dplatt@ntg.com (Dave Platt) (06/28/91)
> It's time for me to do something about the power to my audio system. > What do you think of voltage regulators or something just short of a > UPS for this system? Got any to recommend? The latest issue of International Audio Review focuses on voltage regulators, power conditioners, and the like. The results of their review and lab-tests seem to indicate, in no uncertain terms, that the use of a power regulator is often more likely to compromise the sound of your system, than to help eliminate any problems which may or may not exist. The biggest problem seems to be that a power conditioner is trying to meet two mutually-incompatible goals at the same time. It's trying to buffer your equipment from the power line, in order to block RFI, spikes, noise, and voltage sags... this requires that it have a relatively high impedence at many frequencies. On the other hand, it's trying to allow your amplifier's power supply to recharge itself from the line, on demand, as quickly and easily as possible... this requires that it have a low impedence at the frequencies involved, and/or have a large amount of energy storage of its own. It's not easy to engineer such a device, nor is it inexpensive. The IAR lab tests seem to show that all of the commercially-available power conditioners interfere to a significant extent with an amplifier's ability to "top off" its power-supply energy reserve (typically a bank of electrolytic capacitors). The results are audible. Inserting such a conditioner between a good amp, and a clean power line, can cause a detectable change in the sound of the system... even if there had been _no_ problems due to power-line noise or sags. This isn't what you want to have happen. The popular Tice Power Block (I think that's the model?) turned out to be one of the models which did introduce significant problems when used with a high-resolution playback system. IAR's test did not find _any_ commercially available conditioners which [1] are capable of blocking RFI and EMI, [2] capable of stabilizing the line voltage in any meaningful way, and [3] were free of undesirable changes in the sound of a good system connected through them. > What about the 3-prong > adapter? It has a copper braid to the wall box, which seems to have a > ground attached. Should I really just have an electrician come give me > a grounded 3-prong separate circuit for audio? This is probably your best bet... install a dedicated 20-ampere breaker with heavier-than-usual wiring, so it can handle current surges without significant voltage-drop. Run the cable to the breaker box along the shortest reasonable route. If your house is wired for three-phase (I assume that it is), ask the electrician to connect the dedicated circuit to whichever available phase is least-heavily connected within your house. > When I power on the amps (1 at a time), there is a definate dimming of > the lights, and some time the refrigerator even coughs. (love these old > homes ;-) You might want to consider some sort of slow-start arrangement for the amps. You can buy (for a few dollars apiece) inrush-current limiters which can be placed in series with a power supply... they have a resistance of a few ohms when cold, and drop to under an ohm when warm. They'll limit the turn-on surge of the amplifier's power supply, by allowing the initial charge-up to take place over a couple of seconds, instead of all at once. One could build a power-distribution box for the amplifiers, which would incorporate a few relays and some of these limiters. When you hit the switch on the box, it would route power to the amps via an inrush-limited circuit. After a few seconds, a time-delay relay would close, and close a set of high-amperage relays which would bypass the inrush limiters... thus permitting the amps to draw their full in-use recharge current directly from the line. This box could also incorporate a few MOV varistors or other spike- suppressors, and perhaps a couple of small-value, high-voltage filmcaps to act as a simple low-pass RFI filter. > What is the reasonable solution to the power delivery? I'm sure I'll > hear the difference in the speakers. What is the ultimate solution, > assuming money were not much of an object? (short of my own substation, > of course.) I think you'll be best off "widening the hose" from the grid... add a dedicated 120-volt circuit using wire to reduce the voltage drop.