Isolation Transformers

Tripplites are good rugged units, but not for audio. Too much noise and current limiting. Since you cant do dedicated lines (are you in an apartment or condo? Sometimes you can find an unused circuit, or one that has only one device on it) I'd advise you to buy an Exactpower EP-15A regenerator unit:

http://www.exactpower.com/ep15a.html

It has 8 outlets, 4 of which have digital filters to keep your digital gear from putting "hash" back into your power lines. It also "creates" perfect AC power even better than some dedicated circuits can.

Later on, if you want the ultimate, you can buy an SP-15A balanced power unit which you can plug into the EP-15A and use to provide quiet balanced power to all your front end stuff.

An isolation x-fmr wil only isolate your gear from noise on the power company side of the x-fmr, but not from each other on the "gear" side of the x-fmr.

Clio, I don't think I'm expressing myself properly. First I have to say that for me, the world is divided into those who can implement dedicated circuits, and those who can't.
Your statement about not being able to provide dedicated circuits is, to me at least, the key issue; and the reason I recommend a power regenerator unit.

Yes, I suppose you could get someone with an oscilloscope to look at what's coming out of your wall, and who knows, you might be the lucky utility customer who is getting constant 120V with a perfect 60 Hz sine waveform and full current at all times, but let's face it, that's not likely. And even dedicated circuits can't improve on what's provided by your power company. All they can do assure you that you're getting whatever is coming from the pole; and without noise from intervening devices within your house -- so dedicated circuits are only a "solution" if you have good electrical service to begin with (which thankfully is true probably 90% of the time in this country.)

Audio gear will perform best if it has "ideal" AC power available, and that's what regenerators do. They RE-generate the "house" power into "ideal" power, with negligable losses these days, due to the real-time analysis provided by modern computer processing techniques. This kind of economical "regeneration" was not even possible a few years ago. Normally, any filtration (conditioning) they might also provide is done before the regeneration takes place so it can't affect sonics. Ditto for surge protection circuits, if they are even provided (most manufacturers realize surge protection is a myth, and don't do it -- not to reduce the cost, but because "token" surge protection degrades sonics.)

So bottom line, here's my position on all this:

1.) If one can do dedicated circuits, then 90% of the time that'll give 90% of possible power improvement benefits. If one then wants to add some "finishing touches" with an isolation transformer and/or a balanced power unit for sources, great, but definitely much smaller bangs for your bucks.

2.) If you must use an existing house circuit, be savvy about which one you choose. If you have a choice, pick a 20A over a 15A, and pick one that just has a few low power, low noise devices on it (like incandescent table lamps.) And then plug in a regenerator to take the place of a dedicated circuit. If, (as with dedicated circuits) you want to add other power devices to the regenerator, that's up to you.

That's my thinking on the matter ;--)

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Bob, yes they're all tied together at the panel, but a dedicated line means there is nothing else on that circuit but your audio, so there's no other equipment on that line between your audio gear and the power pole (except for that circuit's breaker and the main electrical cut-off switch) and so nothing (in your house at least) to introduce noise into, or reduce current in, the line used by your audio.

Clio, one thing that you could do to get the most out of your non-dedicated circuit is (first cut the power at the breaker) and rewire all the outlets on that circuit, making sure you use the screw terminals (not the push connections) and making sure all the wire and teminals are clean (you can use Caig De-Oxit) Generally, the electricians daisy-chain the outlets, so if your audio system isn't using the first outlet after the circuit breaker, then there are a lot of connections between it and the panel.

Bob, I'm sorry, i was responding to your question about dedicated circuits. As for equipment with built-in filters (and even built-in surge protection) I'm afraid the answer is a qualified "no". And here's the reason: If it's to be done in a way that doesn't degrade sonics (like happens with cheap, separate, surge protector and/or noise filter units) it's going to cost the manufacturer a lot -- in some cases more than the component itself if the component is in the $1000 - $2000 range. Sure, stuff like a Mark Levinson 33 or 33H amp has its own built-in non-sonically-invasive regenerator power supply but those pieces are so expensive to start with that the additional cost represents (I would guess) only 10% of their purchase price, so it kind of makes sense for them to build it in and do it the way they think it should be done, and not require their customers to have to make those additional decisions/purchases.

For less expensive equipment, what the manufacturer could provide within their pricing target really would do more harm than good. So it makes more sense for the customer to buy a $2000 regenerator/conditioner/balanced power unit which can then supply really properly produced power to a number of components.

Hope that throws some light on the subject.

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Bob, my experience w/ isolation transformers is limited to a brief flirtation about 30 years ago. I'm not sure why people use them. And what you say makes sense at least for most frequencies (although I don't think they pass RF) I think they do offer the ultimate in surge/lightening protection at the possible expense of frying the primary side of the transformer!

As for AC line noise, I can't point you to specific documentation but you shouldn't have much trouble finding it on Google, as it certainly exists. Personally, I'm not terribly concerned with that issue either, as I am with ample, accurate power, and here's why: Most noise in a system comes from what the components and ICs pick up in transmitting and/or processing the audio signals and not from the AC line noise. As you say, decent power supply design should take care of most of that, particularly in power amps. As for source stuff which is processing weak signals, yes noisy AC can be a bigger problem, especially for preamps and more so for tube preamps (and then of course there's the RF your digital stuff (can) put back into the line. But my solution to that is to avoid the problem altogether (if one has a problem) by using noise-cancelling balanced power for the front end components.

Jim Aud (of Purist Audio Design) pretty much convinced me that the first thing to cover is the issue of (AC) energy transfer from the reservoir of electrical potential in your wall, to the component. Which is why that last 5 feet of power cord is so important (I know a lot of folks have a hard time wrapping their heads around this ;--) Using minimum 10AWG PCs for amps, power regenerators, and for some weird reason, DACs, seems to me makes the next biggest difference, after dedicated circuits.

Bob, each separate (branch) circuit in your house is referenced back to the (transformer on the) pole. The (available) energy at the pole is so enormous compared to that carried by each branch leaving your panel that it's virtually impossible for one branch of a house to "inject noise" onto another branch which is also returning its current to the pole. That's why you don't/can't hear it. This is not strictly true, for example in the case of large apt/condo complexes where you have many, many panels working off of the same transformer, in which case the AC at the transformer itself can be pretty polluted -- but in a typical residential neighborhood, there are no more than a few panels (houses) on each transformer. In fact, when I was a homeowner here in Tucson, lightening severely damaged our (1/2 dozen houses) pole transformer, but it was still working (kind of) and noisy as hell before it finally gave up the ghost and got replaced!

As for your arc welding neighbor, he could cause a slight voltage drop in your local grid if the power transformer capacity has become marginal after a few people in the neighborhood have replaced their panels over the years with higher capacity ones, until the utility company finally has to put in a bigger transformer (or the existing one blows!) But the noise and interference from the welder isn't in the electric grid, it's being broadcast over the air as radio frequency interference from the arc -- causing snow on your TV (and possibly noise in your phono or on your FM tuner.)

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