Variac

I just read an article in VGM (Vintage Guitar Magazine) about Variacs...they are used to drop the voltage down from the current modern voltage of up to 130 volts, to the more 'old fashoined' voltage of 115 volts (or lower). The VGM info says that once you get below about 80 volts, benefits are lost. When I ordered my rebuilt Variac from the rebuilder in Van Nuys, I mentioned this to him. He was very familiar with what variacs are used for by musicians, including EVH ... he said you can actually 'dial in' lower voltages, and get great results with either your authentic vintage amp, or a newer tube amp. He told me that the mistake is to go to 'higher' voltages, which should be avoided. I will be playing around with the variac and reporting back...