Friday, 5 April 2013

Mad Professor Snow White Autowah


I did this as a bit of an experiment.  I want to build one and this has always been one of those that would prefer to do on a PCB, but I thought I'd still like to put a layout together to see how small I could get it using my methods and as I have I may as well put the results on here.

At 20 x 29 is may just fit in a 1590B if you aren't using a battery and have the stomp switch mounted right at the bottom, but with it having 4 pots, I think I'd probably opt for a 125B which should be a more comfortable fit.

Avoiding 19 links is another of the reasons why I would prefer a PCB :o)

Info about the great sounding original:

BJF design guitar and bass Auto Wah / Voltage Control Filter pedal

Hand-made in Finland premium quality auto wah pedal.

The SNOW WHITE AUTOWAH (SWAW) circuit is based on a 1991 BJF rack mount remote wah circuit and is tuned like a real wah.

The circuit was redesigned with envelope controls and built into small size pedal.

It has very fast tracking and accuracy rarely found on auto wahs/ envelope filters. With the four knobs you can have total control of the effect.

SWAW works both with guitar and bass and you can fine-tune the pedal to suit your instru-ment, your playing style and your taste of tone.

The pedal has a unique decay control for the filter frequency fall speed. You can set it to be fast for wah effects on every note, or slower for a more traditional auto wah sound.

Like all Mad Professor pedals SWAW is hand made in Finland using only premium compo-nents, to give years of trouble free operation with superb musical tone.

Controls

SENSITIVITY: Sets the filter trigger level, tune this carefully to fit your guitar/bass output and your playing touch.
You can further change the sensitivity from your guitar volume knob while playing.

BIAS: Controls the filter resonance frequency. When Sensitivity is turned fully off the Bias can be used as a sweepable filter.

RESONANCE: Controls the sharpness or Q-factor of the filter.

DECAY: Controls how fast the filter frequency falls back to resting point (that is set with the Bias control). This can be set fast (CW) so you get the wah effect on every note or slow for a more traditional auto wah sound.

PLAYING: Please take time to get used to the controls and as this is a voltage control filter it will react to your playing touch. The envelope control circuit is carefully designed to follow the dynamics of guitar/bass and it might take some time to master the Auto Wah playing technics.

Try also adjusting guitar volume between 8 and 10 to further expand use. 








Modded version as per the improvements discussed below in the comments:






BUY A KIT

125 comments:

  1. I built Harald`s layout of this, a fantastic autowah, I`d recommend sticking this in a bb box with your favourite flavour of fuzz, save yourself the headache of trying to fit this in a smaller box that you`ll probably end up hooking up to a fuzz anyway.

    ReplyDelete
  2. Lot of LM13700s just ordered. Have to build this!

    BR

    ReplyDelete
  3. By the way, any special reason to use LM324 instead of TL074? If I'm not wrong, the original uses two TL072.

    BR

    ReplyDelete
    Replies
    1. Sorry mate I missed this question. I can't see any reason why a TL074 wouldn't work fine.

      Delete
  4. What great timing: I just started bread-boarding this circuit this afternoon! I was planning on building Harald's, now I'm spoiled for choice.

    I'm going to try out the sensitivity pot mod (replace 20k from 220n cap with 47k) since the stock sensitivity pot is a bit touchy, requiring you to set it just a fraction of a hair above minimum for a good response with humbuckers: The 47k should bring this point closer to the centre of the dial. I might also try replacing D4 with a germanium, and the 22u with a 1uF, also supposed to improve the response.

    ReplyDelete
  5. I think the 22uF should be 2u2.

    There also seems to be a difference between this layout and the output on the schematic I've got. Here, the 6k8 from pin13 of the OTA goes direct to output, whereas the schematic i've used has this resistor go to pin 8 of the OT, thenceforth through the output cap. Not sure if it would make a functional difference, though.

    ReplyDelete
    Replies
    1. Thanks for the heads up about the cap, the scheme I did it from was quite low res so it could definitely have been a 2u2. And yes you're right about the output, I'll correct it.

      Delete
  6. Any specific flavor of BC550 required?

    Or, can I flip a 2N5088, without causing any issues?

    ReplyDelete
    Replies
    1. It just said BC550 on the schematic, but knowing Bjorn and bearing in mind some of his other effects, it's probably the BC550C. The 2N5088 would be fine I expect.

      Delete
  7. Built This tonight but I'm only getting a clean signal. I can get a wah type effect if I turn the bias pot up and down as I strum. Bias pot works, as does the resonance pot, decay pot is harder to tell with the unaffected signal and sensitivity doesn't seem to do anything at all. My nephew "borrowed" my build from Harald's layout so I can't reference voltages etc from that. Checked all the usual suspects, solder bridges, cuts, part placement etc and they all appear good :-(

    ReplyDelete
    Replies
    1. Did you use the corrected layout mate?

      Delete
    2. I've just gone over it again and can't see anything wrong, will you check the voltages and post those to see if they point to the problem area. Including the transistors.

      Delete
  8. Used the revised layout ( well actually modified from the original layout as I had already made the cuts so had to alter to suit) will post voltages tomorrow as I'm tucked up in bed going over the schematic :-)

    ReplyDelete
  9. Here's my voltages,
    Q1- d- 7.69, g- 4.89, s-1.91
    Q2- c- 4.98, b- 3.45- e- 3.01
    Q3- c- 4.98, b-2.99, e- 2.49
    Vr- In- 7.69, g- 0.00, out- 4.97

    Ic1. Ic2
    Pin 1, 1.31. 4.16
    2, 0.00. 3.77
    3, 3.84. 3.85
    4, 3.84. 7.69
    5, 5.05. 0.05
    6, 0.00. 0.04
    7, 5.05. 6.41
    8, 3.83. 3.85
    9, 3.86. 3.85
    10, 5.08. 3.79
    11, 7.69. 0.00
    12, 5.08. 3.85
    13, 3.85. 3.85
    14, 3.85. 3.91
    15, 0.01
    16, 1.31

    ReplyDelete
    Replies
    1. Most of the voltages look good to me, but things look a bit strange around IC2 pins 5 to 7. You're getting 0.04 and 0.05V on the inputs, and 6.41V on the output. 5 should be exactly the same as pin 3 because there's a link attaching them so that definitely can't be right. Check your soldering and look for bridges around there.

      Delete
  10. IPad didn't publish that as i laid it out, hope you can understand it

    ReplyDelete
  11. Checked over it again, I was getting continuity between pins 3&5 on the board but not on the pins on the ic, pulled the ic and part of the socket leg was attached to the ic leg, broken socket leg, Stuck a new socket leg in and away it went. Sensitivity, resonance and decay pots need reversed and tag it. Now to try and squeeze it into a 1590b :-)

    ReplyDelete
    Replies
    1. Germanium for d4 does make a difference to the response (recommended) I used an oa90, will try 47k resistor mod later

      Delete
    2. Awesome, nice one matey.

      Delete
    3. I'd love to see a gutshot of your finished pedal. I'd be interested in how feasible it is in a 1590B. :)

      Delete
    4. Not boxed it yet, haven't even checked feasibility myself yet :-)

      Delete
  12. i put together haralds layout of this cause i didnt have a big enough board for this layout. anyone know how to add an led to this to show the envelope effect? i put one between output and ground of one of the op amps (it would be pin 1 of the tl074 on this layout) and it worked but mudded the sound quite a bit. any ideas?

    ReplyDelete
    Replies
    1. so i replaced D4 with a small, less than 3mm red led and it lights up when playing, seems to work with the decay amount. the only side effect is it gives it a quicker attack. right now i actually have that diode connection going to a dtpt with germanium on one side and the led on the other. i dont know which one i like better.

      Delete
  13. Finished this by modifying the original layout to match the revised one and can't wait until I box it and get to use it on my rig.igjt be one of those that never leaves.

    ReplyDelete
  14. Know anything about the bass version?

    ReplyDelete
  15. like an idiot, I downloaded the first incorrect vero layout and built it according to that. when it didn't work at all, I checked the page and found the corrected layout, so I had to mod my build to match it. it works and sounds great now. thanks for posting it.

    and here's two pics of my build:

    http://johnkvintageguitars.homestead.com/Effects/others/SWAW-01.jpg

    obligatory gut shot:

    http://johnkvintageguitars.homestead.com/Effects/others/SWAW-02.jpg

    ReplyDelete
    Replies
    1. Nice one John, thanks for the pics. Was it ok for bass as it or did you mod anything?

      Delete
    2. it perfect for bass just the way it is. (no low end loss). I suppose that MP's bass version might have a slightly lower freq range for the wah circuit but I don't think that it's necessary at all.

      Delete
  16. OK, am I losing my mind (and my eyes) or does this have only 32 cuts?
    I've been over it a dozen times and I cannot see 33 cuts...?

    ReplyDelete
  17. Looks like 32.....but then again, I lost my mind a long time ago :)

    ReplyDelete
  18. Anyone else cares to count the cuts for me? It only takes 15 seconds to get it wrong... :)

    ReplyDelete
    Replies
    1. Yes you're right. I do this sometimes when the layout is finished and I've noticed that one of the cuts isn't required, and so remove it but forget to alter the number.

      Delete

    2. Excellent, thanks Mark!

      I can build it now and only blame myself if it doesn't work. :)

      Delete
  19. Hello,

    Since 2N5457 seems difficult to find, can it be replaced by a BF245C ?

    ReplyDelete
  20. Just built this circuit. Is not so horrible as it seems at first sight, but anyway, you'll take a few hours to build this.

    Sound is f*cking awesome, one of the best autowahs that I've ever listened to. Still far from the Mutron II and the Meatball, but probably, the third better one on my list.

    Worked at first try as usual, I just get in trouble with < 15 components circuit :P. Now have to check how the fuck i get this effect in a 1590B :P

    BR

    ReplyDelete
    Replies
    1. Pride!

      https://www.facebook.com/photo.php?fbid=503227919749061&set=a.404470492958138.93220.404417189630135&type=1&theater

      Delete
    2. Forgot to comment: As the board has to be placed solder side up, replaced the lower left 1uf electrolithic with a tantalum one and bent it to the vero, these few mm were the difference between success or drilling and painting another enclosure :P

      Delete
    3. Why do you need it solder side up? I never do that unless it's a pcb with mounted pots.

      Delete
    4. Because with 29 rows, the lower ones have to rest over the input and output jacks, so you have to put the board with solder side up :P

      BR

      Delete
    5. Well, it's almost boxing time and instead of going sunny side up, I opted for a BB. I have no pedalboard so extra room doesn't come with a cost. :)

      Delete
  21. Hey guys, I've almost got this one going. The Bias and Reso pots work well but the Sens and Decay pots do nothing. There is no triggering going on.
    Interestingly when when I remove the 78L05, only the Decay pot seems to be the only pot NOT working. I'll keep looking for mistakes and take voltages if needed. Anyone got any ideas??

    Cheers, Thommo.

    ReplyDelete
    Replies
    1. Here are my voltages. All pots at Noon. Power supply 9.30v.
      Q1 D 8.33v S 5.44v G 3.75v

      Q2 C 5.05v B 5.77v E 5.05v

      Q3 C 5.05v B 1.5mv E 1.231v

      VR I 8.37v G 1.6mv O 5.05v

      IC1 IC2
      1.1.23v 6.68v
      2.1.03v 4.16v
      3.4.17v 4.17v
      4.4.17v 8.33v
      5.5.37v 4.17v
      6.1.6mv 4.17v
      7.5.37v 4.17v
      8.4.17v 4.17v
      9.4.18v 4.17v
      10.5.39v 4.17v
      11.8.33v 1.4mv
      12.5.89v 4.17v
      13.4.17v 4.16v
      14.4.17v 4.13v
      15.n/a 1.006v
      16.n/a 1.229v

      Cheers, Thommo.

      Delete
    2. I forgot to mention that I'm using an A1Meg wired 'backwards' seeing as I didn't have a reverse taper on hand. Not sure what difference it would make.

      Delete
    3. Got it going!! I found a missing link! The controls seem to have a little less range compared to the original, though. Could be just me getting used to them. I'm going to try the resistor and diode mods and see how it sounds.

      Cheers Thommo.

      Delete
    4. A lot of improvement with those two little mods!! Sounds great now!!

      Cheers, Thommo.

      Delete
    5. What mods did you do? My Sens and Decay knobs have minimal range too

      Delete

  22. Just finished this one... some pics:

    https://lh3.googleusercontent.com/-rouhumMgYdo/UhUzVWWiA_I/AAAAAAAAA-Q/3hE5KCVA5ck/w579-h772-no/IMG_2808.JPG
    https://lh4.googleusercontent.com/-FU6R5DaTim0/UhU08EK4LVI/AAAAAAAAA_Y/DUnrkzVJfUA/w579-h772-no/IMG_2814.JPG
    https://lh4.googleusercontent.com/-YI-u8VaDmEw/UhUzqepUd1I/AAAAAAAAA-k/8930hosdyB8/w1029-h772-no/IMG_2812.JPG
    https://lh4.googleusercontent.com/-rKoQYx5eINY/UhUzcNV8GiI/AAAAAAAAA-Y/xn6oEdsdm7M/w579-h772-no/IMG_2802.JPG

    ReplyDelete
    Replies
    1. Great looking build matey!

      Delete
    2. Thanks buddy!
      I wish I had photographic skills like JohnK, but I dont. :)
      This is the best I could do with a phone camera...

      Delete
  23. Do any diodes need matching (like the Dr. Q type envelope filters)?
    I like to try this one for the bass :)

    ReplyDelete
  24. finished making this FX .. very beautiful in my ear, and I tried with guitar and bass guitar I play the song muse 'city of delusion', keep my playing was good, thank you Ivlark bnyak very helpful: D

    ReplyDelete
  25. thank you Ivlark,, nice work. : D

    http://www.youtube.com/watch?feature=player_detailpage&v=JsIKwX2eoTQ

    ReplyDelete
  26. Just finished building this, but I did not have all the correct IC's, so I used a TL074 and NMJ13600 instead of the specified IC's.
    So far it does not work, and after some probing with the multimeter I discovered that the power input is extremely low after the first resistor (the 47R after the olarity protection Diode).
    I'm only getting about 1,5 volts coming out the other end of the resistor (it measures about 8,7 volts before the resistor) and I suspect that this could be the source of my problem, but I also want to check with you guys if using the NMJ13600 is ok for this effect or if the LM13700 is the only option here. Any clues?
    I will try to replace the resistor to see if it's a faulty one later today.
    I suspect that my IC's are usable for this circuit as I can get the effect to (kind of) work for a few seconds if I bridge the 9 volt input to the end of the 47R resistor (bypassing it and feeding 9 volt directly into the circuit) before it fades away and the effect disappears again. At this point the LED also lights up intensively at this point with a pop/noise as it switches on, but I guess that this might be the result of feeding a bit too much power into the circuit...
    Any input would be very helpful as it seems like I am very close to getting it up and running and I really want this effect on my pedal-board.

    I also just want to add a big thank you, for all the knowledge I have gained from this website. It has made me learn this stuff way much faster than I expected when successfully putting together my first Electra Overdrive circuit 6 months ago.
    Now I'm building large circuits with a very low fault ratio, all thanks to this community's mixture of newbies and pros. (But I still do not actually know what I'm doing, but that is not important since my builds mostly works the first time I fire them up. But with your help, I am sure I will get there soon)

    Cheers!

    ReplyDelete
  27. Just finished putting everything together for this build, and I'm getting sound, but no "auto" wah...I'm stumped!

    I have a couple questions to hopefully lead me in the right direction:

    I didn't have 330 ohm resistors, so I used 390 ohms and 2.2k and twisted the ends together to make them more or less one resistor...all of the online calculators said that this would produce 331 ohms of resistance. Did I do this right? I imagine this wouldn't prevent any auto quacking, but I just thought I'd check. If I didn't quite get the connection good on some of the pot lugs (like connecting lugs 2 and 3 or something) would that cause this problem?

    Also, do I need to match my bc550's? I could see that these could potentially cause the problem of non-auto wah.

    Do I need to do anything special with the IC's?

    Sorry for all the questions, I'm totally lost here...I really appreciate any and all help!

    Jacob

    ReplyDelete
    Replies
    1. Measure and post the voltages you're getting at all the IC and transistor pins. That will give us a good clue where the problem lies.

      Delete
    2. Is that something I can do with a multimeter? I've seen the readings on this blog several times but I haven't figured out how to do it...could you show me the light?

      Delete
    3. This comment has been removed by the author.

      Delete
  28. The last set of voltages were off because I discovered my ground had come loose...here are the accurate voltages (I think):

    Q1 (2N5457):
    D: 7.54
    S: 4.22
    G: 1.91

    Q2 (BC550):
    C: 5.01
    B: .73
    E: .33

    Q3 (BC550):
    C: 5.01
    B: .33
    E: 1.19

    IC1 (LM13700):
    1: 1.19
    2: 0
    3: 3.78
    4: 3.78
    5: 4.94
    6: 0
    7: 4.94
    8: 3.77
    9: 3.79
    10: 4.98
    11: 7.50
    12: 4.97
    13: 3.78
    14: 3.78
    15: 0
    16: 1.19

    IC2 (LM324):

    1: 1.04
    2: 3.71
    3: 3.77
    4: 7.50
    5: 3.76
    6: 3.77
    7: 3.77
    8: 3.77
    9: 3.77
    10: 3.70
    11: 0
    12: 3.77
    13: 3.77
    14: 3.56

    VR:
    I: 7.49
    G: 0
    O: 5.01

    Do those numbers look OK?

    ReplyDelete
  29. Anyone besides me see only 32(thirty two) cuts. Just checkin.

    ReplyDelete
    Replies
    1. Yes 32, I must have removed an unnecessary cut when I did the last update

      Delete
  30. Is a 78L05 the same thing as a 7805 (no 'L')

    ReplyDelete
    Replies
    1. The 78L05 is rated at 100mA, the 7805 is 1 amp. They both do the same thing though so you can use the 7805 if it will fit in the space you have.

      Delete
  31. Build this one yesterday. It works great. Nice wah response. Only thing is I get a big volume drop compared to my clean signal. I checked all components for values and they al match the layout.
    Any idea someone?

    ReplyDelete
  32. Hi, I can't seem to get it working, I only have signal when bypass, please advice


    IC LM324N
    1. 2.49
    2. 4.28
    3. 7.44
    4. 5.86
    5. 7.44
    6. 4.24
    7. 4.70
    8. 7.44
    9. 7.44
    10. 3.64
    11. 0
    12. 7.44
    13. 4.33
    14. 4.70

    VR
    I: 7.44
    G. 0
    O. 5.08

    IC LM13700N
    1. 1.27
    2. 0.03
    3. 6.99
    4. 7.00
    5. 0.67
    6. 0
    7. 0.6
    8. 0.67
    9. 0.56
    10. 6.73
    11. 7.44
    12. 6.73
    13. 0
    14. 6.89
    15. 0.01
    16. 1.26

    Thx in advance to all

    ReplyDelete
    Replies
    1. A lot of dodgy voltages there, the supply is low at 7.44 volts (I assume you're using a battery which doesn't seem to have long left, I'd recommend trying it with a fresh battery or even better a power supply), but you seem to have that 7.44V on pin 3, 5, 8, 9 and 12 of IC2 which shouldn't be there, but not on pin 4 which is connected to the supply rail via a link and so should be at the full supply voltage.

      There is something very wrong with this, so I suggest you start checking placement of the links because you must have put something in a wrong place there. Also check the cut to the left hand side of Q1 drain which could also be the source of your problem.

      Delete
    2. Thanks Lvlark!! You always here to help~ just curious,
      are LM13700'N' and LM13700 the same?

      cos i brought LM324N, LM13700N and VR 78L05

      Delete
    3. Yes it will be the same, the suffix shouldn't matter

      Delete
  33. Is there any way to add an expression pedal input to this pedal?

    ReplyDelete
  34. That 4k7 on the right side of IC1 (upper one), is it LED´s resistor?

    ReplyDelete
  35. I mean upper of those 4k7´s... If I use blue LED on this one, it should be around 30k if I don´t want to became blind...

    ReplyDelete
    Replies
    1. Use whatever value suits the LEDs you want to use.

      Delete
  36. Ok! And thank you very much for this blog. I have done about 20 of these layouts and all of these rocks! I¨'ll send pictures when I have done all of this nasty wiring job...

    ReplyDelete
  37. At last I got it inside an enclosure. And it works like a charm! Here´s pictures of it:

    http://imgur.com/9EEpOEz,PEuOtZx#0
    http://imgur.com/9EEpOEz,PEuOtZx#1

    A bit tricky with this wire, but I made it...

    ReplyDelete
  38. I recently buildt this one and it is a really great sounding effect for both bass and guitar, without any mods. I have a nice box made for it. Hope to share some pics soon.
    I did "borrow" John K's box layout though ;)

    ReplyDelete
  39. So I had this built and working great. Then I decided to rebox it with a fuzz. When it was finished, I turned it on and was not working correctly at all. I then noticed I connected the ground and 9v to the wrong places on the fuzz, which was shared with the Snow White. Fixed that, but the Snow White still does not work, but the fuzz works fine now. Is it possible that I fried something on the Snow White? I replaced the LM324, which did not help at all.

    What should I check? Any ideas?

    ReplyDelete
    Replies
    1. Measure all the IC, transistor and regulator pin voltages. If some of the supply wires were crossed there is a chance that the regulator may be damaged, but the voltages will give us the best clue

      Delete
  40. TL074:
    1: 3.92
    2: 3.92
    3: 3.92
    4. 7.83
    5: 3.83
    6: 3.92
    7: 3.91
    8: 3.71
    9: 3.91
    10: 3.92
    11: 0
    12: 3.91
    13: 3.83
    14: 1.59

    LM13700

    1: 1.33
    2: 0
    3: 3.92
    4: 3.91
    5: 5.14
    6: 0
    7: 5.14
    8: 3.89
    9: 3.93
    10: 5.19
    11: 7.83
    12: 5.19
    13: 3.91
    14: 3.91
    15: 0
    16: 1.33

    78L05

    I: 7.83
    G: 0
    O: 7.19

    ReplyDelete
    Replies
    1. Any of that look suspect?

      Delete
    2. Yes the regulator looks damaged. Your input voltage looks low anyway at only 7.83V, so I'd suggest trying it with a new battery or a power supply so you're closer to 9V, but the output of the regulator should be 5V and you're getting 7.19. Try changing that and see if it fixes it.

      Delete
    3. Okay, I replaced the regulator, and the readings are different, but it still does not work right at all. It wahs a bit with certain settings, but its very week and muffled, dark, etc.

      The regulator now reads:

      1: 7.04
      2: 0
      3: 3.61

      Delete
    4. I have been using the onespot power supply which I always use, and is supplying about 9.4 volts.

      Delete
    5. Right, with that series protection diode you lose around 0.7V straight away, but I would still expect you to be getting 8V+ from a 9.4V supply.

      That regulator doesn't look good either, you should be getting very close to 5V on the output pin

      Delete
    6. hi kinski
      2 regulators working wrong? that's strange...
      are you sure that the resistor after d2 is 47r and not a 47k? cause that's something i did a few times. that would explain the small volts you get. and if the regulator gets much less than 9 volts, it will never work. it needs at least 3 volts more from what it should deliver.

      Delete
  41. Yeah, this is strange. Supply is giving 9.41v. After the diode, its 8.68. The 47ohm resistor reads 8.68 on one end and 7.07 on the other, which is what the regulator IN also reads. I replaced the resistor, no help. Would any other readings help?

    ReplyDelete
  42. Hi all/Mark.
    When a 100n cap is called for in a small space and you posses 'ceramic' 100n caps. Is it advisable to use the ceramics or are they too inaccurate compared to box caps? The physical advantage being obvious.
    jeff

    ReplyDelete
    Replies
    1. Yes ceramic would work fine. I'd prefer to use multilayer ceramic but that's just a preference. What I often do with 2.5mm spans though when there is enough physical space to accommodate them, is use a poly box cap but bend one of the leads in towards the other, and then back out to approximately a 2.5mm gap. Then the poly box fits perfectly in the space and it's body hides the bent leads anyway

      Delete
  43. Hi! Any idea if a BC550B would work? Smallbear has "BC550B" and "BC550CBU". Thanks.

    ReplyDelete
    Replies
    1. Yes the 550B would be fine

      Delete
    2. One more thing, is there a replacement/sub for the 2N5457? Thanks!

      Delete
  44. You can try any N-channel JFET, like J201 though the 2N5457 should be pretty easy to find

    ReplyDelete
  45. Thanks lvlark and Travis for the replies!

    ReplyDelete

  46. Where and how should I conect the VR 7805 ? Because in the scheme there is only a trail to plug it and the LM7805 has three "legs".

    Thank you very much,

    ReplyDelete
    Replies
    1. I don't understand what you mean. The layout show all 3 pin connections, input, ground, output. The orientation shown is correct for the ones I have in stock, although I don't know if all regulators use exactly the same pin and body orientation. You'll need to check the datasheets for the ones you have bought.

      Delete
    2. The ask is: Where do I plug the VR 7805 5 V regulator ?

      Delete
    3. What do you think the transistor symbol reading "I-G-O" is?

      Delete
    4. Thank you very much ! Now everything make sense !

      Delete
  47. This comment has been removed by the author.

    ReplyDelete
  48. Hello guys,

    I would like to know if someone used LM13600 instead LM13700.

    ReplyDelete
    Replies
    1. both will be ok. just do this
      https://www.google.gr/search?q=lm13600+lm13700+difference&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb&gfe_rd=cr&ei=5KkUVOy4A-Lc8gf30ICYDg

      Delete
    2. I made this research before I ask here, however the majority of the discussions about the LM13xxx IC were not for music or pedal effect.

      Delete
  49. an LM13600 will sound exactly the same as an LM13700.

    ReplyDelete
    Replies
    1. Did you already use the LM13600 instead of LM13700 ?

      Delete
  50. Hey guys,

    I have wired this up and it seems to work. Although the Decay and the Sens knobs seems very subtle. Nothing seems as pronounced as the original. Is it just me, or is this what it sounds like?

    ReplyDelete
  51. We don't have 1N34A here, can I use 1N4148 instead?

    ReplyDelete
  52. Hi guys. I have built this, but it doesn't completely work.
    I have taken some voltage readings. Can anyone please help to show me the light?


    LM13700
    1) 1.1
    2) 0.1
    3) 3.8
    4) 3.8
    5) 4.9
    6) 0.0
    7) 4.9
    8) 3.8
    9) 3.8
    10) 4.9
    11) 7.6
    12) 4.9
    13) 3.8
    14) 3.8
    15) 0.1
    16) 1.1


    LM324
    1) 0
    2) 3.8
    3) 3.8
    4) 7.6
    5) 3.8
    6) 3.8
    7) 3.8
    8) 3.8
    9) 3.8
    10) 3.8
    11) 0.0
    12) 3.8
    13) 3.8
    14) 3.7



    D) 7.6
    S) 4.9
    G) 3.5


    I) 7.6
    G) 0.0
    O) 5.0

    Q2
    5.0
    0.0
    0.2

    Q3
    5.0
    0.1
    1.1


    Looks like there's something really wrong with LM324 Pin 1 (when compared to other published readings here). But I have no clue as to how to debug the problem. I have compared my build against the layout, to the point where I am feeling sick (literally, feel like vomiting). I have taken a long break, it has been 3 days, I have forced myself not to look at my board.

    I would greatly appreciate if anyone could give me a tip on what to look out for / where to start. I told myself, I will not begin debugging till someone replies me. Else, I'll be staring at the board for hours, ending up feeling stressed. Thanks guys.

    ReplyDelete
  53. Is it just me, or is this effect very subtle? Ive wired it up and it works, but the Decay and Sens pots are so subtle, it is barely noticeable. The Bias and Res pots seem to work fine. Any thoughts anyone?

    ReplyDelete
    Replies
    1. I built it a while ago and it's definitely NOT subtle at all and it sounds like a real wah-wah as opposed to a envelope pedal.

      Delete
  54. i haven't built this yet, but listening to the video it shouldn't be that subtle. check to make sure you don't have a cold solder joint, and you're getting good voltages at the IC's and transistors.

    ReplyDelete
    Replies
    1. Sweet, ill open it up and have a look, and just double check. Ill post my voltages once im done.

      Delete
  55. Hey guys. I have this working, but there doesn't seem to be as much wah as there should be. All of the controls seem to be changing the tone as they should. It just needs the wah to be deeper. If I play around with the controls, I can get a decent quack, but still not as pronounced as it should be. What part of the circuit should I be experimenting with to add more wah?

    ReplyDelete
  56. I built this off of the first schematic and it fired right up. It sounded pretty good but when I swapped diode 4 for the germanium it sounded great. I tried a variety of different gain pickups with it and didn't see a need to change anything else. As always great job guys.

    ReplyDelete
  57. hi this Thing Kind of works Kind of not. it doesnt do the quack. it ramps up and down but really slow and subtle. ive measured the voltages and they seem right. maybe pin 1 IC2 and B of Q1/2 are a Little low.

    Here are the voltages:
    IC1 / 2
    1: 1,27 / 1,53
    2: 0 / 3,93
    3: 3,97 / 3,96
    4: 3,97 / 7,97
    5: 5,16 / 3,98
    6: 0 / 3,98
    7: 5,16/ 3,98,
    8: 3,96 / 3,98
    9: 3,98 / 3,98
    10: 5,17 / 3,90
    11: 7,94 / 0
    12: 5,16 / 3,98
    13: 3,96 / 3,98
    14: 3,96 / 4,09
    15: 0
    16: 1,28

    Q1
    D: 7,91
    S: 4,92
    G: 1,98
    Q2
    C: 5,03
    B: 1,50
    E: 1,05
    Q3
    C: 5,03
    B: 1,05
    E: 1,22
    VR
    I: 7,97
    G: 0
    O: 5,03

    Thanks for any advice.

    ReplyDelete
    Replies
    1. I had the same problem, so I bought the PCB for $7.95 at:
      http://www.guitarpcb.com/apps/webstore/products/show/3456370
      It works great!!! Just not that in the instructions for the PCB he has the Decay and Sensitivity labels swapped in the PCB layout picture. The values and locations are correct in the parts list though.

      Delete
  58. Buy the PCB for this at:
    http://www.guitarpcb.com/apps/webstore/products/show/3456370
    It works great and is an easy build.
    Note that he has the Decay and Sensitivity labels swapped in the PCB picture in the instructions, but the pot values in the parts list is correct.

    ReplyDelete
  59. Hi everyone! Thanks for the great job you're carrying on! I have a small question: i cannot find anywhere some resistor values such as 7K9 (this project) or 3M (Tillman preamp), i tryied looking for them in several stores (included the kits' stores) and ebay, but no success... should i "create" them linking other resistor in serie or should i use close values resistor calculating the tolerance? I apologize for the noob question but i dont want to get some mistake in my projects, thanks in advice for the help :)

    ReplyDelete
  60. hello,

    I made this circuit, but it did not work.

    Well, I can just hear some strange noise.

    The Voltages of the ICs and Qs are:


    LM 13700

    1 - 1.30V
    2 - 0.01V
    3 - 4.08V
    4 - 3.96 V
    5 - 7.19 V
    6 - 0
    7 - 7.10 V
    8 - 5.93 V
    9 - 6.40 V
    10 - 7.66 V
    11 - 7.63 V
    12 - 7.66 V
    13 - 3.94 V
    14 - 3.85 V
    15 - 0
    16 - 1.27 V

    LM324

    1 - 6.46 V
    2 - 3.83 V
    3 - 3.90 V
    4 - 7.82 V
    5 - 3.93 V
    6 - 4.00 V
    7 - 3.94 V
    8 - 3.95 V
    9 - 3.83 V
    10 - 3.94 V
    11 - 0
    12 - 3.95 V
    13 - 4.00 V
    14 - 3.96 V

    Q1
    D - 7.82 V
    S - 5.61 V
    G - 2.20 V

    Q2
    C - 4.99 V
    B - 2.37 V
    E - 2.88 V

    Q3
    C - 4.99 V
    B - 3.08 V
    E - 3.45 V

    VR
    I - 7.82 V (I am using the right resistor 47R)
    G - 0
    O - 4.99 V

    I already changed the ICs and the problem is the same.

    Any idea ?

    Thank you !

    ReplyDelete
    Replies
    1. Here some Pictures:

      http://migre.me/pOQpz

      http://migre.me/pOQrf

      http://migre.me/pOQsb


      Delete
  61. This comment has been removed by the author.

    ReplyDelete
  62. Does anyone know if BC550b will work? This is the second time I've built the whole circuit, plugged in, and got no sound. Frustrated doesn't begin to describe....

    ReplyDelete
  63. Wow, turned out to be an entire batch of bad 2N5457's... Put a J201 in and fired right up. Anyone know how this would affect the character of the pedal? I also used BC550B's . Sounds great but not quite as much sweep as I'd hope for

    ReplyDelete
  64. Can I connect pot legs together in pot side eg.
    Sensitivy pot 1 > board, 3 > 2 together and leg 2 > board?
    So do I need 3 wires to board?

    ReplyDelete
  65. Ah, judged by gut shot provided by Mr Kallas you can...

    ReplyDelete
  66. I just built 2 of these (with mods). One for me and one for my brother who has been hunting for a nice effect to breath some soul into his bass. It sounds sweeter than I thought at first and I love how it responds as you play. Thanks for the layout, this website and the community rocks! I only started building some months ago.

    ReplyDelete
  67. Hi,
    Is there any way to add an expression pedal input to this pedal?

    Thanks,
    Vlad

    ReplyDelete