Variac Wizards lend me your wisdom!

[mentoneman]

What’s your takeaway?
Good/bad, and is there any opinion on the $60-80 ones on amazon vs other models?

wouldn’t mind trying it on the Peacemaker but shouldn’t it be rated for 120VAC input and not 110VAC?

 

[RedPlated]

Variacs are a great tool. I use mine to run at amps at lower voltage sometimes. But mainly, I use one for consistency. If you want your amp to sound the same from day to day, you need to keep the input voltage the same.

Definitely get one with a digital readout. Having a voltage AND amps readout is also good. Current reading will let you know if something is drawing excessive current like power tubes, excessively high bias etc…

Circuit specialists is a good source. It appears they’re out of stock on the lower priced models though.

https://www.circuitspecialists.com/tdgc3-2d-variac-variable-transformer

 

[Humbucking]

I use a variac on my vintage amps to feed them 110V. Being that I am using one on pretty valuable vintage amps, I wouldnt use a cheap asian made variac. A digital readout is cool, but I am fine with using a multi-meter to tell me what the actual output it. Never trust what the dial says on the top of the variac. The value/readings do drift over time. I always see good ole American made variacs pop up on facebook marketplace for between $75-$150. You can usually negotiate a deal on them as they are heavy and expensive to ship.

 

[JTyson]

Variacs are a great tool. I use mine to run at amps at lower voltage sometimes. But mainly, I use one for consistency. If you want your amp to sound the same from day to day, you need to keep the input voltage the same.

Definitely get one with a digital readout. Having a voltage AND amps readout is also good. Current reading will let you know if something is drawing excessive current like power tubes, excessively high bias etc…

Circuit specialists is a good source. It appears they’re out of stock on the lower priced models though.

https://www.circuitspecialists.com/tdgc3-2d-variac-variable-transformer

“Roasting coffee beans”

Didn’t see that coming!
I always heard Eddie ran them around 95-97 volts, the guy in the first vid was down to 74,
While that 800 sounded killer at that setting, is it safe for the amp to run that low and do you have to re-bias?

 

[mnemonic]

I have seen some horror stories online of those cheap variacs being wired wrong from new, I would confirm it’s wired right before plugging it in.

I would also check digital readout accuracy with a multimeter, when I built my bucking transformer the cheap digital readout I bought for it was off by 4 volts with no adjustment. The new one I bought to replace it was off by 2 volts but at least had a trim pot on the board so I could adjust it to be accurate.

Last time I looked at variacs, probably a few years ago now, there were annoyingly no options between the cheap Chinese widowmakers and super expensive ones (that maybe were still Chinese).

 

[SoooRad]

I have one exactly like the photo in the OP and it treated me well. I don't use it all the time, and I only really used it with my Laney that I had just to screw around sometimes.

if I was trying to build an "Ed" rig, I might invest in a more trustworthy one, but for periodic skulduggery, this one hasn't let me down yet.

 

[Scot]

The reason I joined the forum was due the fact I’d red-plated a tube out of nowhere and I was concerned about my amp. As it turned out my wall voltages, although relatively stable, were pushing 122/123 volts so I came to learn all about the issues associated with increased (or variable voltages) and amplifiers. Typically I’m an “old iron” kind of guy and would seek out a quality variac from the older makers but in this instance I caved and bought one of the orange chinese variacs off ebay (10A). I did check the ground when I received it and it was fine. Haven’t had a single hiccup and my amp sounds more consistent than ever. Mine has an analog voltage gage but don’t rely on it. Instead I go into a power strip and keep my DMM plugged-in to an adjacent socket to monitor voltages. That works great if you don’t gig and in a controlled setting but wouldn’t be the best solution if playing somewhere’s else where someone could inadvertently knock your settings. It’s the best pc of kit I’ve bought in a long time and now consider it essential. I bias to the reduced voltage and have zero concerns (knock on wood) of a failure, and therefore a sudden spike in voltage. Good luck.

 

[Humbucking]

Also, I do bias my tubes based on the voltage I'm running through the variac.

 

[snoqualmie]

I had the same unit you listed on your post and it toasted. T'was a POS.

 

[Scot]

I had the same unit you listed on your post and it toasted. T'was a POS.

That sucks. Mine looks about the same as the one photographed. Did yours throw warning signs or did it just go ‘poof’?

 

[snoqualmie]

That sucks. Mine looks about the same as the one photographed. Did yours throw warning signs or did it just go ‘poof’?

No signs, just failed one day after moderate use.

 

[Scot]

No signs, just failed one day after moderate use.

Noted - thanks. It’s certain I’ll eventually buy a better one when I stumble upon it in real life.

Meantime - I do confess it took me awhile to trust mine. In large part because the first thing I did was let the variac run on its own for a long time while familiarizing. Then (of course) I made-up an outlet cable to run the variac through my cabs and gave all my speakers a good thrashing. It’s been bulletproof and reliable since.

 

[blackba]

Too bad these are discontinued, the voltage reading was within a volt on the few I have seen (my friends have this model too)(
https://www.circuitspecialists.com/variac-variable-ac-ps05kva_with_digital_display

Noticing many are discontinued.
https://www.circuitspecialists.com/variacs-ac-power-supplies

All that said if you can find an old variac for cheap, that is the best, but I highly recommend something like a killawatt to know the voltage.

https://www.amazon.com/P3-P4400-Ele...8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1

 

[stratjacket]

I bought just this past Monday, the one with 2 outlets and 15amps. My wall voltage is a steady 125V. I have a dedicated 20amp circuit just for equipment and have an isolation transformer that displays voltage, amps and watts.

I tried lowering it with the variac and my amps all sounded thin, the punch was gone. I ended up setting the Variac to 120v and had to re-bias all my amps. Pain the ass but they all are sounding mean now. Plate voltages and bias all in a good range.

As a test I adjusted the Variac while checking plate and bias and was amazed at how it impacted them and the sound.

 

[Scot]

I bought just this past Monday, the one with 2 outlets and 15amps. My wall voltage is a steady 125V. I have a dedicated 20amp circuit just for equipment and have an isolation transformer that displays voltage, amps and watts.

I tried lowering it with the variac and my amps all sounded thin, the punch was gone. I ended up setting the Variac to 120v and had to re-bias all my amps. Pain the ass but they all are sounding mean now. Plate voltages and bias all in a good range.

As a test I adjusted the Variac while checking plate and bias and was amazed at how it impacted them and the sound.

Spot on. I hear (and feel) a noticeable difference going between 112 & 117V, it’s wild. Now that that novelty has worn off I just set at 116 and forget it. I, like others, have probably sold some amps that just maybe I shouldn’t have (eg: Mesa Single Rec & VHT 50 Pitbull) <—both amazing amps.

 

[stratjacket]

Spot on. I hear (and feel) a noticeable difference going between 112 & 117V, it’s wild. Now that that novelty has worn off I just set at 116 and forget it. I, like others, have probably sold some amps that just maybe I shouldn’t have (eg: Mesa Single Rec & VHT 50 Pitbull) <—both amazing amps.

On my Diezel Hagen, when I checked the bias it was around 8-10mA per pair which is 4-5 per tube. The instructions on the PCB said to set each pair at 70mA.

 

[harddriver]

If I were you I'd buy a used USA Staaco from Ebay. WOW, they used to sub $100 bucks and alot more plentiful, I just had a look on Ebay.

 

[RedPlated]

I bought just this past Monday, the one with 2 outlets and 15amps. My wall voltage is a steady 125V. I have a dedicated 20amp circuit just for equipment and have an isolation transformer that displays voltage, amps and watts.

I tried lowering it with the variac and my amps all sounded thin, the punch was gone. I ended up setting the Variac to 120v and had to re-bias all my amps. Pain the ass but they all are sounding mean now. Plate voltages and bias all in a good range.

As a test I adjusted the Variac while checking plate and bias and was amazed at how it impacted them and the sound.

Perfect example of why variacs are so important.

 

[Geo]

Been using that same one for a few years no problems but try to get the one that shows you amperage draw as well.

https://www.circuitspecialists.com/?srsltid=AfmBOopPr1VOSm80ybItLytQxYsFE1fNRp-xIPyQdDvtAP1BinkLq9q1

 

[7704A]

If I were you I'd buy a used USA Staaco from Ebay. WOW, they used to sub $100 bucks and alot more plentiful, I just had a look on Ebay.

I'd add Superior Electric to that list.