Thursday, 1 May 2014

Subdecay Stupid Box V1

Request from the forum.  Info from Brian about the original circuit:

The Stupid box was the first pedal introduced by Subdecay Studios in 2003.  I had been looking for something to get a big ballsy sound out of my amp, but my ultra clean 100 watt 6L6 based tube amp combo just did not seem to agree with anything I threw in front of it.  Sustain, and good harmonic response were a must.   After going through plenty of overdrives and distortions, and building a few 'clones', I finally decided to build my own. 

I wanted something with a big low end, without getting muddy, and an in your face sound, without the high end sizzle I got with a lot of other pedals.  After a few weeks of experimenting after band practice, I came up with the stupid box.


  1. Any chance of getting a v2 version? I'm interested in the trim pots on v2 and how they effect the circuit. Thanks for the great site...

    1. I haven't seen a schematic but I'll definitely do it when I do.

  2. just curious about how it will sound with 1n94 + germanium diode.

  3. Got it working the first time with a bit of a squeal but then nothing? Built it again and still nothing?So frustrating , it sounded awesome when working the first time

  4. The schematic that is available on DIYStompboxes contains an error. I guess Mark made the layout according to that (compared to that it seems so, as it has the same error). I made my own PCB based on that and the input cap is going directly to Vref which is wrong. This way the signal that comes from your guitar is effectively dumped directly to the virtual ground and the opamp doesn't get any inputs. A quick fix on the same layout is to move the 500p cap two columns to the left at the very edge of the board. Then you can move the 22n input cap two rows up, connecting the input with the non-inverting input of the opamp. Also the tone pot could be reversed, this way it brightens the sound counterclokcwise (like the Rat). I did these changes on my PCB and it has a very nice sound. Indeed a simple, but good sounding overdrive/distortion.

  5. This one is verified! It sounds nice! Thanks.

  6. Hi,
    I was in the process to drawing this fuzz schematic, and I noticed something odd, should the input 22nF cap go through the resistor divisor and then 100k resistor before the opamp input ? To clarify I made 2 schematics, the first one is the one that matches this veroboard circuit, and the second one, the one I think is the right one, can someone confirm that the resistor divider circuit is in paralel to the input ?

    Veroboard Circuit:

    The one I assume to be the correct one:

    P.S. I have no way of testing this right now btw :(

  7. Assuming the 500pf cap is for noise filtering. What's the highest value cap I could use there for the same or better results? Don't have any 500pf caps laying around...have an 820pf I salvaged out of something and then my caps jump to 2200pf, unless I can find an old circuit board lying around with anything suitable.

  8. Hi Ivlark, this is great. Do you have a link to the Schem?
    thank you!

  9. Mine doesn't work. Checked everything, but don't make a sound.

    1. It's a pretty simple circuit and so should be fairly easy to fault find. If you measure the voltages between all IC pins and ground that will give us a good clue as to where the problem lies

    2. Yeah, i'm surprised.. i did another bigger circuits and worked good.
      The Measures:

      Pin 1 0.06V
      Pin 2 4.68V
      Pin 3 3.98V
      Pin 4 none
      Pin 5 none
      Pin 6 5.24V
      Pin 7 9.14V
      Pin 8 0.07V

    3. Well your voltages look reasonable to me so don't point to anything obvious. No sound could be down to a single bad connection though or maybe a single faulty component such as the volume pot before the output. So if you've gone over it and are definitely happy with all placement, cuts and soldering quality then you really want to make an audio probe which should allow you to diagnose where the problem start exactly. Have a look at the information on building a probe here:

      And then starting at the input (and preferably omitting the stomp switch to remove another possible fault) follow through the schematic to the output and see where the sound drops out. That should give you the best indication of the component(s) to check or where to look for maybe a cold joint. The order you want to check will be:

      Input > 22n > pin3 > pin 6 > 100n > Tone 1 > Tone 2 & 3 > Volume 3 > Volume 2 > Output

    4. Ok Mark i'll try that, everything is fine to me. I changed all caps, wires and diodes. I was hoping a broken wire, but no. The circuit is connected direclty to jacks. I hope it solves my problem

    5. What I could change in the circuit, to get more treble in it? I liked the pedal, but I thought it wouldn't be that low. I'm thinking to put it in a protoboard and try something different, but don't know yet what, maybe changing the tone 100n and 22n? I would like if someone point me what i could do. Thanks

  10. Hey, now is working, i just changed the ic, for a new one, and worked. Don't even tried the probe rs. Thanks man!

  11. Built this one today and must say this is a brilliant pedal. Just has the most beautiful decay and a great Fuzz. Would recommend this as an nice easy and great sounding build.

  12. Hello, I encountered a problem here, I am new to pedal building, this is only my 3rd project so excuse my ignorance :) So with a power supply of 500mA I get sound, but there is a loud hum witch grows with the drive knob. With a supply of 1000mA it is impossible to turn the volume up, as the hum gets pumped! On a Pedal supply delivering 100-150mA, there is no sound at all.(as far as I know, mA output should't make a diffrence, right?)
    Battery also gets no sound or any response.
    Should say that I cheated a bit on the schematic by using 1n4148 diodes, and replaced the 500p cap with two 1000p soldered together. Also, already tested with 3 different Ics (all TL071) with same results.
    Any ideas?

    1. hi there! you didn't cheated at all.both diodes are almost the same. and as long as you've soldered 1000pfs in serries and not in parallel you are ok.
      first of all i would check for misplaced components and unwanted briges.
      and i want to ask something on the hum thing. with the 500mA does the effect work other than hum? i meen are all pots working as they should(tone, gain,vol), but you get a hum?
      and are your supplies regulated?the cheap ones really give tones of hum...
      you can also search in the forum for the "huminator". it really helped me on humming builds.good luck

    2. Hey, ξεναγός, always there for me :)
      Yes, on the 500mA with drive all the way down the guitar sounds through, with a quite loud hum (enough to be unusable), Volume works fine, Tone works fine. Twisting the Drive pot, the hum gets louder. Distortion kicks in but the hum becomes noise. Too much noise :)
      Yeah, the supplies are cheap and unregulated, but I've been using them both on other (non-distortion) pedals with no problems.
      What really doesn't make sense to me is the silence i get from the battery and the low output supply.

    3. Anyway, I wanted to know if the parts I switched were causing the problem. Since that's not it, there is surely a problem on my attempt or some part. So, I will be debugging!

      Still would love an answer to the mA and battery situation though. :)

    4. To whoever it may concern, finally got it working. Seems all 3 Ics I had were from a faulty batch. A new one did the job. Talk about luck there. Cheers and thanks!

    5. Dang ICs. Good to hear you're back in the game!

  13. Hey. Sorry for the dumb question, but can i change the 500pf thing to another value? i cant find it in any shops in hungary. there's only 470 and 560pf what is reachable for me. will it work? thanks

  14. This is awesome, I built this a few times but have this nasty high fizzy sound over the top of the drive. Any ideas why that could be?

  15. ok so its ready, kinda works, but it makes a farting sound like a fuzz on low gain so what can be wrong?

  16. ual!!!!! exelente pedal de fuzz, obrigado pessoal, nesses ultimos dias so comecei a construir pedais funcionais apartir das contribuicoes de vcs, nao sou especialista em eletronica, somente a escola da vida kkkk, o fato e que vcs estao me espirando a continuar aqui, ja estou satisfeito com cerca de 5 pedais daqui produzidos, vou continuar pelo menos com mais uns 10 kkkk

  17. ja ia me esquecendo... posso mudar os diodos para germaniun?

  18. Hello all, i built it today for my first circuit as i'm very beginner, and it doesn't work correctly :
    when i put the effect on,first i had nothing...and now the sound decreases a lot, and there's no distorsion.
    I didn't find error on the circuit, nor soldering problem, so i tried with an audio prob, and with it i got this sound level problem, as a result it's just as like if the sound was bypassed but with a very low level.
    The only place where the sound is the same as when bypassed is on row 3 of the IC. The mesures on the IC give :
    Is it correct ?
    Hope you can help me to understand what's wrong on my circuit, thanks in advance