Noise and DC on mains and new radial

Thanks. But, just to be clear, I never said the hum was caused by RFI RFI came to me as an after-thought in relation to how we should consider the proximity of radial and ring cables to each other when running the radial.

The hum may be caused by DC and if it's there on the radial and it bugs me, I might add the BPS; though I don't know how that will affect SQ dynamics, given it may increase impedance. (According to Naim tech support.) 

ianrobertm posted:

@huge - Good answer there....  

@eagle3333 - Agree with @Huge that the transformer audible hum is not due to RFI. Believe its more due to harmonics (or 'noise') on the incoming mains supply - which the separate spur ought to help with. BUT - it depends whats causing the harmonics......!  If you can identify the source - and fix it, thats best. 

Harmonics - well sort of!

Zero order harmonic (+ even order harmonics):  In other words it's usually an asymmetric mains waveform, where one half cycle is attenuated relative to the other.

This is most often referred to as a DC offset (actually, not quite the same thing, but similar enough to pass muster and same technical fixes apply).

The configuration my sparks is, as I write, putting in, is the recommended separate CSU off the mains tails with a 32A Type C RCBO and 10mm2 cable to twin MK wall socket, TT earthed to a spike. He's told me that there is no reason why this dedicated radial can't be earthed TT, even though the rest of the house and its CSU is on PME.  (Separately, my mains were upgraded last year and are now running a 100amp fuse.) If any (qualified) person thinks he's an imposter pretending to be an electrician with this plan, I'd be grateful for a flag. Thanks.   

eagle3333 posted:

He's told me that there is no reason why this dedicated radial can't be earthed TT, even though the rest of the house and its CSU is on PME.  (Separately, my mains were upgraded last year and are now running a 100amp fuse.) If any (qualified) person thinks he's an imposter pretending to be an electrician with this plan, I'd be grateful for a flag. Thanks.   

My sparks says the same, as did all the other sources, with whom I double checked after concerns were raised earlier in the thread.

Keith

You should have physical separation between the two earth zones so you can't accidentally 'short' across the two earth zones by a person and any equipment or conductive surface between the two (shielded Ethernet leads come to mind). .. if in doubt talk to a commercial electrical contracting consultant (as opposed to a sparky).... I did recently to double check on the advice had been given by the RSGB. At least you need to be aware of the very low probability but potentially fatal risks you are taking. An electrician may well  wire this for you as they will assume you are aware of the risks.... it's not a regulation thing... it wasn't last time  I looked anyway...

Perhaps an audiophile slant on this might help some understand..

http://www.acoustica.org.uk/t/earth.html

Hmm, according to RSGB it happens, so not that rare... their members are perhaps  more inclined to do this than the typical audiophile however.. I don't believe there has been a fatality but there have been shocks and equipment damage, So it's a case of real feedback of affected users or those who think it might not happen. The RSGB has now created a special safety leaflet for PME installations where separate earth electrodes may be used for antenna installations and locally earthed equipment  for its membership and their safety  ... alas there is no equivalent for the budding audiophile.... of course if your primary house supply is TT then having a separate earthed radial is fine ... it's only the PME installations where issues may occur with the potentially large difference in earth potentials.. and not just in fault conditions.

For the record I did experience a shock when I first set a local electrode with PME supply... I got quite a buzz and it frightened me as I was concerned not just for me but also my then very young children. it was then I looked into it.. my house is now fully TT and I have a certified electrode, as well as  my own electrodes... no issues ever since... and nuisance tripping has declined as well.

Thanks for the feedback, Simon. I asked my sparks about the danger of shorting across the two earth zones and whether there was anything I could do, in the normal course of events, which could cause that to happen. His reply was no and that we have a completely safe set up. I hope he's right.

Meantime, the reading at the spike was 130ohms so he's going to sink another, longer spike about 8 metres from the first and join them. 

After a 30 minute evaluation I have to report a disappointing result. Soundstage width and depth is shrunken; warmth and bass greatly reduced; compressed hard edged sound. Dreadful. Plug back into the main ring and harmony restored. Definitely not what was expected. Any thoughts anyone? I remember reading a thread where someone posted the same experience but I discounted it amidst an ocean of positive results. There must be a logical answer..  

Good to hear... and it probably means your  metal switch light fittings and radiators are well away from your independently earthed devices... if your electrician has stated this on the certificate and no special provisions are required, brilliant... keep a safe copy of it.

Yes sinking multiple longer electrodes to reduce earth electrode impedance to below 100 ohms is good practice,.. although upto 200 ohms is valid currently apparently

eagle3333 posted:

After a 30 minute evaluation I have to report a disappointing result. Soundstage width and depth is shrunken; warmth and bass greatly reduced; compressed hard edged sound. Dreadful. Plug back into the main ring and harmony restored. Definitely not what was expected. Any thoughts anyone? I remember reading a thread where someone posted the same experience but I discounted it amidst an ocean of positive results. There must be a logical answer..  

Oh dear that sounds frustrating ... did you hear the radial with the PME earth, so do you know whether it's the radial  wiring and RCD that is causing this or your local earth.... I do think the latter is unlikely, but the former probable... 

Assume you only have your Naim plugged into this radial, and you have thick juicy copper wiring in your radial?

Nope, but that'll be the line of enquiry, so to speak. Thanks, Simon.

He's back on Friday to fit my type C MCB instead of the type B he brought - yes, the amp trips it.. Hopefully he can try it with the PME earth without too much trouble. The difference is night and day - but in the wrong direction!

Yes - just the amp, pre', dac and ndx plugged into the socket via hydra..

eagle3333 posted:

 NDX earth is set to floating because my Turntable is grounded on the pre amp. 

That is grounding the TT arm,  its not an earth as is concerned with NDX 'floating' or 'chassis' earth.   NDX needs to be set to 'chassis'

Just spoke to sparks. 0.03 ohms impedance on socket so unlikely to be cable attachment. He thinks it's the 130 ohms in the earth. He'll try the PME earth Friday evening and then we'll know. If it is is it worth adding a second bigger spike and lengthening the original or just capitulating and going PME?

eagle3333 posted:

Just spoke to sparks. 0.03 ohms impedance on socket so unlikely to be cable attachment. He thinks it's the 130 ohms in the earth. He'll try the PME earth Friday evening and then we'll know. If it is is it worth adding a second bigger spike and lengthening the original or just capitulating and going PME?

Unless you have something very strange going on it shouldn't be the earth... the earth is there for safety... full stop... the impedance of the earth needs to be below 200 ohms to be considered stable and compliant, and typically good practice is below 100 ohms.

So having a safety earth affecting SQ negatively because its decoupled does point to an issue elsewhere.. or even that an issue was previously being masked. 

i could think of one possible situation where your new local earth is providing such a different potential to your previous PME earth, that your Netral/Earth potentials have significantly changed.. Naim would know if that would have a bearing on things in their equipment .. I suspect not but they would know.. and  if the case it kind of reinforces the safety advice I and others made about having mixed earth zones 

eagle3333 posted:

The configuration my sparks is, as I write, putting in, is the recommended separate CSU off the mains tails with a 32A Type C RCBO and 10mm2 cable to twin MK wall socket, TT earthed to a spike. He's told me that there is no reason why this dedicated radial can't be earthed TT, even though the rest of the house and its CSU is on PME.  (Separately, my mains were upgraded last year and are now running a 100amp fuse.) If any (qualified) person thinks he's an imposter pretending to be an electrician with this plan, I'd be grateful for a flag. Thanks.   

Only use an electrician who is registered with a professional body such as NIECE? qualified to test and certify the installation for insurance etc. and recognised by Building Control who must be notified about the installation.

My measured impedance to earth is very low at less than 2 Ohms according to my electrician. It s not PME, but comes through a trench from an overhead pole.

Phil

First post on a Naim forum....so bear with me if you would.  I am not a qualified electrician so my comments are based on experience and may use incorrect terminology. 

My experience with Naim goes back quite a while, to a Linn, Aro, Armageddon, 52, 135s, SNAXO, S-CAP, SBLs on Mana.  Quite a complex system, which I sold some 20 years ago.

Back then I spent a LOT of time mucking around with tuning and optimizing mains supply and several of the most important points I learned were;

1. The system appreciated being fed from a single electrical source i.e. a single socket of appropriate rating

2. If the individual components are plugged into a power block in order to achieve this, it was essential that the block was of high quality and provided the exact same earth 'resistance' at each socket. A poor, high resistance  earth on any single component resulted in major loss of performance.....adding harshness and removing the system's rhythmic agility and 'bounce'.

3. The cable used between hi-fi feed sockets and fuse board has a major influence on the sound.  You need to use audiophile approved cable i.e. cable known to produce good sound, because some don't  (for whatever reason) and will result in a hard, amusical sound. Using cheap power strips was similarly a recipe for disaster.

4. Mains cables are hugely subject to burn-in. I know this a contentious subject...but here's what I found. Whenever I fitted new 'improved' cables (component or supply) the sound would initially improve, then deteriorate markedly after a few hours and would continue to sound bad for week(s), before suddenly improving one day and maybe continuing to improve for a while. This caused a great deal of angst known as ppp, (post purchase paranoia). I got so fed up with this that eventually I rigged up a burn-in jig that allowed me to put power cables into a circuit with something like a fan, which I ran continuously for a week or more  before installing the cable into my system.  The good-bad-good effect disappeared completely, leaving just the upgraded sound.  If I was replacing supply cable or any other component, I used to set volume levels then switch off, disconnect speakers, place them facing one another a few cm apart, reverse polarity of 1 speaker cable and play them for a week continuously at the preset volume (be VERY careful with the volume as its possible to burn out speakers if the volume control is increased, because in this set-up the actual volume you hear doesn't increase when the power to the speaker does).  In this way I could play my system for a week continuously without driving everyone crazy. Doing this, I heard just the improvement, with no more break-in effect, which for me ruled out claims that burn-in is caused by gradual aural acclimatization.   

Some of the cable I used between fuse box and hi-fi mains outlet never improved, so I know some cable is just bad, hence my advice to go with audiophile 'approved' stuff which is known to produce good sound.

5. Experimenting with mains supply and earthing is a very frustrating hobby, full of pitfalls, wrong moves, self doubts and extended burn-in requirements.  Standard OEM cables, a power block optimized for hi-fi, a separately fused, appropriately rated mains supply using cable with proven sonic attributes and a high quality mains socket all properly conditioned (burned in) should be all that's required to achieve really good sound from a well matched, room optimized system.  Keeping contacts clean should be the only maintenance required.

 

 

Sparks has left. First I demo'd the issue - compressed, mp3-like sound off the radial (he called it 'tinny;') big, airy, smooth off the ring. He agreed. Impedance off the ring socket 0.28 ohms; off the radial 0.27 ohms. First we tried a different MCB. No change. Then we took the radial earth off the spike and put it on the PME. A very small improvement. But still nothing like the sound on the ring. Then we tried removing the RCD (it's within regs to run a dedicated, marked, internal socket without RCD on a PME system) No change. We tried a different RCD, with higher resistance; no change. Then we gave up; completely baffled.

What's left? The radial cable is new, 10mm2; the ring cable is well used 2.5mm2. Surely it can't be the wire? Burn-in? Will need to change quite a lot to better the ring. The radial CSU is metal. He's going to find a plastic one; in which we'll try an Eaton Memera RCBO. We'll combine this with installing the balance power supply to rid my 250's transformer of DC hum. It'll go on either the ring or the radial depending on which sounds best after those final changes. Perhaps that bit will actually work as it's supposed to. 

Well I guess you have ruled out the other variables... some say they can hear different mains cables... as HH says above, let it lie for a week or so. I am concerned however  that when you moved the earth back to the PME you heard a small improvement....

I think I remember you saying your electrician was going to sink another electrode to reduce earth impedance... did that happen ok?

But it might just be in your setup, your PME gives you the best ground option for your property...

We didn't bother with another spike, Simon, because the improvement when going to PME earth was so small (assuming I didn't imagine it) that we concluded the spike's earth wasn't the source of the problem. Also, my sparks said we'd never get the TT earth impedance down to the level of the PME. Yep, I'll leave it playing iRadio while at work for a week or so and see what happens.  

My new mains supply is a drastic improvement on the domestic ring (mine is actually a 6mm ring). The improvement is particularly noticeable with the NDS, less so with the LP12.

With reference to the TT and PME issue, my brother knows the author of Simon's link as he built his own hi fi and exchanged emails on super regulation of DACs (I think). The TT stays for now, but I may get it removed. My brother suggested a balanced supply might remove the issue. He suggested the Airlink?

Keith

Thanks Keith. Delighted you've got a great result. I've ordered the Airlink BPS3120 with 230, 240 and 250 incoming taps as my mains read 240 the other day.  We'll try it on the radial and if it doesn't help we'll put it in the main ring. Should be here in a couple weeks. Then I'll report back. 

Hi Eagle,

The whole balanced PS thing is a bit of a mystery to me. I don't even know where you would put it! Clearly, I need to do a bit of research. I also note your choice is relatively inexpensive, but you can pay £'000s so a bit of a mine field?

eagle3333 posted:

Sparks has left. First I demo'd the issue - compressed, mp3-like sound off the radial (he called it 'tinny;') big, airy, smooth off the ring. He agreed. Impedance off the ring socket 0.28 ohms; off the radial 0.27 ohms. First we tried a different MCB. No change. Then we took the radial earth off the spike and put it on the PME. A very small improvement. But still nothing like the sound on the ring. Then we tried removing the RCD (it's within regs to run a dedicated, marked, internal socket without RCD on a PME system) No change. We tried a different RCD, with higher resistance; no change. Then we gave up; completely baffled.

What's left? The radial cable is new, 10mm2; the ring cable is well used 2.5mm2. Surely it can't be the wire? Burn-in? Will need to change quite a lot to better the ring. The radial CSU is metal. He's going to find a plastic one; in which we'll try an Eaton Memera RCBO. We'll combine this with installing the balance power supply to rid my 250's transformer of DC hum. It'll go on either the ring or the radial depending on which sounds best after those final changes. Perhaps that bit will actually work as it's supposed to. 

I can't help thinking that there's still an undiagnosed problem that you should get to the bottom of before changing too much, given that your experience is more or less the exact opposite of what others, including myself, have found. Has your electrician changed out, or at least checked, all the components in the chain. Could it be something as simple as a bit of dirt on a contact or a stray strand of wire - maybe in the Henley block if you have one, or the 100Amp DP switch in your consumer unit, or in the wall socket. The MK sockets are not nearly as sturdy as they used to be, and out of the four I bought, I had to reject two. Out of curiosity, why the plastic consumer unit? I'm not aware of any that conform to the current regs in the majority of UK domestic installations.

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Timmo1341
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