On Wed, 4 Jan 2006 09:43:45 -0600, "Tim Williams"
wrote:

"Arny Krueger" wrote in message
...
Tubes have always been proprietary parts. OK, you HP 200C has say a
6SN7 in it. Which manufacturer's 6SN7 is the right one to use?

Uh..!? Tubes from different manufacturers are _massively_ better matched
than any two transistors or ICs from the _same batch_!

Tim

That's totally backwards.

If you're talking about transconductance, *any* two small-signal
silicon transistors, even of different part numbers, will be better
matched than 99% of tube "matched pairs."

And after three months of use, the tubes will have drifted all over
the place, but the transistors won't.

And if you're talking differential offset voltage or drift of same,
the transistors beat the tubes by volts.

And you can't compare beta, bacause tubes don't have it.

John