One Caveat on the above points re 6ES8 (ECC189).
They actually make a good cathode follower on a line out stage - because of their non-linearity. Run them at around 6 to 8mA. As the output voltage goes up they start putting in some 2nd harmonic distortion. Not too much because there is nearly 100% feedback in a cathode follower stage. I like it that way - it adds a bit of warmth and "tubiness" and is absolutely ideal for driving a SS Power Amp.
Hint: run the 2nd triode in an identical circuit , active but inverted drive, as a "pseudo" shunt reg.
Where linearity is required stick to ECC88 - of the modern production stuff I like the JJ.
I have had bad experiences with microphonics with NOS Philips. I have a prototype amp with 6DJ8 cascode diffamp / direct coupled 6SN7 cathode followers / Parallel Push Pull KT88 Ultralinear (135W in 4 Ohms with Hammond 1650T Output Tranny). It took me ages to twig that that low frequency "surf like" woosh woosh was microphonic 6DJ8 in the diff amp.
Cheers,
Ian
They actually make a good cathode follower on a line out stage - because of their non-linearity. Run them at around 6 to 8mA. As the output voltage goes up they start putting in some 2nd harmonic distortion. Not too much because there is nearly 100% feedback in a cathode follower stage. I like it that way - it adds a bit of warmth and "tubiness" and is absolutely ideal for driving a SS Power Amp.
Hint: run the 2nd triode in an identical circuit , active but inverted drive, as a "pseudo" shunt reg.
Where linearity is required stick to ECC88 - of the modern production stuff I like the JJ.
I have had bad experiences with microphonics with NOS Philips. I have a prototype amp with 6DJ8 cascode diffamp / direct coupled 6SN7 cathode followers / Parallel Push Pull KT88 Ultralinear (135W in 4 Ohms with Hammond 1650T Output Tranny). It took me ages to twig that that low frequency "surf like" woosh woosh was microphonic 6DJ8 in the diff amp.
Cheers,
Ian
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