I'm starting to really dislike JFETs...

[Surgeon]

I'm starting to really have problems with these circuits.

first it was my Dr. Boogie. I got it to work with great tone but I had to bias it by ear and getting rid of the squealing (nothing due to shielded wire or not belive me) took a lot of work. IN the end it worked fine but still, I think I could've gotten it to sound better.

I got a Citrus MKII to work ok.

Yesterday I built the THOR from ROG. It squealed no matter what I did and it's not what I'd consider a high-gain circuit. I got the J201 to bias correctly then by swapping a few 5457 for Q1 I got it to bias properly but it still squeals a LOT and sounds gated on sustained notes...

It's not that I don't know how to bias these things, both with DMM or by ear but I never get them to work exactly how I'd want them.

Either the quality of the couple batches I've had is bad or something else is wrong but I (in all humility) don't doubt the quality of my builds either...

I guess I'll have to work harder at matching these but it just sounds like everybody else is having such an easy time with these and I'm struggling like crazy just removing squeals...

[IvIark]

Yes, JFETs can sound great in circuits but they are inconsistent and generally a pain in the arse.  Especially considering they are pretty much all obsolete now and so expensive to buy in large enough quantities to swap and change.

There's no doubt about it, if you want consistency in sound and reproduction then opamp circuits are the way to go.

[Surgeon]

Amen... It's too ba that there are a bunch of really cool circuits around that sound so good and use them... Still, I can't believe I'm having problems with circuits that have trimmers for biasing.. I don't really feel like trying those mu-amps now, even though they're not really the same, they still use those temperamental jfets...

[Vince]

I had EXACTLY the same issues with the Boogie. Just when I got it where I liked it, it squealed at higher gain settings so I had to compromise between sound and functionality. It was a right pain. Same goes for the Wampler plexi drive, mine just didn't sound good enough to box.

[IvIark]

Bear in mind that trimmers do add noise to a circuit and may be responsible, at least in some way, to the noise.  Ideally if you're getting noise, once you have biased the circuit you want to remove the trimmer, measure the final resistance and put the closest value resistor you can in there.

[JaviCAP]

That's true, I'm not very fond of trimers for this reason. HIgh gain + timmers= lots of noise. I was very lucky with my first Dr.  Boogey, really loud and really silent, but have not been able to get another one like this, forall all the rest I've had to measure resistance and remove the trims being replaced by resistors.

That's the best way to deal with high gain effects built with jfets.

Other pain in the ass is the pedals than need matched ones. Matching a pair is somehow easy, from 10-12 ones, you'll get a pair, but.... gettin' a quad is a real nightmare!

BR