Wednesday 15 February 2012

Maxon / Ibanez SD9 Sonic Distortion

This is an awkward one to do a layout for because there seems to be so many schematics out there that the best one is always going to be a matter of personal preference.  The original used one half of the opamp for the effect, and the other half for the bypass buffer, with a transistor buffer at the beginning and end of the circuit.  This layout is based on the GGG schematic which has an input buffer only and because the layout is designed for use with a 3PDT true bypass switch it ignores the bypass buffering and so only uses one half of the opamp.

Video of rudeez's build:

 




Here is the version with transistor input and output buffers:



Both should fit comfortably in a 1590B.

Many people have reported good results without the output buffer, and so it may be worth trying the most simple option first to see if you're happy with it.

There are so many ways you could do this.  Omit both transistors and use one half of the opamp as the input buffer with no output buffer.  Have a transistor input buffer and the unused side of the opamp being used as an output buffer etc etc.  The possibilities are endless.

Possible mods that have been suggested, if you find the effect muddy then consider swapping the 22u and 47u caps for 220n and 470n respectively (some people believe the 47u is definitely wrong and was actually .47u and just misread).  It may be worth socketing those caps so you can experiment.  Some people have reported that the 220p cap should in fact be 1n, but others have said it sounds better with that cap omitted entirely, so again it may be worth socketing so you can swap and remove to test.  Suggested improvements to the tone control is to swap the 27n cap for 33n, and swap the 100n cap connected to Tone 1 to 47n.  Socket and see.

Happy experimenting.

49 comments:

  1. http://mirosol.kapsi.fi/varasto/boxes/sonic.JPG
    +m

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  2. So I've built the output bufferless version, and I'm currently effectless. It passes signal fine, and the LED lights up, but when engaged I get nothing. I've checked and double checked.. Can't find anything.. I'm using a 2n4401, is that the issue?

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  3. http://a7.sphotos.ak.fbcdn.net/hphotos-ak-ash4/405200_10151115754898988_1429100728_n.jpg

    http://a2.sphotos.ak.fbcdn.net/hphotos-ak-snc6/226127_10151115756008988_1169259053_n.jpg

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    1. your 100µf electrolytic is in backwards. and your bottom 47µf may be backwards also.

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    2. also i checked the 2n4401 pinout and the transistor is flipped backwards as well

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    3. derp derp. Looks Like I'm not very good at this. lol. Thanks for the help nicholas!

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    4. no prob! just keep at it. after a few it comes really easily. second nature, even.

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    5. OK! so i have it passing signal now, but it sounds quite, fuzzy? and harsh. Has a considerable amount of gain with the poot at 0 (though I think that's the same with the original) and the volume and tone pots don't do a thing..

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    6. make sure you go back and look at every solder joint. you might have rows touching. the joint on the jumper that connects the 9v to the opamp looks particularly cold. perhaps it isnt grounded properly? the board, a lug on the switch (depending on the switch wiring diagram you used) and the dc jack ground all have to link together in some way.

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  4. Alright, I don't know what it is, I rebuilt it, and used one GE diode nte110a, and one LED. I can hear distortion behind the crazy oscillation and noise, but the volume and tone pots still dont work.. what am I supposed to be doing with the empty lugs on those two? and what am I doing wrong :(

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    1. empty lugs??? on the tone and volume pots?? it says on the bottom of the layout that they're supposed to connect. that's probably the issue right there.

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  5. Nicholas, if we ever meet, You get a huge hug. And you get to slap me.

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  6. Yessir! went with 2 LED clipping until I get my germs from smallbear, the ones I got locally were not working.

    sounds FAT..

    http://www.youtube.com/watch?v=Wtu0fbLUZs4&feature=plcp

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  7. which transistor do I have to use for this one?

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    Replies
    1. BC546, BC547, BC548, BC549, BC550. Or if you rotate 180 degrees 2N3904, 2N5088, 2N5089 etc.

      They're just unity gain buffers and shouldn't affect the sound in any significant way.

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  8. Anyone ever replaced the Maxon switch with a TB 3PDT switch? I can follow 4 to 5 wires but I'm not sure about 2 wires (gray and white/red)?

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    Replies
    1. I think grey and white/red are board out and board in.

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  9. My take on the bufferless one!
    http://www.youtube.com/watch?v=EHgaIwubxUo

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    Replies
    1. Excellent. That surprised me mate, a lot more gain than I have always expected from an SD9. Does the switch swap the input cap or something else?

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    2. Feel free to add it as a demovideo to the topic :)
      If i'm not mistaken (was some time since i made this one) i just put the stock clipping on there along with yellow led's in down position and non in middle ofc!

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    3. And for adjustments in mods in values I can't really remember what i put in of the above mentioned alternations, think I went with the 220pf at least... wish i made notes on the values :( Might have a photo of the board somewhere but i guess you won't be able to read the values from the caps and so on.

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  10. This comment has been removed by the author.

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  11. Built this some 4 years ago after another vero
    I used: for the diodes 1n4148+1n4148 in series with a white led in paralel, and changed the 22uf with a 200-220nf cap, the 50k pot with 100k, and the gain pot from 250k to approximately 330k. Something on the lines of that, and maybe tweaked the 220pf cap, but can't really remember haha

    https://www.youtube.com/watch?v=sWYddcJJyZ0

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  12. I'm building the one with both input and output buffers, and I only have electrolytics for the 100nf caps. Which way should they face?

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  13. This comment has been removed by the author.

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  14. I built version with buffer. Works great!!! I notice that tone control is way more useful than in original one. Is that normal in this layout?

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  15. But second half of opamp to work, change those two caps to right value and this is very good high gain monsteri:)

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  16. This comment has been removed by the author.

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  17. Hey all! Big fan of what you guys are doing. I own a Analogman modified SD-9. I really dig how there's no loss of bass response with this pedal. But the tone knob bothers me. Seems to be muddy or super thrill. What's your advice for making the tone knob more useable over the whole sweep without changing the characteristics of the gain structure?

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    Replies
    1. Whatever mods you can find for modding the tone control on a Boss DS-1 should equally apply to this, since it is essentially a copy of that design, albeit with some minor modification.

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  18. I was futzing around inside one of mine from this site (the one with both buffers) and I got more volume out of it. I noticed at my output I had 10K instead of 100k. After I clipped the end to ground I noticed really no difference and I got to messing around. So Inow I have the tale of the 470R going to the output, and I jumped that also to the top row of the diode Clippers thru a 10K. I've only got one as it cut volume quite a bit (it's a strange glass diode I had lying around) it gives a boost and the tone is pretty much the same, maybe a touch lighter, more airy not quite as compressed,but definitely louder, and keeping the same flavor of distortion. I haven't the slightest idea how stable, and make no claims whatsoever more than I've got a few of these built and I love the circuit and whoever stole my original is a complete knob.

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  19. I'm Using the GGG project to build my Sd-9, testing the pedal, I see that It has volume and tone pot working but have no drive

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  20. Can someone help me? I built the version without a buffer and I only get a strange hum and the poots don't do anything.
    Pictures:https://ibb.co/y40BBYk
    https://ibb.co/86sDBT8
    https://ibb.co/V0GH5ds
    https://ibb.co/DzZ9nTs
    https://ibb.co/vBpqkk5
    https://ibb.co/FJZSrd2
    https://ibb.co/n1Ywtmk
    https://ibb.co/2nyjWnH
    https://ibb.co/h8wFzgz

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    Replies
    1. Hmm. You seem to have input and output jack tips connected to each other. This means that there's no signal reaching the circuit as the signal passes through the easiest path. In this case, from input jack straight to the output jack.

      Also, the input wire is connected to input jack's sleeve. And there's no ground on either jack's sleeve.

      So. To start with;

      1. Take the board's input wire to input jack's tip.
      2. Take the board's output wire to output jack's tip.
      3. Take the ground wire from the board and daisy chain it with input jack and output jack sleeves, as well as with battery's negative terminal.

      Also. Note that the ground wire on board at the lower left hand side is the "real ground" of the board - and you'll need to connect this also to the upper right hand side "ground".

      This may help you to get it running..
      +m

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    2. Oh. My bad. Your input/output arent connected stright to each other. But nevertheless, your outboard wiring is the main suspect here..
      +m

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    3. If I understood you correctly, you mean it like this:
      https://ibb.co/2jQKhh6
      i still hear that hum but the tone control works so i can now turn the hum up and down

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    4. Now the outboard wiring seems ok. And since tone and volume pots are doing something, my next guess is that the signal isn't reaching the opamp or that the voltages on ic aren't ok. Tone and volume are after the gain stage.

      Can you measure the voltages on ic pins 1-4 and 8? Those should read ~4,5v on pins 1-3, zero on 4 and supply voltage at pin 8.
      Pins are numbered like this:
      1-u-8
      2---7
      3---6
      4---5

      If those are correct, the next guess is the input buffer and all the component on the left hand side of the board.
      +m

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  21. on the pins 1-4 and 8 i have 4,3v , on 1-3 it fluctuates roughly between -0,4v - +0,4v and on 4-8 i have 8,7v

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    Replies
    1. With these readings there are a few things off. First, check the link from bottow row to pin 4. That should give thre chip a ground connection. The pin 4 needs to be zero volts for the opamp to function.

      After conthe you could measure the fourth row from the bottom. That should read ~4,5V - which is the vref (refence voltage that IC needs on pin 3).

      There could be a tiny short somewhere, or the link wire isn't grounding chip. Anyway, if the chip isn't getting ground, the other voltages will be wrong.

      Believe me, i know it can be very frustrating. But the debug skills you'll learn are invaluable.
      +m

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    2. bottom row is connected to pin 4 and the fourth row and pin 3 have 4,3v

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    3. Oh, sorry. I misread your earlier reply. So the reference voltage (~4,3v) is ok. But if there's still supply voltage on pin 4, then the ground connection seems faulty. Pin 4 needs to be zero volts.
      +m

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    4. here are all the measurements of the pins of the ic from what i understood that should be correct right? I measured from the connection clamp to the pins.
      pin1: https://ibb.co/pJ4dDWn
      pin2: https://ibb.co/L9HC28B
      pin3: https://ibb.co/RbS4b6B
      pin4: https://ibb.co/WzFMzWr
      pin5: https://ibb.co/nwZP5h4
      pin6: https://ibb.co/Fhq6mL8
      pin7: https://ibb.co/4ZNpp9S
      pin8: https://ibb.co/4T9qp9F

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    5. Good. The voltages on IC are fine and that is working as intended. But since there's still signal missing, the fault is likely be between input jack and IC pin 3 - so that the signal doesn't reach the IC.

      Next, I'd suggest building a probe. Like this one here: https://www.diystompboxes.com/pedals/debug.html
      It takes just an old guitar cable and a cap with value of anything between 10n - 470n. 100n is quite popular.

      With that you can trace and hear where the signal is present and where it's not.

      There is 1K resistor and 47n cap from input to transistor's base. See if the signal flows from input jack to there. Then there is another 47n from transistor's emitter to pin 3. If the sinal reaches pin 3, there should be louder signal on pin 1.

      +m

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    6. i made the probe and that's my setup but i don't hear anything (the cell phone case is supposed to represent my cell phone) did i build the probe wrong?
      https://ibb.co/hcLdH7t
      https://ibb.co/vmdTDcW
      https://ibb.co/Qjmsv6k
      https://ibb.co/tD584nt

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    7. Probe itself looks good.

      I'm not 100% sure about the photos.. But. You are trying to feed the phone's output as a guitar's signal? This could be, to a degree, an issue due to impedance mismatch.

      Anyway.

      Take the signal to the input jack. Then take probe's plug end to the amplifier's input. In essence, the probe is your output to amp for testing/debugging. And the probe cap's free leg is your "test probe tip". You seem to have gound of the probe connected to other grounds, so that's good.

      Now, touch the input jack's tip with the probe's cap tip. You should hear the signal from the amplifier. Next, take the probe's cap tip to the board's input and either end of the first 1K resistor. Do you hear the signal? How about at transistor base or emitter? Or at Pin 3 of the IC?
      +m

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    8. My guess is you got a faulty tranny sir

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