switching supply for heaters

[Lindz]

Thanks for the additional comments

I would not know where to begin in order to calculate the L and C values - I'm no EE, ha ha

I tried to read up about it but what I found is beyond my paygrade..

Anyone care to chime in with an explanation or calculation a layman might understand.

If I understand what I read the idea is to reduce switching noise?

On a different note, in regard to the above post where Martin suggested I try a battery to see if the hum in my SLO build was filament related, it is apparently not.. battery DC was not noticeably quieter than the elevated AC. Back to the drawing board on that one

Interesting experiment to keep in my trick bag for future use though..

[M Fowler]

Not sure if anyone is interested in these:

http://triodestore.com/pcboardkits.html

[Cliff Schecht]

I'm not a fan of DC heaters on my prehistoric tubes. It's hard on them (the filaments develop weak hot spots) and IME this is an unnecessary complication in most any well designed/built amplifier doesn't need. Not a knock at people who use DC heaters either, it can be very effective when employed correctly and IMO with restraint (i.e. only used where needed).

Somebody else mentioned grounding and IME if you control where your high return currents go in an amp then noise is never an issue. With a switcher (ideally) you are operating well above the audio frequency and so filtering requirements are already minimized.

I've thought about this problem before and what I'd really like to play with is some sort of AC-AC inverter circuit that essentially allows you to dial in EXACTLY 6.3V as well as allowing for an adjustable DC offset and maybe even playing with the phase of the 60 Hz output signal (to see if you can force some extra hum cancellation in SE stages). I haven't pursued this idea much but I figured I'd throw it out there, I think it's feasible and possibly even useful!