Variacs / Line Voltage Regulators

Brett Lanier · From: Madison, TN

I've recently become more sensitive to varying power between venues. Lower power, bad sounding compression, and muffled high end are things I'm noticing more often in certain places. Wondering if anyone out there carries a variac with them for times when the power is bad. I'd be fine with carrying another piece of gear (even a heavy one) to overcome this problem and protect my amps.

Just came across this device in my search. http://www.amprx.net
Maybe there is a better, or less expensive option? I'd rather not use a multimeter and have it all in one unit if possible.

Michael Butler · From: California, USA

a variac is very heavy and would be a bear to carry around with you. also, you would need the multimeter so that you know the input voltage. they basically go hand in hand.

perhaps you could try a power conditioner that MAY keep things cleaner and more stable. but, it may not. and, it is something else you have to carry around.

play music!
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ajm · From: Los Angeles

How do you know that AC voltage from the wall is the problem?
Did you actually measure it?
If so, how much was it?

I had a case years ago at my house.
One night while practicing I noticed that my amp was sounding different, dare I say "better".
After a short time I noticed a couple of other things.
I measured what was coming out of the wall. It was about 80 VAC.
We were having some power problems in the neighborhood, and I immediately shut everything down as a precaution.

All that said...........
I have not tried a Variac, or any of these other devices.
I might be totally wrong on this, and YMMV, but something tells me that this is just more musical gear related snake oil or magic fairy dust.
Especially for the average guy to be worrying about.

I'm with Michael: Just worry about playing music.

Mike Wheeler · From: Delaware, Ohio, USA

Brett, could you be a little more specific about what you are after?

The link you provided shows devices seemingly meant to allow the guitarist to adjust the line voltage to a lower value of his choosing (within limits)....usually a little lower than the 120v. A/C in order to get a "starved amp" sound. Some others think their vintage amp sounds better if the line voltage is 110 or 115 volts A/C...as that was what was the norm back in the day when they were made.

If what you are looking for is a device that will keep you line voltage locked down at 120 volts A/C even when the house voltage fluctuates, or sags, then you want a 120 volt A/C line regulator. Several companies make them...APC, Triplite, Furman, etc. (at least they did last time I looked) The prices vary widely, so shop around. Sometimes Ebay has a deal or two.

Good luck in your search.
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Kevin Mincke · From: Farmington, MN (Twin Cities-South Metro) USA

I know Wayne Dahl has a variac he uses. Years ago I had a smaller version when I was running my TR and playing a lot back then. I think I encountered low voltage/amp issue at Neumanns Bar, No. St. Paul this past Friday.....

Mike Wheeler · From: Delaware, Ohio, USA

Here's a link to the kind of device I was referring to...

http://www.apc.com/shop/us/en/products/Line-R-1200VA-Automatic-Voltage-Regulator/P-LE1200

And it only weighs about 10 pounds and it's good for about 6 amps of current....plenty for a big steel rig.
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Brett Lanier · From: Madison, TN

Mike, ideally the device would tell me what is coming from the wall and then allow me to correct it by bringing the voltage up or down, even dialing it in to wherever the sweet spot for the amp is. Good to know that the Brown Box wouldn't allow me to raise the voltage, I wasn't sure about that. That device you provided a link to looks like a good affordable option, thanks.

AJM, I didn't measure the voltage from the wall but I asked the bass player and other guitar player in the band if they had their amps turned up more than normal and both said they were turned up way more than they should be. That particular venue is an older ski lodge. We went back a couple weeks later (with amps we don't care as much about) and it was the same story. I agree with your comment about placing the concern on playing music but unfortunately there are so many other factors that make it all happen. To my ear, crappy power affects tone (and possibly the well being of my expensive vintage equipment) much more than what type of cable or volume pedal I'm using, and we'll discuss those things all day. Btw, I think Mike Butler signs every post with "play music!"

I had a good discussion with Dan Lurie about this stuff the other day. He had some great thoughts and suggestions but I guess I'm a little surprised that these devices aren't more of a norm seeing as musicians are so often performing in venues that don't have good power. Dan said he actually adjusts vintage tube amps to be better matched for 120V.

John Neff · From: Athens, GA

Thanks for the link, Mike!

I see the "just play music" type of comments on here all the time, and I'm sure they're coming with best intentions, but they kind of sound like "stop your whining" sometimes. This post has been helpful to me -Thanks, Brett!

Brett Lanier · From: Madison, TN

Haha, Japancakes rules John!

Funny, I very recently just played music on a couple tracks by another Mike Wheeler.
https://tidal.com/track/70923566

Thanks for the insight everyone.

Mike Wheeler · From: Delaware, Ohio, USA

That is funny, Brett. I do have a distant cousin named Mike Wheeler who is also a musician. But I've never met him...this guy could be him. Whoa!

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Georg Sørtun · From: Mandal, Agder, Norway

Constant Voltage Transformers are kind of heavy...
https://www.youtube.com/watch?v=VUuJkxmjmOE
...but they sure work.

Carl Mesrobian · From: Salem, Massachusetts, USA

I guess the upside to the voltage problem is that it affects everyone who is plugged in.

I don't think a variac is the thing to use, I use my variac on my bench, in line with a Kill a Watt energy meter to test an unknown device, ike an old amp that hasn't been plugged in for ages. It will only lower voltage, it does not regulate or filter the voltage.

Something like this http://www.iseincstore.com/3pn1010bvariabletransformer120vacsinglephaseinput0-140vacoutput10acasedmodelwithcordplugreceptaclelightedswitchandfuse.aspx

But I think you would be wasting your money, UNLESS all you want to do is cut down the voltage to your equipment. Again it does not regulate Wink

If you buy one please don't spend $437 on it..

What Mike Wheeler mentioned sounds more like what you want.
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Dave Mudgett · From: Central Pennsylvania and Gallatin, Tennessee

If you want a stable voltage/current source, you need an AC voltage regulator. I've been using a Furman AR-1215 AC voltage regulator for close to 20 years now, they work fine. I paid about $350 for it back then, they gradually went up to around $500 when they were discontinued a few years ago. I believe the (more or less) comparable replacement is the Furman M-8XAR - e.g., http://www.americanmusical.com/Item--i-FUR-M8XAR-LIST. No, they're not exactly cheap. The APC unit Mike suggest should work fine and is a helluvalot cheaper, but I really like having a rack-mountable unit that's been pretty much bulletproof.

A variac cannot automatically regulate the supply. You would need to constantly monitor the voltage and manually adjust. As Carl said, they are useful when you specifically want to test something at a lower voltage or bring up a voltage to normal levels slowly, as when forming new capacitors or testing out an amp that has been sitting around for decades and you're not sure what will happen if you turn it on. But not for regulating a supply. I suppose if you knew that a particular supply circuit always had a stable offset, then it might work. But my experience is that supplies that have issues can be pretty volatile, usually due to large load swings on the circuit.

A "Brown Sound" type of box that just controllably lowers the supply voltage by a percentage will not automatically regulate the supply. I personally think that significantly lowering the supply voltage of an amp is extremely dubious unless one modifies the circuit to operate at the lower voltage. To be blunt, my main problem with power is that the supply voltage is sometimes too low, and my amps sound like crap when that is true. I tell this story occasionally - I got the Furman after a gig playing in a barge on the Susquehanna River in Harrisburg 20 years ago or so. Power supply was from on-shore, and every time the bass player hit a heavy note, the supply voltage dipped like crazy. Being an EE geek, I of course always carry around basic testing gear to gigs, so I measured it. My guitar parts sounded like a bad phart. I ordered the Furman the next week. Never had a problem since.

Georg Sørtun · From: Mandal, Agder, Norway

CVTs (Constant Voltage Transformers) are not Variacs, they are "Tuned Saturation Transformer" circuits made for the exact purpose of keeping the Output Voltage near constant where Mains Voltage fluctuates too much, or is too noisy, to run sensitive electric/electronic equipment on.

Input Voltage variations of +/-25% stabilized to +/-2%, works wonders for all kinds of electronic equipment.
No measurements and/or calibration needed, just "plug and Play" as long as the chosen CVT is large enough to handle the Wattage needed.

CVTs only drawback is weight, making the larger ones best suited for stationary use. My 800VA thoroid-trafo based CVT has served me well for about 30 years, correcting for spikes and sags, and protecting from lighting strikes, feeding my CAD/CAM setup with clean and stable power.

Mark Fowler · From: Minnesota, USA

This is a common problem for musicians. How about a Furman voltage regulator they come in many models and/or features from $599 to $2000.

http://www.zzounds.com/item--FURM8XAR

Or if your lugging around old guitar amps that in their day ran on 110v-115v not 120-125v you can make a device to lower that incoming AC voltage.

http://www.geofex.com/Article_Folders/vintvolt/vintvolt.htm

Bob Hoffnar · From: Austin, Tx

Brett Lanier · From: Madison, TN

Thanks for the great explanations. The white standalone unit that Mike provided a link to would actually be more convenient for me seeing as I don't carry any rack gear to gigs. Since it's a fraction of the cost of a Furman I have to wonder if there are any downsides to using that over the Furman. I'm not knowledgeable enough in this stuff to be able to tell by reading the specs.

Also, seems like there's a difference between the CVT's Georg suggests and the Automatic Voltage Regulator (like the white one). I'd imagine the CVT's have a bigger transformer given the size but I'm unclear of how they differ in functionality.

Bob Hoffnar · From: Austin, Tx

You need something that takes the power in and stores it, builds it up the the proper level and then sends it out at the right level.

A great garden hose faucet can do may things but if there is not enough water pressure in the first place it won't help much.

So... we are talking large, heavy transformers and money if you want consistent , clean power.

I have come to the conclusion that anything less then what is really needed is a wasted effort. So I plug my amp into the wall
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Brett Lanier · From: Madison, TN

Georg Sørtun · From: Mandal, Agder, Norway

John Billings · From: Ohio, USA

"How do you know that AC voltage from the wall is the problem?
Did you actually measure it?
If so, how much was it? "

Dropped to 87 volts at a bar out in the sticks, when the bass player played his 5th string open!

At my home studio I used a Furman IT-1220. a balanced power isolation transformer. Very nice! But you wire it like a stove as I recall. Two lines for 230/240 volts.That second line is where the "extra" voltage comes from, if needed. Very heavy and was expensive when new. I think I have that mostly right.

https://www.jrrshop.com/furman-it-1220-balanced-power-isolation-transformer
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Tim Marcus · From: San Francisco, CA

just get a small computer grade uninterruptible power supply or UPS

Those take AC, convert it to DC and store current it in a battery. Then they take DC and invert it into a very clean AC supply that can deliver a rock solid 120 all the time.

They make some small enough to gig with, but they are definitely heavy. I think they use a deep cycle marine battery in there, which most certainly has lead in it, which is not going to be light. But... it will do exactly what you want it to do.
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Eric Philippsen · From: Central Florida USA

Ditto on the Furman. The downside is that any regulator is another piece to carry to a gig. The upside is that you have a constant voltage.

Varying line voltage can cause all kinds of odd gremlins for everyone on stage + the PA. But one difficulty, I think, is that a single regulator will not cover an entire band's gear. The nice Furman I have is rated at 15 amps and definitely takes care of my needs + whoever sets up next to me. But I'm not sure if it will handle everyone all at once.

Maybe someone has some thoughts or experience about that.

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