Question on ups for ht.

I recently bought a Belkin 30800-10 UPS. Its an attractive unit and works well but its transformer hums all the time (YMMV). I have a CRT TV, Onkyo 5.1 receiver (running 3 of the 5 channels), DVD recorder, wireless switcher and two cable boxes plugged into the UPS backup outlets. One thing I'm very sensitive to and find very distracting and annoying is transformer and fan noise. It gets so quite at my house that one night when in bed I kept hearing a hum that was keeping me from falling asleep. Upon further investigation, I realized that it was the hum from the Belkin unit that was travelling up to the bedroom upstairs. I have tried installing some padding under the tranny but that didn't seem to help. I'm going to try some additional padding and see if that works.

I recently purchased the BELKIN PureAV AP30800-10 Surge Protector/UPS. It hums for me too! It's not real loud. Noticable when everything, except the AP30800-10, is turned off for the night. Contacted Belkin & they claim that it is not normal. Anybody else have experience with this unit? Does yours hum? What did you do, or what did Belkin do/suggest? Thanks

When i reviewed the unit a year or so back, I asked Belkin and I was told the hum was normal. From the posts here, it seems so.

What are you getting the UPS for? If it's actually to drive a power amp during a power outage, you need a high-wattage unit (1500 VA or up would be ideal). If it's for power conditioning, then read on.

In general, a consumer-grade UPS will not power the line using the batteries. When the power goes out, they will turn on the batteries and inverter, and use a stepper function to simulate something that looks a little bit like a sine wave for AC. However, the signal has tons of harmonics, compared to pure AC power, so when you're on battery, expect 60 Hz (and harmonics like 120, 180, ...) buzz in your system.

High-grade UPS-es (typically costing thousands) will continually charge batteries, and continually pull power from the batteries, inverting to AC. They may also synthesize real sine waves using basically a really large oscillator. These guys can actually help a lot if you have very dirty power, because the rectifier and then the inverter basically act as a very, very steep filter for interference. That's not something you'll see from a $300 consumer unit, however.

A UPS may also be coupled with a power conditioning device, which is intended to remove harmonics from the incoming AC signal. This can help if you have really noisy power lines, and a weak power supply in any of your components. However, the fact that the consumer-grade devices come with power conditioning and UPS in the same unit, does not mean that it's an online, sine-wave, "active" UPS.

If what you want is clean power, I suggest focusing on some power conditioning unit. I've got an order in for the 1000 VA balanced power supply with conditioner from Transcendent Sound, and I can let you know how it works once I build it (got the kit) and actually get my remodel done (so it'll be two months or so). Or you can go ask others in the same situation for recommendations.

I have an APC unit I use only for my TV. Because my convergence goes back to default settings when the power goes out. As well as some other custom settings.

Anyway, it doesn't hum at all. Completely silent. I've always liked APC stuff, but most of my experience with them has been related to computers.

So if I have a pureav pf60, should I just get a 2-4 outlet ups? Then connect it into the pf60?

If you have a PF60, you could get a 1500 AVR UPS, and then plug the PF60 into the UPS. The UPS will emit somewhat non-clean power, so the PF60 after the UPS will filter that out.

I've used CyberPower, APC and various no-name UPS-es, and prefer CyberPower (but YMMV).