I am working on a headphone amp that can either use a 6sn7 or a 6n6p (or a 6n1p/6n30p/6dj8 etc.) There is one tube per side (both sections in parallel) transformer coupled to the output. Primary impedance of the OPT is about 10K. I am trying to figure out what B+ to use to accomodate both tubes. 300V puts the 6sn7 (biased to about 7V) with a plate voltage of ~200V at 10mA. The 6n6p would be biased at 6V with a plate voltage of ~140V at 15mA. Are these reasonable spots, or would someone suggest a better operating point for one or both.
I am looking into a regulated PS which would mean that it won't change under load, and that altering it for tube changes would be difficult, so the B+ needs to work for all options if possible.
I am looking into a regulated PS which would mean that it won't change under load, and that altering it for tube changes would be difficult, so the B+ needs to work for all options if possible.
Hmm...depends on the 6SN7s you have and the sound you want out of them. For instance I use the RCA grey glass ones which have a very warm & rich sound, when run at 240V & 9mA it was a little too mushy & bloated, but changing it to around 280V & 7.5mA added some needed snap & zing. With my GE 6SN7GTAs it's the other way around, lower voltage & higher current gives a better balance to my ears. They're all good operating points for the 6SN7, it's a matter of taste & tube choice, I'd shy away from running higher voltages in some of the tubes which are prone to arcing over.
The 6n6p I know nothing about so I'll leave that to someone else.
The 6n6p I know nothing about so I'll leave that to someone else.
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