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Soulsonic JFET bias

Started by jubal81, May 04, 2015, 03:36:34 PM

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jubal81

Interesting thread going on at FSB about JFET circuit designs. Soulsonic posted a biasing setup that looks really interesting - the point being you can set the DC bias with minimal effect on the AC.


Here's a link to the thread


"If you put all the knobs on your amplifier on 10 you can get a much higher reaction-to-effort ratio with an electric guitar than you can with an acoustic."
- David Fair

midwayfair

I don't really feel like jumping in a fsb thread, but:

There is nothing you can do to not have JFETs have variable gains.
Positive voltage on a gate will alter the signal level just like baryon the drain or source voltage
Who gives a crap about 'variable drain loads' in most pedals? We're talking about a couple k at most for j201 and a few hundred ohms for 2n5457s. And if it's followed by another stage it's dividing against a 1m resistor, which is an imperceptible amount of division.

I don't see a clear enough advantage to warrant a 66percent increase in resistors and the need for more filtering caps to make the Vb approach how quiet and stable GROUND is.