JFET White noise reduction?

[served]

Hi.

I have an amp. Its a Tace Elliot Super Tramp.
But it doesn't really matter what it is.

The reason why I started this thread was to ask. What is the reason that JFETs in a higher gain circuits produce that much white noise?
I have built couple ob Dr Boogies, its a Hi-Gain pedal, but still the same noise is there. Same thing with this amp.

It has J112 fets inside. And if I turn it to the point when the amp starts to sound a bit heavy I will get also noise.

With op-amps I have seen some cases where the op-amp has gone bad and so it starts to generate noise. But what about JFET?
Is there a chance that this could happen to JFET? I dont want to believe that this amp was made that way.

I don't have a schematic but J112 as a JFET is known. I would replace all the fets to blindly see what is going on if I would have them around.

What do you think about this?

[R.G.]

How do you know it's the FETs?

[DavenPaget]

How would you know if it isn't a power supply issue ? I don't have that with my power supply or my battery powered jfet amps ?

[served]

Well that is a very good question.

I thought that because I have seen and heard hissing-bad op-amps. So this was an idea that I would like to discuss about.
Can J-Fet hiss the same way? It seems like not really, if I take it as a switch or resistor. But still, it keeps hunting me.

[Earthscum]

Jfets are happiest when supplied with their specified current, thanks R.G., the 'happy transistor' gets stuck in my head.

I thought jfets were noisy but I was actually making them work in a resistive region that makes for more thermal noise. I think that is correct anyways. Once I started using proper resistances to make the fets happy they quit hissing at me. I think this is partly why some people end up with strange biases in circuits like the BSIAB to make it sound "the best". The other part being sym or asym clipping component introduction.

[PRR]

ALL "high gain" circuits hiss.

There's hiss in everything.

Amplify (gain) it, you hear it.

If your source (pickup) is strong enough, the hiss should be fairly inaudible. Which means do NOT have any loss between pickup and amplifier. Keep your guitar Volume full-up.

[served]

Thanks, I will have a look at how good is the powersupply in this case.