Clean Power

[manisandher]

... I really want to have a ganged RCD that disconnects in the output of the balanced supply that isolates both 120v phases of the supply is the case of a fault condition on either phase. This will prevent the danger of having say a 120v “neutral” balanced feed into a hi fi component even when the “live” fuse in the component has blown.

Hey Nick, I've just checked and my Airlink 5KVAs have these installed as standard - one on the input, one on the output. HTH.

Mani.

[manisandher]

By the way I did try transformer to "center" the ground , but didn't find that worth it , if yes audible .

Hi Stefano. Audible in a good way or bad? The main criticism of transformers is that they can sometimes seem to compress dynamics and make the sound a bit dull/lifeless. Did you find this?

Mani.

[Nick]

... I really want to have a ganged RCD that disconnects in the output of the balanced supply that isolates both 120v phases of the supply is the case of a fault condition on either phase. This will prevent the danger of having say a 120v “neutral” balanced feed into a hi fi component even when the “live” fuse in the component has blown.

Hey Nick, I've just checked and my Airlink 5KVAs have these installed as standard - one on the input, one on the output. HTH.

Mani.

Mani,

Thanks for mentioning this, I think I will go for a 3 or a 5 kva version like yours. Do you get any audible hum from your units ?

Best

Nick

[manisandher]

Hi Nick, I think there is an audible hum from the unit, but sitting as it does in the cellar I don't really pay much attention to it. What I do know is that it's much quieter than the 15KVA 'yacht hull isolation' transformer sitting below it.

There is one thing I'd do if I were you though. AirLink claims, "The Balanced  Power Supply creates a new ground called a derived ground, that decouples equipment connected to it from the circulating ground currents in the rest of the house wiring.  It also provides one common ground reference for all the equipment connected to it."

One of my 5KVAs has the input ground connected to the output ground. The other has the two grounds isolated, although even in this case, there is still a ~6MΩ resisitance between them. Now I have no idea how you 'derive' a new ground from the house ground, but even with my dire knowledge of electronics I know that this simply cannot be the case if the input and output grounds are connected together. It seems to me that someone at AirLink isn't quite sure how to do it either, so I'd check with them before ordering. HTH.

I won't be able to test various power configurations until some new junction boxes that I've ordered come through. But I'll let you know what I find as soon as I get them.

Mani.

[CoenP]

Hi,

I'm breaking in here since this thread got me thinking. No, not about balanced isolation transformers, I'm far from that point yet, but about having the PE (not peak extension) of the NOS1 and PC on the same connection.

Since my computer PSU blew up, I've been having difficulty with getting the sound back I was used to. I tried several PSUs that should even improve on things but all I got was worse sq.

Then in a flash of Zen I swapped the powercable from the PC that sounded fine even on its mobo codec (the ATOM) to the XX music PC and voilá very nice sound again, I dare say even better than before. And this was just a standard cable.

So what was the matter? I inspected the power cable and it looked a little worn on the euroconnector part. Measuring the wires showed that the cable was not making any contact the PE pin!

Now that the PE is tied to the PE of the powerstrip and hence to the NOS1, the SQ issue is solved. Interesing though is that this loose PE connection did not bother me with the other -blown- supply (or did it blow because of this defective cable?).

I am shure there is more to be gained on this topic, but so is in optimising XX!

regards, Coen

[PeterSt]

Hey hey ...

To make it somewhat more complicated and in case you did not know : The NOS1 is only connected to PE by means of the case (or : PE is connected to the case and nothing else in there).

But it isn't that simple, because disconnecting (cutting) the PE will make all different, if you only know what to look and measure for. This is all about antenna working, capacitive loads and more sh*t, with always the USB connection in the middle of all.

Peter

[PeterSt]

Hi Mani,

Now I have no idea how you 'derive' a new ground from the house ground, but even with my dire knowledge of electronics I know that this simply cannot be the case if the input and output grounds are connected together.

What will happen in this case (of half truths ?) is that the transformer will create a now ground (reference) to the house ring. But again it is more complicated ...

In order to let you understand I will try to give an example which is not about this at all, but from there you should be able to reason out the remainder, or even measure it;
Btw, I do this by heart now, and I hope I'm not mixing up things, bete here to, at applying the practice (of measuring it) you will see what to do exactly automatically ...

Since you should be able to find two separate ground references (like the earth pin from your house ring and the one from the isolated transformer), use those both to find out some interesting things. I thing DV Voltage measurement now, because it is about that (but allpying an AC measurement here and there may also be interesting, so don't forget to do that too). Now :

Hook up your DC Voltmeter to the two ground references. You should see something. Now, start switching on house devices like phone adapters or motors or possibly amplifiers and the like. Watch the DC Offset change with it.
Now envision that this DC Offset mangles with at least your house ring ground reference. So, mid point e.g. goes up, and think about the part of the (hot point) wave above zero (which should be lower now in amplitude ) and the one under it (should be higher). Here you are turning that sine into something else.
In the mean time your AC output changes too. I never looked at it on the analyser, but while net the result should be the same, it won't because of the wave shape and let's say (for easily envisioning it) clipping at one side.

This all is about your consuming devices fireing back to the mains because of they changing the ground reference.
It may not be an official thing, but this is how I once could look at it. So, that consuming device is not a "balanced device" like in "it draws from both the phases separately" (see earlier posts about this - the 115v/115v thing) but as how I look at it, it will draw the ground towards "itself". So, where ground is to be 0V (which is a virtual thing always, but works for the physics in order) and a device is consuming the 230V, the ground goes up by, say 5V. I know, for AC this can't work, but I think something like switching power supplies ay use the positive side of the wave only or more than the negative, which depends on how the AC/DC conversion is done.

I never worked this out really, but saw it happening and now try to see how it can happen. But it does anyway.
It goes as far as that when devices are switched on subsequently, the Offset always becomes more and more. No new device makes it less again.
In that other larger topic about actually the same subject, I think I mentioned that I once could measure 109V AC between the two grounds. However, this was/is groundloop related too, because (back then) I was able to end up in the exact same situation (devices switched on) with 0V AC.
And when that was the case, a few days later it was there again. It is here when I stopped using the PC on its dirty ring (which in my case wasn't even the house ring but yet again another separate one - for the PC to make dirty), because this can't be a good thing.

No such thing happens when using one ring only, but hey, that is because that other reference is unused (now no current or whatever can flow in between them, and btw 6MOhm *really* is sufficient) but now you also won't be able to see the working of -for example- the PC (etc.) hammering on the same ground reference now directly.

(Ehm, after writing this it looks like a made a few mistakes already, and I now think that you must approach it the other way around : have that clean reference (no devices connected to it) to proove how another device connected to the other ground influences that other ground by looking at the diffrerence between the two grounds. So, switch off/on the PC for example)

It is a quite confusing subject, but when you have two ground references you can find out what is going on by means of some careful thinking.
With your PE-PE connected transformers it will be similar to what I described : they will form a ground all right, but it will level with whatever that other ground is. So, assumed your transformer created ground is really zero (and funnily enough this is not a virtual ground but a real one because really zero), while the ring it is connected to is 5V, think like all now being 2.5V for easy thinking. So, transformer got worse, and house got better. Your transfomer now has a DC Offset of -2.5V.


Maybe I suddenly know how to better explain it :
Switch on the DC Metering of the NOS1. It will show ~5mV. Now play a nice bass piece and see the offset change on the rythm of the playing. What happens is that the plus and minus side are not equelly influenced; thinking transients, the plus amplitute of AC which is what music is, will be larger than the minus. How does that show on the metering ? as DC Offset. Now compare this with my switching PSU example, and how that will influence the DC Offset hence wave shape in general. It only needs thinking about here the "amplitudes" are consumed from both plus and minus - and not equally (pushing DOWN the DC level as how it PHYSICALLY will be ), while with music playing they are stuffed through (LIFTING the DC level as how it is MEASURED (which is just averaging)).

And Mani, before you get confused : I am pretty sure that the DC Metering in the NOS1 shows opposed to reality. So, a more minus offset in reality is a more plus (from a transient and assumed absolute phase is all right). So, assumed you have a slight minus offset showing (which is the case for most NOS1's) you will see it more minus at low frequency transients. But in relatity is it plus; it's just where we connected the wires to, which is by accident the other way around (not really by accident, but just unimportant as we see it).

Was this smart or totally stupid ?
Peter

[manisandher]

I am shure there is more to be gained on this topic...

I'm sure you're right. I remember a while ago, with the PC, NOS1 and amp all connected to the same PE, I tried connecting the chassis of the PC to PE too. And guess what? The sound totally changed. At first, I thought it was an improvement, but over a period of time I found it fatiguing. I now think I was getting false detail and brightness through a ground loop somewhere. Or maybe the chassis was now acting as an RF antenna? Who knows...

Mani.

[manisandher]

Was this smart or totally stupid ?

Hey Peter, I think even Einstein would need some time to figure this post out... I'll do my best later this evening.

Mani.

[stefanobilliani]

Hi,


Then in a flash of Zen I swapped the powercable from the PC that sounded fine even on its mobo codec (the ATOM) to the XX music PC and voilá very nice sound again, I dare say even better than before. And this was just a standard cable.



regards, Coen

Just want to add , that also the lenght of the cable make differences .

S

[manisandher]

Ehm, after writing this it looks like a made a few mistakes already, and I now think that you must approach it the other way around : have that clean reference (no devices connected to it) to proove how another device connected to the other ground influences that other ground by looking at the diffrerence between the two grounds. So, switch off/on the PC for example.

OK, I've made some measurements between my dedicated PE (measured by electrician as <5Ω resistance to earth) and my house PE (no idea of what this resistance to earth is):

1) with small load (only NOS1 switched on):
- resistance = 2.5MΩ
- DC = 0.25V
- AC = ~0.6V (varies a little, not totally constant)

2) with ~1000W load (Sauermann amps switched on)
- resistance = 2.5MΩ
- DC = 0.25V
- AC = ~0.6V

No, not a 'copy and paste' mistake, but absolutely no difference whatsoever.

In case it's importanct, the whole AC chain here is: house electricity meter -> dedicated consumer unit -> 15KVA isolation transformer -> 5KVA balanced transformer -> PurePower2000 regenerator -> 8-way distribution unit

The dedicated PE consists of: ionic grounding rod and a star earthing arrangement to all components (including PC)

The PurePower2000 uses a switching power supply, which I assume kicks a lot of noise back into the AC feeding it. But the AC feeding it is balanced, which I suspect helps.

Mani.

[Nick]

Hi Nick, I think there is an audible hum from the unit, but sitting as it does in the cellar I don't really pay much attention to it. What I do know is that it's much quieter than the 15KVA 'yacht hull isolation' transformer sitting below it.

There is one thing I'd do if I were you though. AirLink claims, "The Balanced  Power Supply creates a new ground called a derived ground, that decouples equipment connected to it from the circulating ground currents in the rest of the house wiring.  It also provides one common ground reference for all the equipment connected to it."

One of my 5KVAs has the input ground connected to the output ground. The other has the two grounds isolated, although even in this case, there is still a ~6MΩ resisitance between them. Now I have no idea how you 'derive' a new ground from the house ground, but even with my dire knowledge of electronics I know that this simply cannot be the case if the input and output grounds are connected together. It seems to me that someone at AirLink isn't quite sure how to do it either, so I'd check with them before ordering. HTH.

I won't be able to test various power configurations until some new junction boxes that I've ordered come through. But I'll let you know what I find as soon as I get them.

Mani.

Thanks Mani,

I went ahead and ordered a 3kva transformer from Airlink today. I went for this size purely due to size and the thought that there is no way my system is going near 13 amps of mains voltage draw so I hope this should suffice. If hum is not a problem it will live in my listening room so the 5kva model would rather big.

Air link reckoned that the default PE arrangement  for the unit is that the house PE is connected through to the output ground. They did say this link can be broken to setup your own bespoke PE ground. My plan is to try with the house PE setup first and see what happens.

I have a three phase mains supply into the house and I'am concerned that the load on other phases may also be influencing the PE / neutral potential of the phase used for hifi, particularly after Peters earlier post. Tests switching off phases seem to confirm some interactions between them. I am not sure if the balanced transformer will help here, I can think of arguments for and against but best just to try it and listen I guess.

The Airlink "derived ground" worrys me a bit, I hope they do not mean that the out put is not referenced an external low impedance ground (house or dedicated bespoke earth). Humm I feel the need for another call tommorow with Airlink to understand this.

Did the 5kva transformers come with any Airlink documentation ? There is not much on their website.

Best Nick.

[manisandher]

The Airlink "derived ground" worrys me a bit, I hope they do not mean that the out put is not referenced an external low impedance ground (house or dedicated bespoke earth). Humm I feel the need for another call tommorow with Airlink to understand this.

I think this would be prudent. As I said, in one of the transformers I received, the input/output grounds were both conneced, in the other they were not. Which did they mean? I don't know. But if it's the latter, there had better be a connection made pronto if there's a serious fault in the appliance.

Did the 5kva transformers come with any Airlink documentation ? There is not much on their website.

No it didn't, which was a pain. But I intended to connect the transformer's output ground to my dedicated PE anyway so wasn't too bothered.

I've just checked how loudly the 5KVA hums, and it's actually fairly quiet with a low load. It get's considerably louder with my ~1400W RMS though.

Mani.

[manisandher]

In case it's importanct, the whole AC chain here is: house electricity meter -> dedicated consumer unit -> 15KVA isolation transformer -> 5KVA balanced transformer -> PurePower2000 regenerator -> 8-way distribution unit

Well I've just had my own 'Zen moment'. I'm gonna try the following:

electricity meter -> dedicated consumer unit -> PurePower2000 regenerator -> 5KVA balanced transformer (house PE on input, dedicated PE on output) -> 8-way distribution block

Don't think I really need the 15KVA isolation transformer. Anyone want one? It's 120Kg though!

Mani.

[Nick]

I've just checked how loudly the 5KVA hums, and it's actually fairly quiet with a low load. It get's considerably louder with my ~1400W RMS though.

That's good to know thanks. I think I might hum a little louder though if I had to supply 1400w rms  . Its nice setup in your cellar though, really no problems if the transformers decide to sing along a little 

Nick.