Video Asylum

Posted by Andy Hung on February 02, 2000 at 11:19:41:

Hi all,

The subject of regenerative power supplies is interesting. I’ve seen the effects of good power supply filtration on audio and video equipment with severe AC line noise, such as draw and back EMF from motors. But for moderate AC line noise and minor brownouts, shouldn’t audiophile equipment have sufficient filter caps before regulation, or better yet have true high current switching power supplies as found in computers?

Anyhow, I recently purchased a Best 610 1kVA online UPS power supply and hooked it into my HT system. The Best UPS has been mentioned before on Audio Asylum (the FERRUPS 850VA model), but I'd like to contribute further details and my own experience.

1) Only online UPS systems (versus offline or line-interactive) are of interest for audio because they continuously regenerate power. The output of most online UPS systems is a sine wave (versus square or stepped sine). The output power for the Best 610 has a slight bit of distortion ~4% THD, more than a typical audio amplifier.

2) The Best 610 can synthesize power at 100,110,120,127V. The output frequency is phase locked to the input line voltage when available. It will not synthesize a sine wave at different frequencies like the PP300. Maybe it is possible to tweak the pll circuit if one has the circuit layout.

3) For my applications, the Best 610 has good power headroom: I cannot get my audio setup to go beyond 35% of the Best 610 capacity with my DVD player, Classe preamp, and ATI 1505 connected, unless the volume at my listening position exceeds 85dB! This is with the inefficient Sonus Faber Concertos, too! The TV adds 15-20% additional load.

4) The Best 610 1kVA is cheap compared to the PS Audio PP300. The 1kVA model costs less than $500 at www.buy.com and is a bit over 3x as powerful. As far as cost goes, it is only slightly more expensive than getting one of those audiophile power strips. Furthermore, delivery was only 2 days from order.

5) It has a fan which does produce some background noise.

6) At rated load, the Best 610 UPS is 83% efficient. It probably consumes the wattage of a 100w bulb when going full steam.

7) The Best 610 can be switched into bypass mode (where the output AC is presumably only filtered) and into regenerative mode. During the switchover, which can take a few seconds, you can hear relays switching, but the power delivery is seamless. It is very difficult to tell the difference between bypass and regenerative mode, maybe the bypass is slightly more etched, maybe regenerative is a bit richer and smoother, but this is very subjective and I doubt the difference would reliably show up on a blind experiment. With video it is also hard to tell the difference.

8) Due to the built in battery, I can play my favorite CDs for about 30 minutes after a blackout, while the rest of the neighborhood tumbles into chaos…

9) In any case, the benefit of regenerative power clearly depends on the severity of local AC line noise, so your mileage will vary.

Yours,

--andy

P.S. Anyone with a PS Audio PP300 that lives in the Bay Area interested in doing a blind regenerative power supply face-off with the conclusions posted on audio asylum?