Noise and DC on mains and new radial

It's just because I can see the rest and it looks exactly as it should. Baffling. NDX earth is set to floating because my Turntable is grounded on the pre amp. Oh well. Watch this space.

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'

Thanks Mike. Understood. The pre is a McIntosh feeding a 250DR and NDX only feeds an outboard dac with digital signal. Still set to chassis?

Good to get it right but Doesn't explain current problem, sadly.

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:

Good to get it right but Doesn't explain current problem, sadly.

I realised that when I posted,  should have said so  .....  my bad  .....  good luck with finding the real cause of your SQ problem

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 

From the little I know, agreed Simon. Perhaps he can check the impedance of the PME earth to compare? Beyond the earth it would, presumably, have to be a component in the CSU. There just isn't anything else in the circuit. I'll report back Friday night.

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

He is very registered and able to certificate. But I don't believe anyone else needs to be notified. However CSU and socket will both be clearly labelled for what they are. As is the earth stake outside.

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. 

Give it a week. 

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.

Am I right in thinking that the balanced PS avoids potential issues arising from mixing PME  and TT because it has an isolating transformer?

Keith

I don't know about that Keith. It's meant to cure DC Offset which is likely reason for my humming 250DR. Mike at Airlink said it also lowers the noise floor. 

We tried just about everything Chris. It's baffling. A different RCB and MCB made no difference. We didn't have another switch to try but will get one. Wire connections in back of socket we're checked secure and impedance is almost identical to that in the ring. We didn't check the wires in the two Henley-type junction boxes. Will do so. The idea about plastic CSU followed something I read elsewhere about plastic being better than metal related to Hifi but I suspect it's foo. And you're right - very hard to find a plastic one today. (My sparks said it's to do with containment of a fire in CSU and melting plastic dripping onto firemen.) Meantime we've left the radial on PME because I think it did improve things a little for whatever reason and it reduced the variables between the two in terms of process of elimination. 

I thought the BPS would be worthwhile regardless of whether it ends up on ring or radial?

Ian

Hi Ian,

If your goal is to reduce mains transformer hum from your NAP250 without reducing dynamics or speed of the system, then the Airlink BPS worked very well for me. The icing on the cake was the ability to reduce the output voltage from 240V to 230V.

I have been careful to ensure that the whole hifi is powered off the BPS, as the earthing is different for anything that is not powered off the BPS. If you link your hifi to an AV system, this is an important care point.

I do hope that the BPS works out for you after such a painful journey with the radial supply. My radial is just 10mm2 twin and earth from the main household distribution unit. 

Best regards, FT

FT, why is the earthing different for a balanced power supply?

The transformer is wired Centre Tap to Earth, but the earth can remain the same, it's the line and neutral that are different.
(i.e. instead of  'line-neutral-earth'  you have  'line-line-earth' ).

Indeed Huge, that is what I was referring to. Thank you for expressing it in a better way.

FT

Actually thinking about it perhaps the best way to express it is

+ line  |  earth  |  line -

Am I allowed to ask those who are happy with their dedicated mains what make/model of MCB/RCB/RCBO are you using? I'll acquire the most popular and try swapping in to see if it makes any difference..