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#186200 04/26/09 10:23 PM
Joined: Nov 2008
Posts: 10
I recently moved from a house that had all gas appliances to a house that is all electrical. Since the move I have been unable to listen to my stereo because it clips whenever the stove/dryer/heating/etc turns on.

The voltage seems to fluctuate from about 114~122 Volts all the time. The Amplifier is a Class A amp that draws a lot of power and seems to be extremely sensitive.

I have tried hooking it up to a cheap ($250) UPS that has voltage regulation, but it doesn't seem to make a difference.

Is there any sort of filter/capacitor I can install on the line to keep the voltage stable?

The only idea I have come up with is installing a Pure sinewave UPS, but I don't want to spend $1000+ on one.

If anyone has any idea's I would love to hear them, I miss my music!



P.S. I have run an isolated circuit from the main panel, but that hasn't made any difference.

Joined: Feb 2004
Posts: 1,438
Older neighborhood? Do neighbors have the same voltage issues?
what size is your current service & feeders? With what you list, I'd expect at least 100A. Is it just your voltage to neutral that fluctuates? how much drop is there phase to phase?

A 10 volt drop even with a dryer, AC unit and a couple stove burners seems a little much if everything is sized properly... My voltage at an all electric apt I had only fluctuated from about 121V to 118V even with the 240V window shaker/ dryer/washer stack, dishwasher and the stove running... On top of it all, it had a Zinsco panel tired

Joined: Nov 2008
Posts: 10
It's not really an old neighborhood, it is somewhat rural however. It's a 200 amp service running off a fairly new transformer.

My UPS is telling me there is a large voltage fluctuation, I haven't tested it with my MM yet (I will in the morning).

I will also test the Amp in another building on the property tomorrow (seperate service/brand new transformer, 400 amps).

However I believe it is just an issue of the Amp being over sensitive, in my old house (on the other side of the country) the Amp would also clip occasionaly when a large load was turned on (Table Saw).

The reason I asked about a capacitor is that I know they use them with large amp's in car stereos.

Anyways, I will do more thorough testing tomorrow.

Joined: Jul 2004
Posts: 9,928
Likes: 34
I think I would get the utility involved before I bought anything if you really do have sags. They may just be overloading that transformer.

Greg Fretwell
Joined: Nov 2006
Posts: 23
That would be my first action, look at transformer size and how many houses are fed from it. In my neck of the woods the utility co. figures if you do not burn up a transformer once in a while you are not loading them enough. Get the utility involved before spending too much of your own cash, you pay them for useable power make them check to see if they can do anything.

Last edited by wire twister; 04/27/09 09:30 AM. Reason: spelling
Joined: Aug 2002
Posts: 402
114-122 is within utility specs.
Caps won't work for a AC amp.They work in a car beacuse car amps are DC powered and caps act like a battery and store up a reserve for peaks.

Joined: Dec 2004
Posts: 329
It sounds like you are using an offline UPS, they are for protecting against power loss only. ie the inverter operates only when the power is out, normally it is bypassed. What you might try is a power conditioner or, if you are willing to spend the money an online UPS. With an online UPS, you are always routing power through the inverter, even when the line power is normal. Note that they are(usually) signifigantly more expensive than the cheap standby UPS's that you buy at Office Depot or Walmart.

Last edited by IanR; 04/27/09 11:46 AM.
IanR #186215 04/27/09 01:29 PM
Joined: Nov 2008
Posts: 10
Ok, I did a little more testing this morning (not as detailed as I would have liked, but I'm late for work).

I saw a voltage drop of 3 volts from phase-neutral when turning on the stove, didnt get a chance to test phase to phase.

I have contacted the poco and they are supposedly coming to install a monitoring device, but its been months and they havent showed up.

I am using an offline UPS, I would love to have an online UPS but it's a bit out of my price range (they start around $800 I believe).

I will do further testing tonight and give the poco another call.



Joined: Jul 2004
Posts: 787
First thing I would suspect is loose connections especially the neutral. Next thing to check to see if there is any current flowing in the bonding connections from the water line and ground rods.

Does the furnace run on its own dedicated line? Is it grounded?

Does the stove run on its own dedicated line? Is it grounded?

Does the Dryer run on its own dedicated line? Is it grounded?

Do you sense a pattern here? smile

When you hear "clipping", is that a click or pop when the offending device switches on or off?

Larry C

Joined: Nov 2005
Posts: 827
Likes: 1
Clipping is a special case where the final p-p amplitude exceeds the supply capability. More commonly, low frequency audio requirements overload the supply filtering below the differential needed for regulation. Then, you're effectively modulating your power supply. No well designed amplifier will go out of regulation at 114 VAC.

My stand-in Dad complained about noise he was getting on his Wave Radio, located in the kitchen. I told him that we could find out if it was line sourced or radiated. I built him a filter using a 4" box, single duplex, 3 or 4' 12/3 plug and cord, and a Corcom line filter. It solved his problem so we lucked out and explored no further.

Some power supply designs lack sufficient high frequency bypassing. Huge filter caps prevent clipping but have high equiv. series inductance that lets hi-f noise right on by. If additional line filtering reduces the noise you're hearing, then the supply would be suspect. If not, then it's time to try isolating the inputs, re-orienting the amplifier, checking the headphone output, Et,c.

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