Clean Power

[christoffe]

http://www.whatsbestforum.com/showthread.php?2023-Standard-for-Clean-Power

[manisandher]

Yes, Arthur Kelm is the expert on all of this. Indeed, I based my dedicated mains circuit (isolation transformer, ionic grouding rod, etc) on his ideas.

I'd love to know what he thinks about the use of SMPSs to power hifi components. My feeling is that he would say get the grounding right first, and then don't corrupt it with dirty SMPSs.

Mani.

[Bigear]

From personal experience, I know having a good powersupply gives you a better sound, however understanding why is not so easy. All equipment I use has a trafo and rectifier circuit with caps, filtering, regulation etc. So the 'hot' side is floating relative to ground and independent of the AC-net. That leaves us the grounding when you us RCA mode, however when you play balanced, one should think the grounding is not that important anymore either...

[PeterSt]

Maybe it is ... But it is hard to judge for the real merits. I mean :

I sure see mains noise when things are not "connected" as should, and I see this through the analyser. Big problem : the analyser has to be connected as well. To mains and through interlinks (which I almost always have balanced). So, you never know what you really see, and one connection too many can create the problem ... which can be in-analyser only.

The other way around "works" too : the analyser "eliminates" the noise (because of its connection through PE etc.), and know you don't see it.

It really, really is tough.
Peter

[manisandher]

Well I've decided.

Computer switch mode power supplies are evil.

Right now, I'm sitting in my office with my office system (including a USB-NOS1) sitting right behind me. If I listen to FM radio (BBC Radio 3) with no electrical devices in the office switched on (other than my tuner, preamp and poweramp, all of which use linear PSs), the presenters' voices (live mic feeds) sound so pure and real. As soon as I switch on a PC (either my office work PC or my office music PC), a 'glare' is added to the presenters' voices. It's subtle, but unmissable once you know what to listen out for. Oh and I use Seasonic X-460 power supplies which are supposed to be about the lowest-noise computer PSs you can get.

I hear a very similar effect in my main listening room when I'm using my Atom-based PC with linear PS to play music and I switch on a secondary PC with SMPS - the 'glare' appears there too. Indeed, if I replace the linear PS with a SMPS, the 'glare' is there.

So I've decided that I will elimate all switch mode power supplies from both my office and main hifi systems. If this means that I have to live with a slower XX GUI, and even non-gapless playback, so be it. Now that I know it's there, I can't live with this SMPS 'glare'.

Mani.

[Gerard]

Hey Peter,

Didn't you talk about some power suplie you made for the pc?

 

[PeterSt]

Yes I sure did. This project is postponed because of some necessary chip not doing what it pomises, and now the product is "dangerous" when used other than for what we intend it for (which is out of my control of course). So, not allowed to go to market (yet).

Peter

[manisandher]

I just wanted to resurrect this thread because it's so important and of so much relevance to other topics.

I'm no electrical engineer, and was pretty bad at electronics at school and uni. But here are my thoughts on what's going on with your AC mains. Please feel free to comment on any of the points below:

1. The Neutral of your AC mains is bonded to your house's PE.

2. In an ideal situation, the Neutral and the PE should sit at the same potential.

3. A dedicated PE can never truly be isolated from the house's PE. There will always be some finite resistance between them (MegaOhms) and therefore a potential difference.

4. It's a really, really bad idea to have some components (that are themselves connected together via interconnects, USB cables, etc) using the house's PE and others using a dedicated PE.

5. A dedicated PE on its own is pointless. You just ensure that you invalidate point 2.

6. The only way that a dedicated PE makes sense is to use an isolation transformer that allows you to bond the dedicated PE to the Neutral of the secondary.

Thoughts?

Mani.

[stefanobilliani]

I understand your points Mani .

But imo , the more attention we have to pay , when we connect gear together . For example a cd player to a preamp to an amp .

For decades , in the market hi-fi ( ...) we have seen amplifiers without an earth connection , and lots of differences in potential when we see each component ground .

So I like to connect well my Earth where there is a low impedance point in the chain - the amp . From there I try to arrange well the chain . There is not much to worry about , since you make sure the current would not go trough the imput .
By the way I did try transformer to "center" the ground , but didn't find that worth it , if yes audible .

Just my thoughts


s

[Scroobius]

Hi Mani - this is my understanding for what its worth but if anyone knows more please correct:

1. House (modern houses) PE is connected to the armoured sheath of the incoming mains supply cable. Neutral is bonded to PE and earth at the local substation (i.e. not in your house). House PE is ALSO connected to the main incoming water pipe i.e. to earth.

2. I would think that the ideal situation is that Neutral and PE should NOT sit at the same potential see below.

3. By dedicated PE I assume you mean lets say a direct connection into the earth either by a spike or water pipe - I would agree therefore that a dedicated PE cannot be isolated from the house PE because the house PE will be connected to earth at the incoming water pipe and/or at the local sub-station. There will always be the resistance of the earth connecting your dedicated PE to the house PE and it will vary substantially between different houses & locations.

4.

It's a really, really bad idea to have some components (that are themselves connected together via interconnects, USB cables, etc) using the house's PE and others using a dedicated PE

Yes agreed but the actual impact will vary greatly between different houses / locations. But it seems reasonable to assume that it is a *bad thing*.

5. I do not think that a dedicated PE should be pointless. Assuming a very good bonding of a dedicated PE to earth (i.e. like the one in your very own garden Mani) then it would not be unreasonable to expect that it there should be significantly less hash on it than exists on the house PE. BUT exactly what hash is there in your garden? - mmm how can we know that statement is correct without measuring it?

6. Isolation transformer. Well a standard isolation transformer? yes true it will allow your dedicated PE to be disconnected from your house PE. BUT does it? your dedicated PE is connected to earth in the garden - BUT your house PE is also connected to the earth in the garden via the water pipe and also back at the sub station. What is the effect of that? very dependent on you local situation how near is you dedicated PE to your water pipe? and how close is it to your sub-station?  also how wet is your garden? ha ha very wet at the moment.

Enter the Balanced Isolation Transformer i.e. a 1:1 mains isolation transformer BUT with a centre tap on the secondary that is connected to PE. This means that the output is +115v, PE and -115v (so 230v output with PE sitting in the middle). This has 2 potential benefits:

1. with output PE connected to house PE errors in mains noise should cancel - so if there is an error voltage on the input to the transformer it will appear positive on +115V and negative on - 115v so cancels (a normal transformer will just transfer the error voltage onto the +230v output). Note with a balanced transformer obviously the -115v output is totally disconnected from PE. Note that the bad things like mains droop and distorted waveforms that can occur on the mains supply should be significantly reduced on the output of the balanced transformer.

2. output PE is disconnected from "neutral".

Balanced transformers tend to be used by recording studios etc from what I understand. But they are not necessarily expensive if bought from a proper transformer supplier eg
http://www.airlinktransformers.com/cat10/61/standard_balanced_power_supplies.html

But how to connect a balanced power supply? if the output PE is connected to the house PE then hash from house PE (bad thing) but reduced mains noise is good thing.  Alternatively connect output PE to dedicated PE (garden spike) then mains noise cancelling may not be so effective but a cleaner PE. What is the best way to connect? my guess is that no one could predict it depends on your local situation. One thing that is good I suspect is that the -115v output is totally separate from PE with a balanced transformer - it cannot be with a normal isolation transformer.

My guess is that almost all balanced transformer installations are with the output PE connected to house PE. But and particularly with recording studios some considerable efforts will have been made to ensure that the "house" PE is of the highest quality. So maybe? that means connecting house PE to the dedicated PE - after it is just a more effective water pipe (but do not remove that water pipe connection as that is required by electrical regs). 

At least I think that is how it works 

Paul

[manisandher]

Hey Paul, thanks for sharing. I'll come back to you once I've had a chance to digest all your points.

Balanced transformers tend to be used by recording studios etc from what I understand. But they are not necessarily expensive if bought from a proper transformer supplier eg
http://www.airlinktransformers.com/cat10/61/standard_balanced_power_supplies.html

Yeah I know. For the last 6 months or so I've been using a pair of 5KVA balanced trannies (one for my main system, one for my study/office system) after my 15KVA isolation trannie. I haven't played around with various configurations yet (just no time), but may well bypass the isolation transformer altogether if it's not helping. Furthermore, I now have a PurePower 2000 regenerator in the mix after the balanced trannie for my study/office system. I've just today ordered a new PurePower+3000 regenerator for my main system. These things do something wonderful to the sound, provided everything is plugged into them (including the PC). I'm not sure if it possible to achieve what they do in any other (cheaper) way, but if there is, I've not found it.

Back with more thoughts later.

Mani

[Nick]

http://www.airlinktransformers.com/cat10/61/standard_balanced_power_supplies.html[/url]

But how to connect a balanced power supply? if the output PE is connected to the house PE then hash from house PE (bad thing) but reduced mains noise is good thing.  Alternatively connect output PE to dedicated PE (garden spike) then mains noise cancelling may not be so effective but a cleaner PE. What is the best way to connect? my guess is that no one could predict it depends on your local situation. One thing that is good I suspect is that the -115v output is totally separate from PE with a balanced transformer - it cannot be with a normal isolation transformer.

Boy this is on topic for me right now, clean mains is the most important issue here at the moment. Paul has helped me immensely by highlighting problems with my system that have been plaguing me for months during our recent visits to listen to one another’s systems.

Following this I have been doing some basic testing with the house mains supply by switching off the mains phases in the house that are not supplying to the music systems and then also turning off the other household circuits on the supply phase that feeds the hifi. Early results seem to confirm this is good direction to be looking at.

Following Pauls mentioing balanced and putting me onto Airlink I have been looking at the balanced supply approach carefully and speaking to AirLink. Seems like the first thing to get right is a configuration that sensibly addresses electrical safety. The issue being that when the mains supply is configured to be balanced both the neutral and live connections carry 120v ac whereas the safety measures in a house are in place to trap faults on a single live feed system.

I plan to fuse both the live and neutral connections as they enter into all equipment connected to the balanced supply. Also 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.

Regards the earthing scheme the plan at first is to use house PE on the balanced side to start with. I know this may not be optimal but again I want to be sure of all the implications of setting up a separate earth on the balanced mains side before going ahead.

There are certainly some very positive comments about sound quality of Balanced supply out there together with descriptions of the sort of problem that I have been having which were addressed by other by moving to Balanced supply. If I can get the electrical safety worked through then I am ready now to order a balanced transformer. Will let you know how it goes.

If anyone has already setup a balanced supply it would be geat to hear how it was done.


Best Nick.

[Nick]

Yeah I know. For the last 6 months or so I've been using a pair of 5KVA balanced trannies (one for my main system, one for my study/office system) after my 15KVA isolation trannie.

If anyone has already setup a balanced supply it would be geat to hear how it was done.

Bingo ! 

Our posts crossed over 

Nick.

[manisandher]

Hey Nick, yep they did.

I think you're absolutely right to be concerned about the safety of these devices in a domestic setting. I may well bypass them unti there is a common consensus on how they can be used safely.

But I will definitely spend a day or so trying different direct/isolation-trannie/balanced-trannie/regenerator configurations and report back what I find. It could be that simply sticking with the house mains/PE is the best way to go. (But I doubt it...)

Mani.

[manisandher]

I plan to fuse both the live and neutral connections as they enter into all equipment connected to the balanced supply. Also 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.

This won't be an issue for me as I will now use a PurePower regenerator to feed all the components. This will take the balanced +115V/-115V and reconvert it back to 0/+230V. If there is a fault condition on either phase feeding it, the PP will simply kick into battery mode.

But the isolation- and/or balanced-trannies will not be for nothing even with a PP in place. Other PP users have reported that the better the incoming AC into the PP, the better the sound. Only with the PP running off battery does the sound really become totally independent of the AC (of course).

Mani.