One idea I see bandied around is to connect the central tap on the output side to Neutral on the incoming side so… again I’m not sure of the implications.
In fact a few forums seem to say do NOT connect central tap to earth… but this is the way airlink told me they do it so who’s right?
Just to update… one of the reasons given for NOT connecting the central tap to earth is a potential issue with and RCD not detecting a fault… I admit starting to get beyond my simple knowledge.
I don’t think there is a right and wrong. Clearly the DC is about a constant current flowing to a reference… so if that is ground/earth then that will remain if ground/earth is on the balanced side connects to the supply ground earth.
I can see that connecting the balanced ground to incoming neutral might help, but also can see it not helping, it must depend on your earth neutral supply setup… but if one did, one would need to think how one protects this. [edit I see you have made the same point]
The answer of course would be to have isolated /double insulated loads, but this is not how Naim currently do things… in short I can’t see with total safety how a balanced transformer can be used to effectively remove DC on the mains with Naim equipment… therefore to remove DC probably best use a dedicated electronic DC blocker … and of course that can be used with an isolation transformer if preferred.
Hi Simon,
Safety the very reason why I checked with Naim before proceeding with an Airlink BPS. The response from Naim R&D was that it was safe, so long as the BPS is equipped with double isolators etc…
I’m not going to say more on the forum about this in order to avoid breaching forum rules.
Best regards, BF
Yes, that’s right. Thanks for clarifying. I have a balanced mains transformer. I get DC on the mains often, as that transformer often buzzes. The transformers in the Naim units don’t buzz - at all.
Quite.
Maybe better if I’d said DC cannot pass from transformer primary to secondary windings
Well it’s not a Naim safety issue, it’s how the earthing is handled on the balanced transformer. The point is with Naim is the earth ground is important.
Indeed, understood and agreed.
I don’t have earthing anywhere else than my kitchen in my house. That’s very common in not that old houses in Sweden (required in all rooms from 1994). In what way does Naim equipment specifically benefit from earthing in terms of performance?
Naim amplifiers/pre amplifiers need an earth ground reference for optimum performance, as well on nearly all equipment requires safety earth, hence the three pin mains connectors. (They are not double insulated)
I have the same problems in both homes in Australia & Malaysia. I am using a few units of this to calm the hum from the units in Perth .
While I have purchased a couple for my place in Malaysia, I am contemplating to move the power amps to the next room instead.
I have a oscilating hum after 20:00, it goes with 5 second breaks and 2s duration, could be a waltage peak or something
@joeling is your problem similar?
Did the blocker helped you?
Thanks
Interesting.
I tried the dealer’s Powerline 6 which is a tad cheaper, they’d sold the Axis.
I certainly thought it brought some solidity to the whole presentation, I did not expect it to cure transformer hum, but it would have been nice to try the Axis.
I did demo the more expensive MiniSub Axis - unfortunately for me it didn’t sort out transformer hum - seemed to add more detail but overall I preferredthe Powerline 6 I think.
I get the impression these things may be very system/mains dependent and where possible being able to demo is pretty important.
I tried the MiniSub Axis - it brought detail but made the system sound very anaemic and thin. Was the top end detail due to it removing warmth and bass/mid richness (maybe colouration)?
I wondered if the load (2xNAP 250s and 2 HiCaps) was a bit too much for it. Perhaps my kit wasn’t good enough to show the true benefit, or it’s simply dependent on your individual mains problems.
Transformer hum persisted in the 250s too.
Hi AC, I have a few of these devices. One of my system (300dr based) uses an isol-8 substation axis. It has dc filter but no power filter. The substation on the picture above has power and dc filter, same I believe for the minisub you tried. The dc filter will not always help if the hum is not caused only by dc and power filters can have a negative impact on Naim sound.
Thanks, yes the MiniSub Axis had DC filtering. It seemed a nice well made device.
These mains blocks/filters etc seem to be similar to cables in that you need to demo them in the context of your system as what works for one will not for another.
As nice as the MiniSub was, in practice I didn’t think the rear power sockets would work well with Powerline mains cables as the plugs were upside down, and also there’s the need for an extra shelf/additional support to house it.
I tried the blocker in my storeroom sized room in Perth on 252 & 250 one for each unit. Hum was significantly reduced thought not totally eliminated.
As for the Malaysia system, I think I will just move the Statement amps to the server room next to the listening room and punch a couple of holes for the associated cables.
Testeroo
Depending on the severity of the issue, an isolating transformer can just move the hum from one box to another (the isolating transformer itself). So if possible, that specific solution is best done with a unit rated at the full current of the circuit and located in a garage or something.
Naim’s advice on power conditions is always misunderstood. They don’t advocate them used redundantly for problems that might not exist. All things working well, a redundant filtering mechanism would be worse. If things are problematic, Naim have given the customer the very best options. Use a filter or fix the mains, or skip it if not needed.
I’d always root cause the issue before applying a solution though. You wouldn’t undergo heart surgery because you got out of breath going up the stairs. Yoy’d get checked out and undergo tests first (I would hope).
