Tom Schlangen wrote:
Hi Robert,


Did a little simulating in Circuitmaker.
Using a remote cutoff pentode like
a 6AR11 (compactron with a pair of identical
pentodes) as an emitter follower


You surely mean _cathode_ follower ;-)


looks to give good compression of the level
signal. [...]


Thank you very much, this suggestion is interesting
to me since it would provide real signal dynamics
compression (not only limiting).

But I must admit that I can't find said compactron
(and suitable socket) for a reasonable price over
here in Germany.

Are there any alternatives with more "common" tube
types and sockets? I understand that one single double
triode for _both_ channels can't emulate two
remote cutoff pentodes ... but a real compressor
function is appaling, if it could be done easily with
few usual/common parts. No need for audio quality
compression, it is only an optical feature.

Tom

For your "meter compressor" you don't really need two channels. Just
sample the sum of both channels, unless you listen to a lot of music
with everything in one channel you'll be alright. ;-)

As for common tubes - look for the tubes used in IF stages of AM radios.
These will almost always be remote cutoff, allowing gain to be varied
with DC control voltage (AVC). Here the most common is 6BA6 (and 12BA6),
I don't know what the equivalent is in Euro radios.

Cheers,
Fred