Diy Germanium/Silicone Distortion Pedal need help

Discussion in 'Burnt Fingers DIY Effects' started by IITTII, May 22, 2019.

  1. IITTII

    IITTII TDPRI Member

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    Few months ago i just finished my diy wah wah pedal and i was thinking what to do next so i decided to make a distortion. Btw this is my first distortion including clipping diodes and a op amp so im not an exper.
    I looked a lot of different schematics of other peoples distortion pedals so i started drawing my own. I wanted it to be simple and made from parts i had laying around nothing too big. This is what i come up with.
    20190522_204639.jpg
    Anyway after sorting and testing all the parts i began building it (without knowing how it will sound). This is the end result.
    20190512_150321.jpg 20190512_150330.jpg 20190512_150354.jpg 20190515_122351.jpg 20190515_125846.jpg
    And so after pluging it in for the first time it powerd up perfectly with no "smoke coming out". Succsess i tought i have a distortion/overdrive pedal with an ability to switch between germanium/none/led diode clipping. Sounded too good to be true. Actualy on my sitty amp that sounds bassy without pedals it sound like a very heavy distortion. But when i got it to my friend that haves a Fender Twin Reverb it was tooo Harsh, very bright. It was missing a lot of low end and mid range and the Controls were very sensitive like if you bring it just a hair up its Loud as F... i think the way to fix that is to put a 500K or a 1M pots insted of 100K that is now in there. Now my question is what can i add, remove, modify to make it sound a bit more low end with prounounced mids. When i was building it i was aiming for something like Mxr distortion+ sound i know its a single stage drive and my is two stages. Anyway guys if you could "steer me" in the right direction it would be awesome id really appreciate that. Sorry for the bad english.
     
  2. galaxiex

    galaxiex Tele-Holic Silver Supporter

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    You don't have any "tone shaping" circuitry in there.

    Even just a basic tone control like a TS would help, or some kind of tone network without a control.

    Coupling caps look a bit small to me, might be why lack of Bass. I'm too lazy to do the math....
     
  3. tubejockey

    tubejockey Tele-Meister

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    The poster above is correct. You need to tame the fizz after the clipping. Your amp may have been doing this inherently but a twin will not.
    My advice is to use 1 gain stage in front of clippers with 1 after to buffer output. Put your gain pot in the feedback loop of the first stage for better control of the distortion.
     
  4. IITTII

    IITTII TDPRI Member

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    Tnx for the advice well it a little bit hard to add the tone shaping circutry cuz theres no room for another pot insted i would try bigger coupling caps. Can you recommend me any specific values.
    Tnx for the advice but as i said to do that i would need to start building a new circuit board from scratch the only thing i would want now is just tweek this one a bit to make it sound "usable". As for the next distortion pedal i would keep your advice in mind.
     
  5. tubejockey

    tubejockey Tele-Meister

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    Get clever with some jumper wires and your board will rearrange pretty easily. I think I have built about 150 pedals on perfboard, they can be modded without much trouble.
     
  6. cruisemates

    cruisemates TDPRI Member

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    I build a lot of pedals all on perf, and I believe there are few pedals that sound the same on a TWIN as they sound on a Marshall or almost any other tube amp. Especially if the Twin has JBL speakers. Those speakers are just for clean sounds, and sound awful (yes, in my opinion) in any other amp, but especially an over-driven one like a Marshall.

    FWIW: I don't know what you used for inspiration to design your distortion pedal on. Not many people can come up with their own custom design for the second pedal they ever build. But I think the RAT uses the 5322 as I recall.

    Anyway - I do like the idea of having a choice of diodes for clipping. I find LEDs work best for me (usually red 3mm) - germanium are usually too low gain, but sound good in a KLONE type of pedal.

    Anyway - I think that if a player wants pedal made for a Twin then it is best to ask Twin users what pedal works for them. They are just plain different beasts, IMO.
     
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  7. kbold

    kbold Tele-Holic Silver Supporter

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    The series caps (10nF) are acting as DC blockers, but also as high-pass filters.
    The feedback caps are acting as low-pass filters.
    Perhaps modify one (or both) of the feedback caps to pass more bass. (Or should I say, to attenuate more treble.)
    Like others, I'm too lazy to do the maths: perhaps just experiment to find what works for you.
     
  8. awasson

    awasson Poster Extraordinaire Gold Supporter

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    How did you spec your coupling caps? They’re going to filter lows based on their value and the impedance of whatever they’re driving. Are they necessary on the in and the out?

    A tone stack would be useful, even if it’s just a trimmer or a toggle switch.
     
  9. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    This is a question I'd like to have a better understanding of.
    Also noting what @cruisemates said about a pedal that works perfectly with a Twin (and JBL's) may not work well with a Marshall.

    Seems many of us buy one pedal after another trying to find one we like, when the problem is more often than not an eq issue.

    I can't really use a dist or fuzz that sends a big bass boost, and don't really like bass cut either.

    Since AFAIK there is generally a "coupling cap" that determines how much bass gets in to the circuit, it seems sensible to put 2 or 3 coupling caps on a switch so you can control the bass content.
    That changes other aspects of the sound, but I can work with that.

    I bought a Zvex Fuzzolo and it's just way too bassy.
    Many Muff circuits are too bassy as well.
    Some FF circuits are too bassy.
    But lots of classic fuzz circuits have very little bass, and sound like ants arguing.

    Those old time fuzz' with bass cut sound better into a cranked vintage Marshall though.
     
  10. awasson

    awasson Poster Extraordinaire Gold Supporter

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    Yes a toggle switch on the coupling caps would be like a bright switch on an amp with the right values.

    Without doing the math, the larger the cap, the more bass will be allowed. Looking at similar input circuits where the input goes pretty much straight into the opamp, I see input coupling caps are nearly 5 times the value that the OP is using. @IITTII, A Timmy has an almost identical input stage and it uses a 47nF input coupling cap. I’d try a 47nF or .1uF cap and see how that changes things.

    Your output cap should be ok with that 100k volume control but you can always sub in a .1uF and see if it’s an improvement.
     
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  11. galaxiex

    galaxiex Tele-Holic Silver Supporter

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    For choosing coupling caps, or other places in the circuit ie; tone stack,

    I use a capacitance substitution box.

    With the circuit live, I play through it and flip through the caps to find the one that works best for me and/or the circuit.
    Saves doing a lot of math... :D

    Use caution if planning to use this in a tube amp circuit.
    You MUST be sure the cap(s) in the box are rated for the circuit voltage.

    [​IMG]
     
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  12. allesz

    allesz Tele-Meister

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    I would increase the two 47 of caps; solder a 100 pf (or bigger) in parallel with them, even from the soldering side. It should kill the shrill.

    Also, if you look at the dist+ scheme you will see a 10nf (if I remember correctly) in parallel with the diodes. This should cut some trebles too.

    You can do the same move with the output cap (100 nf in parallel?). This would let out some low frequency.
     
  13. IITTII

    IITTII TDPRI Member

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    Great news!! I fixed the brightness by replacing both 10nf coupling caps with a bigger value. I used 0.15uf film cap and it sounds just right, but only in 2 positions without Cliping diodes and with LED cliping diodes the Germanium diodes position still sound brighter i dont know if thats normal with this type of diodes. Anyway also added a 500kohm pot for the volume so i can dial up just the right amount, i didnt try to replace the 47pf caps but i think i will do that next and as for the germanium diodes im thinking of adding a 10nf in parallel.

    Anyway thanks for all your help guys.
     
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  14. awasson

    awasson Poster Extraordinaire Gold Supporter

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  15. IITTII

    IITTII TDPRI Member

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    I have a problem with this pedals volume "sensitivity" example: I set my amp to 4 and i get my clean sound now my pedal is set to 0 when i turn it on i get no sound normaly now i set the gain to max and start bringing up the volume and this is the problem when i set it just to 0.5 i get a pretty loud sound. Now i think if i continue to take it up to 1 it would be enought to burn my amp with the loudness. Problem is the volume dailing is soooo critical i tought adding a bigger value pot would fix it but no tried with 250k 500k and 1M ohm. Its still too critical then i tought maybe the signal needs to go to ground to make it quieter so i tried adding a 10k but its the same. What too do why is it soo loud i want a pedal that i can set my amp to my clean sound then kick in the distortion to stay at the same volume just distorted sound. Im scared of accidantly touching the volume knob and blowing my ears. Here is the schematic but Note: the 10nf are swaped for 0.15uf
    20190522_204639.jpg
    What em I missing pls help.
     
  16. galaxiex

    galaxiex Tele-Holic Silver Supporter

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    Your op-amps each have a gain of 100.
    Seems like that may be too much.

    Try lowering the gain on both with 100K resistors instead of the 1M you have there.

    Op-amp gain calculator...

    http://www.learningaboutelectronics.com/Articles/Op-amp-gain-calculator.php#answer1
     
  17. IITTII

    IITTII TDPRI Member

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    Ok i did that now it sounds like an overdrive not a distortion any more but now i have a bit more control. I tried experimenting with different values like 10k 100k 500k in both stages then a 1M in first stage but 10k in the second. Anyway i would like to keep the gain in both stages to the max so i can get more distorted sound but would like to get the control. Can i put like a resistor in series with the output to limit the signal or ?
     
  18. galaxiex

    galaxiex Tele-Holic Silver Supporter

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    A resistor in series with the output "might" cut the volume some.

    Try it and see. It won't hurt anything.

    Perhaps a voltage divider/attenuator after the clipping diodes and before the volume control might work better.
     
  19. IITTII

    IITTII TDPRI Member

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    Dude the voltage divider after the cliping diodes worked perfectly after a bit of experimenting i setteld on 10k for the first resistor and 4.7k for the second to ground and now its just right tnx man soo much :)
     
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