Power Conditioning/UPS for Digital Audio Server

Let me be more clear. Some UPS devices (including some by APC) don't produce a sine wave; they produce a square wave. Using such a device could ruin your sensitive equipment.

Most audio equipment internal power supplies are not able to handle the fast edges produced by a square wave. They will not filter them properly and may just pass them though as "noise" to the speaker. This may be heard in the form of a 60 of 120Hz hum or click (or worse).

A computer does not care. Cheaper to make.

I've been priviledged to actually meet with Jack Bybee, developer of the famous Bybee Quantum Purifiers (http//www.bybeeinside.com). Jack has some thoughts on power supply issues that are technically sound. You should email him and seek his opinion(s) on power supplies. I haven't had a chance to talk with him about PC-based music servers, but I'm sure his depth of knowledge and wisdom would be very helpful.

I can tell you that you should really get a good PC power supply that is both efficent and quiet first. http://www.silentpcreview.com recommends the Nexus PC PSUs for their stable power delivery under load and silent performance. You can find some great deals on the Nexus PSUs, hard drive noise reducing cases, fans and heat sinks through http://www.siliconacoustics.com/. Only after you upgrade your PC PSU should you start looking into a power conditioner and UPS unit.

I assume you're just using the UPS on your computer equipment, not the audio stuff.

Cheap UPSs do a couple things:
- Just pass on the input voltage/freq as long as it's within a certain range
- If it goes out of that range, cut it off and replace the power with a square wave (or a couple overlapping square waves).

So, when you're operating on normal wall current, I'd expect the UPSs not to do anything bad or good. It'll only matter when the power is fluctuating drastically, or goes out completely. In either of those cases, you probably want a UPS to protect your equipment.

The middle-of-the-road UPSs will also boost or lower the voltage if it's only off by a bit to keep it within norms. This is also known as AVR (automatic voltage regulation). I'm not sure how that effects the look of the output. But I expect it won't be good. Again, this'll only kick in when the wall power is really bad.

The more expensive UPSs will produce a good sine wave from battery power. But even these (for the most part) just let the power go on thru whenever it's "close enough" to the spec.

If you also want to use a UPS for power/line conditioning, you'll need to get something much more expensive. There are UPSs which (like the PS Audio power plant) will always convert to DC, then from DC back to a very nice AC. That way, there isn't even a hiccup when something happens to the wall voltage, and you get very clean power going to your equipment. Such devices cost money (and lots of it).

Auda ibn Jad