Tripplite’s SU1000XLCD costs $630, but it does a better job conditioning power than so-called audiophile units that cost 10 times as much. If you’re not worried about ground loops, you can find a UPS that will eliminate AC noise (look for sine output) for a little more than $100. Credit: TrippLite
A true online UPS is expensive. The SU1000XLCD UPS that Tripplite sent me to clean up my apartment’s super-dirty AC, for example costs about $630. It’s also heavy, it’s about size of a small dehumidifier, and it has some features (such as USB monitoring, so that it can gracefully shut down an attached computer in the event of a power failure) that bear no real relevance to noise elimination. But darn if it isn’t 100-percent effective, as well as comforting protection against power surges and outages.
It’s also much less-expensive than one of those high-end power conditioners you see marketed to gullible audiophiles. If you’re not worried about defeating ground-loop noise, you can get away for not much more than $100 with a UPS that advertises sine-wave output.
Slightly cheaper than an online UPS, but absolutely effective against all kinds of line noise is an isolation transformer. Tripplite sent me one of these as well: the excellent 1000-watt IS1000HG (Hospital Grade) with four outlets. It’s about $500, but you can easily get away with a lower wattage model for less than $200. An isolation transformer is one of those products whose name describes it to a tee—it employs a special, shielded transformer that turns dirty AC into clean AC via electromagnetic induction—yes, the same thing that causes ground-loop noise.
Isolation transformers are designed for use with delicate diagnostic equipment, where even minimally noisy AC can cause spurious readings. That means they’re substantially more than adequate for multimedia setups.
The back of the IS1000HG isolation transformer, which is designed to eliminate all AC noise that could affect sensitive testing equipment. It works for entertainment systems as well. Credit: TrippLite
There are really only one or two hard and fast rules for cables and noise. The first is to never run a power cable across or near audio or video signal cables, including antenna wires. Modern signal cables are well shielded, but if you’re getting hum and it’s not a ground loop, this could well be the cause. Note that the cables running to self-powered speakers (non-Wi-Fi) are audio signal cables, not output cables.
Note that three-wire balanced cables are far less susceptible to power cable hum and other noise than two-wire cables. If your equipment gives you the option of using balanced outputs, do so. Speaker cables, because of the far stronger signal travelling across them, shouldn’t be affected audibly. But just to be safe, try to keep your AC cords isolated.
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