Colorsound Fuzz Box trimpot to reduce noise?

[pete_g]

Hi. I am still new to pedal building, but i have added a fuzz control pot to a Colorsound fuzz box successfully, but I am wondering if its possible to add a trimpot to the schematic to reduce noise. I tried adding one from Q2's Collector to the .22uf cap like in a tone bender circuit but no success. Can someone point me in the right direction to tame the noise?
Thanks.





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[LucifersTrip]

The one (shouldn't need more than 10K) from Q2's Collector to the .22uf is for biasing Q2 to get a tone you like. Yes, it may be quieter at different voltages, but that's not the purpose.

Anyway, what type of noise do you have? Do you have good working voltages? Without voltages, it's a guess as to what the noise may be: building error,
noisy transistor, etc.

If your voltages are good and it's still noisy...
The 220pf on Q1 reduces high end sizzle (which is "noise"). You can try to increase that a bit or do the same for Q2 (start low at 50pf).
Try a battery instead of a wall wart and see if there's a difference.

[pete_g]

I built it ok. it's the second one I've made. I'm using a pedal power 2 plus so the power supply is ok. The first one is noisy too. I'm not sure whether its due to the fuzz control pot as it disappears a bit when I back it off a bit.
So a the placement of a 10k trim pot from Q2 collector to .22uf is correct I presume? Also does it need to be a 2 pin or 3 pin with the 3rd pin connected to somewhere else?
The noise is just hiss, like a single coil guitar. even when I turn down the guitar's volume to zero.
Thanks.

[pete_g]

Do i need to remove the 2k2 resistor, join lug 2&3 on the trimpot, connect Lug 2 to 82R / 0.22uf and connect LUG 1 to Q2 collector?

[nocentelli]

Yes, that will allow you to bias Q2.

[LucifersTrip]

So a the placement of a 10k trim pot from Q2 collector to .22uf is correct I presume?

yes, to the junction of the .22uf and 82R

Also does it need to be a 2 pin or 3 pin with the 3rd pin connected to somewhere else?

you only need pin 1/2 or 2/3

Do i need to remove the 2k2 resistor

yes (or you would only be able to adjust 2.2K+), but better to have a limiter so you don't hit 0K...putting a 500 ohm - 1K
in there would be cool.

The noise is just hiss, like a single coil guitar. even when I turn down the guitar's volume to zero.

again, check & compare voltages before tweaking...hiss can come from leaky ge's (but this is silicon), power supply, etc...
same exact hiss with batteries or different power supplies?

[pete_g]

Decided to rewire the input and output wires with shielded wire and it fixed the problem. Didn't need the trim pot after all, but it was interesting to hear what the pot did to the overall sound
Thanks again..