WA4SWJ wrote:Distortion at both ends of the audio spectrum was extremely high - in the 70% range or so with the built in distortion analyzers in the program. There was also a huge DC offset at the output, which is also interesting since the output is capacitively coupled, but it is a rather large coupling cap.
This is kind of unfortunate. Do you still recommend that I use this topology? The individual parts in TubeCAD had very little distortion... I'm a bit hesitant to build the circuit, but my one consolation is that if I leave myself enough room, I might be able to build Fred Nachbaur's phono stage with the space given.
WA4SWJ wrote:I would be interested to know if you've constructed this circuit and if so, how it sounds. It doesn't simulate well in SPICE - of course that could be pilot error on my end or some less than perfect tube models. So the analysis itself could well be flawed. When I have some more time I might post some of this stuff but, with some more international travel coming up, it won't be for a couple of weeks. It would be interesting to hear how this circuit works out in real life. Simulation is not always the same. Good luck with it.
Regards,
I haven't built it. I have the filament transformers, 3 7AU7's and and 4 more coming in the mail, and a 10x7" aluminum plate and top cage. I'd love to build something of my own design but if there's another pretty high-current, lowish-gain circuit that can drive low-impedance headphones, I'd love to see it :D