Any Variac Users here?

SatelliteNine

Member
Messages
290
I haven't but the other player in my band once used one on a Line6 AX212 at the suggestion of another player who told him it would sound rad.

....It didn't :) But that's not exactly the variac's fault.
 

Jon C

Gold Supporting Member
Messages
17,348
have one but only used it once to form some caps on an amp... anyone want to buy it?

jc
 

bigboy

Member
Messages
1,113
Those things are dangerous if you don't know how to use 'em right. They have no regulation, just a variable transformer.
 

ricoh

Member
Messages
1,195
I use one on my 67 Marshall because of the advice from Greg Germino. I do not use the device for any kind of brown sound however. Greg told me emphatically that the old coot wanted to see 110 and nothing else. Who am I to argue!!!!!!!!!!
 

swankmotee

Member
Messages
763
I use em' always with my vintage Marshall's because around NashVegas we're hovering at around 127v these days and it's hell on tubes and tone! Also use a Furman AR1215 voltage regulator because most clubs run everything through the same mains and I couldn't deal with the fluctuation because my amp would sound great one second and like ass another. It's really worth the investment if you really want to use these kind of amps.
 

audiozone

Member
Messages
280
i have one, i bought a rebuilt one on ebay about 3 or 4 years ago. i forget how much i paid, maybe $150.00 with shipping? i used it once to try to reform caps on a vintage 1968 sunn 1000s amp. it didn't seem to help, but i didn't have that much time or patiance that i could let the thing sit there and turn it up 5 or 10 volts every hour or two over the course of a day or two. i decided it is easier to just replace the filter caps.

i don't use it on the new amps i build. when i was first starting to build amps, i asked about buying one at the local electronic supply. the guy was experienced and knowledgable. he told me that for new manufacture amps using new filter caps i could just build and apply power. i have not had any problems, and almost everyone who has tried my amps is impressed by how little hiss and hum they have.

i suspect what you really want to know is about how it sounds running an amp at a lower supply voltage. never thought about it, never tried it before, but i will right now

we have about 125 volt from the wall here. i hooked it to my basic model 5 watt amp and set it for full volume, full treble and 50% bass. when i reduced the varic to 100 volt i noticed the amps volume got just a bit softer and the bass seemed looser. when i went to 90 volt the amp lost a little more volume and got more distortion. when i went to 80 volt the amps volume was a noticeable amout less, maybe 75% or 80% from regular wall voltage. the amp also had a fair amount more distortion. its a useable sound and i could see that working for someone in an apartment or home situation.

i also cranked the voltage up to 135 volt for a minute, but really didn't notice any difference.

so is it safe for the amp or person playing? i'm not sure because i saw that post above about them being unregulated. mine is a good quailty one, its been rebuilt, and upgraded to have a grounded outlet. its rated for 7.5 amp and has a fuse. i put an amp on it that only draws an amp or less.
 

bigboy

Member
Messages
1,113
I use one on my 67 Marshall because of the advice from Greg Germino. I do not use the device for any kind of brown sound however. Greg told me emphatically that the old coot wanted to see 110 and nothing else. Who am I to argue!!!!!!!!!!
i have one, i bought a rebuilt one on ebay about 3 or 4 years ago. i forget how much i paid, maybe $150.00 with shipping? i used it once to try to reform caps on a vintage 1968 sunn 1000s amp. it didn't seem to help, but i didn't have that much time or patiance that i could let the thing sit there and turn it up 5 or 10 volts every hour or two over the course of a day or two. i decided it is easier to just replace the filter caps.

i don't use it on the new amps i build. when i was first starting to build amps, i asked about buying one at the local electronic supply. the guy was experienced and knowledgable. he told me that for new manufacture amps using new filter caps i could just build and apply power. i have not had any problems, and almost everyone who has tried my amps is impressed by how little hiss and hum they have.

i suspect what you really want to know is about how it sounds running an amp at a lower supply voltage. never thought about it, never tried it before, but i will right now

we have about 125 volt from the wall here. i hooked it to my basic model 5 watt amp and set it for full volume, full treble and 50% bass. when i reduced the varic to 100 volt i noticed the amps volume got just a bit softer and the bass seemed looser. when i went to 90 volt the amp lost a little more volume and got more distortion. when i went to 80 volt the amps volume was a noticeable amout less, maybe 75% or 80% from regular wall voltage. the amp also had a fair amount more distortion. its a useable sound and i could see that working for someone in an apartment or home situation.

i also cranked the voltage up to 135 volt for a minute, but really didn't notice any difference.

so is it safe for the amp or person playing? i'm not sure because i saw that post above about them being unregulated. mine is a good quailty one, its been rebuilt, and upgraded to have a grounded outlet. its rated for 7.5 amp and has a fuse. i put an amp on it that only draws an amp or less.
Here's the issue, let me give you a for instance: You get to the club. Its a hot summer day and the AC and refrigerators are working overtime. All that stuff is hooked to the same supply lines that power the stage. You measure the current at the stage "85 volts! DAMN... that won't do!". Out comes the variac. You dial it in at 110 volts. You start to play the gig, sounds f'n great! Suddenly the AC hits 70 degrees and the thermostat shuts her down. Coincidently, the refrigerators reach the end of their cycle and shut off as well. All of a sudden that voltage that wasn't there when you measured, returns and the variac boosts it accordingly. Now you favorite tube amp is running on 150 volts. Meltdown is near. Fires have been started this way. USE REGULATION WITH A VARIAC!
 

GerryJ

Member
Messages
5,005
If you're wondering about a Variac because of the rumor that EVH used one early on for the brown sound, I believe that was Bullsh*t on his part.
Around then he also claimed that Cesar Diaz had specially modded his MArshall, but later on said all he did was keep it stock, that he spun the 'mod' thing to give Cesar some business.
 

swankmotee

Member
Messages
763
Well, without sounding like I'm being a condescending jerk, I'm a little perplexed that an "amp builder" doesn't know what raising and lowering the mains voltage to an amplifier will do to the tubes! It's very important that you NOT go below your paticular tube types heater voltage or you will strip the plates and ruin them. And vise versa, if you go too high you'll melt them and possibly some other components as well! Also as the other poster pointed out, having a regulator is very important to keep the mains constant to keep the amp running and sounding consistent no matter what the supply voltage may do which is a constant problem in clubs where you never know how much stuff is running off the mains. But, variacs are for the most part very sturdy and well built devices because they have to be to deliver upwards of 150v for a 10 amp device ( which is the safe starting point amperage to work from if you're working with a 100wt amp) and are UL approved for industrial applications. I own two refurbished Superior Powerstats that are very overbuilt for my application and have never gotten hot during long gigs.The only thing to really worry about when using one is making sure nothing or no one changes the setting during your performance!:dude
 

swankmotee

Member
Messages
763
If you're wondering about a Variac because of the rumor that EVH used one early on for the brown sound, I believe that was Bullsh*t on his part.
Around then he also claimed that Cesar Diaz had specially modded his MArshall, but later on said all he did was keep it stock, that he spun the 'mod' thing to give Cesar some business.
He "did" use one early on which is evidenced by quite a few photos in the studio recording the first album and onstage during that period. He has said he lowered the voltage to around 90v on his 68' Plexi 100wt loaded with 6ca7's which I believe because it definitely sounds like that when you lower a vintage Marshall setup with those paticular output tubes to that level. There is a wealth of information on the subject here at TGP and especially sites like Metroamp, Marshall, Plexi Palace, and other amp forums so check them out for detailed analysis of the EVH "Brown Sound". Bottom line is, a vintage Marshall was designed to run at 110v which was the standard during the 60's and seventies, not the higher voltages we have today so if you use the old stuff then it is wise to invest in a variac and voltage regulator if you want great tone and longevity from your beloved amplificator.
 

ant_riv

Silver Supporting Member
Messages
5,460
Thank you all for the input!

I really appreciate your knowledge and experience, as opinions seem to vary widely concerning the use of Variacs.

John Phillips had a very informative (and educated) post either here or on BaM concerning Variacs.

My reason for asking:
I recently started using a mid-'60s Bassman or an early '70s Quad Reverb as part of my set-up. When I initially plugged them in, there was a crackling, as if tubes or something were frying, like eggs on the stove. I immediately shut the amps down.

In doing research, I found that current from "the wall" since the late-'70s/early-'80s is around 120v, or as another poster mentioned, 127v in his area, as opposed to the more common 110v in the '60s.

I have read opinions that the higher voltage is too much for the older components, and could cause early failure.
By using a Variac to lower the voltage into the amp, it seems to serve as a buffer. Lowering the voltage should protect the semi-fragile electrical components by allowing the "original" components to operate within their designed range. This should also maintain the originality of the amp. And, as mentioned, the plate voltage has to remain high enough to keep the tube heaters operating properly.

EVH used to use one, but I think for different reasons. He hasn't been very forthright, so we may never know the full story.

As an FYI, once I dialed the voltage down on these two amps, the crackling went away, and both are functioning perfectly. I only brought the voltage down about 10-15%. Please note, both of these amps have been in storage for quite a few years, unused, and are entirely original.

If anyone else has older amps, and this has been an issue, I hope this info helps to protect some older, incredibly cool amps. Of course, before I make this assertion, I hope to learn from everyone else's knowledge and experience.

Thank you all!
 

sampleinajar

Member
Messages
1,254
I use one, but only to drop voltage, never boost. I have since built a static transformer box, that drops 12V of the input line voltage. It is always up for debate, but many people agree that a 10% drop in voltage won't do that mcuh harm to the tubes in terms of cathode stripping. I am sure it shortens them a tad bit, but I don't have NOS tubes in my Germino so who cares? Well, I do have one mullard 12ax7, but that'll be the cost of doing business, for me. People say those old mullard 12ax7s will last 5000 hours, so if it only lasts 4000, I don't think it will impact me!

Steve
 

jcs

Member
Messages
8,064
i've used a variac for years i keep it around 110 or so with all of my old amps,never had any problems.

just remember to measure the actual volts coming out of the variac itself,which will vary with the wall volts fluctuating.
 

Freedom

Member
Messages
565
I use a variac with my 69 plexi clone only to keep it running constantly from 230 to 240V since its wired for 240V and the voltage on the wall socket one day can be 220V and the other 250V in my area...

There is always a digital Volt meter connected at the variac's output (green arrow) which i have double checked that it shows the precise voltage so i can easily monitor whats going on and adjust it...


 

swankmotee

Member
Messages
763
I use a variac with my 69 plexi clone only to keep it running constantly from 230 to 240V since its wired for 240V and the voltage on the wall socket one day can be 220V and the other 250V in my area...

There is always a digital Volt meter connected at the variac's output (green arrow) which i have double checked that it shows the precise voltage so i can easily monitor whats going on and adjust it...


Where did you get that totally trick plug in meter???? I need one for my variacs too!
 

louderock

Member
Messages
4,865
Always measure the output of your variac with a meter. Just because the dial says 110 doesn't mean that you're actually getting 110. The dial will just give you a percentage of the incoming voltage + or -. So, if you have 127 coming in and turn the dial to 110, you're likely getting 111 or 112 on the output.

I also spoke with Greg Germino about this and he was saying it is a good idea to run the old amps at 110. He said he even takes a variac and meter to his gigs to make sure he is at 120. Also, if you are changing tubes and biasing your amp, you'll want to be sure you are making adjustments with exactly 120v or 110v feeding the amp.
 




Trending Topics

Top