Apologies - I missed the words 'and isolated' in your earlier post. For me, isolated filament supplies are definitely non-preferred.
I'm very much aiming to have just ONE filament supply. Eventual aim is to have a switchmode converter supplying HT, LT, and GB. And while adding extra outputs is simple in principle, filtering thereof is very much not - and I'm looking at this AF amplifier being part of a rod-pentode radio.
They certainly are a challenge at times, but then so are indirectly-heated valves where significant h-k voltage exists. And as for filament valves - I have a pair of 2A3 triodes which are DH, some day I'll make an amplifier with (and these WILL have separate filament supplies, but this will be mains operated with AC on the filaments and the 'cathode' connection taken to a CT on the filament winding).
Somehow, the symmetry is more appealing than the essential asymmetry of a DC filament.
I'm very much aiming to have just ONE filament supply. Eventual aim is to have a switchmode converter supplying HT, LT, and GB. And while adding extra outputs is simple in principle, filtering thereof is very much not - and I'm looking at this AF amplifier being part of a rod-pentode radio.
Murphyv310 Wrote:To be fair a PP audio amp is messy with filament valves IMHO, no matter what way you achieve it. The power valves are really just a bit of fun.
They certainly are a challenge at times, but then so are indirectly-heated valves where significant h-k voltage exists. And as for filament valves - I have a pair of 2A3 triodes which are DH, some day I'll make an amplifier with (and these WILL have separate filament supplies, but this will be mains operated with AC on the filaments and the 'cathode' connection taken to a CT on the filament winding).
Somehow, the symmetry is more appealing than the essential asymmetry of a DC filament.
