weird hiss on DIY FX when I turn my axe vol down...

[csmatt45]

I've built a couple of fx from scratch (treb boost, clean bst, FF). They all sound and work great, but when I roll my tele or strat's volume down, as soon as I hit the "all the way down" point this loud hiss comes in. A/B'd it with some commercial pedals, boss, ibanez, they don't do it. None of them are non-buffered, true bypass though, and I don't have any true-pass to compare but my own.

Anyone have this? I can't imagine I miss-biased all my projects the same exact way...

Thanks in advance.

Matt

[Paul Perry (Frostwave)]

It might be, that when you roll the tele vol pot right down, the wiper loses contact with the pot element and just 'floats'. Or there is an earthing problem in the guitar electronics (unlikely).
If this were the case, then when you have the vol rolled down, there is a high impedance and no signal to the amp. Whihc is likely to give hiss.
Whereas, with the non-bypass effect, ther eis always a low impedance output from the effect. Whihc will sound quiet.
If that is the case, then fixing the pot would give you a low impedance to the amp, when the pot is wound down.
You can test this theory, with another guitar.

[csmatt45]

no, that was the first thing I tried, happens with both guitars. Just to clairify, this happens when the effect is ON, not bypassed. Pedal on, I roll back the vol in my guitar between songs, everything is fine, until I hit the all the way down, then loud hiss...

anyone have this happen?

thanks!

[brian wenz]

Hello Hello--
     Yeah, it's been happening quite alot with my Fuzz Face and Tonebender circuits.  I finally raised the value of  the Q1 collector resistor and that helped to remove the hiss.  Maybe this has to do with the fact I'm not using "stock" transistors and by increasing Q1's value it biases the circuit a little better [thus removing noise...]
Brian.

[Fp-www.Tonepad.com]

I had something like that happen to me... I think what I did was add a 1k resistor in series with the input and that seemed to have solved the problem.

Also, I've seen it happen with wirings like the standard les paul.

I wish I could be of more help.

Fp

[brett]

Also, I've seen it happen with wirings like the standard les paul.

Ditto.  My old Les Paul copy used to do this big time.  Roll the volume down to about 2 or 1 and it sounds just like rain on an old tin roof.

I never solved it, but FP's idea seems reasonable - add some resistance in series so that the guitar's innards and cable can't act as a white noise receiver.
cheers

[brian wenz]

Hello Hello--
   What about any general comments regarding raising the resistor value of Q1 collector?  
Brian.

[Fp-www.Tonepad.com]

Simple and effective, as far as I'm concerned it fixed the issue.

Try it and let me know.

Fp

[brian wenz]

O.K  O.K---
   Now I'm confused!
Are you talking about putting the 1K in the guts of the guitar or the fuzz??
Brian.

[bwanasonic]

This is why I find an Ernie Ball volume pedal such a useful contraption in my signal chain. That series resistance comes in handy for more than just turning down the volume. Certain combinations of effects and guitars can yield some strange noise behaviors that are alleviated by backing off the pedal slightly.

Kerry M

[csmatt45]

thanks guys, I was hoping Aron might chime in.

Just FYI, the reason I was guessing it might be related to buffering and/or impedance (I have only a vauge sence of how buffering works) is because the problem does'nt occur if I put a boss ped or a ts9 etc. in front of it.

Also FYI I have a trim pot on Q2 to adjust the bias (by ear, gotta buy a MM). Maybe I'll try Q1's collector. Still left wondering why this has happened on other pedals.

Anyone else's 2 cents is welcome!

thanks,

Matt