AC power supply to NOS1

[manisandher]

I couldn't find a nice thread to put this in, so thought I'd start a new one.

As part of my preparation for my new Orelo MkII speakers (see http://www.phasure.com/index.php?topic=2886.0), I now have my NOS1 pretty much totally isolated mechanically from the listening room.

I've been thinking about how best to power it. I already have two separate 5KVA balanced transformers in place - one solely for linear PSUs and one for SMPSs. The PC runs off the latter and the NOS1 and amps together off the former. And it's this that I've been thinking about...

Up until recently, I've been using class-A power amps. So even with loud peaks in the music, there should not have been any voltage modulation on the AC line. But with my current setup (BD-Design gainclone amps and low-efficiency Celestion SL600 speakers), there might be some voltage modulation. My hypothesis was that this might affect the performance of the NOS1 - a tiny, tiny modulation on the supply voltage in sympathy with the music signal. In any event, I thought I'd try to minimise this as much as possible by employing an old PS Audio P300 balanced AC regenerator that I had lying around doing nothing. I now have the P300 plugged directly into the 5KVA balanced transformer and have it powering nothing but the NOS1.

Well, what can I say? The sound seems to have been transformed. Really... transformed.

But before I get too carried away, I'd like to live with this setup for another couple of days and then go back to the setup sans balanced AC regenerator. Will be back with more views...

Meanwhile, I'd be interested in hearing any opinions on my thinking here...

Mani.

[Stanray]

Since day one I have my NOS1 (and computer) plugged into my Purepower 1050 regenerator.

One time I bypassed the Purepower and plugged it in the "normal" (dedicated) mains, but that lasted only for a few tracks.
It sounded "sloppy" by comparison.

Regards,
Stanley

[manisandher]

Hey Stanley, I have a PurePower 2000 regenerator. It definitely changes the sound - there's no question about that. And I think you're right to plug both the NOS1 and computer into it. But here's another thing you might want to consider...

The Purepower regenerators having big switch-mode power supplies. These (as all big SMPSs) are prone to inject a lot of noise back into the AC line. If you have other components on the 'regular' AC line, they might be affected by this noise. My feeling is that it might be better for you to run your whole system off your single Purepower regenerator.

Of course, this assumes that your 1050 has a big enough output. If you're using high-efficiency speakers, then you might be OK.

I know people who have bought multiple Purepower regenerators - one for the power amps, one for the digital sources and one for the preamp, etc. But this doesn't really work, apparently. What seems to happen is that the noise injected by each Purepower unit back into the AC line starts interfering with the other Purepower units.

For my part, my Purepower 2000 sits gathering dust in my basement. Having spent a fortune getting a dedicated AC line installed with a couple of balanced transformers, I can't bear the thought of injecting noise back into the AC line. But this is probably more of a psychological issue on my part than anything else.

Feel free to totally ignore this post if it's of no use to you.

Mani.

[Stanray]

The Purepower regenerators having big switch-mode power supplies. These (as all big SMPSs) are prone to inject a lot of noise back into the AC line. If you have other components on the 'regular' AC line, they might be affected by this noise. My feeling is that it might be better for you to run your whole system off your single Purepower regenerator.

Of course, this assumes that your 1050 has a big enough output. If you're using high-efficiency speakers, then you might be OK.

I agree with you that it would be better to plug all the audio components into one Purepower, but that isn't possible.
First, my speakers are not too efficient and have a 1 ohm impedance  , so my poweramps are not small. 

Second, the poweramps are located near the speakers away from the Purepower and it would require very long powercords. So even a bigger Purepower model isn't usable in my situation.

I have a 3 phase connection, one phase dedicated for audio, the other 2 for different floors in the house. I plan to plug the Purepower in one of the non-audio connections and see if it makes a difference.

But in the current situation the Purepower give a better SQ than without or with the PS Audio Power Plant Premier I had earlier.

Regards
Stanley

[Nick]

Mani hi,

Your experience using separate balanced transformers sounds similar to what happened here.

A while ago I was getting with slightly confused sound which got markedly worse on complex music with lots of bass energy. When this was happening I had the complete system plugged into a single 3kva balanced mains transformer. I tried plugging my active speaker bass amp modules (rated at 150w class B i think each) into the normal house supply (eg not the balanced transformer) and was supprised that sound got much better. The improvment was so good I bought  a second 3kva balanced transformer just for the active bass amp modules. The original balanced transformer powers PC, NOS1, balanced gainclones (these only typically draw 9 watts from the transformer). The second transformer to power bass really improved sound at lot.

Best Nick.

[manisandher]

Oh dear, what have I done?

Whilst walking past the stack of PSUs outside my 'vinyl studio', I noticed that the PS Audio P300 regenerator powering just the NOS1 was quite hot to touch. This seemed strange, as the NOS1 isn't really drawing much current. In any event, I thought I'd try things without the P300 to see if I could eliminate it. And...

... no way! The sound without it is too 'shouty'. In your face. The delicacy has gone. Seems I've become addicted to the sound with the P300 in place.

So what exactly could be going on here?

Well, first the heat being generated. The P300 accepts the UK's 240V no problem. However, it is only designed to output balanced 120V. Because of this, PS Audio fitted a beefy 1:2 step-up transformer at its output. This is obviously not very efficient and gets pretty hot itself. Also, I regularly measure 250V+ AC here. I have the P300 set to output a stready 230V 50Hz. I wonder if this is stressing some of the voltage regulators in the P300. Dunno.

And as for what's causing the obvious improvement in the sound? Well, going back to the 250V+ here, maybe this is simply too high for the NOS1 to work optimally? And there's also the main reason I wanted to try the P300 in the first place - to minimize any affects of running the NOS1 off the same circuit as the power amps.

The upshot of all this is that the NOS1 works much better powered from the P300 than it does powered directly. I'm a little worried about the heat. I can replace a fan that I took out of the P300 when I bought it >10 years ago, knowing that it would only ever power low-current source components. This should obviously help. But beyond that, it's got me thinking about buying a new AC regenerator. Does anyone know of one that outputs balanced 230V (without the need of a step up trannie) and that does NOT use a switch-mode power supply (like the Purepower units, one of which I already have)?

Maybe a much cheaper option would be to replace the NOS1's transformers and PSUs for ones optimized for 240V? Peter?

Mani.

[PeterSt]

Mani,

And as for what's causing the obvious improvement in the sound? Well, going back to the 250V+ here, maybe this is simply too high for the NOS1 to work optimally?

I wouldn't know why.

I have the P300 set to output a stready 230V 50Hz. I wonder if this is stressing some of the voltage regulators in the P300. Dunno.

I don't know how the regulation of the P300 works, but I'd say that the lower you go (like from 230V to 220V) the more heat. So why not trying it the other way around ? make it 240V and see whether it's more cool.
If the regulation can be switched off I'd try that too. But don't forget the step-up - that should remain active of course.

Peter

[christoffe]

Hello,

I read a review about a turntable battery PSU in a German HiFi paper today. The shop price is € 1700,00. A similar unit should be possible to built for a NOS1?!?
The Dartzeel preamp has a built in battery banque and an external PSU too, and the difference of the SQ is relavant.

http://clearaudio.de/en/products/electronics-accu_drive.php

The PDF shows an open PSU housing.

Joachim