"Scott Dorsey" wrote in message


Arny Krueger wrote:

What would stop one from doing state-variable filters
with
tube op amps, patterned ofter the Philbrick modules of
the
days of tubes?

Slew rate and bandwidth. Those Philbrick and HP tube
op-amps
really did not have the bandwidth for anything approaching
audio. --scott

I didn't know that tubed op-amps were that bad.