Monday, 19 March 2012

Tone Bender MkII - PNP with negative ground

Request.  This will allow you to use the better quality PNP germanium transistors, but keep a negative ground so it can be daisy chained with all you other NPN effects.


79 comments:

  1. Interesting! So the 47 cap is doing double duty as the power filter cap and the charge pump's negative well cap?

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    1. I think the datasheet shows a 10uF from pin 5 to ground, but I'd always use a filter cap anyway with a fuzz pedal, so I just included a single 47uF.

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  2. I'm going to breadboard that soon and take some readings, compare to using the 10µF. You're correct, that pin 5 to ground 10µF cap is the well or output cap for the charge pump. Always nice to eliminate a component if you can.

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  3. Awesome! Making this when I get back up and running!

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  4. Awesome! Making this when I get back up and running!

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  5. Replies
    1. Yes any PNP transistor at your preferred gain

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    2. Used the AC128s and this thing sounds amazing! Thanks for the layout!

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    3. Great stuff, no more daft polarity power supplies required! :o) Send me a pic if you get chance for the collection.

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    4. Really proud of this one: http://flic.kr/p/cJSa8m

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  6. Hi Mark, I have been looking at this layout, and reading up on this circuit at fuzzcentral, one of the things I would like to do is add a trim pot so I can dial in the bias on Q3 correctly. I am going to build up two of these, I have some Tonbender matched OC75 from smallbear, and some 2n404 (I think) from somewhere that I might try as well.

    Two questions: First, do you think adding the trimpot is really necessary??
    Second, to do that I would just replace the 8.2K with a trimpot wired as a variable resistor?? Is there other values I should be tweaking as well?

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  7. Hi mark i have sorta the same question as dave above here. I also have oc75 and ac128 that im going to use. But im uncertain how to add a trimpot, so i wonder were to put the 3 legs of the trimpot? And what vaule should the trimpot have 10k? Ok thanks
    Jens

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    1. Swap the 8K2 for a trimmer and yes 10K would probably be the best value. Solder 1 and 2 into the top and bottom resistor connections respectively, and ignore the third pin.

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  8. Would a MAX1044SCPA work in place of the ICL7660S?

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    1. Yes. Those are pretty much the same converters.
      +m

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  9. i love this pedal, used ac125's with gains of 57. 59. and 130
    i also used an external bias pot. very versatile and beautiful sustain.

    http://img.photobucket.com/albums/v355/tomkogut/photo1-2_zps6040a582.jpg

    http://img.photobucket.com/albums/v355/tomkogut/photo2-1_zps5519e47b.jpg

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    1. Nice jobs Tom, thanks again for the pics, they make good additions to my collection!

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  10. i'm using a 7660scpaz and getting a weird low volume, high pitched squeel ONLY when the guitar's volume is all the way down? any ideas what could be causing this?

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  11. I finished this one up, but unfortunately the volume is pretty low even when cranked all the way up. I tried the 470R to 1K mod, and it just became very noisy so I changed it back. Is there any other way to get more volume?

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  12. It sounds like you wired in your volume pot with the wrong value, I did the same thing. I wired the 1k instead of the 100k because I had the pots installed in the unit and didn't realize the screw up until I fired her up.

    Here's some shots of my build. It's bigger than a standard Big Muff Pi.

    http://users.eastlink.ca/~aszwec/pics/Black_Dragon1.jpg

    http://users.eastlink.ca/~aszwec/pics/Black_Dragon2.jpg

    http://users.eastlink.ca/~aszwec/pics/Black_Dragon3.jpg

    http://users.eastlink.ca/~aszwec/pics/Black_Dragon4.jpg

    http://users.eastlink.ca/~aszwec/pics/Black_Dragon5.jpg

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  13. Hi,

    I just built the MkII and was getting some great tone until I noticed that it was a bit low on the volume. I'm using three different germanium caps - AC127, AC128, and a 2n388. Not to sound entirely stupid (I am new to building pedals) but, could that be the basis of my problem? Also, I'm using a B5k for the attack and A100k for the volume.

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    1. hey mate it seems to me you have the wrong transistors, the ac127 and the 2n388 are NPN germanium trannys and the ac128 is PNP, this circuit calls for ALL 3 to be PNP transistors and then the polarity is converted to be +ve ground by the charge pump so you can chain it up with your other effects, i would cease using the pedal until you have the correct trannys or you will damage them, if you have more ac128 then use those for all q1, q2, and q3 and remember to keep them in the proper gain range. If you dont have the ac128 but you have another NPN transistor then you might want to consider mirosol's mindbender which is a NPN tonebender. Hope this helps mate

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  14. Thanks, Souljah. I wrote the trannies wrong. I have a 187, 127, and the 388. I read that I could switch out the 470R resistor with a 1k to get more volume. I also have that B5k as the Attack knob. I'm looking at replacing it with a resistor just over 1k.

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    1. yeah mate but they are still NPN trannys where you need PNP for this circuit, read the small txt underneath the vero layout

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  15. Yeah. I'm red faced now. Can't believe I mixed that up. Probably fried the trannies. Thanks for the input though.

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    1. oh man don't worry about it, these things happen, i did the same thing myself last week and the trannys were fine, you might still be alright, its all part of a learning curve, definitely give the mindbender a whirl.

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  16. Is the little tab on the electrolytic caps negative?

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  17. little tab? if u mean the lighter patch on the layout? yes that relates to the strip on -ve lead of the electrolytic caps

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  18. hi,
    Here is my attempt on that build. So far no luck getting it to work.

    https://picasaweb.google.com/115698165454918398886/TonebenderAttempt02?authuser=0&feat=directlink

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  19. i'm getting a lot of noise on this considering i used shielded wire for the input and output. could it be the layout has the transistors too close to each other?

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    1. I don't think that's the issue. Some individual transistors just are noisier than others. Figuring out which one is the hard part...
      +m

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    2. well smallbear has agreed to send me a new set! so hopefully that fixes my problem!

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  20. This comment has been removed by the author.

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  21. Had to re write this comment as I did several errors on my original build.

    Finally this effect souns just incredible, but you have to take in mind some hints:


    - I strongly believe that the volume mod (1k-1k2 instead of 470r) and 20k trimpot instead of 8k2 resistor are a must.

    The output is really weak if you stick to GGG recomendations, and bias the Q3 collector at 4.5 volts. Once again, David Main is "the captain": Q3 collector should be biased from 7 to 9v volts. With this voltage, the output is greatly improved, and the sound gets more fuzzier and aggresive.

    - NEVER use a russian germ for Q1 or another low to none leaking trannie. If you do so, you'll get an overdrive sound, but not a fuzz. Besides, the sound will get flarty and dull with low attack settings. An about 200uA leaking, 50-70 germ will do the trick flawlessly.

    - If you bias the Q3 collect over 7 volts, you can forget too the GGG recomendation of using a 2k pot for Attack.

    By the way, my set of transistors: Q1 AC184 60hfe, 200ua leaking, Q2 GT308B 70hfe, no leaking, Q3 AC184 109 hfe, 90uA leaking. Q3 collector biased finally at 7,8v.

    Enjoy this build!

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  22. I also mentioned this at stompbox.org. I posted images of my build that used this exact layout which is excellent. The following is an excerpt of that post:

    Dialing in -4.5v is totally wrong, I measured my collector voltage at Q3 and it came in at -5.04v, and it sounded squishy, farty and compressed. After I installed a 10k pot, I dialed it in by ear and it no longer sounds the same, but, aggressive, more bottom end, richer. I uninstalled the pot to measure it, and it measured at 1.088k. Wow, the measured voltage installed on the collector of Q3 was 8.77v. Now I was in the ballpark. I decided to install a 2k pot permanently instead, I didn't want all that play in the bias knob, I didn't care for that farty squishy sound. It now has the qualities of the tonebender sound that I was chasing after.

    I posted a sound clip for sonic approval (enjoy my mediocre playing skills, put earmuffs on your cat or dog.) .

    The clip was recorded with a Classic Series '72 Telecaster Custom, into the pedal, into a THD tube amp, plus a touch of reverb.

    http://users.eastlink.ca/~aszwec/pics/huh.mp3 (19M)

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    1. Transistors used are TUNGSRAM ac128 (66hfe, leak: .160mA) Q1, Russian 1t308B (79hfe , leak: .000mA) Q2, and lastly a NTE158 (120hfe, leak: .230mA) Q3. All measurements done by the Peak atlas DCA55.

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  23. This is an awesome layout but it DESPERATELY needs modding, as all Tone Benders do. Here's some mods I tried and find all of them useful. Most of them are already mentioned here but.. you know.. here:

    1. BIAS THE TRANSISTORS PROPERLY! This is the most important thing. Q3 needs 7V or more and Q2 should be biased to taste also so It'll work correctly in conjunction with Q3.
    2. This thing sounds the best (most loose and natural) if Q1 leaks like hell. Throw in your crappy trannies that leak too much (preferrably 70hfe or more) and swap the base resistor from 100K to 10K.
    3. Try playing around with the axial 4u7 electrolytic and the 10n cap. Up them for a smoother sound (bassier, less trebly)
    4. Sub the 470R for a 1-2K for more volume. I used 1K and I'm happy with it. Biasing the trannies hotter also helps with volume.

    It's just way too shrill and uptight as it is. Mod the hell out of it! Here's my take on the subject:
    http://tinyurl.com/ohvhlht

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    1. Myrkky

      That burst finish just looks great. Really impressed. May I ask how you get the stippling of color in the brown region? It looks like there are all kinds of different shades stippled in there. Would love to try that on one of my builds ( been building for 3 years and still just use the plain metal enclosure - time to try some color...)

      Thanks

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    2. Thanks man! I really like how it came out too. Well the thing is that I painted the bottom with a grainy texture silver sparkle/gray paint. I noticed that it isn't such a good Idea after all 'cause the texture will eat crraappplloooaads of lacquer. But a plain sparkle/flake or something that cuts through will do fine. The blacks are pen sprayed and the burst color is vintage amber mixed with brown. Just a dyed lacquer, no paint. And a finishing touch with a clear coat makes it look more 3D.

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    3. Appreciate the info. I'll give a try on the next enclosure.

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  24. Made another one based on this. Slightly different from the previous one and with a magic BIAS-pot called "Character". I tweaked and tweaked and tweaked and then I tweaked to make it work correctly. The other end is a tight, overdriveish fuzz with a very sharp bottom end and the other end is full blast nintendo hell. I think this is the best fuzz build I've ever done, I'm gonna make more of these.. Also improved the burst with a delicious caramel touch. Doesn't really sound like a tonebender anymore but I've always thought that genuine benders are a waste of a perfectly good concept. Too shrill and uptight for my tastes. I'm pretty proud of this one, it's my baby. Check it out:

    http://s7.postimg.org/ck4nzvb3u/FUZZ.jpg

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    1. Another great looking burst...I'm gonna get up the nerve to try that someday.

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    1. Hi, I not boxed my yet, but it sounds great. I started to measure hfe in my transistors, and do not know if I'm doing something wrong, because at least I have a 90, then 100, 120, 140.150, 220, 310! Is it possible? I bought them once unused, AC128. I have not tested all yet, for now the best is 90 100 120, I only swap q3 for 220 and was too farty, but 330 was ok.
      Maybe my meter is broken :) because everyone have hfe from 65 to 110?

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    2. What are you using to measure them?

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  26. such a cheap meter, Vortel 81780
    http://media.toya24.pl/media/catalog/product/cache/2/image/b6938671c34937894d4f3f52c30ec4f7/8/1/81780_1.jpg

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    1. You can't accurately measure germanium transistors with that kind of meter. You will need one that is designed to measure and take into account leakage to get accurate numbers. Something like the Peak DCA55 or DCA75 will do this.

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    2. Yup. That can't measure germanium transistors accurately, but it is very nice cheap meter. I have one of those (same meter, different brand) that i bought about 12 years ago. It reads resistance very steadily. Sadly it's not in active use anymore as i got Uni-T with automatic range and other features. Sometimes i hope it would be as steady as that old one...
      +m

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    3. thanks for the info, this time I will select at my ear :)

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  27. I built this one the other day seemed to be working just fine but today i wanted to give it a try before boxing it and suddenly stopped working now it just makes noise every component seems to be working I even tried building it again (same components diferent board) but still making the same noise I checked the IC voltage is
    1-9.62
    2-4.83
    3-0
    4- -4.64
    5- -9.40
    6-4.99
    7- 4.29
    8- 9.62
    What do you think? I'm new on this I really have no idea of what could be wrong every component seems fine to me

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    1. IC voltages look fine, as long as you're getting -9V on pin 5 it's performing its intended function. What are the transistor voltages?

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    2. They're all toshiba 2sb56
      Q1 base 0, collector -6.80, emitter 0
      Q2 base -0.09, collector 0, e 0
      Q3 base 0, c -5.55 e -5
      I dont get it :(
      I don't get it

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    3. No there's definitely something wrong there. Post a front and back pic of the board, see if we can spot something obvious

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    4. http://es.tinypic.com/r/11l7y8w/8
      http://es.tinypic.com/r/14cw786/8
      http://es.tinypic.com/r/muh1rd/8
      I had to improvise making my own stripboard since they're hard to find here in mexico,
      Ground wire is not in the 1st hole I just moved it but it's in the same strip so it should be ok right?
      What do you think?
      Thanks for helping me man i'm new on electronics and I really dont know what could be wrong

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    5. I just replaced all the electrolitic caps and it started working for 20 seconds and then it made the same thing started making noise and suddenly just noise, i get pretty much the same readings on Ic and tranies maybe I should just try another brand of caps what do you suggest?

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    6. I changed every resistor and every cap and it kinda works but makes a lot of unexpected noises and the actual sound of the guitar is too weak, I really dont know what else to do maybe the transistors aint working properly or maybe the IC , Maybe the transistors leakage is too much i measured 300, 122 and 133 hfe

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    7. Have you got any other transistors you can try, because they seem to be the common denominator

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    8. Not right now, but I'll buy new ones tomorrow I'm thinking on tryin lower hfe transistors, I'll let you know when I get it running , thanks

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    9. Have you got any silicon PNP? It won't sound spectacular or anything but it should give you an idea if the circuit works ok and if at least one of those Toshiba's are dodgy

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    10. I tried another set of pnp silicon and got the same result, this is really weird

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  29. Is the difference in voltage between pin 1 and 5 of the 7660 a possible indicator that they are not directly coupled (and therefore not engaging the boost function)?

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  30. Oh wait.. That's 1 and 8.

    What kind of power supply are you using Leon? In my experience, sometimes a MKII just needs to be powered by a battery. I don't understand why, but I've had a lot of problems with MKIIs and wall warts

    Try powering your build with a battery and see if that works

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    1. I just built it on the proto board and it works perfectly, there's something wrong with my board I'm thinking a solder bridge, but it sounds great on the proto I think I'm gonna ad the bias trimpot to the Q3
      Thanks!!

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    2. I cleaned every line real good it's working perfect, I didn't notice much difference adding the 10 k trimpot for biasing Q3
      Thanks guys

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  31. Built this one today! My second Tone Bender MKII (used a different layout for the first one though, which I didn't like so much ;)). Used a TC1044S CPA from Tayda and it works wonders here. I got the first IC fried though - when I plugged in this old power supply there was this little spark coming out of the DC jack - I still don't know if the problem was the supply or the IC...

    I biased mine by hear, using a pot soldered to the board, while playing with the gain and volume control. Checked the voltage later and it was ~6V.

    Oh yeah, one more circuit that needs to get boxed!
    Thanks, Mark!

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    2. Just for a little update:

      I still don't have this boxed, so I got my Test Box and started playing with it once again. Took some measurements and Q3 voltage was exactly @ 7V lol I'm not sure if it's because we're in Summer here in the southern hemisphere or if I made some resistor change and can't remember (I have an 18K resistor going to Q3 C now).

      Anyway, this thing is animalesque as hell - loads of volume and thick fuzz. Actually, I can't tell much difference in fuzz with the gain control past noon or so (I'm one of those using a 2KB gain pot and a 1K resistor instead of 470R). Even with gain on "0" it's pretty fuzzy. Volume is plenty loud by the same 11-12:00 mark also (louder than both my Si and Ge fuzz faces). Still cleans well on those higher gain settings, especially considering the amount of fuzz this circuit puts out - possibly better than my Si fuzz face.

      I think my transistors were in the 70's - 90's - 120's range.

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  32. Just built this. Very nice. I'll post some pics when I get it boxed. All MP20A.

    I probably can't trust my HFE measurements on my crappy multimeter, but I ended up choosing ones that read the standard recommended HFE. Biased a bit past 8v.

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  33. Hey! I'm excited to build this pedal. I have ordered all the parts, and am 100% ready to go! It'll be my first build.

    I have a few questions first, regarding transistors. I ordered a matched OC77 set from Small Bear. I want to know how to put the transistors in, so that it's right. What pin where. Does it matter where I put which transistor, say Q1 in the Q3 spot, or does it not matter where, as long as they're matched? I don't want to blow anything up!

    Thanks for any help you may have!

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    1. awesome, and welcome. if you take a look at the layout you'll see on the transistors the letters C, B, E which stand for the legs of the transistor. C is for the collector, B for base, and E for emitter. i haven't ordered a set from smallbear, so i'm not sure if the legs will be marked so you'll know what leg is what. short answer is yes, it does matter what transistor goes in each position, and they should be marked which transistor is Q1, Q2, and Q3. if when you get them the legs aren't labeled, i believe the leg by the dot should be the collector, middle will be base, and the last will be the emitter. you can always post up later if you're unsure or need more help when you get them.

      my suggestion is to get some sockets so that you can easily install and remove the transistor, and not have to worry about burning them up when soldering.

      http://www.taydaelectronics.com/30-pin-dip-sip-ic-sockets-adaptor-solder-type.html

      good luck buddy, and again welcome to the site.

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    2. Okay! Thanks!

      Do I just break off 3 little things from the 40?


      Thanks in advance, Zach!

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    3. exactly, and solder them in where the transistors would go. it's always suggested to socket your transistors and IC's (get IC sockets)

      these will work for 8 pin IC's like the charge pump here
      http://www.taydaelectronics.com/8-pin-dip-ic-socket-adaptor-solder-type.html

      this way you can easily swap out IC's if you get a bad one, and it allows you to experiment with other IC's of the same type to see how it affects the circuit.

      and no problem buddy. glad to help.

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  34. So built this the other day and it goes but I can't get it to clean up on the guitar volume. Also it has huge fuzz but crackles out if you let the note ring out (kind of fuzz factory gated sounds). Anyway I might get this to 'tone down'. Tried AC128's, AC132's, 2SB54's. Mostly the same outcome.

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  35. Hello, hoping someone can help here. I built this and it's squealing on my test board. Also, the attack pot doesn't seem to be adjusting the gain as it should be.

    Any suggestions? I see a few others have had similar issues.

    Thanks in advance!

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  36. What charge pump are you using? If you use a 7660 instead of a 7660S it will squeal.

    If the attack pot isn't working properly, you may need to try some different transistors, or you may have made a mistake in your build.

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    1. Thanks, Travis. I was using the 7660SCPAZ from Tayda, but I switched is for a TC7660SCPA and the squeal is gone. I dont know what the deal is there, but it's working. The attack pot is also working now. Thanks for your help though!

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