Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: frank57 on November 22, 2011, 09:51:22 am

Title: Are these heater voltages now too low?
Post by: frank57 on November 22, 2011, 09:51:22 am

Well I've gone from 7.7 down to this:
Voltages on el84:
pin 4 2.87
pin 5 2.96

so a bit off.
The balance was off by 3.86 and 2.97 before.
 12ax7:
2.87 on both
pin9 2.98
9 to 4/5 5.87

Can any problems result from these voltages?
I'll check with my other multimeter.
What I don't get is why there's an unbalance there.
It's less than before.
If I use one set of diodes an artificial ct it's balanced but adds hiss.
Not sure what's the best route.

voltages today a little higher at 6.16 and 3.02 3.13

Title: Re: Are these heater voltages now too low?
Post by: tubenit on November 22, 2011, 12:15:26 pm

I played a Dan Electro Centurian 275 for yrs with heater voltage at 5.76 vac. It was the best sounding mass produced amp I've owned.

With respect, Tubenit

Title: Re: Are these heater voltages now too low?
Post by: frank57 on November 22, 2011, 03:18:30 pm

I think I'm ok too.
I don't think it will go below 5.87.

Title: Re: Are these heater voltages now too low?
Post by: FYL on November 22, 2011, 04:34:03 pm

Quote

Can any problems result from these voltages?

The spec is 6.3 V ± 10%, anything between 5.67 and 6.93 V is AOK.