chrisc@gold.gvg.tek.com (Chris Christensen) (06/27/91)
There seems to be a lot of interest in mains supplies for audio and I thought that I would throw in my two cents. I have a sound system that amp specs indicate a total of 2600 watts. This is RMS and doesn't include and peak capability. I usually spec two decidated 30 amp mains supply. I have run the system on two 20 amp circuits. If one believes that a well designed amplifier has an efficiency of 50% that the peak power draw fron the mains would be (in my case) 5200 watts and that translates to about 42 amps at 125 volts (no power factor correction included to keep it simple), so two 30 amp mains circuits work well for me and thats how I get away with it on two 20's...... Some of my colleagues have suggested that an audio power amp can draw 4 times the RMS rating on peaks. The above discussion applies to "analog" power supplies for audio power amps. It has been my experience that there is no substitute for raw power. My suggestion to those concerned is to have a dedicated mains supply for the audio system. This circuit should be of the heaviest guage pratical and a home run to the main power box feeding the house. The reasoning behind this is to have the lowest impedance supply to the lowest impedance source. I located my studio in a berdoom that my sons vacated when we added on to the house, the mains sypply just hapened to be located on the outside wall of that room. I have glitch free power in the room due to the fact that I am in a dedicated home run to the house power box. I believe that my suggestions will provide the best possible "sonic" results as well as minimise the dimming of the lights in the house. Chris Christensen
jhenders@wimsey.bc.ca (John Henders) (06/28/91)
In article <13497@uwm.edu> chrisc@gold.gvg.tek.com (Chris Christensen) writes: > > >If one believes that a well designed amplifier has an efficiency of >50% that the peak power draw fron the mains would be (in my case) 5200 >watts and that translates to about 42 amps at 125 volts (no power >factor correction included to keep it simple), so two 30 amp mains >circuits work well for me and thats how I get away with it on >two 20's...... > This calculation assumes a duty cycle off 100%, which very few amplifiers or speakers are capable of sustaining. As 50% is more the rule, halving the power spec here would have very little effect on system performance. This spec also ignores the leveling effect of the capacitors in the amplifier power supply. The only application where this much power would be needed that I've run across would be if you were using Carver amplifiers which don't use filter capacitors, and as this group is for high-end audio, I wouldn't think Carver would enter into the discussion. ( Check out the damping factor on a PM1.5a ) Having a separate feed for the audio system is still a good idea, and using heavier than normal gauge wire is also a good idea, but using the larger breakers is a waste of $ and panel capacity. John Henders Vancouver,B.C.