DC heater supply on HRM Bluesmaster

[rackandroll]

I am thinking of building an HRM Bluesmaster. Just considering using a 12VDC heater supply. From my experience with other desigins noise performance is of course improved greatly, but have never seen a HAD design incorporating DC on the heaters. Anyone have any ideas?
I appreciate all input. This site is awesome!

[jelle]

IHMO, if leaddress is OK you won't need it. I suppose it wouldn't hurt anything if you did use DC heaters.

[ayan]

I am thinking of building an HRM Bluesmaster. Just considering using a 12VDC heater supply. From my experience with other desigins noise performance is of course improved greatly, but have never seen a HAD design incorporating DC on the heaters. Anyone have any ideas?
I appreciate all input. This site is awesome!

I'd say not worth it, based upon my experience putting a regulated DC heater supply in a couple of Dumbleator clones -- I tried that when I had too much time in my hands. The amps are very, very quiet if built well, not surer you;d hear a difference.

Cheers,

Gil

[dave g]

If you use the hum balance pot/heater ground lift combo, you don't need DC heaters. Just take a 100 ohm linear 2 watt pot (works best with something like a 10 turn, but I've used regular old PECs or claros) and tie the top and bottom lugs to the heaters. Then, create a voltage divider coming off of the lowest B+. Something like a 470k in series with a 33k or a 47k to ground works well. Throw in a small filter cap and then tie the wiper of the 100 ohm pot to the ~20VDC node you just created. Adjust the pot until you get the lowest amount of hum.

I should also mention that this method replaces whatever sort of heater reference you already have going on - be it the two 100 ohm resistors to ground or a grounded center tap. If you use this method, you have to make sure to get rid of those resistors or remove your heater center tap from ground.

[drz400]

I think DC heaters are WELL worth it, just because I cant stand ANY hum at any volume.
Also dropping the heater voltage a little really sweetens things up and you can dial in this in.
Use a 12V regulator for the first 2 tubes, no reason to do the phase inverter