baronkyle Posted January 5, 2016 Share Posted January 5, 2016 Hello, What is a good Variac to purchase for running old tube gear while listening? The goal is just to prolong the tubes and transformers. Should I buy the latest "chi-fi" from China, or look to older Variacs? $100 on eBay will buy the following: 20 amp max output 2000VA Variable Voltage Regulator input voltage: 110VAC output voltage: 0-130VAC 60Hz Analog Output Power Meter Included On/Off Power Switch is Lighted Weight: 24 lbs Dimensions, approx: 7.5" H, 8.5" D, 7" W Quote Link to comment Share on other sites More sharing options...
JBryan Posted January 5, 2016 Share Posted January 5, 2016 (edited) While its nice to have a variac around if you bring a lot of vintage electronics home, I don't think it'd provide much if any benefit to keep one hooked up to your gear. A variac is quite handy to ramp up the voltage so you can check for problems and re-form the capacitors in gear that's questionable or hasn't been used for a while. Most vintage gear is designed to handle the initial power up easily and with no deleterious effect on tubes or the transformers. I've picked up a slew of old gear and several variacs over the years (including the one pictured in your post) and aside from testing, re-forming and the occasional sound experiment with guitar amps (ref: J. Page), the most use I get from a variac is when I roast coffee - works like a charm in that capacity but then I'm not concerned with how nice my roaster sounds. In my opinion, a variac in front of your equipment won't offer much longevity or safety but it will add a lot of noise. Particular to the unit pictured above, it works fine but mine has a pronounced HUM as you approach 100 volts and do not use it in a 15 amp circuit or it'll trip the breaker every time... take my word for it . Have fun! Edited January 5, 2016 by JBryan Quote Link to comment Share on other sites More sharing options...
baronkyle Posted January 6, 2016 Author Share Posted January 6, 2016 Thanks JB, here's where I was going with this: "In the USA, voltages have been creeping upwards for years. Back in the 1960's, standard voltage was 110 volts. Over the years labeled voltages have crept from 110 to 115 to 117, and the now 120 volts. – Marla Jun 24 '14 at 19:04" On 120 volts, vintage tubes and transformers run hotter. I was thinking about feeding my vintage gear a steady 115 volts. Didn't think about adding noise to the mix from the Variac . Anyone do this or more trouble than it's worth? Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted January 6, 2016 Share Posted January 6, 2016 IMHO, definitely more trouble than it's worth... Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted January 6, 2016 Share Posted January 6, 2016 Most vintage equipment was designed to work fine over a fairly wide range of operating voltages. For example, the popular Scott 299 specified a line voltage range of 105 to 125V. I find the biggest issue to be filament over-voltage when the line voltage is on the high side. And, as William pointed out, that is easy to deal with using resistors or other methods. If heat is your main concern a small, quiet running, muffin fan can work miracles in terms of cooling things off. That is certainly the least costly way to deal with it.Maynard 1 Quote Link to comment Share on other sites More sharing options...
mike stehr Posted January 6, 2016 Share Posted January 6, 2016 In my opinion, a variac in front of your equipment won't offer much longevity or safety but it will add a lot of noise. Particular to the unit pictured above, it works fine but mine has a pronounced HUM as you approach 100 volts and do not use it in a 15 amp circuit or it'll trip the breaker every time... take my word for it I have a old vintage 5 amp Lafayette variac, and I never had any of the problems you describe. No hum, no tripping breakers at 100 volts. I can agree that it won't matter much using one in front of a perfectly functioning tube amplifier, but if that tube amplifier has been sitting for a couple few years, then I tend to use the variac to ramp it up nice and slow. That's just me... Quote Link to comment Share on other sites More sharing options...
Marvel Posted January 6, 2016 Share Posted January 6, 2016 (edited) Or... if the power tranny is made with the windings, it could be changed to 120-125 volts. We usually get right at 125 VAC here, due to the TVA power grid. My Dynaco used to run really hot, the power transformer couldn't be touched after it had be on for a while. I use an old theater light dimmer. Same thing but no fancy wiring. Bruce Edited January 6, 2016 by Marvel Quote Link to comment Share on other sites More sharing options...
Wolfbane Posted January 8, 2016 Share Posted January 8, 2016 If you buy and on occasion restore old tube amps, etc. the advantage of owning a variac (or two) is the ability to slowly power up old equipment. Wb Quote Link to comment Share on other sites More sharing options...
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