Fetzer Valve causing distortion in certain application

[rosssurf]

I made a Fetzer for a friend to use in his acoustic duo. I thought it would be nice to use as a volume boost for solo's. I have built several of these and all of them, including this one worked fine on my electric rig, as well as with my Larrivee' acoustic into my compter. When I used it on his acoustic rig it caused an overdrive kind of distorion sound, even when it was the same voulme as when it was bypassed. I am confused as to why this might be?
his rig is a Gibson chet atkins solid body acoustic electric in to a mixing board. My build is exactly part for part as the following link (I used a J201)http://aronnelson.com/gallery/album18/FETZER_VALVE_001.

He does use a beringer compressor but says it is set so low that it could not be hitting it.

any thoughts?

[ildar]

Booster + compressor = distortion.

[d95err]

First of all, you need to find out where the distortion occurs. You need to try the Fetzer without the compressor and vice versa. There is a pretty good chance that the Fetzer is overdriving the compressor or the other way around.

I've breadboarded a Fetzer and it resulted in quite a bit of overdrive with hot humbuckers. Perhaps the output of his acoustic is fairly high.

One simple solution is to get more headroom by using 18V (two batteries) instead of 9V (although it won't help if it's the compressor being overdriven).

[petemoore]

  Often those accoustics electric outputs are already 'boosted', adding a second booster is kind of like turning both into a distorter...?

[Ronsonic]

A couple of thoughts here. I don't have first hand experience with the Fetzer so I could be wrong but .....

Many acoustic electrics are looking for an extremely high impedance input and all have an extremely broad dynamic range. They will overdrive a some inputs and be loaded down by others. The Fetzer doesn't seem to have a huge amount of headroom. Not with those resistor values and that PS voltage. First thing I'd try is running the Fetzer inside a loop on the mixer. Try it before and after the comp. Upping the supply voltage seems like a reasonable suggestion also.

Ron

[rosssurf]

So, could I up the input resistance of the Fetzer? how would I do this?

[Ronsonic]

Test the principle first. Run it in the loop. It's free. IINM the Fetzer emulates a Fender preamp stage. It should already be a 1Meg Z in.

Ron

[lovekraft0]

Guitar=>booster=>compressor is impractical, since the compressor is just going to try to turn down the gain generated by the booster, probably resulting in the  compressor clipping when it's pushed past its limits. Guitar=>compressor=>booster should work fine, provided the comp's output doesn't overdrive the booster. Most stompbox compressors have enough make-up gain to make the booster virually redundant, though - a volume pedal following the comp might be a better idea. Just turn up the mixer channel fader to solo level, and back it off with the volume pedal for rhythm. Besides, those guitars have active electronics, so they have a pretty healthy output level without any boost.