High Current Power Supplies (mains "replacement")


I have no intention to buy any of those high current power supplies, whatsoever.

But I’m rather curious. Especially about the IsoTek which is designed and probably built in the UK.

Who uses those high current power supplies?

There are several Naim customers interested in dedicated mains, mains filters, fancy power strips and cables, etc.

So why not those eyes watering expensive high current power supplies?

Some members use Audioquest power conditioner with Naim, and found an improvement.
Like the Audioquest 5000 recently bought here by one person.


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From a technical perspective you should measure your mains first in order to recognize what aspect you need to address.

In former times frequency of mains was stable but today frequency is becoming an issue since more and more wind turbines are used, because with changing speed those deliver current with changing frequency.

But ground loops in house wirings might be found more often; especially when it comes to old buildings.

Both aspects interfere with your HiFi gears transformer and therefore might produce a tiny effect in music reproduction. Why am I saying it is a tiny effect? Because it depends also on the transformers quality and PSU design.

With NAIM internal PSUs as well as Hi-Cap, FlatCap or SuperCap the issue of ground loops is already adressed virtually. So no need to worry or to follow the flock of sheep. :sunglasses:

A midical grade isolating transformer mounted directly after the consumer unit on a dedicated circuit will get you most of the way at a fraction of the cost. No conditioning. The galvanic isolation blocks DC offset and that’s most often what makes toroidal transformers misbehave.

Anything more exotic should really be aimed specifically at a problem you know you have. Anything else is just a generic solution to a problem you might not have.

I’m not really against main filters/conditioners/high current supplies etc. But, as they can have an impact on sound, I’d want to ensure they target a specific (and noticeable) problem. I think most people buy these things to calm some paranoid OCD aspect whereby they worry that something might be wrong with the mains. If I had a problem that had been accurately root caused to the mains supply, I’d happily pay for such a device. But I’d stop using it again if I moved and the problem didn’t persist.


Maybe we could at the very least settle on a name for these devices? We’ve got Power Blocks, Power Supply’s, etc. There are actually Three basic types of units. There’s Power Regenerators the best know are the PS Audio units. Then we have Power Blocks which best I can tell are just really nice Wiremold type strips that don’t have any active components in them but have nice outlets. And then we have Power Line Conditioners. These would be Audioquest units, Shunyata, Isotech. These have active filters and surge protection. The trick with any of these is not to impede current delivery. Back in the day that’s exactly what happened and what led to many companies to recommend against any type of PLC

Yes, as described on the thread’s topic :wink:

I also find this topic very interesting! For different reasons I happen to have six different options to get the power from the outlet to the system that I plan to evaluate during fall: from cheap powerstrip (Deltaco), expensive powerstrip (Nordost qb8 with filter possibility and V2 Powercord), Musicline Powerigel, ifi Powerstation (active filtration), Torus isolation transformer (rm15 I think) and Adept Response power conditioner.

There are of many variables as the power cords will differ etc but I do this to get the best possible sound not as a scientific evaluation.

No high current power supply however…next week the electrician will install a dedicated circuit with AHP Klangmodul breaker, Furutech cables and outlet to establish a high quality baseline. I will post findings later.

As long as the isolation transformer is able to provide enough current, especially at peaks, this is a rather simple and cost effective solution to isolate ones HiFi equipment, or whatever equipment, from the grid.

In a way, there is already some isolation within every power supply. So why bother? As you said noisy, or somewhat noisy, mains might not be a problem.

But the question remains, are Naim’s power amps and power supplies immune to this common noise, and self-induced noise? If so, to what extend/degree?

There seems to be a market for those über expensive high current power supplies.

Considering their price, especially the IsoTek one (up to £28 500, with all “options”) they should provide a very immediate and noticeable effect. It can’t be this marginal/placebo effect of some fancy cables :grin:

A bit like this Thomas?

An Airlink Transformers 5kVA balanced power supply on a dedicated 10mm2 radial, as suggested by @feeling_zen.

Simple, inexpensive and very effective for those of us with dirty mains and the space for the box.

It stopped the Naim power supply transformers from humming, made music sound sweeter and calmer yet with greater dynamic range on transients as the Naim transformers are no longer saturated due to the “dc offset” on the incoming mains. On the other hand, if your mains supply is already symmetrical and your Naim boxes don’t suffer transformer hum, then the benefits of a BPS will be somewhat less.

Best regards, BF

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Interesting, and pretty cost effective compared to those high current power supplies.
Is that installed in your own home?

Your power supplies did really stop humming?

My power supplies hum like a flok of hungry goats, unfortunately :sweat_smile:

But I use not to bother… too much. But now, with that fourth power supply installed… it’s becoming slightly annoying :pensive:

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That Airlink thing looks very interesting. I saw on there website also 3-phase and up en down conversions. But I don’t really know what the benefit wil be. It is a transformer. And this will transformate every alternating current. Maybe that the impedance of the transformer do something. But this is exactly what will happen in the amplifier itself. So except the humming from dc offset can moved to a other place i don’t see the benefit. Maybe someone can explain or show it by voltage graphics.
Sorry for my bad English. I can’t translate al the technical words. How will it eliminate high frequency from dimmers, sunpower etc etc

Hi Thomas, there is a thread on the old forum called “Suffering from those transformer hum blues?” which explains the history.

The photo is ours, yes.

As a first estimate, take the total size of all your Naim transformers and double it to size your ideal BPS. In your case, a 10kVA unit would be a good place to start. Better still, an email to the Engineering Director of Airlink Transformers should sort you out. I ended up with a model that allows you to alter the output voltage in 10V steps, so you can try 220V, 230V etc. I used this to dial back from 242V to 230V.

Did it knock out transformer hum? Yes, instantly and for ever since.

Best regards, BF


I use a PS Audio P12 in my mid-range system and wouldn’t be without it. The differences are very obvious.

I’m in the US, so I don’t know if UK/European users would have the same experience.

Mark Dunn

Paul’s, from PS Audio, interesting thoughts on isolation transformers.

Hi Thomas,
He makes a number of very good points in his videos about the limitations of isolation transformers. If it is fed with a “distorted” waveform on the primary coil (i.e. not a perfect 50/60Hz sine wave), then it will reproduce a similarly “distorted” waveform out from the secondary coil.

Hence it is helpful to be clear about why you may or may not want an isolation transformer. It is not a cure-all for every form of dirty mains.

We wanted to block so called dc offset or asymmetric mains, as this is a major cause of saturation and mechanical hum in Naim’s toroidal power supply transformers. The isolation transformer or balanced power supply has done this for us.

If you want to block higher frequency harmonic distortion on the mains waveform, then a BPS such as ours is not very effective. Airlink offers an optional module which you can specify as an add on to the basic BPS which claims to do this. However, we didn’t want to go there. We just wanted to block the dc offset with a very low impedance (hence large) BPS.

A full-on mains regenerator should remove both dc offset and any waveform distortion so sounds ideal. The catch is that it has to be a very big beastie in order to have a very low impedance - the low impedance that a Naim power supply expects to function well. And that means large, heavy and expensive.

Hence the choice: find your own dc blocker that works without degrading the Naim power supply performance, pay about £500-800 for a BPS which knocks out dc offset but not the waveform distortion, or pay about £10,000 for a beastie of a mains regenerator.

There may be a secondary benefit of a BPS, though would welcome comment from those who understand such matters better than I. With the output from a BPS, the “neutral” wire in a hifi component’s mains cable is no longer at zero volts but is at the opposite voltage to the live wire. Does the electromagnetic field from the neutral therefore cancel out the EM field from the live, resulting in almost zero EM fields from all the mains leads. If so, this would result in less sensitivity to cable placement and the need to avoid keeping interconnects and speaker cables away from mains cables. I would be really interested to learn if this is true or false.

A couple of forum members have their own dc blocking circuit. I am not competent to go there so have gone with a BPS after having an unsuccessful trial with a very well regarded, £3k mains conditioner. You may choose try a mains regenerator.

Whichever option works for you, go for it and enjoy your music even more.

Best regards, BF

Hi BF,

Thanks for detailed reply.

Glad to could get rid of your humming issues.

As said previously my PSs tend to hum like a folk of goats :goat: :goat: :goat:

Interestingly it depends of the moment of the day/week. I should say it is very neighbours activity dependent.

What unit have you installed?

Did you install a “simple” isolation transformer or an actual balanced power supply?

AirLink offers interesting products, for a tenth of what offers IsoTek or PS Audio :


Probably less sophisticated.

I’m not planning anything at the moment. The first step would be to test the mains with an oscilloscope.

Hi Thomas,
Like you, the volume of transformer hum varied through the day, depending on which appliances we and our neighbours had running at the time - a classic sign of inflicting dirty mains on Naim’s high performance transformers.

Ours is a BPS5120MP, so that’s a standard 5kVA balanced power supply with multiple primaries, so that it can take 240V in and deliver 230V out. We tried both 240V out and 230V out. Naim said that 230V out would not impede performance of the Naim equipment but would “give the power supplies a slightly easier time of it”. We found that the last residual transformer hum that we could hear from the 555PS at 240V disappeared when we used 230V, so it has stayed at 230V ever since.

For your system, I would start with something like an MP100230MP, then ask Airlink for their thoughts. Airlink also offers Conditioning BPS and Advanced BPS, which feature some form of filter or conditioning circuits. We didn’t want extra filter/conditioning circuits, so settled for the basic BPS. It’s a matter of personal choice.

Best regards, BF

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Indeed. All they do is provide galvanic isolation and block DC. The latter being the most common cause of a physical humm. They do not provide conditioning. Their reasonable cost is because the are very simple devices. They should be sited away from anywhere you spend time. If there is DC to block, they’ll likely move the hum from your component transformers to the isolating transformer itself.

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Paul of PS audio makes a good point in his video about low impedance supplies and the quest for isolation.

I used to wonder why more committed ‘Audio types’ didn’t use a motor-generator set up, where you have a speed regulated mains powered motor driving a dedicated alternator to produce clean/ isolated power specifically for your HiFi. Of course you have the inefficiency, the vibration and the noise, all of which you can deal with, (much like the military do who use exactly these types of power units), given sufficient space, good design and lots of money, but hey lots of ‘audio types’ have all of these.

But fundamentally the size of the machine, (alternator and thus motor) is going to need to be big and heavy in order to keep the impedance down to levels which might match or better your average utility connection.

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