Voltage stabilizer / Mains conditioner

Hello to everyone.
I would like to ask your opinions & experience about voltage stabilizers / mains conditioners?
Do they harm the sound quality of the system?
Thank you in advance.

Some say yes, some say no. Those with high end systems say it strangles dynamics. I have an IsoTek Aquarius on my Uniti Star and I like the complete black background the music performs on. I also have the phono stage and the Gyro SE power supply on it. It seems to help them too. I prefer with mains conditioning at my price point.

Personally, I would try to avoid them with a Naim system. I’ve tried a number of conditioners over the years of different makes, and we even had some at the factory to evaluate; all impaired performance in some way or other, some badly so, and one or two, even when they were plugged in on a different outlet with no kit plugged into them.

I recall setting up a demo evening at a dealer in Sweden. I had spent the afternoon setting up the system, clearing the room as best i could, and getting everything looking and sounding as good as possible. I had unplugged everything else in the room apart from the Naim system and gone around the dealership looking for any mains conditioners that might still be plugged in and switched on, and unplugging them. It sounded pretty good, but it lacked a sense of life - I knew there was potentially more there but I just couldn’t figure out what the issue might be. I double checked all the connections, mains plug polarities, etc… but no big change. With the start of the event rapidly approaching, I decided to have one last check around the dealership. What I found hiding behind a curtain was what I thought was a big power amp, but in fact was a very high end mains conditioner - still plugged in! I unplugged it and went back to the Naim system. I once more played one of my reference tracks. WOW! what a difference! All of a sudden that sense of life returned. And all because of a very expensive (and very highly reviewed) mains conditioner, which had been plugged in to the same mains…


I have spent some time experimenting with a couple of commercial mains filters determined to see whether it would have an impact/benefit in my system. Can I remind anyone without relevant electrical knowledge or experience not to undertake any work at mains voltage.
My system is Melco N1ZH/2, NDX2, ATC CA 2, ATC SCM40A. The filter was installed in a box with output sockets for each component and a star earth point to create a power block. The unit uses standard mains flex. The filters tested were a 2-stage high spec and a single stage lower spec mains filter from Schaffner.
Results using the highest spec filter:
The Melco was agnostic - no noticeable effect
The NDX2 did not like the filtering - the sound became flat and lifeless
Filtering both CA2 and SCM40A’s relaxed the sound expanded bass significantly but lost bite in the treble and seemed too relaxed spoiling one of the best attributes of the SCM40A’s.
Filtering the SCM 40A’s only is the Goldilocks option, more expansive and subjectively deeper bass; a more relaxed sound (perhaps not good for all genres) and a sweeter treble.
The lower spec filter did not achieve the same differentiation in sound.
I reconfigured the speakers 5 inches further into the room to restore the previous bass balance! This resulted in deeper and more even overall bass response by significantly reducing room nodes (measured result with a DSPeaker DAC). It also improved balance by bring the mid-range forward a little. Overall, £200 well spent.
So the answer to the question posed by Vaggoz is maybe!
In my experience Naim does not like mains filtering but ATC active speakers (and pre-amps) are significantly impacted by it. I have heard it said that active speakers are prone to variation in SQ and mains interference may be a cause. Getting a good result was by luck and experimentation though; another system might respond completely differently.
This result was the silver lining from lockdown!
I post these thoughts for interest and I am in no way decrying commercially made power blocks as I have not tried them.

I think installing a dedicated line is the first step one should take. The cost is less than just about every decent PLC out there and often gives good results. Second, you have to determine if you even need a PLC. These are several meters available to measure noise- both common and differential mode- to see if a PLC is needed. I use an Environmental Potential EP-2050 in my mains panel and the noise in my home is very low via measurements. We have a few rental properties- condos, townhouses, that typically share transformers much more so than single family homes. When I measure the electric noise in these places it is very high, sometimes maxing out the capacity of the meter. If I were in these places, I’d sure as heck be using PLC on all my electronics plus a surge protector in the mains panel.

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Conditioners are a bit like unnecessary heart surgery. You just don’t do it. That doesn’t mean they are bad per-se but you need a reason use them.

They all do different things, be it filter noise, stabilise voltage, frequency (exotic), DC offset, earth shunts to reduce feedback, and the list goes on.

Naim’s advice should be interpreted as not to use them without a reason. If both of the following conditions are true:

  • You have an audible problem like a humming transformer or unwanted distortion from the speakers.
  • You have accurately identified the mains supply as the culprit and specifically measured and identified what is wrong with the mains.

… then opting for a device specific to that problem makes total sense. The cure, in that case, is better than the ailment. Ideally, if you move or fix the mains, you then stop using such a device.

I think the only truly benign device is a balanced isolating transformer rated at equal or greater than the circuit, That gives galvanic isolation and blocks DC offset which seems to be a common problem in some rural areas. Such things are best installed by an electrician and put in-line on a circuit dedicated to the hifi though.

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I bought an Audioquest Niagara 1200 a month ago and have been very pleased with it in my 82/250 system. My old Wiremold strip now has a new home and will not be returning.

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Regarding dedicated circuits. I don’t fully understand why a dedicated line helps since all phases are connected to the central which should mean DC gets distributed in any way even to a separate line to the amp? Doesn’t it always require an isolating transformer on the line to for my amp?

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The main reason for dedicated lines is to isolate the audio system from other devices that would be on a typical circuit. Say you have a room for your audio system. That room will be on one circuit and the outlets daisy chained to each other. In that room you might have lamps with LED or CFL bulbs. Both of these inject measurable noise into the electrical system- and the audio components plugged into the same circuit. Add in a computer, electric clock, etc., and the noise becomes very high. You can evaluate this with a Trifield or Entech meter.

Dedicated lines should be the first power-related “accessory” one should invest in, and most often the least expensive and most substantial.

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Yes but all lines in a house goes back the central unit meaning it’s all in the same loop for each phase. So even if my Naim get its own lines directly from the central it will share the phase with other rooms and equipment no matter what (3 phases here in Sweden). Like in my case even if I had a separate line to phase 1 it would share phase with say heat pump, fridge, heated floors etc. And we often have to spread out these machines across all three phases since they consume so much power that fuses will burn if you use one phase for your stereo and bunch the noisy machines up on another.

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