vinyvamos
Well-known member
Is there anything to say that a pentagrid compressor cannot be built around a pair of ECH81 or ECH83 with the cathodes grounded, and the triode sections used as the next gain stage? A reference negative grid bias would be needed on both the heptodes and triodes due to the cathodes sharing a pin. Or... how about using LEDs to ground from the cathode pins to provide a fixed bias point, which would have to suit both sections of course. Or would this simply not work? I am assuming here that the use of LEDs means that no bypass caps are needed and that the voltage will be constant regardless of changes in Heptode current during gain reduction.
On that topic, how does the heptode cathode current vary WRT gain reduction compared to a more common vari-mu triode/pentode stage? Is it pretty much the same scenario?
Why were pentagrid compressors forgotten about? Do they exhibit higher distortion/lower GR capability than the later designs using triodes and pentodes?
On that topic, how does the heptode cathode current vary WRT gain reduction compared to a more common vari-mu triode/pentode stage? Is it pretty much the same scenario?
Why were pentagrid compressors forgotten about? Do they exhibit higher distortion/lower GR capability than the later designs using triodes and pentodes?