Hi,
here is a link from Gary Pimm about CCS loade pentodes. Hope it helps a bit!
http://www.pimmlabs.com/web/drivers.htm
Erik
here is a link from Gary Pimm about CCS loade pentodes. Hope it helps a bit!
http://www.pimmlabs.com/web/drivers.htm
Erik
it is a fine gain stage - but the gain is so high small device variations cause relatively large changes in the exact value - so it needs to be used inside a feedback loop - and global feedback loops are not popular with some tube circuit designers
the output Z is high too so it needs a hi Z input in the next stage to realize the high gain
the output Z is high too so it needs a hi Z input in the next stage to realize the high gain
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I had tried a CCS a EF183 as cathode biasing for a differential amplifier consisting in the two triodes of a two ECL82, and it is great work. And tried as active loading for a 12AX7, the work is properly AT LOW AUDIO FREQUENCIES. As capacitances are in parallel with so high impedances, they effectively shunt the CCS. As an example, this circuit work with a gain of almost 100 times, but the -3dB was at only 8KHz. Not for high quality audio reproduction.
Best regards.
Best regards.
The OP was asking about using a CCS as a pentode load, not using a pentode as a CCS.
I gave him my two points of view, from my own experience. He will use which he believe best for his case.
Cordially.
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