[sdiy] heater voltage: how much is too much?

[Bob Weigel]

No it'll be fine.  Heaters usually have a lot of overvoltage tolerence.  
That would be like running the 12.6V tube at 13.some volts so it's ok.  
Could probably run it at 15V and it wouldn't hurt anything.  Above that 
and I'd think life might be shortened or performance might change 
appreciably. -Bob

anthony wrote:

> For the heaters in my 50L6 amp I used a 50C5 in series with the 50L6GT 
> and the 12SQ7GT to get a more proper heater voltage of around 112 VAC. 
> However my wall voltage is 120 VAC. I was wondering if this difference 
> would be too much. My first thought was that it shouldn't be 
> problematic at all and the extra 8 volts is distributed over all of 
> the tubes and since the tubes are designed for slow turn-on series 
> connections, they should be able to handle. Or should I try to squeeze 
> something like a 8Ohm, 10W resistor in series with them? I thought 
> using just the heater of the 50C5 was a nifty if hackish trick to get 
> the heater voltage right though. Especially since I do not forsee 
> wanting to use it for an amp anytime soon since most of the accounts 
> that I have read concerning amps made from 50C5's is that they just 
> don't make the magic that a 50L6 can. (Although I have read similar 
> things about 6AQ5A's, but that when connected in "triode-mode" they 
> sound great...)
>
> aa
>
>