Sounds like an ideal application for an SMPS. I use them exclusively now for heater supplies in my tube mixers and they are far quieter than any linear supply I have built as well as not suffering from magnetic coupling to mic transformers. I use MeanWell SMPS as I have found them to be consistently quiet and reliable and I do not nrmally ad any additional filtering. Remember to rate the supply to approximately double the nominal heater power being drawn. This allows the hiccup mode of current limiting that Meanwell uses to cope easily with the tube's inrush current.Ian,
If I may, what are your thoughts on using an SMPS as a filament supply for a directly heated single ended triode (2A3, 45, 300B, 845, etc)?
Living the dream eh? Me too. I am 72 and becoming creakier by the day. Soldering and cabling is not too bad but the heavy mechanical of mixers are becoming increasingly difficult.These days, having lived to an age I thought to be impossible (68) pretty much all I build are single ended triode hifi amps and tube mic pres, both of which I have a waiting list for.
Being a bit of a left over hippie type there are only two sources of misery in my life: my Xwife and hum. While I’ve become rather skilled at ignoring the X, any sort of hum or noise in my valve amp builds is a source of misery for me. The high sensitivity speakers my clients and I tend to use (100 Db+ doesn’t help).
An LC filter design works very well but results in gear I can’t comfortably lift these days. A SMPS filament supply is a very attractive alternative, particularly with a high current triodes such as an 845
I cannot help with the X (my wife. and I celebrate 50 years marriage this year) but I think and SMPS has a very good chance of minimising if not eliminating you rhum problems.