New Naim owner here, but not new to massive (1.4kVa+) toroid power supplies. Every toroid based power amp I have owned has had some level of hum. No exceptions. My SuperNait 3 is by no means the worst offender of the amps and equipment I’ve had. I’m U.S. based.
However, I have recently acquired both a 2.5kVa 1:1 MGE (Topaz) .0005pf Isolation Transformer -31 Series that feeds into my also-new Furman Elite 20 PFi (made by Garth Powell while at Furman; it’s like a cheaply made AQ Niagara 3k and it also drops the output impedance for the high current outlets along with providing current reserve). Compared to direct into the outlet, the SuperNait 3 TX is silent even with my ear pressed to the case, and there are also audible improvements (with no demerits; equal or better in every area) through the speakers. Bass is just as well delineated, but slightly more dynamic. Could be due to the blacker background though. On isolated banks of outlets I have my BS Node2i and RME ADI-2 FS v2 DAC. Only those three things are plugged in.
I have two circuits within reach for my system; one sits at 119-121v, the other at a steady 125-126. When plugged directly into the outlet for each, the noisier circuit was the lower voltage one. I’m in an apartment and these are both on a common wall with an adjacent unit. Who knows what the neighbors have going on in their unit. I don’t know what DC is or is not on the line for either. TX based setup sounds more lively in the higher voltage circuit than the lower voltage one. But this may not be due to voltage alone (likely isn’t).
We are talking about mechanical hum and not coming through the speakers right?
My XPS-DR hummed loud enough to hear from 3 feet away. It always bugged me. Finally I took off the cover and found the bolt holding the transformer was loose. Tightened it up and now I can only hear it if I stick my ear right next to it. I’m happy again
Yes your right, much higher that I would have thought. Of course forum members with hum issues would answer the poll, and perhaps members that dont have an issue may not bother to respond, but I cant see that being that much higher. It seems to be a decades old issue that no-one has managed to solve completely yet. Of course a lot of the issues are environmental, but still, surely someone can create a back box that can give out a clean current - so back to Naim
This is actually an area where EI transformers excel over toroids.
Given an equally stable and clean mains feed, an EI will emit a fair amount of EMR as a large flux arc. That must be mitigated with both shielding and/or distance to sensitive components. A toroid, on the other hand, will emit very little at all as the flux is confined to the core. So sensitive components can go fairly close to one without shielding.
However, feed both with crappy mains and DC offset and the tale is reversed. EI transformers cope very well. There is minor elevation in their EMR. Their hum threshold is much higher and overall, the continue to provide stable performance. Those toroids, loved by audiophiles, go nasty. They start to hum. Their EMR goes up way beyond what an EI design emits, and now not only are they humming but they are polluting audio circuits with EMR that wasn’t factored into the design by way of distance and shielding.
Some very high end kit has bucked the trend and firmly goes for EI transformers because they are so consistent in real world conditions.
Luxman is a good example of that. They proudly advertise the fact they use EI cores and even design their own - to hell with what the audiophile crowd believe.
I always respond with my findings, even if I do get flamed for not being a Naim ‘yes man’. I can’t see the point in a forum that just pats itself on the back for spending silly amounts of money on a stereo.
And my experience is that my Naim stereo components don’t hum to any noticeable degree. I suspect (no more than that) that this is in large part because I am lucky enough to have a relatively good utility mains supply. I might take a look at it one day!
My XPSDR and HCDR are virtually silent, but the 200DR has always hummed, most of the time unobtrusively but it does have its moments. A DC blocker might solve it. Also considering a dedicated circuit with unswitched sockets in the future.
Honest user reports are the key for Naim to identify issues that may be affecting their sales or reputation. This forum does pretty well in that respect I feel. Of course people will identify with forum subjects that affect them. It is for Naim, if they wish to, to decide if a forum poll means anything to them against total numbers sold and profit made.
I don’t know what kind of technical feedback there can be but I bring my experience here.
Respecting the correct sequence of power on, before the hicap and after the nap250, waiting about 5-10 between one and the other, the hum that is usually audible from the hicap is almost equal to 0.
I bought it used so maybe during shipment it shook it loose. Or maybe that’s the reason the person sold it. Maybe on the boat ride over here it worked itself loose. It was just a little loose. Just needed to be snugged down.
Why wait 10 minutes? AFAIK the order with source - pre - power amp is just so to prevent any audible pops from source/pre switching reaching the speaker:
my system is made up of 62 / HC / 250. I have always turned on the HC first and immediately after the 250. I have been trying to solve the buzz due to the hicap for some time. I tried with dedicated line, mains filter, isolation systems. three days ago by pure chance I turned on the hicap and after 10 minutes (the phone had rang) the 250. I performed this test three times and the buzz of the hicap seems to have disappeared three times. Could it have been a coincidence? I don’t know, but 3 times out of 3…
