Power conditioner help

The best power conditioners were not offered to high end audio.

They were made by Elgar (still in business). They used a massive isolation transformer which had a feedback winding on it. A low distortion oscillator was used, synced to the AC line frequency. The output of the transformer was then compared to that of the oscillator and a correction voltage was generated and applied to the feedback winding.

The result was AC voltage regulation and THD of no more than 0.1% at full current (one of the larger units could supply 28 amps).

The biggest problem that power conditioners face is the 5th harmonic of the line frequency, which most conditioners can't filter out. This harmonic heats up power transformers, causes rectifiers to become noisy and causes reverse currents to exist in AC synchronous motors. IOW its pretty pesky. By comparison, spikes and high frequency noise are non-issues!

The Elgars are some of the few conditioners that not only eliminate the high frequency noise but also the 5th harmonic. The SP Audio regenerator conditioners can filter this noise but don't have the capacity for high current. So they can be problematic if you have a higher power tube amplifier or a higher power class A transistor amp where there is a larger amount of steady state current draw.

Elgar saw years ago that the power conditioner market was shrinking and moved their business model away from that part of the market. So these days to get the best you have to buy them used and have them refurbished. Its rare that one can talk about the best in high end audio but this is one of those cases. 

We just finished the rebuild of one of the lower powered Elgars (which is to say that it handles 1000 VA; about 8.5 amps at 117V).

It regulates the line voltage such that with 100 - 130 volts input, the output is rock stable, with no distortion of the AC waveform output. We ran a pair of our M-60s on it- pretty nice; no 'high end audio' conditioner even comes close.

Before I became aware of these conditioners (thanks to Michael Percy) we were constantly running into the problem of our amps sounding **worse** on most 'high end' conditioners; at best no difference.

Given that in high end audio, price for performance is often no object, it really puzzles me why no-one makes a decent power conditioner, but that's how it is. Most of them are a waste of money. One thing that really gets me is how a glorified power strip is supposed to help- now you are forcing everything on the box to run through the single power cord that feeds the box. You're pretty well guaranteed some sort of power sag. So unless you're really serious about getting a decent power conditioner, you're probably a lot better off just getting decent power cords and making sure you have good quality AC outlets in your audio room, per stringreen's comment above. 

An isolation transformer would be beneficial; 2 would be better. 1 for your digital player and 1 for analog source; however "balanced transformers" like Equitech are better yet.

An isolation transfomer that is being used as a passive device will contribute harmonic distortion to the AC output if loaded past about 50% of their rated capacity. One should always observe this characteristic when using isolation transformers! Otherwise the resulting harmonic distortion (particularly the 5th harmonic) can have highly deleterious effects.

For those with an interest in this topic, Fluke has published a number of papers on the topic over the last 20 years. Here is a good example:
http://support.fluke.com/find-sales/Download/Asset/1260362_6003_ENG_K_W.PDF

Atmaspere; nice to hear your thank you to Michael Percy. My experience with him goes back to the early 90's and I've appreciated his knowledge and integrity.

One time when I was visiting Michael he was servicing out one of the Elgars similar to the type I mentioned earlier. That was over 25 years ago! That these conditioners hold their value as well as they do says something.

Ebay and Valuetronics are two good sources.

I think any balanced transformer, actually any transformer, would benefit greatly from a reduction in incoming ac line harmonics; just as industrial users do. Suggestions atmasphere?

Of course! Line harmonics are quite deleterious to transformer operation.

The Elgar so far is one of the few conditioners I have seen that can actually filter out line harmonics, but if you have an Elgar, no need for a transformer after it!