Ralph, very few real audiophiles want an industrial, discontinued power regenerator, especially one that would or might need service from a company that really doesn’t care about the consumer market way too impractical.The Elgars I mentioned are not regenerators. Plus you can get them cheap, and service isn’t that hard- we’ve serviced a number of them and so has Michael Percy (known for selling high end precision parts).
Here’s one that can do 1KVA:
https://www.ebay.com/p/Elgar-6006B-Series-6000b-AC-Line-Conditioner-XLNT/841727168?iid=263635111143&...
The thing is, they are so much better than anything offered to high end audio that essentially the ’high end audio’ stuff is roundly embarrassed.
Of course you can’t know that if you haven’t experienced it. Sort of like trying to convince a 4-year old the value of brushing their teeth.
A passive conditioner can’t really do the job. The problems you are dealing with is of course spikes and high frequency noise, most of which is easy to filter, but also you have harmonics of the AC line frequency (distortion), DC on the line, and finally the raw AC voltage.
The 5th harmonic (300Hz) is known to be particularly troublesome (it is caused by transformers like those on power poles that are loaded past about 50% of their capacity). It causes power transformers to become mechanically noisy and run hotter, causes power rectifiers to become noisier and causes a reverse force to appear in synchronous motors (used in turntables and tape machines). Fluke Instruments published a paper on this over 25 years ago. Its not like its anything new, but most ’high end audio’ conditioner manufacturers won’t even know what you’re talking about if you bring it up. You can see though that just using an isolation transformer as part of your passive scheme can introduce harmonics if you load it too heavily!
That takes a bit of magnetics (very large chokes) to filter passively! There is an attendant voltage loss- so that technique is impractical.
DC on the line (often caused by electric heaters running at less than full power) causes transformers to become mechanically noisy due to core saturation. This also means their output waveform is distorted, which is not good for rectifiers. This is of course cheap to remove by itself.
Finally, if the line voltage sags, amplifier power can be severely curtailed and distortion higher. This can mess with the regulator overhead in preamps and sources like CD players. Modulation on the AC line can result in added distortion. Again this is something that no passive can sort out.
To add insult to injury, most passive units force the user to use the power cord supplied by the passive conditioner. Obviously the conditioner has to get power, but if it can’t compensate for the losses in the power cord, it isn’t helping.
This is why the Elgar is so good at what it does- it deals with all these problems. That no-one in high end audio has chosen to use their techniques is embarrassing. It would be expensive, but not if an audiophile is already willing to pay $1000 for a power cord or flush $$$$ away on ’conditioners’ that don’t do anything.