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In Reply to: RE: Are filters necessary if you use dedicated lines? nt posted by bogartg on December 26, 2007 at 18:55:43
I have dedicated lines: a separate circuit for each component; and I still find benefit from filtering noisy appliances on other circuits. Dedicated lines offer the best isolation from current draw of other audio equipment, but they are still fed from the same circuit breaker panel buss bars as all the other loads in the house.
Each dedicated circuit can also ring. Some sort of damper on the circuit will suppress the ringing and improve the sound. The Hammond choke should work. I use R-C filters mounted as separate plug-ins that go into the other outlets of the duplex fixtures fed by the circuits.
Follow Ups:
My sub panel has a verticle column of circuit breakers on the right and one on the left. My understanding is the right column is a phase and the left is a separate phase. I'm told its more beneficial to treat the outlets on the some phase as your audio. My video is on the other phase and I couldn't care less about it. BTW what is a "phase"?
Your (USA) domestic power is supplied as 240 volts from a utility company transformer. The transformer secondary winding has a center tap that is connected to earth at the transformer location and again at your entrance panel. Thus, the power has two legs, each of which is 120 volts with respect to earth. These legs are of opposite polarity, so that when leg A is instantaneously at +170 volts (the AC peak) with respect to earth, leg B is at -170 volts. However, there is only one phase, since both legs come from the same transformer winding. The legs are commonly, and mistakenly, called 'phases.'
Large loads are typically three-phase, and take three transformers or a complicated transformer with three secondary windings to supply the power. You don't have this setup.
Your circuit breaker panel feeds branch circuits that go into your house. A couple of them use the full 240 volts: a range, a clothes dryer, an electric water heater, and a whole-house air conditioner would use 240 volts. If you look carefully, you will see that these appliances have two circuit breakers with handles connected by straps, so that both trip if either one is overloaded. Each of these breakers is on a different leg, so that tells you that both legs are present in each rank of breakers. The other circuits, that feed lights and outlets, are 120 volts and take single circuit breakers.
I don't know if your subpanel is wired with the legs separately feeding the two ranks, so you would have to take the cover off or ask an electrician. If this is too scary or impractical, take a simple AC voltmeter and an extension cord, and measure the voltage between the hot outlet slot that feeds your audio system, and the hot slot that feeds the video gear. If they are on opposite legs, you will measure 240 volts. If they are on the same leg, you will measure 0. The hot slot is the smaller of the two on the outlet.
A common bit of advice is to put all the audio circuits on one leg and all the noisy appliance circuits on the other. This advice was useful when there were not so many noisy appliances. However, these days, almost any appliance is likely to contain a small computer and switching power supply that are always on. It is impractical to put the audio circuits by themselves on one leg and everything else on the other, so I think it is easier to forget about the circuit disposition and just filter the noisy appliances where they are. Even if the noisy gear is on the opposite leg, it will still affect the audio system.
Al,
I read your post this earlier and it's been rattling around in my brain for hours. I think phase is actually the correct term unless you also eschew it for three phase systems.
Here's my feeble reasoning...
Think of a split phase and a Y-connected three phase system. They are directly comparable. To wit:
-Each has a neutral wire (ground).
-Each has multiple "hot" wires with a defined phase with respect to one another that equals 360 degrees/number of hot wires.
So a "split", or 2 phase scheme has a relative phase of 180 degrees and a 3 phase scheme has 120 degrees. Why would "phase" be the accepted term for the leads on one but not the other?
Regards, Rick
> >
Thanks Jim, very nice reference.
Nomenclature in any field is a rather interesting study. Names for things are usually an odd mixture of logic, history and politics. Annoying for those that long for consistency, comforting for those that enjoy the linkage to culture and history, and somewhat confusing for everyone.
But somehow we muddle through and even manage to feel OK about calling today New Years even though the solstice is long gone.
Happy New Year!
Rick
the domestic consumer is a single-phase load.
In general circuit usage, a phase angle of 180 degrees results from time delay due to reactive circuit elements. Sine waves don't care, as each cycle looks exactly like the one before and the one after, so the practical effect of reversing the wires is the same as a phase angle (delay) of 180 degrees. The phases in a three-phase power setup are delayed in time from each other by the motion of the generator.
There is no harm done by using the term, 'phase' for the legs of the domestic power setup. The OP asked what it was, and I tried to give an exact answer to help him avoid future confusion.
Going beyond that, who knows, I suppose a grid fed from two arms of a three phase system.
Sometimes seemingly common terms can mean different things to an electronics guy, an electrician and an auto-electric chap. And these are rather simple technical things. Imagine being in politics! No don't, that wouldn't make for a very...
Happy New Year,
Rick
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