Virtues Of Paralleled FETs?

[Paul Marossy]

So that same noise rule applies to preamp tubes? I read somewhere that paralleled triodes cuts the noise in half, but I guess that was not quite right.

Brian did get back to me on that. It has to do with the sound of that combination not really anything else.

[PRR]

> If you use two devices in parallel, the noise does not go to half, it goes to 1/root 2 or 0.707.  You need four devices in parallel to get half the noise.

Right; but also you must multiply the *current*. Use 4X the current, in 4X the devices *or* one device 4X larger, get 1/2 the noise voltage.

Keep the same *total* current, the hiss advantage is little to none.

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> what benefit is there to having the FETs paralleled in such a manner?

In theory, if matched, it is no different from using one JFET with twice the area, *or* one same FET with double the resistor values.

Even if loosely matched, the combination acts like one FET, with perhaps a small difference at the clipping zone (which may be why it is different in this use).

If badly matched it is in-effect the one active FET doing the work.

If Brian has found more mojo this way, more power to him.