Power Conditioning in the Studio

July 11, 2009 · Posted in Audio Engineering

Firstly, it is of little use to condition the incoming power if there are pieces of equipment within the system which are introducing electromagnetic interference (EMI). Nevertheless, additional filtering of the supply ought to do no harm. The trouble is, that so many EMI or RFI (Radio Frequency Interference) filters (or suppressers), fail to dispose of the problems, and merely result in dumping even more electrical hash on the earthing system. In fact, the notion that uninterruptible power supplies will supply an absolutely clean supply is often very misguided. Only units with internal output voltage feedback control will ensure a clean waveform, and such units often need to be of substantially higher capacity than initially assumed, or even they may cause more problems than they solve. The problem is that they rarely have sufficiently low output impedances to ensure freedom from the production of harmonics by mechanisms such as power amplifier transient demands. Some of these things can actually cause computer crashes unless they are connected to individual computers without any other equipment sharing the supply.

Summary: One of the best protections against earthing problems is to ensure low impedance mains supplies. Harmonics on mains power supplies can be very detrimental to system performance. Studio power wiring should be taken from the primary inlet to the building. Sensitive and interconnected equipment should all be connected to the same phase. Line filters and power conditioners can actually create problems if they are not installed with a full understanding of how they work. Balancing the power can be highly beneficial in circumstances of high mains-borne interference levels.

Reference: Recording Studio Design Second Edition by Philip Newell