[sdiy] tube filter topologies...

[Michael Buchstaller]

>i've seen the schematics for the 2-tube
>opamps <philbrick/EB> and was wondering if anyone has acutally
>built one and done any characterization on this type of design.


I have built the philbrick Opamp and made a smiple Twin-T filter
with it.
It worked fine, although there were no benefits over the same
circuit with an 741 instead. (OK, the voltage peaks  are much higher at
resonance, but this has to do with the higher operating voltage)


-Michael Buchstaller