Furman power supply or Isolation transformer?

[punkykatt]

Hello all, my band just started playing at a couple of clubs that our guitars buzz like crazy when the guitar volume is up. We both have single coil pup and noiseless single pup guitars. Even the noiseless are noisy in these clubs. All the other places we play, we have no problems. I dont see alot of neon signs or light dimmers in either of the two clubs. Will the nasty buzz go away if we invest in a Furman power supply, or can we get away with an 115vac/115vac@ 8.7A  Isolation transformer that Mouser sells to plug the two guitar amps into?
Any help or advise is much appreciated. Thanks
Punky

[PRR]

Get a 3-light outlet tester, $5-$10 in the electrical aisle of the home center. See if the wall outlets are actually grounded. Tell the owner to fix them. Don't play there until he does.... it aint worth your life.

[triode]

Actually, anyone who owns a tube amp should heed PRRs advice and get one and check every outlet you plug an
amp into. I suggest this in my guitar amp manuals. Too many outlets are wired with hot and neutral reversed or
no ground. It is a crime against humanity how many electricians do not know what they are doing or just don't
care to wire an outlet/breaker panel/sub feed properly.

If you want to get fancy, get a tripp lite isobar which tells you the line status (proper/improper) and has some
filtering built in.

[eleventeen]

Those little $5-$7 outlet testers can save your life. No more need be said.

I see no reason why you couldn't buy one of those Furman deals from a Guitar Center and return it the next day if it didn't function for you. Be a nice guy and ask for a demo unit so you can test it and return it without opening a brand new box, in case it doesn't do the deed.

I would expect a passive isolation transformer to have essentially no effect at all.

It might help some to use a SOLA "constant voltage" transformer, not cheap if you have to buy it new. There are several models/grades. On ebay search for "sola constant" for some pix. I would contact the factory to see if they claim their product(s) can eliminate this type of noise.

"Hash" noise can be very tough. It can be the switching power supply "box" style bases for a row of track lights. It can be a bunch of those curly fluorescent lights. It can be exterior mercury vapor lights. (much less likely)

You might have to show up in the afternoon, before the club is active, and get one of the guys there to selectively turn off breakers in the place one by one to locate the culprit.

[Fresh_Start]

I hope this is on topic - I've got several older un-interruptible power supplies for computer equipment.  The amp rating(s) seem high enough for a guitar amp (but not a laser printer - ugh!).  I ASS-U-ME that there has to be some kind of isolation in a UPS unit.  Is that correct? 

Any potential benefit to using a UPS?

Cheers,

Chip

[sluckey]

Yes, there is lots of isolation. A typical UPS consists of 3 major blocks... rectifier, inverter, and battery. The AC from the wall simply connects to the rectifier. The rectifier output is used to keep the battery charged and also provides the dc input for the inverter. The battery provides another input to the inverter. The inverter converts the dc back to AC to be used by external equip via the output convenience outlets.

I can't think of any reason to use an UPS for my amps.

[Fresh_Start]

Yes, there is lots of isolation. [edit] I can't think of any reason to use an UPS for my amps.

I seem to have a lot of electrical noise in my AC, especially on one particular circuit.  Of course it's the circuit I want to use for playing amps.  A old UPS just seemed like "free" power supply isolation.  Those Furman units sure aren't free!  Might provide some voltage regulation too...

Cheers,

Chip

[sluckey]

I seem to have a lot of electrical noise in my AC, especially on one particular circuit.

A good UPS can probably fix that.

[DummyLoad]

UPS in normal mode, recto & charger & sine generation is bypassed. only the usual iso-bar protection stuff while in normal operating mode. if you want full isolation w/ UPS, charge it up and unplug it form the wall. who the hell wants to haul around 200#+ UPS to gig with for a couple of hours w/100W draw amp. if you have excessive line noise, look for dimmer packs on same ckt or faulty neutral/ground bonding. if you experience excessive hum @ gig - there's a faulty line supply - don't play.   

--ISO

[punkykatt]

Thanks for great advise everyone. I will pick up one of those three light outlet testers and keep it in my effects/tool case to have on hand. I will definitely try to get back into those clubs with the tester before we gig there again.  Thanks again. Punky

[PRR]

> I ASS-U-ME that there has to be some kind of isolation in a UPS unit.  Is that correct?

No.

Sluckey may see it different, because his shop works with high-end gear.

The $69-$499 UPSes mostly pass-through when not on battery.

One affordable brand had buck/boost to keep you near 120V with 100V-150V out of the wall.... but if the input was ugly (or UN-grounded) the output was still ugly.

The on-battery output of the affordable UPSes is VERY ugly. Near-square-wave. Actually worse: it pauses at zero twice a cycle so that both the RMS (lights) and the peak (electronics) are similar to nominal sinewave values. In addition to all the harmonics of a squarewave, there's another overtone series. This may be modestly filtered, but is still worse than about any wall-outlet unless it is overloaded with SCR dimmers. (I used to work next to large dimmers and it need not be a problem.)

> wall simply connects to the rectifier

That's a high-end UPS. Critical-mission stuff.

> benefit to using a UPS?

You can play in the dark?

Same as the laser-printer: you "can" buy a UPS to hold-up anything through any failure. But for a gig, or a print-out, it is usually better to wait until the power comes back.

I did know one stupid reason to run audio on a UPS. A guy had a TV set which remembered the last volume setting. But forgot after a power-loss, and the default was LOUD. And his power blipped a lot. He ran just that set on a UPS just to hold the volume setting. It would have been better if the TV designer had made better choices, but what can you do?

Many UPSes also have line-grounding diagnostics equivalent to the $8 tester.

[Fresh_Start]

Thanks guys.

BTW I never had any thought of using the UPS for battery backup power.  Just thought it might be a cheap alternative to a power conditioner.

Chip

[sluckey]

Sluckey may see it different, because his shop works with high-end gear.

Yes, I was describing the only UPS I've been trained to maintain. It's a 208 3 phase 160KVA model made by Eaton/Powerware that's capable of running my entire radar facility for 45 minutes. After reading ISO's post, I realized that my UPS may not be so 'typical'. I just made another bad assumption... 

[Jack1962]

Actually, anyone who owns a tube amp should heed PRRs advice and get one and check every outlet you plug an
amp into. I suggest this in my guitar amp manuals. Too many outlets are wired with hot and neutral reversed or
no ground. It is a crime against humanity how many electricians do not know what they are doing or just don't
care to wire an outlet/breaker panel/sub feed properly.

If you want to get fancy, get a tripp lite isobar which tells you the line status (proper/improper) and has some
filtering built in.

I am a electrician brother if the wiring is reversed a electrician didn't do it our work has to be inspected is has to pass building codes. However yes I to recommend buying a tester to check for this as well , simply because there is no gaurantee that the outlet you plug into was installed by a electrician. I do also recommend a Furman as well.

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