Using 12.6vac heaters in Dumble amps?

[Mark]

http://www.valvewizard.co.uk/heater.html

I've been reading some Blencowe articles, (I'm a Blencowe fan as it's science above folklore) I can't but help think elevated 12.6vac heaters would be a better idea than 6.3vac heaters, the current draw is less so the noise will be less. The output stage can be wired in series as well.

The obvious reason to use 6.3vac is in case a heater goes open circuit, if the heaters went in one of the output valves, the loss of volume coupled with the hum would be pretty bad. I'm not sure I'd like to limp through the gig under those circumstances.

I suspect HAD used 6.3vac heaters as this is what came with the transformer sets he bought and he didn't get custom transformers sets as Ken Fischer did.

I think it is fairly safe to try and improve the heaters as it won't impact on tone and will hopefully improve the signal to noise ratio of these amps.

Any thoughts?

[martin manning]

IMO there isn't any noise problem running the heaters at 6.3VAC, so I don't see any advantage there. With a 50W, power tube heaters wired in series would kill all output. For a 100W there would be a power loss and 2x miss-match in impedance unless the failure was noticed and corrected with the impedance selector. Better to just switch over to the back-up amp...

[Mark]

Thanks for the reply Martin, I doubt the heaters would be an issue for clean tones, it's the overdriven tones I wonder about, and I haven't really quantified what causes all the noise in an amp.

It would be quite an achievement to get a Dumble dead quiet so you wouldn't know it's on when an instrument isn't plugged in. My brother gave me a run through of Guitar Rig, it sounds a lot better than the Line 6 POD Farm and it's dead quiet. The tones from it are pleasing and perhaps the quietness is the next frontier?