On Sun, 16 Jan 2005 19:36:48 +0000, Nick Gorham
wrote:

Iain M Churches wrote:
"Eiron" wrote in message
...

How strict are the negative feedback rules?

It has to be single ended with no NFB as far as I recall.

I presume a Darlington pair or triple is allowed but if I use a triplet
of NPN/PNP/NPN or even an NPN/PNP pair then someone is going to argue
that it has a load of negative feedback even though it behaves like a
high gain transistor in emitter-follower mode.

The SET uses two halves of a 6SN7 and then a 300B, so three stages
per channel.

I may join in then, my 211 only uses three stages per chan as well :-)

But doesn't that have a *lot* more power?

My paper design does indeed have three stages, a central MJL4281
voltage gain stage which dominates the 'sound', flanked by emitter
followers at input and output. Four transistors in all, very simple
design, 5-8 watts of Class A operation, no loop feedback. Frankly, I
don't care what Turner et al think, it is a KISASS design which uses
BJTs in a way suited to that technology, in the same way that the
6SN7/300B is used in a way suited to that technology.

--

Stewart Pinkerton | Music is Art - Audio is Engineering