or image file please?
I used Eagle for layout prototyping, as usual.
Here are the imgs:
(http://www.dumparump.com/thumb/273/4a2p4ko.png) (http://www.dumparump.com/view.php?id=4a2p4ko)
(http://www.dumparump.com/thumb/48/v922g3X.png) (http://www.dumparump.com/view.php?id=v922g3X)
Quote from: Basicaudio on March 28, 2007, 02:38:04 PM
I could not get to the file either. I can host it for you if you want. just email me.
A schematic would be good as well as the layout. I know Gauss will amend his layout as well when he gets back here.
John
John, check your email please. ;D
As much as we all appreciate the image files... PLEASE WARN BEFORE SENDING US TO A WEBSITE WITH PORN ON IT!
Yikes!
Yeah, maybe that isn't the best place to host stuff...or at least to send links to people here ...
Nothing wrong with sex but there are way too many issues with porn to get into here.
Ah the internet!
Heres the schematic at any rate.
(http://www.mrdwab.com/john/Boogie_with_buff.png)
With the Layout you should probably take out the registration marks so you can read the values. Also, the pots won't fit unless you are using long PCB lugs (do they even make those anymore?) The pots overlap...
John
Sorry,
I had some trouble using imageshack.us here........ :icon_redface:
Let me try again to see if works..... :)
If we were "Bender" from Futurama, all the stuff we work on would be porn..
Thanks god my 4 year old nephew is not into bouilding a DB!!! fuiuuu
now These one could be called a "dual rectal" as mine does!!! hahahaha
Quote from: Basicaudio on March 28, 2007, 04:24:45 PM
Heres the schematic at any rate.
Great evolution in this thread as you've stated.
I was about to ask what's different on this schematic.
Now I see the file name for the image, "Boogey with Buffer".
So is the buffer the only difference from Guss's last schem?
Good idea to keep Guss's component reference numbers. Just seeing C17 thru 22 tells me a lot.
Quote from: Basicaudio on March 28, 2007, 04:24:45 PM
With the Layout you should probably take out the registration marks so you can read the values. Also, the pots won't fit unless you are using long PCB lugs (do they even make those anymore?) The pots overlap...
John
I considered the idea of using pots directly soldered to the PCB, but it was not going to be very practical, at least for me..... then I re-organized the pots' holes so I can solder wires to them and minimize those crossing lines between floating components (oscillation madness).
Is C22 Necessary? The Tone stack decouples the output of the buffer already.
Don't forget 1M pulldown at the end of the circuit right before the output jack.
Pushtone
Q6 and it's components (Source 10K and C22 and C23) are the only additions to the schem as gauss had it.
I'm sure you could add in the buffer as a small satallite board. Shame to waste all your work on the one you have now.
Gauss should chime in soon as he's "back" tomorrow.
Anyone see anything we can improve on with the output buffer? I don't know my buffer theory.
Will it do for our purpose as Q5 does fore the tone stack?
John
1M pulldown resistor at the end? If we add it to the circuit, I believe that the output impedance would be its value in parallel to Q6's source resistor....... resulting in about 9.9K ohms, aprox........ is that correct? And why would the circuit need a pulldown resistor just at the end of it?
I also believe the output buffer is OK, gain is around unity, a little less. Source follower has high input impedance and low output impedance.
The puldown resistor at the end is for pop protection and discarging the output cap...with the bypass switch.
I didn't think about it enough though...
The Impedance is 10k at the output of the buffer correct?
So maybe adding a pulldown resistor to equal 10K overall resistance to ground would be fine...
Maybe making the buffer have s light bit of gain would be good as well. The tone stack eats up a lot of signal gain.
John
Quote from: Basicaudio on March 28, 2007, 08:57:15 PM
The puldown resistor at the end is for pop protection and discarging the output cap...with the bypass switch.
I didn't think about it enough though...
The Impedance is 10k at the output of the buffer correct?
So maybe adding a pulldown resistor to equal 10K overall resistance to ground would be fine...
Maybe making the buffer have s light bit of gain would be good as well. The tone stack eats up a lot of signal gain.
John
We should proceed with caution about that. Dr. Boogey has a lot of gain, I believe it wouldn't be necessary to add another "gainy" stage (even with JFET topology in common drain config - gain around -10). Our main goal at this moment is just to lower the output impedance, I think. A buffer w/ gain can cause some frequency boosts (or not). And almost all the pedal schems seen around have a source follower buffer after tone-stack and/or vol. pot.
I'll try to add an external buffer to my Dr. Boogey (Buck layout), and see what happens with it on and off my signal chain...... maybe is worth the shot.... :D
There you go, finally Imageshack.us worked here......
Layout with just components names:
(http://img357.imageshack.us/img357/4042/boogeywbufferlayout1yg3.png)
Layout with just components values:
(http://img230.imageshack.us/img230/1523/boogeywbufferlayout2qk1.png)
Schematic:
(http://img338.imageshack.us/img338/1622/boogeywbufferschemsc1.png)
Victor
The ground jumper at the bottom doesn't do anything because the ground connects almost everywhere across the board already. Gaussmarkov made grounding points to form a star ground but your layout mostly does not use this approach.
The "crosses" that center each component should be turned off or switched "off" so they are not seen. They obscure the partes values and names.
Some of the parts names and values are overlapped as well.
There are also some missing values, and you should probably use the transistor component outline as well to make sure you have the correct orientation.
I don't mean to pick apart your layout but it's hard to follow.
John
Hi all,
I'm jumping on the Boogie bandwagon, albeit on vero, and doing F4T from the original Dual Rectifier schematic.
Just to check (there's a LOT of talent posting in this thread!) - I'm not using the tonestack, and I only have 4 J201s to hand (nicely matched, by coincidence). Since Q5 is a buffer, can I just drop in a 2N5088?
Many thanks for everyone's great work.
Quote from: Victor on March 29, 2007, 10:13:12 AM
I'll try to add an external buffer to my Dr. Boogey (Buck layout), and see what happens with it on and off my signal chain...... maybe is worth the shot.... :D
I just finished a GGG IC buffer on perf last night for just this purpose.
It was too late to test last night. Give it a go when I get home.
I was also thinking about the AMZ MosFET boost as an output buffer.
It's input impedance is very high, 10meg I think.
Back to work now.
Great stuff. Every day is a new day! ;D and every day is a full day of improvements.
All I wish is that all of you electro gurus to keep up with this great project. This must be the greatest topic on this forum in terms of ideas and self-development. every morning i come here only to be amazed with your stuff :icon_eek:
I've learnt great things with you guys. Althought, i wish i could participate more in this, but i don't have the knowledge it demands.
I've built a Dr. boogie (failed! - too many osc), but now, i'm willing to build another.
Thank you very much.
John,
Thanks for the tips. There are some little things in Eagle that I don't know yet, and I'm glad I "found your help". :icon_razz:
I'll delete those two jumpers located at the bottom as you said, since there's room to connect gnd to it without the need for more wires. Just moving some components and it's done. A "jumperless" layout would be very nice. :icon_mrgreen:
I'm also worried about pots connections in the board. They look nice, no-crossing lines, but "presence" wires will still pass close to "mid" wires. :icon_neutral:
Pushtone,
In my opinion, I don't think you need to worry about AMZ Mosfet. Its input impedance is high, but we don't need that, I believe. And also it is much more components than another single fet source follower stage using another J201. But that just me..... :icon_wink:
Cursor,
You can't just swap a BJT (bipolar junction transistor) for a FET. Each one needs different polarisation techniques, so be careful. It's possible to use something similar to source follower FET - emitter follower - but, in my opinion, it's going to be some waste of board space to accomodate another components. :)
The main thing to worry about in crossing wires is that the connections do not cross the later connections off board.
This means that the gain control wires are short and stay clear, as far as posible from the tone controls.
The closer the in and out connetions the worse the oscillation will be.
A good way to look at it is:
Input on the left and the output on the right. Try and keep the parts placement starting on one side in and moving to the other side and then out. This gets a little tricky with the switch wiring but that's where shielded wiring helps.
Any buffer should work well I think. BJT or FET. They both should use about the same number of parts.
Using the Mosfet buffer isn't really the thing we need though. That's mainly an input circuit not necesarily on to tack on the end. The input impedance is too high I think. Victors look good as far as I can tell. A BJT should work as well but not a drop in for the fet circuit already posted. You will have to bias it a bit differently.
John
you all have been busy!! :icon_biggrin: it's nice to come back and read through all the posts. and to find that pushtone has completed a successful build that has no oscillation problems, even without shielded connections. i hope we hear from some other builders who were waiting for his report. i am wondering whether abandoning the star grounding system is a good idea at this point. it seems like that is where victor is headed. or am i misinterpreting? :icon_confused:
the output buffer seems like a good idea. i'm with john on bjt or fet. many, many circuits use an emitter follower in the same location, including the good old reliable ts808. but let's go with the source follower that victor advocates. pushtone's build suggests to me that we have room to reconfigure for either type of buffer and i'd be happy to adjust my layout for that. given how tight it is at this point, i would probably end up moving things around a bit. i don't think we need more room for the caps, WIMA box caps will fit fine, but i will keep my eyes open for that concern also.
it's good to be back, gm :icon_biggrin:
Alright, here we go!
Glad to see your back now gauss.
I don't see the point of abandoning the star grounding. May not be crucial to the circuit but it's good practice to get into the habit of and you've already done the work! Can only help.
Adding a buffer seems like the way to go. High impedance input, low imp output is where we need to be. One FET, an output cap and a source resistor, no biggie! Does C22 on Victor's schematic need to be there? My understanding is that the Tone stack blocks DC and there isn't a need for a coupling cap before the volume pot. Right?
John
Quote from: Basicaudio on March 30, 2007, 12:47:05 AM
Adding a buffer seems like the way to go. High impedance input, low imp output is where we need to be. One FET, an output cap and a source resistor, no biggie! Does C22 on Victor's schematic need to be there? My understanding is that the Tone stack blocks DC and there isn't a need for a coupling cap before the volume pot. Right?
John
i think you are right about what is coming out of the tone stack, but the source follower -- even though it is near unity gain -- introduces a DC offset also. so i think we also need C22.
gm,
Nice to see that you are back to work with us....... :icon_mrgreen:
My idea on using some kind of approach that minimizes jumpers on PCB does not leaves off star grounding...... I believe we should maintain that idea, to star-ground the external connections such as jacks, 3dpt, and other things that are necessary......... but I'm working on a jumperless board, and with each pots wires going as straight out from the board as possible, not crossing any of them, if that is possible (I don't know if you guys can fully understand me, my english is kinda bad these days :-X )
By the way, my layout on output buffer of boogey has thinner copper traces, as you'll see below. I hope that does not look like a problem, maybe PNP or couche, nicely applied, can transfer that to the board with no problems. Here's the progression on it (without bottom GND jumpers):
(http://img67.imageshack.us/img67/5517/bufferboogeylayoutpo7.png)
Victor
Looking better with the cleaner layout.
Star grounding means that each sections ground connections go back to the star point without passing through the other sections.
If you can imagine all the different grounding points within each stage connected together, then a sible wire from each section connected at the point of the cleanest ground source which is the power supply capacitor and single ground point which connects to the battery or DC jack.
The Jumpers in Gauss's layout are the connections that connect each gain stages star point. with your board layout the grounds are all connected together to one big ground plane. As I mentioned above, this may not be too big of a problem, Gauss is just working with the theory of star grounding.
The thin buffer traces aren't a problem I don't think. Why not just fasten them up? There seems to be room.
Gauss I'm not sure about C22... Are you thinking DC is coming from the tone stack or are you thinking DC is coming from the Buffer back to the volume. My ignorance showing here...
John
John,
So you're saying that, in order to tame down noise and oscillations, we need to isolate every stage of the circuit and connect each ground path from them individually to the "lowest/better" ground point, to do the star-grounding? In my board, stages' grounds are all mixed up, so can we expect some kind of noise/osc coming from one stage from another, even if the're all connected to star-ground point?
In my head, I imaginne that your star-grounding technique could still cause some kind of noise/osc problems, mainly because all GND points are still connected together, similar as in my board, to the main star ground junction point. Is this makes any sense? Or am I just confused? :o
I need my books! hehe :icon_lol: :icon_redface: :icon_mrgreen:
Quote from: Basicaudio on March 30, 2007, 12:55:36 PM
Gauss I'm not sure about C22... Are you thinking DC is coming from the tone stack or are you thinking DC is coming from the Buffer back to the volume. My ignorance showing here...
sorry, i got my labels confused. i think we need C23. like you, i don't see a need for C22 except to change the highs with the volume level.
Quote from: Victor on March 30, 2007, 01:32:51 PM
So you're saying that, in order to tame down noise and oscillations, we need to isolate every stage of the circuit and connect each ground path from them individually to the "lowest/better" ground point, to do the star-grounding? In my board, stages' grounds are all mixed up, so can we expect some kind of noise/osc coming from one stage from another, even if the're all connected to star-ground point?
exactly. and our collective experience seems to show this. pushtone built both versions and his star-grounded version is tamer. here's the an example of how the experts explain this: you don't want the ground of a sensitive part of the circuit (like the input) passing by (or through) the ground of a high gain section. there is a more detailed explanation on Aiken Amps that is commonly referenced: Star Grounding (http://www.aikenamps.com/StarGround.html).
cheers, gm
Quote from: Victor on March 30, 2007, 12:32:15 PM
I'm working on a jumperless board, and with each pots wires going as straight out from the board as possible, not crossing any of them, if that is possible (I don't know if you guys can fully understand me, my english is kinda bad these days :-X )
victor, that's fine. lots of people like to avoid jumpers. in some cases, jumpers are like crossed wires that lead to noise/oscillation problems and should be avoided. in other cases, jumpers are just resistors with no resistance. :icon_wink: we run traces under resistors all of the time. so why not under resistors with no resistance? :icon_cool:
in the case of my layout of dr. boogey, the jumpers are for ground and they are crossing supply rails. no traces carrying signal are involved. the supply rails and ground rails are next to each other on purpose because our experts (e.g., R.G.) tell us this is usually a good thing to do. it's like twisting power supply wires around each other, a common stompbox building practice. passing a jumper for one rail over the another rail seems to me like it is in the same spirit. but i could be wrong. maybe keeping things parallel is critical. i just haven't seen such advice yet.
Quote from: Victor on March 30, 2007, 12:32:15 PM
By the way, my layout on output buffer of boogey has thinner copper traces, as you'll see below. I hope that does not look like a problem, maybe PNP or couche, nicely applied, can transfer that to the board with no problems. Here's the progression on it (without bottom GND jumpers):
for a long time, i also used thinner traces, too. some of the older layouts on gaussmarkov.net still have 16mil traces. but several folks on the forum have commented that fat traces and pads are preferable and that makes sense to me. so i am switching over. :icon_biggrin:
thanks for your input! gm
Quote from: gaussmarkov on March 30, 2007, 02:05:56 PM
for a long time, i also used thinner traces, too. some of the older layouts on gaussmarkov.net still have 16mil traces. but several folks on the forum have commented that fat traces and pads are preferable and that makes sense to me. so i am switching over. :icon_biggrin:
thanks for your input! gm
For me fat pads are more important than fat traces.
The home etched boards lift pads real easy after the second or third soldering.
I've never lifted a trace, just the pads.
Basicaudio's suggestion about the PhotoShop filter "Filter ->Other ->Minimize"
works great for fattening up bitmap traces before printing.
Great tip, thanks Basic! I'll be using that one fer sure.
Comparing my two builds the biggest advantage this new layout provides is the single edge of off-board connections.
Both my builds work but the Buck version squeals when nothing is connected to the input jack. I can also make it squeal by pushing the MID pot wires closer to other ones. Both builds produce the same amount of buzz and hum. If the star grounding was making a difference wouldn't it produces less hum and buzz? Can the lack of oscillation in the "Gauss" layout be attributed to the star grounding or is it solely the off-board connections?
I still have yet to try MPF102 trannies which might go a long way to lower the hiss.
I'm still biasing both units at around 7.5V to get lowest amount of hum and buzz.
This weekend I'm going to swap out the 100K VOLUME pot I used in
the "Buck" build with the stock 1meg to see if that makes to two units sound identical or not.
Tried a second time to get a good sound out of the DB with a 2005 Fender Twin.
Still yucky, harsh, high-end heavy, not enough bass.
Anybody getting good tones with this setup cause I'm not.
Other amps sound OK to very good with the DB. ???
Glad to see your back on this thread Gauss.
Trying to clarify.
Grounding has to do with Buzz/noise/a little to do with hiss and general cleanliness of the circuit as far as grounding noise.
In amps the grounding is crucial to the noise floor of the amp. In pedals it's to a much lesser degree but still a good thing to look at in making layouts.
Oscillation comes from sensitive high impedance points of the circuit. gate inputs of fets and to a lesser degree the resistive dividers at the inputs/gates. The more resistance in line the higher the noise. Make the the resistor a larger suface area (although not at all not practical for PCB pedals) and the noise will go down. Using metal film resistors will make a big difference as well.
Keeping the snsitive ares away from the high gain areas is the thing we want to do.
Setting up the board so you don't have to cross sensitive areas when wiring up the pots iis a good thing.
I'm curious how the Slo century at OLCircuits layout looks. To sell a pedal without all this fiddly osc issues is a feat. Maybe they used all MPF102s or something.
________________
Larger pads are very much nicer where you can fit them. I try to use .100 pads as much as possible if not bigger even. Soldering them is simpler and getting a good shiney connetion is easier because you have a bigger metal surface and it gets hotter and works with the tip of the iron better at leasty to me. I use a 1/16" screwdriver tip in mr iron.
Bigger traces are nice for Photo paper etchers (me included) .040 or .050 is what I use.
John
gm,
Thanks so much for your help (and thank others too). I guess I'll leave aside my board and work on a new version based on yours. Since Pushtone had built it successfully, and now I have a clue about star-grounding, I think the winner for me is still the stock version of the board, made by you... :icon_mrgreen:
So, maybe star-grounding is not the main issue on gm's board, as we can see.
I was wondering if maybe using some more theory to determine an optimum operacional point for all FETs would be nice. I still have some doubts regarding the fact of drain's voltage being half of supply voltage, if it's worth to maintain that (I've tested some trimmers tweaking on my Buck's Boogey to see and there are not so much sonic differences between some close values of drain voltages to my ears) or just replace all trimmers (I read somewhere that they're "noisy") by fixed resistors........ to do that, we need to determine Vp and Idss of all FETs, and calculate a closer drain's voltage assuming comercial resistor values...... JFET matching is the solution for this, and some paper and pen, maybe.....
Vp in J201 is around -0.3V to -1.5V.
Idss in J201 is around 0.2 to 1mA.
I'm working here with Vp= -0,9V and Idss=0,6mA, so far I found Q1's drain resistor = 22Kohms, for Vdrain=1/2 of Vsupply..... I'll keep working on that to see the possibilities..... :icon_razz:
And I'm worried about those floating wires crossing in tone-stack pots....... would it be nicer if we made them on the board?
So, the ouput buffer, no tone-stack scaling, maybe some new copper traces to give tone-stack a "neater floating look" and the possibility of working into FETs matching plus resistor on drains....... does it sounds good (at least on paper)?
Quote from: Victor on March 30, 2007, 04:17:55 PM
So, maybe star-grounding is not the main issue on gm's board, as we can see.
...
And I'm worried about those floating wires crossing in tone-stack pots....... would it be nicer if we made them on the board?
i guess that's right. the star-grounding does not seem to matter much after all, according to pushtone's latest report. too bad. nor does all the care to get a simplified signal path. it seems like this supports a hypothesis that i have been wondering about for quite some time: the care used in building amps often does not make any difference in stompbox builds. but it is also consistent with another hypothesis: that i have not implemented star-grounding and signal path protection sufficiently. :icon_confused:
if neither star-grounding nor signal path protection matter here, then we should just follow victor's suggestion and focus on the pot connections.
I think all the details to groyunding and placement does matter maybe not as much in an amp but were going down the right theory path at any rate and that can't be a bad thing.
If we can get the pots pacement and wiring worked out then that's as good as it's going to get.
See if you can work in a buffer gauss and we'll move on to something else.
Just like trainwreck amps, the wiring layout is key.
It would be good to have a wiring layout to go along with the board layout.
John
on second thought, maybe the signal path routing has made a difference. as john points out, we can protect ourselves from oscillation by careful routing of the signal path. also, pushtone said that he didn't use any shielded wires for his hookups. so doesn't that suggest that we should stop worrying about pot wiring?
Quote from: Basicaudio on March 30, 2007, 07:52:47 PM
I think all the details to groyunding and placement does matter maybe not as much in an amp but were going down the right theory path at any rate and that can't be a bad thing. If we can get the pots pacement and wiring worked out then that's as good as it's going to get.
See if you can work in a buffer gauss and we'll move on to something else. Just like trainwreck amps, the wiring layout is key. It would be good to have a wiring layout to go along with the board layout.
John
o.k. i started looking at it last night and it's going to be a bit of work. even though the buffer is really simple, it still takes up too much room to just squeeze it in there.
pushtone, i hope that you get a chance to try that buffer you were going to insert in your build.
cheers, gm
I agree with John. We should care about all, simplified signal path, star-grounding, and pots connections...... they all matter, in my opinion...... maybe tube amps need those techniques more because they work with "larger" signals, higher voltages, longer wiring and signal paths...... but we shouln't make this an "excuse" (please, don't read this as an offensive word, I don't mean that :icon_redface: ;D) to not to worry about it, no matter how small and "potentiometer-less" are our pedals..... my 2 cents :)
Quote from: gaussmarkov on March 30, 2007, 08:01:02 PM
on second thought, maybe the signal path routing has made a difference. as john points out, we can protect ourselves from oscillation by careful routing of the signal path. also, pushtone said that he didn't use any shielded wires for his hookups. so doesn't that suggest that we should stop worrying about pot wiring?
My Buck Boogey has a major problem. It goes into oscillation just by moving tonestack pots side by side, or close to each other. Maybe those tonestack-only wires, that connects Bass to Treble and others should be in the board, so we can solder wires directy and straight to each pot ....... I believe that will make some difference..... ;)
Quote from: Victor on March 30, 2007, 08:13:07 PM
Quote from: gaussmarkov on March 30, 2007, 08:01:02 PM
on second thought, maybe the signal path routing has made a difference. as john points out, we can protect ourselves from oscillation by careful routing of the signal path. also, pushtone said that he didn't use any shielded wires for his hookups. so doesn't that suggest that we should stop worrying about pot wiring?
My Buck Boogey has a major problem. It goes into oscillation just by moving tonestack pots side by side, or close to each other. Maybe those tonestack-only wires, that connects Bass to Treble and others should be in the board, so we can solder wires directy and straight to each pot ....... I believe that will make some difference..... ;)
right. but with the layout that we have been working on in this thread, pushtone had no problems:
Quote from: Pushtone on March 26, 2007, 02:41:26 AM
I'm finished with the build. Fired up great.
100% No squeals at all, even with all unshielded wire, even with all controls maxed.
so maybe we should just move on to incorporating your output buffer, as john suggests?
all the best, gm
gm,
That's ok for me. Please proceed. ;D
>Instead of messing with the tone stack why not just add to the layout a simple buffer /switchable?/ after the TS like the one found in Randall's preamp?
With the scaling idea you aren't "messing" with the behaviour of the tone stack, it behaves the same. Unfortunately people are brainwashed by the "standard" tone control pot values because they don't really understand how tone stacks work. The buffer will work course but it adds circuit, which is probably unnecessary.
Ok, Lets go with George's scaling idea. Seems simpler. Less craming on parts on the already cramped layout.
The buffer is doing what the scaling will do so let's keep it simple and go with the scaling.
Here is what george sugested:
Slope Resistor: was 47k now 4k7
Treble Cap: was 680p now 6n8
Mid Cap: was 22n now 220n
Bass Cap was 22n now 220n
Treble Pot: was 250k now 25k
Mid Pot: was 25k now 2k5
Bass Pot: was 1M now 100k
Volume Pot was 1M now 100k
Presence Resistor was 22k now 2k2
Presence Pot was 100K now 10k
Presence Cap was 3n now 30n
A 2k5 pot might be harder to find but you could go for say a scaling factor of 5 instead of 10 in the example.
The mid pot could be 5k and still be ok, Or else just add a resistor across the outside lugs to make it 2K5.
The layout remains the same, Just plug in these values and we should be set.
Waddaya think!
John
If Pushtone is willing to try the tone-stack scaling...... 8)
Quote from: Victor on March 30, 2007, 10:23:32 PM
If Pushtone is willing to try the tone-stack scaling...... 8)
Having built two I would prefer to leave the Gauss version as a reference so I could come back and compare.
I have another etched Gauss board. If I had the parts, which I don't, I would put it into the Buck version enclosure.
I prefer the scaling option to the buffer as an immediate path of experimentation in order to document a final outcome to the output impedance issue.
And George gave anyone all the info needed to start experimenting back on page three I think.
I've had a nice long morning rockin' out with BOTH Dr Boogey's. They definitely have different characters.
Sometime the Buck (100k VOL) sounded better while at other times the Gauss ( 1m VOL) sounded best.
Overall I'm leaning to the Gauss version because of better midrange response.
Remember, other than the PCB layout and the VOL pot these two builds use EXACTLY the same components.
The EQ controls go a long way in getting a good sound.
I hope to get around to replacing the VOLUME pot in the Buck version tonight. To see if they can be made to sound the same.
However, the 500k GAIN pot option still seems to make sense.
I've been trying different pedals following the DB and I'm starting to wonder if all this tone stack and output impedance is a red herring.
I tried a couple of Boss pedals, a Digitech RP-80 and a GGG IC buffer built into it's own box. I did all the testing with the 1m VOL pot version.
Yes there is a slight decrease in high-end with the Boss and RP-80.
But with the DB this is not a bad thing and the TREBLE control can make up for it.
With the GGG IC buffer the level was reduced by half and slightly less high-end. I compensated with the DB VOL control to get the same level as without the buffer following. Volume pot ended up at 2 o'clock which worries me it might run out of travel before reaching unity gain on some amps.
The sound without the buffer is more raw and open. With buffer, a little more compressed but smoother top-end which is a good thing. But both sounded good.
SUGGESTION: PCB layout that allows you to have un-buffered AND buffered outputs so you have the choice.
Bottom Line: IMHO, the tone loss from the high output impedance is not significant to worry about modifying the values or layout. If your dying to build a DB then grab Gauss's layout and do it. Anymore work done will be a minor refinement that is the work of those dedicated to making it the best it can possible be from a technical standpoint.
It was my Honor to beta test a new layout. Great circuit.
Thanks to Electrictabs, Bucksears and Gaussmarkov for their work.
A challenge of a build and something to work up to.
Not as tough as one would think from the previous reports.
Sounds totally different from my other JFET distortions.
IT WORKS, GO BUILD ONE!
Anyone interested in pictures comparing the two builds ?
absolutely!
Pics are always nice!
Thanks for the report Pustone. Interesting that the IM pot didn't change the sound more with pedals following it.
Theoretically th impedance should be low at the output so I say we should scale the tonestack and call it finished.
Either way will work. If you notice a problem with a dulled output with the 1M pot then you know what to do...
+1 Go build it!
John
Geez, I was gettting more confused anytime I saw this topic...... it's so many things we can improve and see...... maybe maintaining standart approach would be the best for me...... so I can get started to build another one..... :o
I did some math with the circuit today and found out the "numerical explanation" for gain behave in boogey. I'll try to use a 220k log pot to see if I can explore more those nice "low gain almost crunch" sounds of it.... :icon_twisted:
And thanks Pushtone, for your new impressions about it. :icon_biggrin:
What supply voltage are you guys using? I believe that 18V give Boogey more definition on notes and tighter bass..... and also trimpots resistances are increased, so gain is also increased, maybe (Zo got higher, Av too).......... makes sense?
In terms of printing the layout onto PnP Blue and etching the PCB, how big should the circuit board be in millimeters/fractions of an inch?
Also, its really great to see folk working together like this, world needs more if it i think...
Adam.
Use Gaussmarkov's PDF project file to print it in scale.
http://gaussmarkov.net/index.php?page=layouts#drboo
http://gaussmarkov.net/
Quote from: Pushtone on April 02, 2007, 04:41:19 PM
Use Gaussmarkov's PDF project file to print it in scale.
http://gaussmarkov.net/index.php?page=layouts#drboo
http://gaussmarkov.net/
Yeah I was thinking about that, only when I print anything onto PnP Blue I usually put a bunch of layouts onto into a word document so as not to waste a whole sheet on one pedal, just wondered how big I had to re-scale it?...
Adam.
Quote from: kissack101 on April 02, 2007, 06:11:58 PM
Quote from: Pushtone on April 02, 2007, 04:41:19 PM
Use Gaussmarkov's PDF project file to print it in scale.
http://gaussmarkov.net/index.php?page=layouts#drboo
http://gaussmarkov.net/
Yeah I was thinking about that, only when I print anything onto PnP Blue I usually put a bunch of layouts onto into a word document so as not to waste a whole sheet on one pedal, just wondered how big I had to re-scale it?...
Adam.
on gaussmarkov.net, every project has a pcb.png file listed. this is a graphics file with a 300dpi resolution. if you "insert" this file into MS Word and do not rescale, the image will scale correctly. at least it did for me. :icon_wink: :icon_cool:
i just posted the latest consensus version: rescaled tone section, no output cap (C22 removed), 24 mil pads :icon_eek: :icon_wink: of course, with every new version there is always the chance that i introduced an error but i double checked. so i'm confident we are o.k. :icon_biggrin: the only change to the pcb was moving a couple of components over at the output to take advantage of C22's departure. i'm mostly thinking of errors in part values. ah yes ... i also increased the pull-down resistor value at the input to 2M.
go crazy, gm
argh!!! i forgot to change the MID pot around. one more try coming soon. :icon_confused:
Quote from: gaussmarkov on April 02, 2007, 06:40:25 PM
argh!!! i forgot to change the MID pot around. one more try coming soon. :icon_confused:
done. :icon_biggrin:
Thanks Gauss
I have one built up with the scaled tone stack values... except for the pots and trimmers.
It gets pretty tight even with 63v box caps and some resistors on end.
The soldering isn't too bad though.
Once I get the rest of the parts I'll report back.
John
Quote from: Basicaudio on April 02, 2007, 10:25:46 PM
Thanks Gauss
I have one built up with the scaled tone stack values... except for the pots and trimmers.
It gets pretty tight even with 63v box caps and some resistors on end.
The soldering isn't too bad though.
Once I get the rest of the parts I'll report back.
John
in the spirit of responding to the comments that i originally sought :icon_wink: what do you all think of this version? i have re-inserted a column that we removed a while back and spaced out the capacitors some. does this address the tightness issues enough? i believe that we want to keep the signal traces as short as we can because that is helpful in high gain circuits.
(http://i41.photobucket.com/albums/e270/gaussmarkov/Forum%20Posts/boo030407.png)
Looks good!
Comparing my board to the layout gauss just posted, the new layout looks a lot better and has more space.
Looking good. Thanks for doing that.
Also in looking at the way the pots are layed out I think the bass pot is good is best next to the gain pot since the oscilation is more likely at the higher frequencies...so this gives a little buffer zone between the gain control and the mid and treble pots. Nothing need to be changed...just thinking out loud.
John
I'm just looking at the outline for C1.
Are there any 1uf film caps that fit that outline? Or the leg spacing?
I had to use electrolytic at C1.
Fitting a 1uF film cap at C1 looks hard, but I'm sure it can be done if it has long legs.
I'm interested in what caps others are using/planning for the 1uf film caps.
Quote from: Pushtone on April 03, 2007, 01:22:50 PM
I'm just looking at the outline for C1.
Are there any 1uf film caps that fit that outline? Or the leg spacing?
I had to use electrolytic at C1.
Fitting a 1uF film cap at C1 looks hard, but I'm sure it can be done if it has long legs.
I'm interested in what caps others are using/planning for the 1uf film caps.
WIMA MKS 2 16VDC 3.5mm x 7.2mm and 5mm lead spacing. i think that's what i have shown.
all the best, gm
hi, my name is gaussmarkov. i am a layout addict ... this is a little simpler ... i need help ... :icon_biggrin:
(http://i41.photobucket.com/albums/e270/gaussmarkov/Forum%20Posts/boo030407a.png)
Here's my board so far.
The blue 1uf caps aren't Wima brand but they are 5mm spacing I believe...They fit at least.
(http://www.mrdwab.com/john/DBboardsize.jpg)
John
ah, and it's a beautiful sight, too ... that 22nF for C7 is a healthy sized cap. :icon_biggrin: you and pushtone do lovely work.
is this layout the latest you posted on your website?
Not to derail all of the work done on this or hi-jack this thread, but to take it in a slightly different direction.......
I know that we (myself included) have looked at making PCBs as small as possible (to fit in cases as small as possible) due to pedalboard real estate being at a premium.
But why not simply give up a little bit of space and spread things out a bit? I'm definitely taking some of the cues from this new thread (scaling down the values in the tonestack/volume), but my next DB build is going to be in a case larger than the 1590BB that my current DB is in. The gain controls are going to be far from the tonestack, volume and input. The PCB is also going to be at least 50% larger than my current one so things will have room to breathe. I'm pretty sure that my PCB has pads for everything on the ground rail, so that's a universal grounding point.
I'm measuring centering the case now and will be drilling it tonight for a precoat of primer; I'll have more info as soon as it's available - waiting on some more trimmers from Smallbear.
Anyone else have any input on the physical proximity playing a part in the noise generated in high-gain devices?
- Buck
Quote from: Nashtir on April 04, 2007, 09:43:36 AM
is this layout the latest you posted on your website?
yes. :icon_biggrin:
Quote from: Bucksears on April 04, 2007, 10:04:27 AM
Not to derail all of the work done on this or hi-jack this thread, but to take it in a slightly different direction.......
no worries! i think you are completely inside the spirit of this thread. :icon_wink:
Quote from: Bucksears on April 04, 2007, 10:04:27 AM
I know that we (myself included) have looked at making PCBs as small as possible (to fit in cases as small as possible) due to pedalboard real estate being at a premium.
But why not simply give up a little bit of space and spread things out a bit? I'm definitely taking some of the cues from this new thread (scaling down the values in the tonestack/volume), but my next DB build is going to be in a case larger than the 1590BB that my current DB is in. The gain controls are going to be far from the tonestack, volume and input. The PCB is also going to be at least 50% larger than my current one so things will have room to breathe. I'm pretty sure that my PCB has pads for everything on the ground rail, so that's a universal grounding point.
i think you are correct that component placement can make a difference. and trying your experiment seems well worthwhile. i suppose we would all like to know where the boundary is between too close and unnecessarily far apart. or principles for keeping components from interacting badly. what i tried to do was follow some of the principles that i had seen described: a signal path that does not double back on itself, grounded guard traces, and star grounding. the first two address the same issues that you are talking about, i think.
some of the noise, and i don't think we know yet how much, is fundamental to the character of the circuit. the high gain of the dr. boogey is going to come with higher noise than other circuits. no matter how we arrange the components that noise will be there.
i don't think a "universal grounding point" is the same thing as star grounding--but i also don't know how much that has helped us. a good test of the layout i posted above would be to build it, your original layout, and your newest layout all with the same components and enclosure and make a side-by-side comparison. unfortunately, that is unlikely to happen. we do have pushtone's two builds to go on and they suggest that we have made progress on the oscillation issues but not the noise. if i were placing a bet, i would go with saying that we cannot reduce the noise appreciably from where it is. but i certainly do not know this for a fact.
so i (for one) certainly want to encourage the additional discussion and experimentation that you are bringing to the table. i'm sure everyone else feels the same way.
cheers, gm
Other than fitting the pots in a 1590BB there seems to be spare room for a larger board.
Bucksears's layout
(http://www3.telus.net/public/david65/pedal-pics/DrBoogey-Buck-InLow.jpg)
Gaussmarkov's layout
(http://www3.telus.net/public/david65/pedal-pics/DrBoogie-Guss-insidesB-.jpg)
Why a bigger box? Both these builds work fine.
The biggest difference is how the two builds handle the grounding.
For Buck's layout, the shield on the I/O wires go to the nearest ground point
and the LED, I/O jacks and DC jack connect to the PCB ground trace.
I did something strange I didn't remember.
I used the two conductors of shielded mic cable to connect the MID pot lugs 1 & 3. Why? I don't know.
I really need to get back to the Buck build and replace that weirdness.
It needs a few thing to bring it into line with some of the Gauss build improvements.
For Gauss's layout all grounds go to the out jack.
About the noises.... hum and hiss.
Hum:
I'm biasing at 7.78V at Q1 to reduce the hum and buzz.
What do you all think of that?
Hiss:
I'm hoping that the MPF102 at Q1 and Q2 will reduce the hiss. Just ordered some.
Maybe then I can get closer to 4.5V on the bias with it.
The BB size layout is a good standard standard to use. Most people use those size boxes.
Personally I use larger than that but...
It would be nice to have a larger sized layout but I'm not sure how the noise will change. The "noise" from my Buck Sears layouts (when they were working well) was just a bit of "snow" / rushing noise, that's per usual with all high gain builds as well as the actual amp!
Making the board larger is fine with me because I make large pedals in general, but I'm not sure is making it larger would cut down on any "audio boogers" It would make sense that a larger layout would help...I'm just not sure in our case here.
Pushtone
Near 8v is pretty high on the biasing. I usalluy go something like 4.5-6v across the board with all the trimmers depending.
Turning down the gain pot takes Q1 out of the mix pretty well. I don't have a DB here that is operational to try it out now, but you might want to experiment with the trimmer voltages other than Q1. Set Q1 about 5v... Q1 sets the gain level of the first stage which is the most critical signal, so setting this too far off may throw of the initial gain to the whole circuit. Whereas adjusting the voltages here and there may give you a better all in all tone/noise floor.
Also, individual FETs can ne noisey and have higher or lower gain. Making that FET matcher is looking better and better!
Try a few Fets (J201s) in the first position and see what you come up with.
John
John
Overall, I guess are we moving away from biasing to 1/2 the supply voltage and simply biasing each transistor to a 'sweet spot'? Mojotron mentioned this when he first introduced his Plexizer, he said that he would turn the gain up and then adjust each trimmer to the 'loudest' point. I've always been biasing to 1/2 voltage, but I'm open to suggestions.
Thanks guys,
- Buck
Quote from: Basicaudio on April 04, 2007, 02:19:29 PM
The "noise" from my Buck Sears layouts (when they were working well) was just a bit of "snow" / rushing noise, that's per usual with all high gain builds as well as the actual amp!
Thats exactly what I meant by "hiss". I also call it "waterfall noise".
Both my build have it in equal amounts.
There is little difference in sound between my two builds and what difference there is I guessing is caused by the 100k VOL pot and lack of the 68k input resistor. I need to normalize these differences to make the builds more comparable.
About the bias. Adjusting Q1 bias does the most for reducing hum and buzz and does not seem to effect the amount of gain, just the smoothness of the distortion. Adjusting the other trimmers seems to do little to reduce hum or effect the tone. I set Q3-5 at 5.5v
Pushtone
Q1 is the most sensitive FET I would think. It sets the level for the whole circuit and is the most sensitive to hum, noise pickup and external noise getting in the circuit.
Hum is a grounding issue, or at least a layout/wiring issue. I don't think the biasing will affect it. Q1 biasing will affect the input level and any hum there but otherwise I think hiss will be affected by FET choise (gain and noise inherent to the particular FET and FET number (MPF102, J201, 2N5457 etc)
The general hiss/waterfall/snow is just the circuits noise, I would think will be in any build using these parts values.
John
Quote from: Basicaudio on April 04, 2007, 04:29:25 PM
Pushtone
Q1 is the most sensitive FET I would think. It sets the level for the whole circuit and is the most sensitive to hum, noise pickup and external noise getting in the circuit.
Hum is a grounding issue, or at least a layout/wiring issue. I don't think the biasing will affect it. Q1 biasing will affect the input level and any hum there but otherwise I think hiss will be affected by FET choise (gain and noise inherent to the particular FET and FET number (MPF102, J201, 2N5457 etc)
The general hiss/waterfall/snow is just the circuits noise, I would think will be in any build using these parts values.
John
Is there any chart/value/graphic/indication that shows those noise characteristics on each FETs datasheets?
I recognize those caps John :icon_wink:
MM.
Yes, Thanks again Marty for sending those. I was babying my dwindling suppy of the ones I got from RDV a while back (1uf box caps)
Sure wish I would have just bought a bunch (more) of those then! The other caps and even the Ge transistors will get used as well marty!!!
Too kind.
Victor
Despite the data sheet specs on FETs they will all sound a little different and at different gains.
Run off groove does have a table of average values in their Fetzer valve article. No noise specs though.
Did I say that I was going to build a FET matcher...?
John
why not just breadboard the FET matcher? that's what i do with R.G.'s HFE measurement circuit as well. :icon_wink:
Yeah, I could breadboard it but may as well commit to it. I'll use it, may as well get it off the bread board to free up space.
Make a little proto box for it....
John
Quote from: Basicaudio on April 04, 2007, 07:08:26 PM
Victor
Despite the data sheet specs on FETs they will all sound a little different and at different gains.
Run off groove does have a table of average values in their Fetzer valve article. No noise specs though.
Did I say that I was going to build a FET matcher...?
John
Hm... and what's gonna be your approach on bulding this? I have some sheets of paper that I did some math envolving Vgs and Idss on Boogey...... let me know if you want some of my impressions..... :)
I was going to build one of mark M's in his gallery. Maybe there was another one in the gallery as well.
I don't know the details. I was just going to match fets for gain etc as some kind of standard to sort gain levels etc for these multi fet builds.
John
Matching FETs is good. Especially for replacing trimpots by resistors. Althought our impressions about drain voltage being equal to half supply voltage are going to a new path (setting to an ears' friendly voltage and it's done, maybe :D), I've found some values for Rd of each stage with 9V supply....
for Q1, Q2 and Q4, Rd=22k, Vd=4.4548V and Q3, Rd=33k, Vd=4.875V, with Vgs(off)= -0.9V and Idss= 0.6mA in all J201....
Next week my pots arrive so I can start my 2ยบ Boogey..... can't wait any longer ;D
I can't see the value of c21 neither in the scheme nor in the part list..which is its value?thanks!
Quote from: Nashtir on April 08, 2007, 04:19:29 PM
I can't see the value of c21 neither in the scheme nor in the part list..which is its value?thanks!
If I'm thinking of the same schematic you are, C21 is a coupling cap that blocks DC from preceding effects. I have a bunch of (NP or film) 1uF caps that I use for these kinds of caps, but you can use a .1uF or .01uF film cap. If someone has a different understanding of this let me know, but this is how I would compute the value of caps like C21 for maximum signal coupling:
Assuming R=1M, C=C21, for different values of C21:
1uF, - the attenuation is -3db at frequency F= 1/(2*Pi*R*C) = 1/(2*Pi*1)=.16Hz
.1uF, - the attenuation is -3db at frequency F= 1/(2*Pi*R*C) = 1/(2*Pi*.1)=1.6Hz
.01uF - the attenuation is -3db at frequency F= 1/(2*Pi*R*C) = 1/(2*Pi*.01)=16Hz
So at .001uF you are going to hear the lowend start to drop off.
I'm guessing you could use .1uF and not hear any change to the low end - your ears will vary.
my thought was .1uF but i left it open because the coupling cap is there by request, not because it is necessary. look at the runoffgroove emu circuits and you will see them without the coupling cap as well. if anyone wants they can just short the coupling cap connection and leave out the pull down resistor.
all the best, gm :icon_biggrin:
hey guys!!
i breadboarded the buffer, and did no mods to the tonestack or the volume pot (1M), it sounds good, but the presence control seemed to stop making any effect..i put the buffer after de vol pot, 0.068uF coupling cap...did i missed something??
Do i have to change the cap and/or pot of the presence control?..
please help!!
Sometimes the presence control is not vey noticable.
Try turning down the treble and see if you can hear the presence control doing anything.
The Buffer shouldn't affect the pres pot.
I still have not finished my build with the scaled down tonestack. Just need those pots... I'm broke..
http://www.diystompboxes.com/smfforum/index.php?topic=56188.0 (http://www.diystompboxes.com/smfforum/index.php?topic=56188.0) :icon_cool:
ehm... :-[ :icon_redface: :icon_redface: the pot was broken... i have to replace it... :icon_rolleyes: :icon_rolleyes:
I got around to replacing the 100K VOL pot I used in my Buck version to the stock 1M.
The two builds sound the same now. With the 100K pot the sound had a lot more ultra high end hash.
Can't wait for someone to finish a scaled TS version.
I'm still liking the 500k GAIN pot over the 1M. Better low-gain tones.
With the 1M the sound past 12 o'clock is about the same. It gets thicker with low mids like an angry swarm of bees
Quote from: Pushtone on April 10, 2007, 01:52:36 PM
It gets thicker with low mids like an angry swarm of bees
With the 1M or the 500k?
Quote from: Pushtone on April 10, 2007, 01:52:36 PM
I got around to replacing the 100K VOL pot I used in my Buck version to the stock 1M.
The two builds sound the same now. With the 100K pot the sound had a lot more ultra high end hash.
Can't wait for someone to finish a scaled TS version.
I'm still liking the 500k GAIN pot over the 1M. Better low-gain tones.
With the 1M the sound past 12 o'clock is about the same. It gets thicker with low mids like an angry swarm of bees
With my strat I get some useful tones from 1/2-3/4 on the 1M gain pot - but with a humbucker, ya, about 1/2 on the 1M gain does it for me. I'll try the latest build with the changes and let you guys know what I get.
The thickening "like swarm of bees" comes with the 1M GAIN pot from 12 o'clock to max.
I've only tried it with humbuckers. Good point about single coils Mojotron.
Quote from: Pushtone on April 10, 2007, 01:52:36 PM
I got around to replacing the 100K VOL pot I used in my Buck version to the stock 1M.
The two builds sound the same now. With the 100K pot the sound had a lot more ultra high end hash.
Can't wait for someone to finish a scaled TS version.
I'm still liking the 500k GAIN pot over the 1M. Better low-gain tones.
With the 1M the sound past 12 o'clock is about the same. It gets thicker with low mids like an angry swarm of bees
And how are you biasing all the J201? Half supply's voltage, or just by ear?
Quote from: Victor on April 10, 2007, 04:06:26 PM
And how are you biasing all the J201? Half supply's voltage, or just by ear?
All J201's
Q1 biased by ear and set for least noise while still sounding full (not gated). Reads 7.7V
Q2 at 6.5V
Q3-5 at 5.5V and biased with fixed resistors.
Will have some MPF102's to try soon - Thanks SB.
Well, I've just spent some hours today with my Buck Boogey, a screwdriver for trimpot adjustment, and some of the usual components and tools for pedal DIYing...... let me post some of my impressions:
I was trying to find sweet spots in Boogey's sound dialing in those trimmers, and I found out that I'll just leave aside that half-supply-voltage-at-fets-drain" approach. Just tweak by ear, and should be nice. The key to success here is to carefully find the "magic point" that gives you almost no hiss and a open sound as possible ... :icon_biggrin:
I also put a MPF102G in Q1s position, to tame down noise, and set its drain voltage at 1,5V (yeah, that's right) of 18V supply voltage (yeah, that's right again) and the sound is just nice. Now it is not noisy as it was before, even with gain maxed out, but still with plenty of clarity and "chug", well-defined, agressive as usual. This beast running with 18V is just awesome, nicer n' meaner than the 9V version, and more responsive.... less muddiness more volume as usual, a little less gain (or at least, I've got more control over it)...
My gm board is ready, tomorrow i'll start building it. All fixed resistors, a switch to change between some caps n' resistors values of Q1's source, and maybe another switch to jump over 2 stages (orange channel?) ...... ;D
Hmm... I'm having some trouble when I use my Boogey on my Laney LC30II..... it's too bassy, like tone at zero, and it's only crunching a little.... bateries are at 9.20 and 9.14V each, in series. Same setup worked just fine on a cheapo SS practice amp here..... all solders, connections and components are ok.................. what could it be? The same thing happened with Wylde Overdrive a while ago...... same sound, seems like is gating, overdrive sound level is lower than clean sound...... bypass is working ok......
fixed. :)
Ah come on...we want the details... User error?
John,
I took off Q1 for Idss and Vgs measuring, and when I put back, it was backward..... :icon_redface:
There you go, extreme noob mistake, but now I have a clue on what happened to my Wylde OD also..... hehe :icon_mrgreen:
Here's a pic of gm board.... I'll finish pot wiring today, I believe..... layout is very tight, I had some trouble soldering input wire, but all turned out ok.... :icon_biggrin:
(http://img476.imageshack.us/img476/329/p4142686bq7.jpg)
(http://img219.imageshack.us/img219/7820/p41426922wl5.jpg)
I spent some hours playing with the pedal, and I can say that it's a winner. ;D
No noise, hiss or anything like ...... even with tone controls maxed up..... I put a 220k gain pot to explore more of the crunch sounds of it... and a switch (as you can see in the first picture) to change between caps of Q1 source..... and the scaled tonestack worked just fine, very similar, if it's not better, to the original schem.......
Maybe we can try Boogeyman now .... there were some complains about its tonestack (not very responsive), but it seems that there are missing some jumpers in mid and bass pots (lugs 2 and 3)..... doing that, it'll behave similar to a Fender tonestack......... what d'yall think? :icon_wink:
Here's a couple of ideas to make the gain control a bit more variable (as I have found that with different guitars/gear - I liked different levels of gain on Buck's layout):
- A thing one could do with the gain control is to use a 1M pot and use an on-off-on 3pdt switch to swap in a parallel resistor on the gain pot to get ~250k, 1M, and 500k.
- What I am planning to do is to put a 500k pot on a DPDT stomp switch so that I can switch it in/out in series with a 500k gain pot to get a 'boost' control for soloing, but I will likely need play with this a bit to keep from increasing noise.
I built this several months back using Bucksears layout. I liked it a lot but my only complaint was that in order to open it up a bit, I had to stack my MOSFET booster behind (huge difference btw). I ended up trading it for something else but I am sort of having sellers remorse having seen the latest work that has been going on.
Can anyone summarize the tonal differences between the early layout versions vs. the latest modifications? Maybe I should give it another try???
I don't think there are any tonal diferences, it's just more behaved with the squeal kept under control and the impedance was corrected at the output with the new tone stack values. The power section and grounding were bulked up a bit as well so it will be quieter under different situations...
John
I built both the Buck and Gauss layouts.
They sound exactly the same to me.
I have only recently started to have issues with my Dr. B., so I'm considering trying Gauss' layout. I do have concerns with the close proximity of everything, but the results are coming in that it's working well/quietly, so I might give it a go.
I'm definitely doing the scaled-down tonestack on my next one.
- Buck
I want to build this effect but i have question.
I live in Europe and there is different marking of potentiometrs ( Linear is "A" and Log is "B") and i heard that in some potentiometrs in USA Linear are "B" and Log are "A" and im not sure what potentiometrs i should use.
So i ask
are the Volume, Treble, Gain and Bass are Logaritmic pots or linear?
Quote from: konradf13 on December 22, 2007, 12:50:48 PM
I want to build this effect but i have question.
I live in Europe and there is different marking of potentiometrs ( Linear is "A" and Log is "B") and i heard that in some potentiometrs in USA Linear are "B" and Log are "A" and im not sure what potentiometrs i should use.
So i ask
are the Volume, Treble, Gain and Bass are Logaritmic pots or linear?
Only the mid and presence knobs are linear. But I used a set of all-linear knobs, and the bass maxes out at 9 o'clock haha! I just deal with it by fine-tuning.
cheers,
Dan
Quote from: Victor on March 26, 2007, 10:49:14 PM
2) Is there any way to implement a Road King switch mod, like Raw/Vintage/Modern switch? I was thinking of using it to change between Q1's source cap values in order to get those sonic variations......... Raw would be standart cap, Vintage equals no cap, and Modern would be a bigger cap, but I don't have any Mesa Road King sound references, so I'm a bit confused........ can someone enlighten me about this?
Any chance we can get an update on how to implement this? I've seen some finished builds utilizing it in the "Pics" thread, but haven't been able to track down a method... I'm planning a Dr. Boogie with THE WORKS!
My dr boogey has great distortion (pot is with 500k), and even when excessive bass pot 1, voltages of q1 the q5 all 4.5v, which would be ideal for voltages less severe (bass) in the sound.
Q1 =?
Q2 =?
Q3 =?
Q4 =?
Q5 =?
Hi, first thanks aron & all the community for this awesome dr. boogie project to get so real and good.
I'm a newbie in audio electronics and encounter terrible difficulties to get some components in the gaussmarkov latest part list for this enhanced 5 stage, low noise dr boogie :
- 2.5k-b mid pot , does it exist ? -> took a 2k one
- 6.8nf chicklet film ? i found 68nf chicklet film format but only standard filmbox for this value..
I was just wondering if s/o that already realized this awesome preamp version had the same problems and how we could find solutions/equivalent products ?
TIA,
Fabien
Wanted to simulate this schem to TINA but i'm getting 0V as output. Any idea about the mistake i've made?? ??? ???
(http://img855.imageshack.us/img855/7389/drboogieschem.th.jpg) (http://img855.imageshack.us/i/drboogieschem.jpg/)
Uploaded with ImageShack.us (http://imageshack.us)
Quick question: isn't the diode D1 (9v to ground), isn't it the other way around?
or because 9v is higher than the reverse voltage, it's just regulating current - so either impeding current of going "up into 9v tap" or "down into ground tap" be our "safety"?
Apologize for my electronenglish. Just trying to pass the bit that is confusing me across :)
Bottom line - Any difference in having diode facing cathode up or cathode down (towars/away 9v tap) as long as we tap after the cathode?
what can you say about this one?
are there any pros and cons in using this layout?Quote from: frequencycentral on April 04, 2010, 01:18:59 PM
I wanted to board mount all the pots and use vertical trimmers for this layout. I'm pretty sure the layout is correct re the connectivity (though there may be errors as I haven't triple checked it yet), I'm just a little concerned about the proximity of the gain control to the input section.
Oh, the input is the green pad, the output is the blue pad. :icon_biggrin:
(http://i210.photobucket.com/albums/bb292/frequencycentral/BoogiePCB.gif)
(http://i210.photobucket.com/albums/bb292/frequencycentral/BoogiePnP.gif)
From what I read on another post, I think the only problem was to fit all the caps together (too tight). That other than that was working.
whats the deal with the trimpots lugs?...shouldnt there be a join on em...like the gaussmarkov version...?
Quote from: deadastronaut on July 18, 2011, 03:02:34 AM
whats the deal with the trimpots lugs?...shouldnt there be a join on em...like the gaussmarkov version...?
That's not crucial, just good practice.
ok!...cheers!..
Quote from: Scruffie on July 18, 2011, 08:10:33 AM
Quote from: deadastronaut on July 18, 2011, 03:02:34 AM
whats the deal with the trimpots lugs?...shouldnt there be a join on em...like the gaussmarkov version...?
That's not crucial, just good practice.
What join?
The trimpots are configured as variable resistors in the Boogie. For a variable resistor it's only necesary to use two lugs: the wiper (ie lug 2) and one of the outer lugs (ie lug 1 or 3). The unused lug can be left unconnected (as I have done). However, as Scruffie said, it's good practice to connect the unused lug to the wiper, so that if (and it's a big if IMO) the trimpot fails then there's still resistance rather than an open circuit. I personally don't buy in to this 'good practice', as IMO a misbiased Boogie (ie 100k resistance on a trimmer were the wiper to fail) would be as much use to me as a Boogie with an open circuit trimmer (ie the wiper fails and the 'unused' lug was unconnected). In both cases I'd replace the trimmer (in the very unlikely case of a trimmer failing). Hands up all those who have had to replace a failed trimmer in their Boogie.......oh, I don't see any hands.
I built the frequency layout and it's a squeeze but it went together fine in the end. Cap choice is more limited is all.
Thanks for the layout. Onboard pots beats space saving when its 6 pots to off board wire...
Quote from: frequencycentral on July 19, 2011, 05:49:01 PM
The trimpots are configured as variable resistors in the Boogie. For a variable resistor it's only necesary to use two lugs: the wiper (ie lug 2) and one of the outer lugs (ie lug 1 or 3). The unused lug can be left unconnected (as I have done). However, as Scruffie said, it's good practice to connect the unused lug to the wiper, so that if (and it's a big if IMO) the trimpot fails then there's still resistance rather than an open circuit. I personally don't buy in to this 'good practice', as IMO a misbiased Boogie (ie 100k resistance on a trimmer were the wiper to fail) would be as much use to me as a Boogie with an open circuit trimmer (ie the wiper fails and the 'unused' lug was unconnected). In both cases I'd replace the trimmer (in the very unlikely case of a trimmer failing). Hands up all those who have had to replace a failed trimmer in their Boogie.......oh, I don't see any hands.
Hey Thanks a lot that makes all the sense in the world now :)
@frequency central
@frequency central
how can i print your layout on it's actual size on the pcb board?
do you have the dimensions? (if i resize your layout)
Quote from: mr_deadmaxxx on July 21, 2011, 04:30:43 AM
@frequency central
how can i print your layout on it's actual size on the pcb board?
do you have the dimensions? (if i resize your layout)
Most people import DIYLC files into Publisher or Photoshop and scale it to a 0.1" (2.54mm) grid, as the pads are that distance apart. I've heard of people scaling to 47% too.
Quote from: mr_deadmaxxx on July 21, 2011, 04:30:43 AM
...how can i print your layout on it's actual size on the pcb board?
Open with Paint.
Set page scale to 47 or 48%
Works like a Champ! ;D
Quote from: Govmnt_Lacky on July 21, 2011, 01:14:40 PM
Quote from: mr_deadmaxxx on July 21, 2011, 04:30:43 AM
...how can i print your layout on it's actual size on the pcb board?
Open with Paint.
Set page scale to 47 or 48%
Works like a Champ! ;D
Paint kinda pixelates it. But it looks perfect in Publisher:
http://dl.dropbox.com/u/967492/Scale.jpg
i noticed there's a difference between your input pulldown resistor and input capacitor to the schematic that i saw.
resistor (R3) : 1M instead of 2M
capacitor (C4) : 1uF instead of 0.1uF
that's not critical, am i right?
no big deal?
anyways, will a J202 work instead of J201?
Just looked at the datasheet for J201 and J202 just a slightly "lower" cuttoff voltage and "higher" saturation voltage.
That would just mean a higher headroom, no?
Also, higher forward voltage. Would this impact into the next stages?
what if i used this one for tonestack?
(http://img109.imageshack.us/img109/636/61876921.jpg) (http://imageshack.us/photo/my-images/109/61876921.jpg/)
no reply?
I'm no expert but I guess the first bit would get the impedance to match.
There's a couple of toneless dr. Boogey stack around that had to be changed to match this.
There's also some other posts of people that introduced other tone stacks.
I have the impression that regardless stack you choose, the impedance would have to be matched after the 4th J201 and the tonestack.
Also, what is the IC you have in that stack? 2 dual IC's?
yeah.. dual opamp IC.
Guys, question on this, more of a me trying to understand something than anything else but :)
I understand Q5 is acting as a buffer, as it was explained by John Lyons a couple of pages (way back! I think page 4???) but what about Q3? there's no miller cap there either. Any reason?
Hey people,
Newbe to this forum and long story short: I made a SMT version of Gaussmarkov's layout, essentially because the J201 seems hard to get and the SMT version is readily available (even in low qunatities at Farnell/Digikey and the likes). The board's just a little over 43 x 49 mm and consists mostly of 0603 components, with the exception of the pots and trimmers (although in my build I bypassed the trimmers by 33k resistors).
I did a quick and dirty build (even using flatcable for pot wiring) and took it straight into band practise (only scope testing it on the work bench) and we were all blown away by the very powerful sound of the box. My fellow bandmate is on his way making one as well :icon_mrgreen:
Anyway, if anyone's interested, I could post some pics of the layout and build. Same for the Eagle design files.
Quote from: Ajay on November 20, 2013, 09:44:00 AM
Anyway, if anyone's interested, I could post some pics of the layout and build. Same for the Eagle design files.
Welcome Ajay!!!!
Sounds like a GREAT project and kudos on getting it running and offering to share!!!
By all means.... post it. I am sure there are plenty of people who would be interested in it! ;)
Thanks GL,
The first pic is a screen shot of the Eagle layout. It's a two layer board btw, I found a company in China which makes double side 5 pcs of 2" by 2" for less than $10.-, so no stoppers there ;).
(http://i819.photobucket.com/albums/zz113/Ajay-71/designs/DrBoogeyLayoutSMT_zps73e5844e.jpg)
Then there's the initial build of the board (with the trimmers bypassed by fixed resistors):
(http://i819.photobucket.com/albums/zz113/Ajay-71/designs/C255D799-0F90-41E8-AF35-DCD5ED224081_zpsznrg53ql.jpg)
After that the quick and real dirty flatcable wiring and first bench test:
(http://i819.photobucket.com/albums/zz113/Ajay-71/designs/5EA0568C-F7A3-4665-ACCC-984465F474CC_zpsgameqlar.jpg)
And the prototype I took to band practise:
(http://i819.photobucket.com/albums/zz113/Ajay-71/designs/F1066CC0-1429-4B6E-A54E-D7E762B5D580_zpsnc7jlmt8.jpg)
The three spare holes are for an MXR noise gate (also in SMT, if anyone's interested, just let me know) and a solo booster in '3D electronics' (without any pcb, just hardwired on the pot).
btw: does anybody know how to post a zip file to this forum?
Ah, schweeet! nice man! want to build that! dr boogie was my 1st project, yeah i know, anyway, would love to do a good variation. this one seems to cut it. cheers mate!
Thanks :-)
Actually, the Dr B. got me very excited about doing SMT boards, so tonight I kinda finished the JCM800 Emu. I guess I'll post that in a new post.
Anyway, I'd love to share my design files, but so far I haven't found out how to add them in this forum? Any suggestions?
Okay: sneak of the JCM ;)(http://i819.photobucket.com/albums/zz113/Ajay-71/designs/JCM800-emu-smt-brd_zps276d0a22.png)
hi ajay, welcome aboard..
try 'dropbox', its free and really useful. ;)
Seems Aron already provided for this:
http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/drboogey_smt.zip.html (http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/drboogey_smt.zip.html)
If you click on the download archive, you should be able to get the files
(just hoping that I'm not abusing a feature that's intended for other use :icon_redface:)
not at all...
in a few peoples opinion, including mine, it could do with a tweak here n there anyway...usually the tone stack comes under fire...
My starting point was Gauss' layout, which essentially I just converted to SMT without any mods. I had already sent the gerber files away before I became aware of any tone stack discussions :icon_redface:
For the SMT version of the JCM800 which I'm currently working on however (I've posted that somewhere else on this forum), i did incorporate some of the tone stack discussions; I've added some resistors and caps there so one can choose between the regular TMB, the Big Muff or the extended Big Muff tone stack. Also in that design I reserved room for more bypass caps, so it allows for more flexibility and room to experiment. Based on my experiences and hopefully comments from others, I will update the SMT Dr. Boogey design (or just hardwire it ;) ).
So if anyone has suggestions/comments on either design, I'm open to it :-)
Cheers,
Ajay.
Quick question
how do i set up the trimmers in this build.
I have just recieved a populated board from a buddy and all i had to do was wire up some pots. so not having read alot about it i'm not sure how to bias the jfets. I guess thats what the trimmers are doing.
Thanks
Rich
Quote from: Kipper4 on November 23, 2013, 01:15:27 PM
how do i set up the trimmers in this build.
I have just recieved a populated board from a buddy and all i had to do was wire up some pots. so not having read alot about it i'm not sure how to bias the jfets. I guess thats what the trimmers are doing.
Yep: aim for 4.5V on the drains of Q1-4. According to the madbean build notes, you can get oscillation with everything dimed, so ease back on T1. If this sucks, put it back, then try backing off T2 instead. If this sucks, . . . (You get the picture.)
Thanks Mark
I'll give that a go. I'll report back later
despite not being boxed I can tell it's going to sound good already even with unbiased fets. especially with a SS amp, tube amp testing when i get back from work tommorow as its too late to crank that baby up now. I't blow the wife out of bed :)
Rich
Kipper looks like that board is already getting better use than on my bench. I hope it fires up no problem. And blue bunny was right its 4.5v do you have a link for the pot wiring?
ajay, could you please share a link to the chinese company that made the board for you? how much for shipping?
thanks
BTW your layout looks good, I always wanted a Dr. Boogey in a B-sized box, maybe with a 1 knob tone control
Yes thanks Dizzy and thanks for the board, superbe qaulity etching btw. nice componants too.
I have the Dr Boo pdf from mr Markov so the pots are all wired up. It's ready for biasing now
Seriously good people here. Amazing generosity and willing ness to share parts and knowledge.
I love it here. Hence how come i have over 1k posts already in a year, admittedly most of its drivell but i'm starting to help a few newbies gain new knowledge too.
I feel the same way exactly I don't have nearly as many posts but I do read through the forums at least an hr or 2 a day. And I think we formally met when I was helping you get that 45 running. Or that's what stands out. Btw you should be able to match all the fets w that matcher I sent you! Was the pinout description w it? Ok enough of. Do let me know how the pedal sounds.
Quote from: chobot123 on November 23, 2013, 02:29:53 PM
ajay, could you please share a link to the chinese company that made the board for you? how much for shipping?
thanks
BTW your layout looks good, I always wanted a Dr. Boogey in a B-sized box, maybe with a 1 knob tone control
Thanks :)
The company is Elecrow, http://www.elecrow.com/services-c-73/ (http://www.elecrow.com/services-c-73/) Once you'd make a selection of the board size you'd like, there's an option to estimate shipping cost.
For a B size box the Big muff Pi Tone control could be an option. For the Dr. Boogie that would mean changing C17 to 4n7, R13 into 0 Ohm (or just bridging it) C18 should be a 39k _resistor_. Furthermore, add a 22k resistor to ground on pin 3 of the High pot and a 10nF capacitor from pin 1 of the High pot to ground and you should be good to go.
(BTW This mod is also available the tonestack of the JCM800 board I posted, always better to see the picture than just text ;))
Quote from: Kipper4 on November 23, 2013, 01:15:27 PM
Quick question
how do i set up the trimmers in this build.
Well, I did it with fixed resistors of 33k which give about 4.5 volt on the drains, except for trim 2. A 12K resistor (equalling to 6.5 or 7. something Volts, can't remember - I'd have to recheck) just sounded better to me.
If you have trimpots, I'd suggest to start with the suggested 4.5V and listen if a change of the trims sounds better or not.
Quote from: chobot123 on November 23, 2013, 02:29:53 PM
I always wanted a Dr. Boogey in a B-sized box, maybe with a 1 knob tone control
Actually, I've been thinking to make such a box too for a friend of mine. And maybe with a little less gain, as he's not so much into metal as I am ;)
But first I have to finish my MXR noise gate clone, which I need up and running in two weeks :-)
I'm struggling with this so far. But I'm tired from a long day.
I'll look again tomorrow night. I need to play with it .
It's screaming like a biatch so far but it's unbowed and I'll put a shielded wire on the output. I already did the input.
I can't get the 500k gain pot past 9 o'clock I'm a stubborn so and so. I'll have it fixed. I'm confident with a gaussmarkov pcb it will have the best layout possible.
Thanks again to my old buddy Dizzy for the loaded board. I can't thank you enough.
Report back later and thanks for the tips.
When I have a few hours spare I'll read through this whole thread too.
Quote from: Kipper4 on November 23, 2013, 04:45:28 PM
It's screaming like a biatch so far but it's unbowed and I'll put a shielded wire on the output.
It's pretty high gain and I found it was relatively easy to get it to feed back (in a nice way). I think this is intentional. Will be quieter in the box. I may have to build another: my first one (http://www.bouron.org.uk/marc/boo639.JPG) was snapped up by yet another tame guitarist buddy.
Quote from: Kipper4 on November 23, 2013, 04:45:28 PM
I'm struggling with this so far [...] It's screaming like a biatch so far
Same hear last night when modding the box. Once outside the enclosure, I heard sounds unheard before :icon_eek: As soon as the box was closed again it was over.
I guess proper shielding is a must for this build (but isn't it always ;))
Quote from: bluebunny on November 24, 2013, 09:35:29 AM
Quote from: Kipper4 on November 23, 2013, 04:45:28 PM
It's screaming like a biatch so far but it's unbowed and I'll put a shielded wire on the output.
my first one (http://www.bouron.org.uk/marc/boo639.JPG) was snapped up
Cool graphics! I'm noway near that, so... How did you do that? :)
Quote from: Ajay on November 24, 2013, 09:41:50 AM
Quote from: bluebunny on November 24, 2013, 09:35:29 AM
Quote from: Kipper4 on November 23, 2013, 04:45:28 PM
It's screaming like a biatch so far but it's unbowed and I'll put a shielded wire on the output.
my first one (http://www.bouron.org.uk/marc/boo639.JPG) was snapped up
Cool graphics! I'm noway near that, so... How did you do that? :)
Thanks. It's a waterslide decal on top of car paint, underneath acrylic clearcoat. The graphics were worked up in PowerPoint of all things. The "Boogie" part (complete with vegetation) was found on Google.
while researching Dr Boo voltages yesterday i found this page (about half way down) read this guys voltages they seem a little lower than i would have expected
http://www.ultimate-guitar.com/forum/showthread.php?t=1561701
Quote from: Kipper4 on November 24, 2013, 12:54:36 PM
... voltages they seem a little lower than i would have expected
http://www.ultimate-guitar.com/forum/showthread.php?t=1561701
Have you had the opportunity to test this? My box does sound better with a different than 'standard' voltage (6.5v) on the second FET, but I haven't tried the other (yet)
So I'm curious what voltages work best for you.
imo its down to your ear at the end of the day..
when ive tuned up boogies i turn my guitar to its lowest point and get rid of any gating first...so it is at max open/release if you like,
then go from there...4.5v is a ballpark, but not a rule for these beasts.
Quote from: deadastronaut on November 24, 2013, 06:59:19 PM
imo its down to your ear at the end of the day..
4.5v is a ballpark, but not a rule for these beasts.
That's why Boogey #2 will have trim pots (and a different tone stack ;D)
i've had another go and i've stopped the whine, but i reckon when i get it boxed up i will be able to do a better job.
I'm building the second one now, but have to wait for the pots & dc plugs to arrive :-\
This one will have the single pot tone control btw and trimmers for biasing iso fixed resistors.
heres how i set mine up (outside the box)
Q1 1.35v
Q2 7.89v
Q3 8.46v
Q4 5.26v
All this may change when i get it boxed
sounds great