Can a variac be used to maintain constant voltage?

The Monster AVS2000 voltage regulator is a giant automated variac like device. I had one. The rheostat inside has a mechanical wiper which is electronically controlled to maintain the 120 volts. regardless of the incoming voltage.

So it keeps the voltage output steady with variable incoming.

Somut,

Just curious why you think you need to run the amp off the variac. On the back of the amp what is the input AC voltage rating? 120V? 125V line voltage will not hurt the amp.

Depending on how big, (VA rating), the variac is the variac could be starving the amp of power.

Plug the amp directly into the wall and set back and listen..... Post back your results.

I stand corrected! The power supply I used at home(test purposes), would only maintain, or maintain at at a reduced voltage. The veriac(Ohmite) I had on the job could up to double the voltages, presented to it(but still directly proportional to the input). Gotta stop the early morning posting.

My own reason for having this variac in the first place is that prior to the Threshold, I was using a pair of vintage vacuum tube monoblocks running 8 el34's per side: when turned on the amps would spike to the maximum level as gauged by their ammeters and then settle back down to the nominal 6 amp running rate: so, rather than having to deal with this initial surge and its potential negative impact, I bought the variac to slowly bring up the amps to running voltage. The variac is selling for a few dollars short of $600.00 now and I do not if its worth keeping this expensive piece for any valuable audio uses -- i.e. reduction of high frequency noise as Almarg mentions above -- or sell it off to someone with a more suitable application. I still find it amazing that the variac is showing a consistent 120 volts as set by my original dial setting. I had a PS Audio Power Plant Premier at one time and the incoming voltage showed as high as 125 volts sometimes. So it makes me wonder if the variac is not in fact more useful in my current Threshold application as might otherwise seem.

I still find it amazing that the variac is showing a consistent 120 volts as set by my original dial setting.

If you have a descent true RMS DVM meter you should check the voltage at the receptacle the amp is plugged into at start-up. That will tell you what the true voltage drop (VD) caused by the inrush current draw of the primary winding of the power transformer of the amp.

Next voltage reading to measure is with the amp loaded. That is with music playing, volume set to where you normally listen. Play something with lots of dynamics.

Measure the voltage... If the voltage is fluctuating in rhythm with the music that will tell you the variac is voltage/current limiting. To verify the variac is causing the VD repeat the same test with the DVM at the wall receptacle the variac is plugged into.

Dynamics performance of the amp will suffer.
Your amp should sound best connected to a dedicated 20 amp branch circuit without being restricted, choked, by the variac.
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