Sunday, September 4, 2011

More thoughts on Power Plant Premier

On the plus side, I tested the Tensor lamp plugged directly into wall while starting the vacuum cleaner on same outlet.  The tensor lamp did indeed briefly dim.  On the Premier, it was rock solid.  That's a big score for the Premier, and I expect that within it's power ratings (which most audio systems don't come close to exceeding) it actually makes the AC voltage more stable, just as Paul McGowen has said, for better transient response.  I think of it as much like converting your power amp into one with regulated HV rails, like Krell FPB amplifiers.  As I said before, the whole purpose of this design is that you can (most likely) plug your entire system into it, with the power amp quite likely getting the biggest advantage, unlike low power regenerators like the PowerPlant 300.

The downside is first that I'm not even sure this can really justifiably called a "regenerator."  Yes, it can, but actually it's more like an instantaneously tracking corrector.  From what I've read, the entire power supply follows the incoming AC voltage, so all the power plant amplifier has to do is make up the difference to ideal.  The first consequence of that is you can't play games with the output frequency, as on earlier (and later?) PowerPlants.  The second it that in some sense you are not as completely removed from the incoming AC as you would be with a full regenerator, it doesn't seem to me it would give as much isolation.  And the third might be that under some circumstances, the tracking doesn't work perfectly or interacts with the unit in some way, making the line noise in certain situations worse.

I might have found such a situation.  It seems like when I use the dimmer on my kitchen light, the noise as revealed by the Noise Sniffer is actually greater through the PowerPlant than straight on the wall.  Perhaps it isn't really greater, but the Noise Sniffer is simply more sensitive to the noise frequencies coming from the PowerPlant in this situation which have been shifted somehow.  I haven't yet done a full sweep test using the "volume" control on the sniffer yet.

Now even if this is true, I have fanatically avoided using a dimmer in the bedroom area.  I don't trust dimmers anywhere near audio, but capitulated to convenience in the kitchen.  Dimmers generate horrible noise and distortion on the powerline.  So this might not matter much for me, it is merely a small disappointment.

On retesting today, using a full sweep of the noise sniffer in both cases, it's clear the the PowerPlant is reducing the dimmer noise after all, plus some other noise that is very annoying now.  (In fact, over several days of testing as of this edit, the reduction is quite remarkable...the PowerPlant is actually performing like a very good regenerator.)  The difference around 3pm on the volume control is enormous, with a very nasty buzz straight from the wall, and sounding like ordinary clean power through the PowerPlant.  But at max volume, they are both about the same, with the wall socket possibly having a deeper quality that is more easily ignored from the other room.  Also, the X10 dimmer control signals are very audible at the wall socket, but completely hidden through the power plant, making the background sound at the wall socket seem softer by comparison.  Still, the PowerPlant obviously does not eliminate the dimmer noise completely, you can hear a very phasey sound on the noise sniffer as you change the dimming.  That same phasey sound is also present at the wall socket, but less obvious amidst the high level of noise generally.

One thing I've noticed that is rather despicable about my Smarthome remote dimmer.  Even at full output, it makes a lot of line noise.  I would have expected line noise to pretty much disappear at full output.

Finally, in spite of my thinking this is not truly a regenerator, I think the general design is a good one, whatever it is called, perhaps the best one possible.  The earlier approach to PowerPlants wastes huge amounts of energy, and even then is hard to scale to meet the needs of an entire audio system, with possibly the power amp needing the most stabilization of all.  And it should be noted that the earlier approach didn't, nor could any approach, perfectly limit the influence of incoming noise.  If Class AB amplifiers eliminated the effect of incoming noise, it wouldn't be necessary to use the PowerPlant at all.  The only reason why power conditioning is needed is precisely because amplifiers are not perfect in rejecting incoming line noise.  Having a full regenerator merely adds one more degree of Class AB amplifier separation from the line noise.  And possibly adding an instantaneously tracking corrector based on a smaller Class AB amplifier adds about 1/2 a degree of Class AB amplifier separation, in principle.  But as always, the results can vary by implementation.

I suspect, however, that the fully regenerating power plants like P300 limit the dimmer noise better, and possibly don't make the line they are plugged into noisier.  But they don't provide much power, run incredibly hot, and have a constantly running fan.  It's the fan noise issue that has kept me from using my P300 much.  I tried using a quieter fan and it didn't help much.  My plan has been to use an even quieter fan and change to a lower speed, but the project has been stalled for awhile.  But I never even imagined using the P300 to power an entire system, mainly it was just for powering standalone equipment like my CD duplicator and electronic synthesizer.

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