remove noise in dist+ at max settings?

[sineSurfer]

Hi everyone, I'm testing my diy dist+ from tonepad (with DC adaptor), on the guitar at max settings it has some noise, nothing to be bother about, but if I use with a synth the noise just gets too ovious like at 75~80% of max. drive.
Any tips to get rid of the noise?

[Mark Hammer]

At max gain, you have multiplied whatever noise there was in the input signal by a factor of 213.  So, besides starting with a cleaner and hotter input signal, yuo can stick a cap on the input to shunt high frequencies to ground, stick a small cap in the feedback loop of the op-amp to provide less gain for high frequencies, and increase the cap in parallel with the diodes to shunt even more to ground.

[sineSurfer]

thanks Mark, i'll try all that!!!

[grapefruit]

What synth are you using? If it's a mono analog synth you may be able qieten down the VCA or whatever is after it by using lower noise components. Apart from the VCA being noisy, it should only be noisy when the VCA is on...

Cheers,
Stew.

[sineSurfer]

Hi Stew, well is a x0xb0x(really don't want to tweak it any more after going thru construction and adding some mods already).

Checking more carefuly, I think the amplified noise is ground noise or regulator noise 50- 60 hz.?(is this correct?) but I'm not sure.
On the fx box (12v AC. transformer --ripped from an old 80's tape recorder-- with tonepad power supply, PCB here:http://www.tonepad.com/project.asp?id=59) I put together the dist + and Rebote 2.5 delay, the delay works ok, no noise at all, is just the dist+ 

[petemoore]

  I use the DIST+, w/guitar, comp, boost, afterboost, etc. the circuit itself is particularly not realy noisey, even with the 'noisy' reputation of the LM741 in it. I'd call the noise level normal to low for that amount of gain/distortin.