On Mon, 01 May 2006 11:39:50 +0100, "Dave Plowman (News)"
wrote:

In article ,
Don Pearce wrote:
Yes that is very similar. The great thing about using these discretes
as front ends is that the knee frequency for 1/f noise is way lower
than the transistors in the average op-amp. So not only don't they
hiss - they don't rumble either. Three of them in parallel is about
right for a mic at about 150 to 200 ohms.

Last time I played with this idea I found it very sensitive to RF
interference.

Well, there should have been nothing inherently RF sensitive about it.
Like any other sensitive system, it needs all the usual RF-proofing
tweaks to keep it sane.

d

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Pearce Consulting
http://www.pearce.uk.com