any noise reduction suggestions???

[iainpunk]

im building a fuzz pedal without controls only a bypass switch, it needs to not be complex since i have a current part count of 6 resistors, 3 diodes, a led and a dual op amp. im not really convinced at the use of a 'crossover distortion gate' but i don't see any other option.

it doesn't have to much gain, the front end has a 20dB gain (x10) and there's no gain after it, just a tricked out whacky wave folder. idk where the hum comes from. its battery powered so its not from a noisy PSU. It could be the breadboard, but i haven't had so much noise from way higher gain circuits before.

cheers, Iain

[antonis]

No schematic, Iain..?? 

[Mark Hammer]

By "crossover distortion gate", I assume you mean a back-to-back pair of diodes in series with the signal path?

It works, but it eats up some of the signal.

[iainpunk]

No schematic, Iain..?? 

forgot to add it, sorry all diodes are 4148 except teh one marked LED

[iainpunk]

By "crossover distortion gate", I assume you mean a back-to-back pair of diodes in series with the signal path?

It works, but it eats up some of the signal.

yes yes

i know it works, that's why ist in 80% of my builds, even medium/high gain overdrives. but im already straining with the headroom since its only +3 and -3V from a 3 wire battery pack and the biggest problem is having to push the signal in to distortion before the wave folding which has some adverse effect on the clean-ness coming through the distortion.

cheers, Iain

[antonis]

Schottkies..?? 

[iainpunk]

Schottkies..?? 

or maybe germaniums
aren't schottky diodes inherently noisy?
i suppose that's only when conducting so not when blocking the signal... ill look in to that.

[Rob Strand]

The 20dB is going to up the noise.  I guess the question is the noise complaint *only* because of that.

You could add some low-pass filtering that would remove a lot of noise.   Either on the first stage or across the diodes in the feedback network.

[iainpunk]

the biggest part of the noise is 50Hz Hum, so i'm trying to cancel that.

when im back at the hobby table, ill try putting in some capacitors parallel to the batteries to check if that works... and ill experiment with schottky's or germaniums in line with the signal path

[Mark Hammer]

There don't seem to be any DC-blocking caps in there anywhere.  It likely wants a cap on the input, and a suitable value on the 1k ground leg in the first stage....at least.

[Rob Strand]

ill try putting in some capacitors parallel to the batteries to check if that works

Very much worth trying.

[iainpunk]

but its working with a dual supply, +3 and -3 volt, so it kinda doesn't need any dc blocking caps.

i got a bunch of quad AA battery snaps with 3 wires coming from them. this eliminates the need for DC blocking. also its a fuzz so i want the lowest bass guitar frequencies to come through. with relative power.

cheers, Iain

[Mark Hammer]

but its working with a dual supply, +3 and -3 volt, so it kinda doesn't need any dc blocking caps.

For blocking pure DC, yes.  Bu one of the traditional functions of those caps is to roll off unneeded/unwanted low end that goes down to DC, but also includes things like AC hum.

[Steben]

Isnt that diode to gnd after the first opamp shutting the dc bias to gnd? It must give lots of current as well. Or is the gnd 1/2 Vsupply?
EDIT: dual supply....  sorry