I have an old (and much beloved) K-12M tube amplifier - significantly upgraded from the original kit. I'm looking at my next set of modifications (adding a CCS to the cathode and an IR remote control) and was wondering if I could convert it to a balanced amplifier by changing the pre-amp wiring slightly. Here's my quick sketch on one channel - I'm picturing the + & - of the balanced line to be connected to the two points at "RIGHT IN".
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(Pre-warning that I'm an electrical engineer who was schooled well after the days of tubes so I'm mashing some of my op-amp knowledge in here... likely poorly.) Wondering if someone could sanity check this for me - is this do-able and are my mad scribbles the way to do it? Would my pre-amplification losses, going from a 2-stage amp to a single differential stage, be worth the change or would it sacrifice too much? What would my R1/R3, and R2/R4 values be to set the gain as best as possible?
As a side note, I just noticed tonight that I've been running 10GV8 tubes on this rig for years (no idea how I came to that change)... they seem quite happy and sound awesome... but I would have thought they wouldn't like the higher grid voltage or cathode current and end up burning out pretty quickly (or letting the smoke out of some other part of the system). Is this weird?
