Calling all critics: Please verify my Boogey Layout!

[ayayay!]

Good evening gentlemen.  Please critique and verify my layout.  Don't be bashful.  Against the recommendation of some of you, I went with the original Electrictabs schematic.  http://geocities.com/electrictabs/dr.boogey.png

I chose to lay it out on the Small Bear 371 hole board so that I can share it.  I'm still not so sure I have all the EQ controls correct.  I included the link in case the .gif is too big to view.  (Don't you hate that???)

http://farm4.static.flickr.com/3273/2848849231_025e9eea44_o.gif

[John Lyons]

First off, the input signal and other ins are connected to the Source in your layout.
They should be connected to the Gate which is the top pin as you have then oriented.
I'll look at it some more for other things.

john

[John Lyons]

The lead length from Q2 to Q3 is pretty long. Possible source of noise and oscillation.

And although you know this...
The tone stack needs to be scaled to prevent loading of anything after the DB.
(In the amp there is a power section that can work well with a high impedance
so that's why the values are as they are)
The use of small caps (150pf) from gate to ground on Q1, Q2 and Q4 will help
with ocillations and smoothing out the high frequency response.

john

[ayayay!]

Thanks John!  I will modify and re-post.

After Dinner...

Long after dinner...

[ayayay!]

Okay, fixed a few things...

Changed orientation on all FETs.
Added 150pf from Gate to Ground on Q1, Q2, and Q4.  Because of this, I'm assuming I can drop the 20pf off the Gate of Q2 now right?

Question for you John. 

The tone stack needs to be scaled to prevent loading of anything after the DB.

I've read about the scaling down (what was it, 1/10th?) and understand the necessity of it, but what does the "DB" mean?   (By the way, the reason I'm sticking with this schem was that I had already ordered the parts before becoming aware of the other version(s).)   

http://farm4.static.flickr.com/3288/2849303825_1b74559063_o.gif

[John Lyons]

Yes, the 20pf is replaced by the 150pf.
It's not crucial that you use exactly 150pf, 120pf... you know...

DB = Dr Boogie   

Yes, 1/10th is the scaling ratio.
Go to gaussmarkov.net and look up the dr boogie.
The schematic is there with all the revisions.

[ayayay!]

Thanks John.  Yeah I spent a lot of time on Gaussmarkovs site, but only after it was too late!  Parts were already ordered by then.  Actually I had printed off both Electrictabs and Gaussmarkovs and was on the couch reading them when I realized what had happened.  I'm hoping your cap tricks will be enough to tame this DB down! 

Thanks again John.  Everything else look okay? 

It's always so nice to have extra eyeballs 'round here. 

[John Lyons]

Just noticed...the signal should come off the drain of the FET.
You have it connected to the source.

Gate = input
Drain = output/connected to trimmer
Source = bias/closer to ground...

I think you are getting confused with the usual transistors.
Look up the pin out for a J201

john

[ayayay!]

Nuts!  Thanks John.  First build using FETs if you can't tell...     No biggie, I'm patient and that's why I put it here in the first place. 

I'll rework this again tonight.  I have just pulled up the pinout in the FAQ.  I'll pencil in the DSG on the schem now so I won't get them confused . 

[ayayay!]

They say the third time's a charm so here goes...

-I shortened all the distances to the sources of all FET to as little as possible.
-I managed to lop off 2 rows worth of holes on the bottom. 
-Can somebody please check all 5 pots on the right to make sure I have that right?

http://farm4.static.flickr.com/3290/2853940258_da0be4a503_o.gif

[John Lyons]

Look ok to me. I'd still scale the tone stack parts though...
To clarify, I didn't have anything to do with the pf caps to ground at the gates.
That was someone else's idea.

The sensitive lead length is the gate input not the source. It's probably ok though as you have it.

I guess it's just you and me here huh?

john

[asfastasdark]

I see half of a jumper under C8, that might be confusing as people may think a jumper and capacitor are put in parallel.

[ayayay!]

OK I just processed your thoughts John.  And a hearty "salut" to you for helping me out!!!

Yeah asfastasdark, C8 definitely was a pain.  I couldn't get that jumper out of there for the life of me, but like you said, it shouldn't damage anything.   I'll try to fix that again but it's good for now.

Anyone else have problems with this program?  I'm not griping because I know it's free, but dang is it temperamental (not to mention a CPU hog!)

What impairment will I have by using the values on the current tone stack vs the scaled one?

[ayayay!]

Well, this went great!   A couple tiny things to debug once I got it wired up, but otherwise it went surprisingly well.  I did get a tiny bit of oscillation, but that went hand in hand with being too close to the squealing.  Trimmed it back a little, boxed it up, all was well.

So I have to dig through some of the myriad other Dr. Boogey threads to find a mod to give it just a wee bit more treble if possible. 

Also, would a larger valule pot work for the Presence control?  Say a 250K Linear?  I don't have a 100K Linear available (at the moment.)  I slapped a temporary 100k Audio in there and it obviously isn't doing the job well enough. 

Other than that I'm VERY happy with this circuit! 

PS:  I am going to rework the layout above.  It's fine, but a couple spot were too tight and there's room to fiddle with it on the layout.  Man I LOVE those tiny Bourns trimpots.  They take up only take up 9 holes.  http://www.bourns.com/PDFs/3362.pdf

[John Lyons]

Jono
100k audio should be fine for the presence pot until you can find a 100K lin pot.
The last part of the knobs rotation will be where more of the action is though.
You could also put a 250K (or whatever value you have that is close) resistor across the outer lugs of the 250K pot and
That would make the pot roughly 125K which is close enough. The taper will be reverse log then, might be fine.

To get more treble you will basically have to cut a little bass and mids with the tone controls.
You should be able to get plenty of treble that way. If not them you will want to make the .02 cap after the Drain of Q1 .004 and possibly redo the tone stack a little. Start by trying to get a good sound with the bass turned half way up or less.

One reason the circuit sounds dull (Possibly) is that the tone stack is high impedance.
By scaling it down it becomes lower impedance.
The high imp tone stack may be loading down your amp or pedals that come after the DB circuit.
This is why the tone controls were changed in the gausmarkov version.
In the original amp version the tone controls feed into the phase inverter and the power section so it's not an issue.



john

[ayayay!]

Got it thanks!  I was thinking about the 250k pot & resistor and that should be acceptable.

I was also horsing around w/ the tone stack calculator last night and basically came up with what you suggested. 

Thanks again! 

[ayayay!]

I slapped a 1M resistor across the outer lugs of the 1M output pot (thereby making it 500k,) and it worked great.  Took out the overbearing flabbyness and brightened it up.  Also did find a 100kB pot for the presence which was huge.  Other than respacing a few parts on the layout, this project is done and it sounds great. 

...If only I was a big Dual Rectifier fan...  I'm building this for someone else so there's no heartache in giving it up.  I gotta admit, a couple of the sounds I get out of it sound close to the real thing.