In Reply to: RE: 4P1L in filament bias Andy's amp posted by Chip647 on February 10, 2016 at 14:07:31:
I now just use 4P1L into 4P1L. No need at all for the 300b. I have Alpair 10 speakers and a 2v input from a ES9023 DAC. Here's a better and updated schematic. I actually just use the single 4P1L output, though I have another amp with PSE outputs.
In response to "strident violins", Ale and I puzzled for a while over this. There was a hint of sharpness. What I've found is that this was in the filament supply. With a quite large choke input and a good quality EI transformer the sound got smoother. A lot of this is in the filament supply with filament bias. It's a lot more important than many of us thought at first. I'd say you have to hear a choke input supply into Rod's Regs to be able to properly judge filament bias.
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Follow Ups
- That circuit is out of date for a few reasons - andy evans 10:48:39 02/11/16 (0)