Klon Centaur

Here’s a layout I did for the Klon Centaur overdrive based on a schematic by soulsonic.

Update (28.02.2011): I finally got around to boxing the Centaur. This time I felt brave and decided to try an artwork technique courtesy of “frequencycentral” over at freestompboxes.org (described in this thread). I thought I gave it a good go being the first time and all, but needless to say from looking at the picture my only option was to leave it to dry outside in -20 degrees Celsius (that’s -4F for you Americans) and the result was less than optimal. Looking forward to spring and my next attempt.

Update (18.03.2012): I’ve had several requests for voltage readings from my build and here goes:

Battery at approx. +8.90v and all pots at zero.

1  +4.43V  +4.6V  +8.84V
2  +4.44V  +4.43V  +4.52V
3  +3.45V  +4.43V  0V
4  0V  -8.44V  -4.13V
5  +4.43V  +4.42V  -8.42V
6  +4.43V  +4.43V  +3.97V
7  +4.41V  +4.26V  +5.29V
8  +8.87V  +15.92V  +8.82V

I don’t know whether these are the “correct” voltages, but mine sounds good so…

Update (21.06.2012): Fixed an error on the layout where gain lugs #1 and #3 were swapped. Thanks to Dieter Brenner for pointing this out!

Updated: 12 April, 2013 — 15:31


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  1. Ok, this turned out to be a very simple error or my part, I’m so glad it was nothing more. I had erroneously connected GAIN lug 5 to ground :)

    … And wow, this pedal sounds unbelievable! I prefer low gain crunch so even at GAIN=0 & VOLUME close to 10 this thing produces amazing tones for me. It seems to add some amazing type of harmonics to the tone.

    This might even beat my Zendrive and Sweet Honey clones.

    Thanks Harald for a great layout!

  2. Hi Harold, do you know if the caps C12 through C22 must all be polarized? I installed bi-polar caps and my IC1 & IC2 voltages are way off and the pedal sounds terrible. All I get out of it is popping and crackling, mostly when I pick hard. Same thing in bypass. I’m wondering if it has anything to do with the caps?

    Readings with PS voltage at 8.61v and all pots at 0.

    IC1 (this IC was soldered in, I ran out of sockets… maybe I killed it?)
    1: 1.36v 5: 0v
    2: 1.36v 6: 1.5v
    3: 0.96v 7: 8.0v
    4: 0v 8: 8.6v

    IC2 (socketed, notice NEG voltage on PIN 1 ??)
    1: -4.2v 5: 0v
    2: 0v 6: 0v
    3: 0v 7: 4.26v
    4: -8.16v 8: 15.3v

    IC3 (socketed, this is the only one that looks about right)
    1: 8.6v 5: -8.16v
    2: 4.4v 6: 4.2v
    3: 0v 7: 5.6v
    4: -4.0v 8: 8.6v

  3. I just finished it… have a problem:
    TONE and VOL POT works fine… gain not..It cause the sound get dark way up from 0 to 3/4 then it starts overdrive for the last 1/4 to end.
    checked circuit 2 times and i didn’t forget anything… all things are allright!
    Ic2 and Ic3 are allright…Ic1 has some issues…
    PIN3 1.20V
    PIN6 1.80V
    PIN7 8.50V
    and with gain at maximum
    PIN3 still 1.12
    PIN6 3.50
    PIN7 3.50 Already changed R9 and C3..any idea? i’m getting mad!

  4. You’re right about the Klon having non-standard wiring requirements. It’s because it’s a buffered effect, and not a standard true-bypass setup.
    As for salvaging what you have now, maybe, but you’ll have to do a bit of thinking. The easiest would be to remove the true-bypass wiring and just set it up as per the layout.

  5. I feel as though I may have used my minimal knowledge to answer my own question but I don’t yet trust myself as I am a novice builder.

    I got the klon board populated and began to move on to the switch wiring (which I used http://tagboardeffects.blogspot.com/2012/02/offboard-wiring.html for my off board wiring. Worked perfectly for the Timmy I built not long ago). I got the switch mostly wired up when I noticed that the switch wiring specific to this project was actually on the layout. duh.

    So, my question is, can I salvage this/leave it this way or am I going to have to undo what I’ve done and follow the layout exactly for the switch? If I can salvage it what would I need to do differently from the layout?

  6. Yes, that looks like the correct pot, though they’re out of stock. You could also get them from smallbear, who seem to have them in right now: http://www.smallbearelec.com/servlet/Detail?no=736
    As for the diodes I’ve heard that the 1N34A ones are pretty crucial to get the same tone, though that’s not to say you can’t get a great sound using other diodes. The reason it has to be these ones is because of the very low voltage drop (less than 0.3V). They shouldn’t be that hard to find on ebay, but make sure to check the ones you get for duds (in my experience about 9 out of 10 are good and the rest are dead). Sucks to add a dead one to the circuit; could take a while to debug.

  7. Those voltages look very similar to mine, s that’s goo at least. I can’t tell what the problem is, but if power suddenly drops a natural place to start would be the voltage converter (IC3). Do a closer inspection of the components in that area of the circuit board, maybe you’ve got a solder bridge, misplaced component (electrolytic the wrong way?) or something like it.

  8. Using a poweradapter @9.06volts
    the top TL072
    Pin 1 = 4.47v Pin 8 = 9.04v
    Pin 2 = 4.47v Pin 7 = 4.47v
    Pin 3 = 3.45v Pin 6 = 4.47v
    Pin 4 = 0v Pin 5 = 4.47v

    The middle Tl072

    Pin 1 = 4.47v Pin 8 = 16.31v
    Pin 2 = 4.47v Pin 7 = 4.09v
    Pin 3 = 4.47v Pin 6 = 4.47v
    Pin 4 = -8.69v Pin 5 = 4.47v

    The bottom ICL7660

    Pin 1 = 9.05v Pin 8 = 9.05v
    Pin 2 = 3.79v Pin 7 = 7.04v
    Pin 3 = 0v Pin 6 = 4.6v
    Pin 4 = -5.01v Pin 5 = -8.69v

    And after a while when the pedal has crapped out, most of the pin values on all the IC´s go down to half of these measurements. And Pin 7 on IC2(TL072) goes down to -6volts??

  9. Hi Vidar,
    I have no knowledge of that layout, but it’s probably quite similar to the one I have here somewhere. I’m not sure what could be wrong, but consider checking the voltages before and after those 30 seconds, and also comparing with the ones I have posted (do mind that the component labels might differ since you use a different layout). Could help point you in the right direction if there are any anomalies.

  10. Hi! im having some trouble with my klone build(the one on tagboardeffects.com). the klon clone starts to crap out more and more, and in about 30 seconds of use it is all crackling and popping noises. it works fairly well up to that point… its the same if the effect is on or off. i´ve built myself an audio probe but not sure where/how to begin with it. any help is apreciated

  11. Thanks Harald. The parallel trick doesn’t work like with resistors then? I’ll read up on that.
    Also, I found another source, a brick&mortar store even, pretty nearby. Will hit them up for the right values tomorrow.

  12. You can use the 330n in both circuits, but it will change the frequency response, by how much I don’t know. Alternately you could use the 330n in parallel with a 68n for a total capacitance of 398n; pretty close, but it might be a bit clumsy when it comes to the physical size of these things.

  13. Hi Harald, I’m coming up on building this, but can’t get 390nF/0,39uF from my supplier. Should I substitute C2 with 330nF or with 470nF?
    Same question for the 5bandEQ, I’ll post a comment on that page.

  14. Just went through every single part and found that I had 560K at R25 instead of 560R. I had put 560R in my first build, but somehow put 560K in my second build. No wonder I couldn’t hardly hear anything. They all came from the same mammoth bag, but I guess a 560K slipped in there. I learned my lesson to always use my MM and check the values no matter what the bag says. Thanks so much for your help Harald, and the layout. I’m gonna use one for a clean boost, and one for OD.

  15. Heh, hard to say, but you could start by A/B-ing the voltages on your circuits (or use the ones I posted). This could help you narrow the search down at least.

  16. I’ve built two of these, and the second one doesn’t work. I got the polarity on C17 wrong with an electrolytic on the first one, and I got the polarity right on my second build, but it doesn’t work properly. It has great buffered bypass, but hardly any volume. All the controls are working, but just barely any volume. Any suggestions? I can’t see a difference on either board, after checking the traces and reflowing some iffy looking joints, still the same problem. The first one works perfectly, haha.

  17. You could of course wire it as true-bypass, but you might learn a lot more if you take the time and try to sort out the buffered wiring. Go over it another time and see if you can find where the problem is. If I had more time I’d do a wiring diagram specifically for this layout, but that’s probably not going to happen anytime soon, sorry.

  18. Hi Harald, finally got around to putting this in a box but Ive it a problem. I lose the signal completely when I switch the pedal off, still connected to the power. I normally run my builds in true bypass & not buffered. Surely the signal should get through as long as the power is still on to the box? I think I must have the switch wired up wrong as when I just use a direct feed from the board at on/off sw2 to the jack it works fine. Could i just wire it up in true bypass on the understanding that the buffer will only kick in when the pedal is engaged? Id wire it up with the buffer if I could just figure out what going wrong the switching :-)

  19. I finished it yesterday (finally get one 4.7 cap). Awesome sound! Made with MAX1044 and 9.1V Zener, In case someone doesn´t find easily the 7660 like me.

  20. Hi Roque. You’ll probably be fine replacing either one (or both) with a slightly larger cap, like 10u. These control the frequencies you output and the larger the value the lower the frequency threshold.

  21. Hello, I realized I only ordered one 4.7uF cap. Can I change any of the 2 in the layout to other value? I this 10uF is the next value I have, maybe 3.3uF but not sur.


  22. Hi Harlad, just a quick couple of questions. Have you already altered the vero board to reflect Deiters recommendations & do you still need to connect A2 & B3 on the pot? Excellent layout dude.

  23. Being a circuit with multiple audio paths I don’t think there’s one single “tone cap” but quite a few of them, and I have no idea which ones to change really. I suggest reading up on the relevant threads over at FSB. As an alternative you could try to breadboard the whole circuit and start experimenting with cap swaps.

  24. I’ve made the correction…

    Before it was: WOW!

    Thanks a lot guys!

    Just a little question: can you say me which is the “tone” capacitor?
    I’d like to put an DPDT switch to “switch” from these capacitors…but i don’t know which capacitor i’ve to substitute (or better make in parallel way).

    Thanks a lot!


  25. Holy shit! Thank you SO MUCH for the gain pot correction!!!

    If ANYONE out there built this originally and is having this unholy squealing when all the pots are turned up, THIS was the problem. I have been banging my head on this build for months and this was the solution. Thank you thank you thank you!!!

  26. Interesting. I think you just discovered an error on my layout! I’ll fix that right away. Nice catch, thank you :)

  27. I solved my “muffled-gain-problem” as follows:
    Connect the dual-pot (level A and B) like this:

    Lug A1: Gain4
    Lug A2: Gain5
    Lug A3: Gain6
    Lug B1: Gain3
    Lug B2: Gain2
    Lug B3: Gain1

    Also connect A2B3

    Now it sounds goooood!

  28. Can’t be the pot. Mine works fine except for that muffled thing you mentioned. I measured my IC voltages and I also get approx +1.6V from pin3 on IC1. I’m sure I built the vero 100% correct, I went over it several times.

    I’m really stumped here, don’t know what to do next, and I REALLY don’t feel like rebuilding the whole thing ;)

  29. Luka, I have completely rebuilt the Klon because I did notice a few mistakes on mine. I am having the same problem with my gain pot but other than that it sounds good. When the gain is all the way off, it’s muffled, but as soon as I bring it up even the slIghtest, it’s clear again. Which makes me think the pot is wired wrong. I wired based on the 123 – top 456 – bottom with shaft up and lugs facing me.

  30. I’m having the same issue as Josh. It’s safe to say that C3 is not the culprit, as I’ve tried several others and with other IC’s and with the same results.

    Josh let me know if you’ve solved the problem and how ;)

  31. Great news, Andrea! :) I’ll consider adding this info to other builds as well, though it’s a bit of additional work.

  32. Yes Harald, I fixed. Awesome.
    The IC’s voltages is a good idea that you probably should inert in every pedal (from now on). it may be so helpful!

    Thanks again


  33. Ok guys, i think i’ve found my definitively Overdrive!

    This pedal is simply fantastic…no other words.

    The circuit is just a little long to make…but the final wiring is simply and clear!

    What can i also say?

    Thanks Harald!
    Thanks a lot!

  34. I don’t know about the IC being bad, but it won’t hurt to try another if you’ve got extras. I assume you’ve gone over the circuit looking for short circuits like solder bridges and trace cuts not actually breaking the connection completely? Other than that there isn’t much I can do with the limited knowledge I have. Maybe consult the debug FAQ at http://www.geofex.com or the debug thread at the DIYstompboxes forum.

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