DHT heater supply

[MrCurwen]

I've been fantasizing about an all DHT amp, with a pair of 26's and 45's. I intend to make it work for headphones, which is my main thing. I don't know if many people have done this, but I guess it's only about getting all the DC supplies super clean and then no problem.

Currently I am listening to my AKG K601 headphones thru my DC Darling, driven with 6SN7 (much less volume than with previous 6SL7, but still way plenty, volume at 21% at source and 50% at Darling). Output is taken at 4 ohm tap. Works great!

But my question is regarding the DHT heater supplies - I would have four heaters to attend to. My first thought is:

In the PSU chassis:

6.3 VAC transformer -> SS rectification (bridge probably) -> 33 ohm 25W rheostat (to get the voltage spot on) -> 9400µF -> Hammond 60mH / 0.7 ohm -> 9400µF ->

In amp chassis:

A common mode choke -> DHT heater


If each DHT has it's dedicated CMC, would it be necessary to have the PSU section also dedicated to a single tube, or could I have the 26 supplied by a single PSU feeding the separate CMC's? The Hammond can put thru 2A, and I believe the 26 needs 1.05A.

So, all the way separate or not? Also, how good do you estimate this arrangement would sound? Any suggestions?

[andyjevans]

Have a look at DIY Audio thread "26 pre amp" and you'll see Rod Coleman's filament supply at the end of this long and informative thread. That sounds really good so you may want to try it - PCB is available.

andy