[guitarista]

Posting here because I'm seeing a lot about rolling tube rectifiers.  Since audio doesn't go through the rectifier, and they basically affect the power characteristics, are enthusiasts using variacs as a way to limit the voltage their equipment sees?  I purchased one to use with vintage guitar amps that predated the universalization of 110v (really more like 120) in the US.  Never thought of trying it with my 70's stereo/quad amps.

[opnly bafld]

Never thought of trying it with my 70's stereo/quad amps.

Solid state? No reason to use it.

[FullRangeMan]

Variacs are a great solution as power transformers, Joule Electra used Variacs in all his expensive OTL amps.

[opnly bafld]

Posting here because I'm seeing a lot about rolling tube rectifiers.  Since audio doesn't go through the rectifier, and they basically affect the power characteristics, are enthusiasts using variacs as a way to limit the voltage their equipment sees?

I haven't heard of anyone using a variac when trying (rolling) different rectifier tubes.

Based on years of reading various forums I would say many tube amplifier users in the audio world don't know enough about their amplifiers to know if they are doing something "wrong" or not and as long as it continues to put out noises all is good.

[lokie]

A good first step is to check the voltage that's in your house. Mine was at 124V and it took me a while to figure out that my vintage Eico amps did not like that!
I tried a Variac to experiment with and the sweet spot on those amps after biasing accordingly was 110 V's.

I also got a  bump in quietness and blacker background out of a DAC who's transformers said 115V's. They were built in Northern Europe.
Most everything I've read says it doesn't make any difference but all I can say is to experiment.

[Speedskater]

Yep, AC power line voltages are drifting higher over the decades. In the distant past it was 110 Volts, then 115V, 117-118V, 120V but now NEC specs 125 Volts.
Very old transformers designed for 110V may be unhappy with 125 Volts.

[Bill Baker]

Voltages vary all over the country. I have had to use a variac several times when doing repairs on most tube products out of China as they rate their product for 220/110. Plug into our 120-125VAC and you get over voltages.  I now use one at all times when servicing any tube product.
Depending on the transformer design in the product, there are times when using a variac will allow the component to run in it’s sweet spot and not destroy components within the product. This was a big problem years ago when the Ming-Da products came to the US.  Nothing wrong with using one in your system.
We use them along with step-up transformers for all of our international builds as well.
Not seeing why one would be needed for use with tube rectifiers as you can just estimate the B+ voltage by the voltage drop of the tube. Compare with the tube you normally use (if a different model) to the voltage drop list for rectifiers.

[FullRangeMan]

The Variac you guys use are able to vary the voltage in how many Volts per step?
 
It can vary 1 Volt per step or 5V per step etc ?

[Bill Baker]

If I understand you correctly, you’re saying your variac is a stepped unit? Most are variable ‘vari’. Here is the one I have.

[FullRangeMan]

I dont own a Variac yet, I want a model with fine tuning variations of 1 or 2 Volts per step, a Variac with steps of 5V dont fit my needs.