Power conditioners - reduce transformer hum?

Noticing when it’s very quiet, my UQ1 occasionally make a bit of a ‘humming’ noise - sounds like resonance or something coming from the transformer. If that’s the case, would a power conditioner (like an Audioquest Powerquest) make a difference and potentially reduce the hum?

Or do I have another issue unrelated to power? The unit just went in for a full service last year…

Transformer hum can be caused by DC Offset. Ty using a DC Blocker to reduce it.

There are many available on the market, with varying prices.

I’ve previously used the IFI DC Blocker with great success.

There are many threads on this Forum which will give further information.

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Can you use this on the end of a power strip, or directly at the unit?

And now I see all the threads on DC blocker…Thanks for the heads up.

The IFI one is used in-line.

Like this.


Some power conditioners reduce hum (DC offset), for example selected products from Puritan Audio Labs and ISOL-8 do address the problem. There are likely other manufacturers with similar solutions in the market.

Be aware that a conditioner can also cause sound quality issues. Where possible it’s a good idea to see if you can locate the cause, and the solution may well then evolve from that result. Have a look through the following guide to help narrow the cause

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True, some conditioners can cause SQ issues, but most quality conditioners from well known manufacturers will not. Generally speaking it shouldn’t be a concern. Trial and error will beat maxims anytime.

I’ve seen lots of reports on this Forum of improvement, reduction and no change in SQ. I couldn’t say any one of those outcomes are higher than others. Naim themselves found it reduced SQ, however every house conditions are different, and so no-one can say definately what will work in each case.

The link I gave may help to identify issues that may be solvable without conditioners (e.g. over voltage, faulty Fridge/freezer components, or even HiFi hardware problem). Because all houses are different, there can be no study in a definitive answer of whether a device will help or not. So really all I’m saying it it may not help SQ. Certainly if the suggestions in the link dont help, by all means try these conditioners, but best to look for a try-before-you-buy deal, or returnable if no improvement.



Having no experience with DC Blockers or hum on my NAIM System. I must be lucky and have star Earth points and a 230-volt supply from one source.

  1. Would it make sense to turn off all circuit breakers and all appliances?
  2. Turn on the circuit breaker (C/B) for the Naim system and turn one component at a time.
  3. Turn on one circuit breaker, possibly the one for the fridge (listen to what happens) turn on the fridge and listen.
  4. Slowly go through one appliance at a time by turning on their circuit breaks one at a time, then the appliance and listen.

This may be basic, though. Hopefully, I hope it helps isolate the offending appliance and circuit.

Please let us know you you go.

I had a noise issue and turned the main breaker off at the house, and it turned out the noise was coming from the neighbour’s cheap air conditioner. The air conditioner was on standby and not running, yet it was putting out a bucket full of noise, which was interfering with my amateur radio.

Warm regards,



Naim always used to strongly discourage the use of power conditioners in the ‘Olive’ days. Has that advice changed?

No. The advice was merely misrepresented. Naim often test such things and have merely stated that of those they have tested, they haven’t yet heard one that made a positive impact and some made it worse. So they don’t use them.

It was the Naimite customers who translated that to a dogmatic commandment.

I think at most, Naim, or perhaps just Richard, give good advice that if you use one and didn’t have a mains issue to begin with, to at least try the system without it.

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Don’t confuse power conditioners with DC blockers (DC Offset filter).

Conditioners will have at least common & differential mode filters, these consist of series chokes & shunt capacitors and its these that are ‘reputed’ to affect SQ.
Power conditioners will invariably have other components to protect against ‘surges’ and whatever else has been added to the design.

DC Offset filters are normally large series capacitors with overload bypass diodes. They don’t generally have a negative reputation, in fact some folks have remarked that SQ is marginally improved. This was certainly the case with my DIY DC filter experiments.

The only other thing I can add is all transformers will make a noise, even though some/most may be inaudible.
If you do have a DC problem the transformer will have variable noise in tone & volume, A DC filter will possibly help.
However if a transformer is ‘naturally’ noisy, i.e. the noise is constant and unchanging, then a DC filter probably will not do much.

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Don’t forget isolating transformers. No filtering. By design, an offset isn’t able to traverse a transformer.

Though best located in another room. If a hum is offset induced, this tends to simply move the hum from one box to another.

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If you make a list of all SMPS and products that generate noise in your home (and all your neighbours) these days compared to the olive days you will understand why great conditioners have a good effect these days. Things change.


I think the same could well apply to unshielded power cables, think of all the Wi-Fi, mobile signals, Bluetooth etc that’s flooding our environment these days, all that RFI/EMI can’t be good, if you have 6 boxes that’s 12m of cable picking up all that stuff :thinking:

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Been cautioned with power conditioner’s especially with power amps and active systems as they can curb the rapid power delivery.

I use Isotek including their power cables and am very satisfied. NYC has lots of power issues. Reduced line noise.

It seems like most of those trying a power conditioner of good quality today is happy with the result, and those complaining about conditioners are those who never tried and obey what naim said was the truth some 30 years ago? :slight_smile:


I’ll add that it might have been true for the power conditioners they tested, but not as a general rule.

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