Hi All. I am currently in the process of copying the Boss Metal Zone Schematic into DesignSpark and then I plan on making my own pcb layout. I've got another thread on here where I used a layout from the internet but it had a few problems and also I plan on making 2 differences:
- Remove the switching and modify for true bypass
- Introduce a noise gate as it can been a noisy beast
Can anyone please advise on what I should be omitting to remove the switching and any buffer so I can use true bypass?
Heres the schematic:
(http://www.hobby-hour.com/electronics/s/schematics/boss-mt2-metal-zone-schematic.gif)
(http://i.imgur.com/IJWn0M4.png)
I think that's it Nick.
The output buffer probably can go too. So connect from the level pot wiper as far as that 10uF output cap (C001?).
Brilliant Jim, thanks as always. Once I've finished the redrawn schematic, I'll upload it before I get cracking on the layout.
(http://i.imgur.com/hv1NiYZ.gif)
Sorry, those borders always irritate the crap out of me. Looks much simpler with all that stuff out of the way.
botophucket.com screwed up the clarirty of my original upload.
Thanks Eric. Yes those border things are highly annoying and takes something away from the clarity.
Consider the possibility to introduce some mods. I modded my MT-2 stock using the Deizel mod, and though I have a cheap solid state amp, now I can use the pedal without feeling bad. ;D
I just had a read of this (http://www.lonephantom.com/2010/03/modding-the-boss-mt-2/).
The mods on there are either swaps or removals.
Well, that mods (and also the Bogner mod, it is pretty similar) is an ensemble of modifications.
If you don't have problem of space you can fill the pedal of switches, but I don't know how much sense has this. Every mod changes a bit the sound, and all together change more, perhaps not change a lot, but change enough in my opinion.
A consideration: testing the mods in a pedal after an interval of some minutes make hard to notice much difference. Anyway, I tested the sound of the pedal after every step, and I can say I could hear the difference of the sound after the whole "These three mods remove the harshness somewhat" (See the link of the previous post).
C35: remove
C34: 0.047uF MKT Capacitor
C25: remove
And after the diodes mod I noticed the difference.
You could keep the original clipping diodes, them have still a kind of harshness and compression, and to use a switch to pass to the other clipping (D3: Red LED; D4: 1n4001), those make the sound rounder, fuller and dynamic.
For the other mods I suggest you to make some tests and to choose the best components and the best result to your ear. I don't see the reason to choose between two sound, one bad and one better.
I prefer the MT-2 after the mod, and I will never want a switch to remove the mod.
I wish I helped you. ;)
Quote from: nickbungus on September 26, 2016, 11:58:12 AM
Thanks Eric. Yes those border things are highly annoying and takes something away from the clarity.
Bear in mind that the schematic we are looking at here is from the SERVICE manual for this particular manufacturer's product (not a clone/workalike). This product has 3 PCBs; the borders are an aid to make it clear to the service tech (who may not have seen an MT-2 before) where the various bits of the circuit physically live, which will save him/her bench time, and thus (more important), reduce the cost of a repair to the client*... Admittedly, this is a fairly simple circuit, and any tech worth his salt would not really need this kind of breakdown - but conversely these border markings are unlikely to cause that same tech any confusion,
Speaking (typing? :) ) as one who has had to earn a crust fixing electronics quickly and efficiently, I have to say that a nice service manual (like this range of pedals has) is a godsend (and I have seen some TERRIBLE manuals** in my time)... :)
* this ignores the present economics of repairs, but when these were new, they were fairly expensive, and labour costs were much lower than now...
** and this is getting worse because of the economics of repairs...
david
What I meant was I am grateful for Eric's help and for my purposes the borders are annoying and it's much clearer with them removed.
I totally understand why they are there and who the schematic is aimed at.
Updated my original post since botophucket screwed up the clarity of my first schem pic. Now it is much clearer.
Anyone wanting to cast a beady eye over this before I start my layout, I would be more than grateful? Thanks :)
(https://s18.postimg.org/7hteruqvt/My_Schematic.png)
I haven't ticked it off part for part, but I don't see any loose ends or wrong polarities.
You are missing a 0.047uf cap connecting to the positive input on U01b.
Thanks Jim and Chugs.
Chugs - Great Spot! I went through it marking everything off but that one got through the net. I know it was a bit of a cheeky ask but its much appreciate having a second set of eyes!
I've been battling away at this on my lunch breaks at work and have a layout that fits into a 1590b. Might have to choose my pots wisely to squeeze it all in but think it can be done.
While I have been making this I've done a bit of reading and Youtubing and its such an interesting pedal. Hated by so many but I had one and really regret selling it. I'd never gigged with it but its brilliant for bedroom metal. Some of the mods seem to make it a bit more friendly for gigging etc but I plan to make one as a 100% replica (albeit with the switching removed) and then make some more experimenting with the mods.
(https://s22.postimg.org/btuigy66p/20161016_173647.jpg)
I'd appreciate, and I think everyone else would too, if you would post the layout and BOM once verified. Of course, you don't have to, but we would like it, lol.
Sorry Eric. I should have said. I always intend on sharing 100%. I just don't want anyone wasting their time if I've made a silly mistake somewhere. Once built and working expect all files, layouts etc.
Anyone know what the analog man mods are?
Quote from: nickbungus on October 16, 2016, 05:19:54 PM
Sorry Eric. I should have said. I always intend on sharing 100%. I just don't want anyone wasting their time if I've made a silly mistake somewhere. Once built and working expect all files, layouts etc.
Anyone know what the analog man mods are?
Sorry, didn't mean to imply you weren't. Just been interested in making one of my own. Of course, you want to verify before people waste their time with it if there's a mistake. Got an issue with my 6 0DD FOxes chorus myself and been meaning to get back to it. Looking forward to the results.
One thing I found odd about the Metal Zone is that unity-gain inverting op-amp after the gain stage and clipping diodes - U04a on your schematic. It doesn't actually do anything. I can only assume that either they were concerned about the pedal being inverting or they had an op-amp left over (or both, I guess). It'd be seven op-amps without it, which isn't a particularly convenient number.
Tom
Edit: 04a not 04b
Correcting U02a inversion?
Those 10p caps over 22k are either the designers go to stability/anti rf or place holders in case more high cut was needed. You could fit anything up to 330p in lieu of 10p if you want without cutting any high end - and maybe you wouldn't know if you left them out altogether?
Well I have a working board. As predicted I made a few silly mistakes that have now been corrected and I'm going make another one this week.
Theres a few things which I need to address before I make a final version:
- Get each set of Pot pads together and on the board edge
- Look at the physical size of the caps. All the electros are occupying too much space and some of the others are too
Anyway the board is 52mmx 100mm
(http://s25.postimg.org/a3r1wwxj3/MZBoard.png)
And the layout:
(http://s25.postimg.org/n96k30ren/MZLayout.png)
And the bom:
Ref Name Component Value
C001 Capacitor 10uF
C002 Capacitor 10uF
C005 Capacitor 10uF
C008 Capacitor 220nf
C009 Capacitor 47n
C010 Capacitor 10p
C011 Capacitor 1uF
C018 Capacitor 10p
C019 Capacitor 100uF
C020 Capacitor 220nf
C021 Capacitor 1uF
C022 Capacitor 47p
C023 Capacitor 15n
C024 Capacitor 15n
C025 Capacitor 1n5
C026 Capacitor 100p
C027 Capacitor 10uF
C028 Capacitor 47p
C029 Capacitor 33n
C030 Capacitor 10uF
C031 Capacitor 47n
C032 Capacitor 100p
C033 Capacitor 15n
C034 Capacitor 27n
C035 Capacitor 10n
C036 Capacitor 22n
C037 Capacitor 1uF
C038 Capacitor 100n
C040 Capacitor 100uF
C041 Capacitor 100uF
C042 Capacitor 47nf
C043 Capacitor 8n2
C044 Capacitor 10n
D003 Diode 1n4148
D004 Diode 1n4148
D006 Diode 1n4007
U01 Opamp TL072
U02 Opamp TL072
U03 Opamp TL072
U04 Opamp TL072
R001 Resistor 1k
R002 Resistor 10K
R003 Resistor 100K
R004 Resistor 100K
R012 Resistor 2k2
R013 Resistor 100k
R014 Resistor 22k
R015 Resistor 22k
R024 Resistor 10K
R025 Resistor 470k
R026 Resistor 22k
R027 Resistor 470ohm
R028 Resistor 22k
R029 Resistor 100K
R030 Resistor 3k3
R031 Resistor 4k7
R032 Resistor 10K
R033 Resistor 2k2
R034 Resistor 1K
R035 Resistor 47k
R036 Resistor 47k
R037 Resistor 10K
R038 Resistor 47k
R039 Resistor 1M
R040 Resistor 100K
R041 Resistor 1K
R042 Resistor 10K
R043 Resistor 100K
R044 Resistor 220k
R045 Resistor 10K
R046 Resistor 2k2
R048 Resistor 2k2
R049 Resistor 330ohm
R050 Resistor 330ohm
R051 Resistor 1K
R053 Resistor 47k
R054 Resistor 10K
R056 Resistor 10K
R057 Resistor 10K
R058 Resistor 1M
R059 Resistor 10K
R060 Resistor 10K
R061 Resistor 2k2
R062 Resistor 2k2
CLR Resistor 2k2
Q001 Transistor 2N5088
Q007 Transistor 2N5088
Q008 Transistor 2N5088
Q010 Transistor 2N5088
Q011 Transistor 2n5457, 2n5484 etc
Good work Nick! You'll get it.
Cheers Eric. My v1 is built and works although I totally messed up the transisitors (fixed in the above layout) and also, I got a lot of lifted pads as I used some old copper clad board that had been printed on and then rubbed off.
I've just bought some new board so I'll be on it again soon. I think I'm going for the Deizel Mod with this one
Heres my V2 board. Unverified (update: Verified!) as I'm just on the vinegar strokes now but I'll report within the next couple of days.
I've got all the pot pads next to each other but it I've now had to add a couple of jumpers. Still I reckon I can squeeze it home into a 1590b.
The sizes are 52mm x 94.5mm
(https://s25.postimg.org/tr7vt17sv/MTv2_Layout.png)
(https://s25.postimg.org/4in1zd2v3/MTv2a_Board.png)
(https://s25.postimg.org/8t1puy7y7/MTv2_Board.png)
Liking this one better nick. I started to do my own the other day and realized I wasn't interested enough to go as far as designing my own board for this pedal when I already have an original and there are a couple of layouts available already. I'd like to know when and if this latest layout works. I'll give it a go when you've verified it.
Hi Eric
I've just finished it bar the boxing and its 100% working. :)
I used a dual Linear pot (B) instead of the Reverse Log (C) for the parametric mids and will probably change it as its only useful in the last third.
Sounds awesome for bedroom metal (I actually love the fact so many people hate this pedal!). Dont know if its because I built it myself or because my practice rig is better or its just a bit better with the modern subs (ICs and trannies) but to my ears it sounds better than what I remember my original sounded.
I'll post the board size and also an alternative version that I didn't do a copper fill on. I actually made the one without the copper fill but etched a filled one too. I'll use this one for my modded version.
For this version I thickened the traces and the pad sizes.
Chuffed to bits that it works! :P
If you want Eric, I'll send you the DesignSpark files, if you want to make some improvements. Don't know if you've ever used it but its free, quite straight forward and the files can be converted to Eagle.
That's cool nick. Don't bother with the files unless anyone else is interested. Please do let me know the dimensions of the board though.
Sucks about the pot. All I could get was a dual linear as well. Bought several the other day just for this build. Thinking maybe of trying this stock first, compare it to my original, and then with a few mods. There are some I found that are supposed to get rid of the harshness and better the tone control. There is a guy on youtube.com I like to watch who does guitar builds and has modded this pedal. CSG guitars I think is his brand and his name is Collin, maybe. I think he is in the U.K. somewhere. Good shredder and funny to watch.
I like how everyone hates this pedal too. Then you look on ebay and all the reviews are mostly positive, from what I remember. Agreed, it is good for bedroom playing. My amp is SS anyway so it doesn't really matter to me, I guess, though.
Thanks for the hard work.
I've updated the images. The sizes are 52mm x 94.5mm
I had a few places where I had holes for a ceramic but used a mylar and the other way round. These are now fixed. Also, the schematic has polarised 220n's but I used some ceramic non-polars for these.
I dont know how genuine these are as they were stolen from another forum but heres a list of mods:
Diezel mod:
C35 : remove
C34 .047uF
C25 : remove
these three mods remove harsh
C42 1uf
D3 DEL
D4 1n4001
------ make the sound more dynamic and full
C36 .1uf----- EQ more usefull
Boogie/Bogner mod:
C35 a enlever
C34 .047uF
C36 1uF
D3 led
D4 1n4001
EN PLUS:
R46 increase values, more pre-distortion + mids
R41 reduce value you obtain more distortion (470ohms to start)
Mods don't have the same sound of diezel amp or Bogner amp, but it can be better tant the stock sound.
Keeley mod:
C20 .22uf
c42 .1uf
c37 , c39 , c17 , c11 1uf
c8 .22uf
c9 .1uf
c20 .22uf
d3 , d4 LED
I'm going to give the Keeley one a shot.
I'd like these sort of mod suggestions much more if they came with some more detail about *what they actually do*.
No criticism of you intended, nickbungus. I know how it goes, and we look for clues wherever we can find them. Me too. But I wish the people who came up with mod X or mod Y actually bothered to understand what it was their mod had altered and quantified it in some way.
What I'd like to see is stuff like "Change C46 from 330n to 470n to move the midrange peak down from 2KHz to 1.4KHz" or similar (I made that up - don't try it). But instead we mostly get touchy-feely stuff, like " change C46 to 470n to remove harsh top end". One person's "harsh top end" is another's "cutting solo tone". I'd rather have a few facts.
</grumpyoldman>
Tom
Sorry. It was a blind copy and paste job as is looking for what he mods are. For the uneducated like me, I usually find a YouTube video comparing the stock model against a modded one.
I do wish I understood more though and had the facts.
I etched my copper fill board and it was a bit tight with the gaps so heres a later version:
(https://s25.postimg.org/5cetjbrun/MTv2_Board.png)
I am going to perform a dark magic trick and resurrect this thread just to say a big thank you to Nick! I think more people should see this.
I almost shed a tear when I heard this amazing "djdjdj" for the first time since around 2003 when I bought the original. It was the first pedal I ever bought, also with my first self-earned money (I think I was still in high school).
Anyway, I've got mine up and running. For some reason my low pot does not work. It seems like it stays in it's neutral position, because there's just enough of it, haha. Let's see if I can find what's wrong once I am sober :icon_mrgreen:
(https://s13.postimg.org/r2itnwjj7/image.jpg) (https://postimg.org/image/r2itnwjj7/)
You're more than welcome. I love mine and still use it although not for gigging. I use it in the house for those hair metal moments.
I'm not sure whether it's better to start a new debugging thread or not so I just post here. For some reason my LOW control does not seem to work properly.
My LOW control does not seem to work correctly. At first it did not work at all, then I found a broken pcb track around c008 and fixed it. Now it seems that the control works as some sort of a mixture of gain and volume control (my wild guess is that it could be a way too low Q, but I am absolutely not sure).
When I started debugging, I noticed that C009 was missing in the redrawn schematic. However, it is present in the layout. I checked all the components that I believe to be the low freq control gyrator and all the values appear to be correct.
(https://s13.postimg.org/91soa6etf/low.png) (https://postimg.org/image/91soa6etf/)
(I added the c009 to the drawing)
I am almost certain that it's some sort of silly mistake I made somewhere (as always), but I am clueless. Any suggestions please?
Chuggs spotted the missing cap. I fixed it but didn't upload the amended schematic
I am still struggling to get the LOW control working right. Could someone please suggest me something else to try before I go nuts and smash the board with a hammer, start running naked in the street ect?
Sorry, I would love to be able to help but I'm an idiot and I dont really understand electronics.
But if you want me to test anything on my working board I will gladly help.
Thanks for your support, Nick! You've done a great goodness for the community already by making this thread happen!
It would be really helpful if you could measure the DC voltages at all pins of U01 and U04 IC's. Or, if you really don't mind, at all the IC's and transistors so that I don't molest you again later.
Talking about being an idiot and not understanding electronics, I am a damn expert at that stuff :-[ :icon_rolleyes:
I'll get it sorted. Wont be until about this time tomorrow though. Sorry
If you post the voltages of your ICs and transistors we could probably at least point you in the right direction for where to look ;) When you've been around them enough you start to figure out what to expect on each pin regardless of what circuit it's in, moreso when it's accompanied by a schematic.
How heedless of me not to post my voltages :icon_redface: Here's what I get now:
Bat:9.16
+9: 8.94
U001 pin1: 5.74
U001 pin2: 5.74
U001 pin3: 5.71
U001 pin4: 0
U001 pin5: 4.28
U001 pin6: 4.33
U001 pin7: 4.33
U001 pin8: 8.94
U002 pin1: 4.33
U002 pin2: 4.33
U002 pin3: 3.93
U002 pin4: 0
U002 pin5: 4.28
U002 pin6: 4.34
U002 pin7: 4.33
U002 pin8: 8.94
U003 pin1: 4.24
U003 pin2: 4.27
U003 pin3: 4.22
U003 pin4: 0
U003 pin5: 4.22
U003 pin6: 4.28
U003 pin7: 4.27
U003 pin8: 8.84
U004 pin1: 5.75
U004 pin2: 4.26
U004 pin3: 4.26
U004 pin4: 0
U004 pin5: 2.75
U004 pin6: 2.74
U004 pin7: 1.96
U004 pin8: 8.82
Q010 E: 3.60
Q010 B: 4.17
Q010 C: 8.79
Q011 D: 8.79
Q011 S: 3.68
Q011 G: 3.82
Q008 E: 3.59
Q008 B: 4.16
Q008 C: 8.77
Q007 E: 0.07
Q007 B: 0.07
Q007 C: 8.77
Q001 E: 3.53
Q001 B: 4.09
Q001 C: 8.76
By the end of the measurement the battery (disconnected) voltage was 8.76 volts. I am not sure if it's just because of the cheap zinc-carbon battery I used or if something actually draws way too much current.
Hi. I'll get you my voltages tomorrow when I get a moment. I'm sure we can work it out.
U4 is an immediate red flag. I'll sit down with the schematic when I have more time and give a solid look through (nick will probably have his voltages by then :P), but I would check your connections around U4. Also, did you socket your ICs? if so, pull U4 out and check the voltages in the socket. You should be seeing about 1/2 of your battery voltage on pins 5, 6, and 7.
That might be a bit of meter loading Nathan. I'm no expert. I just remember PPR mentioned it a few times. :)
Shouldn't Q7 voltages match those of Q8?
Looks to me like the BE junction is shorted.
Behringer ultra metal UM300 is said to be a copy of the metal zone though with SMD components and on a youtube vid someone
picked out the matching mod components on boss and Beringer board .
C35 -> C18
C34 -> C16
C25 -> C19
C42 -> C12
D3 -> D4
D4 -> D3
C36 -> C27
I've put my voltages to the right of yours.
Quote from: swever on January 29, 2018, 03:03:19 PM
How heedless of me not to post my voltages :icon_redface: Here's what I get now:
Bat:9.16
+9: 8.94 8.94
U001 pin1: 5.74 4.43
U001 pin2: 5.74 4.43
U001 pin3: 5.71 4.41
U001 pin4: 0 0
U001 pin5: 4.28 4.33
U001 pin6: 4.33 4.40
U001 pin7: 4.33 4.40
U001 pin8: 8.94 8.82
U002 pin1: 4.33 4.40
U002 pin2: 4.33 4.41
U002 pin3: 3.93 3.96
U002 pin4: 0 0
U002 pin5: 4.28 4.36
U002 pin6: 4.34 4.41
U002 pin7: 4.33 4.41
U002 pin8: 8.94 8.92
U003 pin1: 4.24 4.37
U003 pin2: 4.27 4.39
U003 pin3: 4.22 4.33
U003 pin4: 0 0
U003 pin5: 4.22 4.33
U003 pin6: 4.28 4.41
U003 pin7: 4.27 4.39
U003 pin8: 8.84 8.92
U004 pin1: 5.75 4.41
U004 pin2: 4.26 4.37
U004 pin3: 4.26 4.39
U004 pin4: 0 0
U004 pin5: 2.75 4.31
U004 pin6: 2.74 4.35
U004 pin7: 1.96 4.36
U004 pin8: 8.82 8.92
Q010 E: 3.60 3.68
Q010 B: 4.17 4.28
Q010 C: 8.79 8.92
Q011 D: 8.79 8.91
Q011 S: 3.68 7.54
Q011 G: 3.82 3.91
Q008 E: 3.59 3.68
Q008 B: 4.16 4.28
Q008 C: 8.77 8.82
Q007 E: 0.07 0.09
Q007 B: 0.07 0.09
Q007 C: 8.77 8.90
Q001 E: 3.53 3.70
Q001 B: 4.09 4.20
Q001 C: 8.76 8.91
Because of the way it was squeezed in I was working on the back so I had to mirror the layout and find my way around so I might have made a mistake. I also think I may have sprayed the circuit afterwards with some protective stuff but I cant confirm this but if I stabbed hard enough I could get a reading.
Most of those look like they're in the right ballpark apart from Q11 and the second amp on U004. Swever's Q11 source is low, and the U004 amp is way low.
Something is pulling pin-5 on U004 low. The entire trace to R029 and C021 is surrounded by ground-pour, so it wouldn't be very difficult to get a solder-bridge there. It can't be on the *other* side of R029, though, because that would screw-up U003 too.
Pin-1 is high because that half is inverting the too-low signal going in. It's also connected (through R014) to pin-3 on U001, which explains the too-high voltages on pins 1-3 there.
I'm having trouble wrapping my head around how that could affect the tone pots, but it somehow seems reasonable that it would.
As for Q011, I dunno... the gate definitely shouldn't be higher than the source, but aside from that, JFETs are so variable that different voltages don't necessarily mean much. Double-check the pinout (it's not especially uncommon for different manufacturers to use different pinouts even for the same part-number), but since it's a source-follower input buffer for a distortion pedal, I myself would be inclined to let that particular sleeping dog lay where it is as-long as it passes signal.
One thing I was pointed to on a local forum is that the polarity of C021 was reversed on the redrawn schematic and layout. I've been told that it could cause some leakage and be the reason weird voltages on U004. So I flipped it and got what looks like more correct voltages to me:
U004 pin1: 4.09
U004 pin2: 4.09
U004 pin3: 4.09
U004 pin4: 0
U004 pin5: 4.05
U004 pin6: 4.10
U004 pin7: 4.10
U004 pin8: 8.34
However, that has no effect on the LOW behavior - it's still the same.
Quote from: vigilante397 on January 30, 2018, 11:31:13 AM
U4 is an immediate red flag. I'll sit down with the schematic when I have more time and give a solid look through (nick will probably have his voltages by then :P), but I would check your connections around U4. Also, did you socket your ICs? if so, pull U4 out and check the voltages in the socket. You should be seeing about 1/2 of your battery voltage on pins 5, 6, and 7.
Yes I did socket. Not sure if it's still relevant after swapping the C021 polarity, but here's what i get on the socket with the IC removed:
pin1: on the first measurement starts with about 4.8 then drops rapidly to about 0.8 then start to rise slowly. After a few measurements settles at about 2.69
pin2: same as above
pin3: 4.10
pin4: 0
pin5: 4.06
pin6: seems to be the same as pins 1&2
pin7: seems to be the same as pins 1&2&6
pin8: 8.36
I have a gut feeling that the problem is within the LOW gyrator. Maybe a dud or mislabeled cap. What would I do if I wanted to increase it's Q?
EDIT: dammit there's no caps in the gyrator other that 220nf, which I actually desoldered and tested. Anyway, how do I increase Q?
Alright, guys. I am feeling very embarrassed right now. It was a cold solder on one of the C009 lugs. :icon_redface:
Thanks everyone for support and shame on me, lol. Again.
Hooray!!! 8)
Well done. I'm glad its not my crappy layout then!!
The layout is top-notch! I started trying the various "mods" to find a configuration that I like the most.
I've spent another weekend playing with the circuit. One thing I've discovered is that C017 is missing in the redrawn schematic as well as the layout. I thought I wanted to see what kind of effect it has so I made a small modification to my board (breaking two tracks and adding one jumper as well as the capacitor itself). I edited the component layout and pcb files to allow for adding this cap. I think it should be correct but take anything I say with a grain of salt.
(https://s18.postimg.org/e31jencfp/MTv2_Board_fix.png) (https://postimg.org/image/e31jencfp/) (https://s18.postimg.org/ic69gtnet/MTv2_Layout_fix.png) (https://postimg.org/image/ic69gtnet/)
Also fixed C021 polarity.
I actually liked the effect of adding this capacitor. It makes the whole thing sound even more "90's hifi" and again adds a mid-scooped character. The circuit is absolutely usable without it and has a tad more focus on mids and low mids. In fact, that may even work better at rehearsal/live levels with other musicians etc. For bedroom use I clearly prefer it with this cap.
I tried all the mods listed earlier (and tried different component values at each "mod point"). Ended up with this (I used a b100k dual pot for mid frequency which may have affected some of my choices):
C017: 47nF (473) (stock value)
C009: 100nF (104)
C024: 18nF (183)
C025: 330pF (331)
C034: 47nF (473)
C035: 5.6nF (562)
C036: 8.2nF (822)
C042: 1uF (105)
D003: 1N4739A
D004: d9d germanium
I think it sounds divine now :P Am going to etch a new board and make a new clean build (I completely ruined the current board with all these mods).
Brilliant.
Whoops, sorry for missing something. I can add it tomorrow and post an updated board if that helps.
No worries, man. I am actually fine with my quick and dirty photoshop fix - so no need to fix it just for me. :icon_biggrin: I am sure other builders would enjoy an updated layout by you, though. Which they should because it is an amazing circuit and deserves much more attention among diy'ers than it gets.
Etched, tinned and drilled a new pcb this weekend. This will hopefully make a "final" board to go into an enclosure.
(https://s10.postimg.org/dgj1tjw7p/mz_pcb.jpg) (https://postimg.org/image/dgj1tjw7p/)
Also spent a few hours more playing with my "prototype" board. I can't say enough how much I like this circuit. It's all sorts of 90's metal tones in a box at bedroom volume.
I noticed, however, that either with gain or guitar volume set low, or just very soft picking - basically anything that makes the input level go low, I get a nasty layer of fizz. It actually happens all the time, even with louder signals, but it get buried in the wall of METAL. But once I pick lightly or just let a note fade out naturally I get that bzzzbzz kind of "satellite" sound. It's also quite noticeable with those chugga-chugga palm muted notes and chords. I will try to record a sample later.
I've been wondering if it's an inherent feature of this circuit or not. I think I do remember my original one doing that, but I may be remembering what did not ever happen, lol. I also wonder if there is anything I can try to address this issue.
Nick (or anybody else who built this or has the original and see this message), could you please check if yours does the same?
I'll have a check when tonight if possible but I cant remember it doing that and I have tested all the pots
I tried recording it with my phone but it wont cature the very high frequencies where all the undesired stuff happens. I will have to wait to receive my replacement RAM to get my recording PC up and running again so I can record with a proper microphone.
What I hear sounds like there is a certain threshold at which clipping occurs very abruptly creating a lot of harsh harmonics. It's much less noticeable once all or most of the signal is above that threshold. It becomes a lot more noticeable once the signal level jumps around that point, causing the harmonics to appear and dissapear quickly. Things like playing realy softly, setting the gain to minimum or playing (heavily) palm muted notes/power chords makes this stuff really prominent.
Just wanted to inform that the issue completely fixed by replacing the first opamp (U03) from lm358 to a 4558. Now everything is smooth and nice at any gain level.
I am still tweaking mine after all these months... loving this so much. All the time I keep on finding ways to make this thing sound more like I want. Gotta build the final board and box it up someday :icon_cool:
I guess I'm done with modding and I finished my clean pcb yesterday. Just need to box this bad guy up now. This is going to be some kind of special box for sure.
Anyway, here's a few pics:
(https://scontent-bru2-1.cdninstagram.com/vp/a3e744fcde43b46ce5535ad8ad2b7ad6/5BFD6C75/t51.2885-15/e35/39144965_1035911486586173_1678491636096565248_n.jpg)
(https://scontent-bru2-1.cdninstagram.com/vp/c9aa7d9d4f9a8f4b359009084497b605/5C03865E/t51.2885-15/e35/39404239_2148446015418627_3572109705784328192_n.jpg)
(https://scontent-bru2-1.cdninstagram.com/vp/0957f6adf8a27eebd7e731e9675c0556/5C38EEFE/t51.2885-15/e35/39024077_619918558402173_3627172728412307456_n.jpg)
And, more importantly, here are samples I've recorded: 1 (http://picosong.com/w5SqQ/), 2 (http://picosong.com/w5g7r/), 3 (http://picosong.com/w5gzY/)
Sounds great. I'll never understand why people diss the mz.