too much gain.... im missing something here

[bufferz]

    I breadboarded this circuit and I am getting way to much gain pretty much fuzz territory. I feel like I am missing something simple.

      If i place a volume control at the beginning of the circuit and send most of the signal to ground I have a very usable circuit.

[allesz]

Hallo, the input cap seems quite big, I would try a 10nF instead of 100nf; bigger input caps always go in fuzzland to me (not necessarily a bad thing).
The second stage (I admit that I don't understand it completely) maybe could benefit from a smaller input cap too?

[bufferz]

interesting, that would be an easy fix. Ill try that out

[vigilante397]

In my experience lowering input cap values usually filters the sound and makes it thinner. 1 uF on the output is pretty beefy though, and that could be making it overly dark and maybe a bit muddy.

[slacker]

With the gain pot turned up, especially with the 5k6/10n switched in you are applying a lot of gain to high frequencies, that might explain why it's fuzzy.

[GGBB]

^+1.  By my calculation the max possible gain is about 1890X.  That's a lot of gain.  Try reducing the 500K pot, 470K resistor and 10K resistor in the feedback loop of the first op-amp to 50K, 47K, and 1K.  This will give you 10X less gain.

EDIT: And that 100pF should go up to 1000pF to keep all things equal, but that's up to your tastes.

EDIT 2:  Forgot to add 1 for non-inverting - that makes the gain about 2060X.

[bufferz]

lol, that sounds like alot of gain....ok thanks I will try this out

[bufferz]

if I add 1 or 2 4148 diodes in series withe the exiisting 4148's will that lower the gain?

[ashcat_lt]

if I add 1 or 2 4148 diodes in series withe the exiisting 4148's will that lower the gain?

No.  It will increase the portion of the signal swing for which there is more gain.  It will probably be louder, and might sound cleaner, but the diodes don't really "set" the total gain.

So are we confused yet?  One person says too much bass is causing the fuzziness.  Somebody else says too much treble.  I personally would say that too much bass creates fuzz, and too much treble makes fizz.  But I don't think that's the question anyway.

[bufferz]

yes, I am confused...

so because the circuit sounds as intended when I place a volume control at the input and send most of the signal to ground - is it safe to deduct that it is not the capacitors, but rather the amplification that is causing the high gain super distorted sound?

[ashcat_lt]

yes, I am confused...

so because the circuit sounds as intended when I place a volume control at the input and send most of the signal to ground - is it safe to deduct that it is not the capacitors, but rather the amplification that is causing the high gain super distorted sound?

Yep!  Change the R's in the feedback loop as noted above.  This will affect the filters in that section also, so you might need to change some cap values.  One step at a time, though...

[PRR]

> the circuit sounds as intended when I place a volume control at the input and send most of the signal to ground

So do that. It's perfectly valid audio engineering.

[bufferz]

Thanks ppr, I think I might just do that because it's kinda nice to have the option to dial in the crazy high gain... I tried a 5k and 1m pot at the beginning of the circuit and there is more gain with the 1m. I found a website that showed how to alter the range of the pot and I think I will do that to try and achieve the desired max setting for a palatable taper....my only concern is how this might react if the signal it is receiving  were something other than a guitar as I have not tested that , perhaps a buffer prior to the volume attenuation is wise

[vigilante397]

> the circuit sounds as intended when I place a volume control at the input and send most of the signal to ground

So do that. It's perfectly valid audio engineering.

+1

Brilliantly put.