Low household voltage causing noise (1 Viewer)

[michael_f]

Periodically (more often lately), I get low buzz/hum out of my speakers with no signal present. I believe it's coming from my H/K AV6-65 receiver. It doesn't appear to be tied to volume, other components (I disconnected them one by one), or other electrical appliances in the house. My home was built a little over a year old in a new development.

This is driving me crazy and I purchased a Monster HTS5100 hoping the clean up the AC power going to the receiver. A day after hooking it all up, the hum is back. Grrr. The benefit of the HTS5100 is that there's a digital readout for voltage and amps and the unit will shut down when voltage is < 90 or > 132. With this constant readout, I'm making some progress in finding a cause.

When things are good, the voltage moves around between 111 - 118, usually sitting at 114, and there's no audible impact. I've only ever seen the voltage reach 120 once, around 2 am late one night. The buzz/hum shows up when the voltage drops to 105 and below. The lowest I've seen the voltage is 103. The system draws 0.9 amps with everything off and idling and 3.8 - 4.0 with everything powered up at normal listening levels. I've started to track it and the low voltage times occur in the late afternoon until late evening (5 PM - 10 PM).

I've been doing a bit of research and have found lots of conflicting information. I've read everything from "the power company should be delivering 123 volts +/- 6%" to "some areas having frequent brownouts where household voltage regularly drops to 95 volts". My home is at the end of a long road at the back of the subdivision and, my feeling is, during the hotter summer days the power delivery system in the development just isn't up to par.

I am trying to determine what, if any, options I have. Are these voltage ratings "normal"? Should I be calling the power company, the home builder/developer, or resolving myself to the fact that I'll need a balanced power unit?

 

[Kevin C Brown]

A balanced power unit would take care of the noise problem, but not do anything for the voltage problem.
You might take a look at PS Audio's power plants. Not cheap, but that's probably the best AC you can get.
Furman has very cost effective voltage regulators as well as balanced power:
www.furmansound.com
I have an Equi=Tech balanced power unit with a voltage readout. I'm kind of lucky: I live in the heart of Si Valley, but the largest swing in V I've seen is 117V on the low side to 121V on the high side. I've seen the same thing as you: low 5-6pm, and the high later at night.
You also might want to take a look at Link Removed too.
You also might want to bug your power company too!

 

[John Michael]

I also have a hum in my speakers.I purshased the HTS5100

but like you no luck.My voltages are between 121 and 124

usually.I have a Rotel RMB 1095 amp.I did find the hum

diminish when I used a cheater plug.Now I have to put my ear right up to the speaker to hear the hum.seems to come

out of the horn speakers only(Klipsh RF7)I re did the ground outside my house but still no luck in removing hum.

I'll keep trying.

 

[ChrisB]

Alpharetta Ga, I used to wire houses down there, which builder built your house, I might have worked for them when I was down there. If you are looking for a electrican I know a few down there.

On to your problem, you are right about the power company allowing 6%, actually I have heard 5%, but it may vary in GA. What you are saying about voltage drop during peak periods makes since, even though there are probally anywhere from 2-4 houses on your transformer, if the input voltage lags it would drop your voltage also. If you have a spare UPS laying around I would be curious if that would help you out, since it is always working off the battery, you would have constant voltage at your units. Since you are only drawing 3-4 amps it might not be to difficult to find one that would work.

 

[michael_f]

Chris,

It's a small world sometimes. Tom Sharp is my builder. I found one of your helpful replies on another topic and it actually prompted my original post. I figure there's a wealth of power supply and electrical knowledge on the forum.

In your experience, is this type of voltage fluctuation normal? I'm guessing this can't be good for all the other electronics in the house.

 

[ChrisB]

I think I did work for him, its been 5 years since I worked down there, but I worked for Cutini Electric(its in Alpharetta).

I have run into problems like you are having, but not as drastic on a swing in power. You actually are dropping below 5% of 120V. The only thing is you are taking readings down the line from there point of attachment(meaning where the power company enters the meter). It still should be very close to the readings you are getting. I would call them up and see what they have to say(the electric company).

As for not being good for your electronics you are right, the lower your voltage drops, the higher your amps are going to get, then the more heat will be generated. It also is not good on your motors in the house, refrigerator, AC unit, furnace motor, etc..

 

[Eric Samonte]

A vote for the Furman. I got the AVR 1215 for $350 shipped at Zzounds. While I didn't have the "hum" I was worried about the voltage my stuff was receiving since this house of ours is over 80 years old. I honestly don't know if this info would help u though....just putting in my 2 cents..sense...

 

[Norm Strong]

Why not just buy a 7 amp Variac, and when the voltage starts to go low, turn it up. Costs a lot less than $350.

 

[Kevin C Brown]

7 amp probably wouldn't be enough for a typical system. Not unless you could put them in series (or parallel) or something...

 

[Nathan Cook]

just buy a generator and use that for your stereo.

 

[Todd Hochard]

Sounds like you need something like the
Tripplite Pure Sine, Always On UPS. This will provide a constant, regulated 120VAC output for varying input conditions. It will completely isolate your gear from brownouts and momentary (several minute) power losses. It will provide one of the cleanest sine wave outputs you've ever seen.
They are slightly pricey, though.

 

[Gifford L]

I think the power company needs to have a look and see if the mains voltage into the house is ok. Then I say you call an electrician to track down the problem. I have seen this from bad connections. On some outlets we had 90 volts but the upstream was at 120v so we found the bad connections (fire hazard as well) and the electrian re-did it.
If it truely is coming from the power company then yes your power supplies are working too hard and I would recommend something to stablize the voltage like a variac. The Monster Cable AVS 2000 is a computer controlled Ultra High Current Variac for just this sort of thing. A power conditioner or balanced power conditioner will not work for this and a UPS for computers are not for higher current applications. Some of the PS Audio Power Plants should do the trick as well but are much more $$$.

 

[ChrisB]

I would agree with Gifford, if you had a digital volt meter you could read your voltage at the service, and see what it is there. If it read the same as what you have at your duplex where your amp is plugged in then, it would be a electric company problem. If you checked voltage on both legs of your service and one read low and the other high, that would be a indication of a broke, or lose neutral.

 

[Todd Hochard]

When things are good, the voltage moves around between 111 - 118, usually sitting at 114, and there's no audible impact. I've only ever seen the voltage reach 120 once, around 2 am late one night. The buzz/hum shows up when the voltage drops to 105 and below. The lowest I've seen the voltage is 103. The system draws 0.9 amps with everything off and idling and 3.8 - 4.0 with everything powered up at normal listening levels. I've started to track it and the low voltage times occur in the late afternoon until late evening (5 PM - 10 PM).

This is why I don't think the problem is in his home. Voltage sags specifically related to time of day are an indicator of a neighborhood issue. 5-10PM is peak capacity time for many utilities, due to AC loads when everyone returns home (and typically the hottest part of the day for your home). One possible exception- if YOUR AC unit is causing the droop at your house, due to a high resistance connection near the meter. That's the only giant load in your house that's likely to cause such a droop, given the time corollation.
Sorry, I can't help myself- I troubleshoot for a living.
Todd

 

[Doug EL]

Anything below 114VAC at your main panel should be reported to your local Utility. If you are measuring at the main panel levels below 100 you can even wear out your refridgerator motors early as they draw extra current to keep up with the power output. Extra current means excessive heat in the windings. I am surprized you don't have computer problems which usually occur at 105VAC and below. When I worked for PG&E as an engineer we use to (try to) regulate the voltage +/-5% (114 to 126). Good luck.

Doug L

 

[michael_f]

Thanks for all the input.

For the past couple of days, the weather's been cool here and no major voltage swings - holding at 117 - 119. I'm checking the HTS5100 voltage reading every few hours and am ready to check the service voltage coming into the house when it drops again. I am guessing late this week as the temps are predicted to rise.

I read in another post that the Monster AVS 2000 doesn't have the power/reserve/capacity to run a complete system AND RPTV. Can anyone comment on this?

 

[michael_f]

If I don't care much about powering the system during a total power loss blackout, would http://www.tripplite.com/products/co...?model=LCR2400 from Tripp Lite work just as well as the SmartOnline 2200 listed above? This seems very similar to the Furman AVR 1215 at a better price.
Am I missing anything?

 

[Glen B]

I agree that any unusual low voltage situation should be reported to your utility company. It would be good to have information to show that there is a pattern of this low voltage. Radio Shack sells an inexpensive digital multimeter (Cat. # 22-805, $59.99) that hooks up to your PC and comes with interface software. I own one and it can be used to continuously log voltage levels over a 24-hour period. The logging data can be saved and printed.

 

[Todd Hochard]

I'm not sure that the LCR2400 would maintain a tight enough voltage output to minimize your noise/hum under drooping line voltage. It indicates the output range is 106-132VAC.

Perhaps you can call Tripplite to compare the differences.

 

[Gifford L]

The AVS-2000 should be fine for your whole system as I believe it's capacity is the same as houshold circuit. Stereophile reported that during their show last summer when the country was having all the power problems the hotel was have serious voltage sags and many displays were having problems but Krell was fine using the Monster piece. I really think this is the way to go if you can't find a problem elsewhere.

When the voltage does sag check some other areas of the house besides the mains as well.