Audiolab DC Block

Anybody dabbled with this yet? Saw one You tube video that suggested it might just be the next big thing!!!


If its Chord its bound to be an expensive solution…
That’s if it is only a Dc blocker.Hardly next big thing.

Studio Incar

Ah…you mean Audiolab DC blocker…

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Put the DC Blocker into your car?! :woozy_face:

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I put a Audiolab DC Blocker on my 555ps and it’s made a subtle but positive difference to the sound of my NDX2. It’s also reduced the hum of the transformer which is a very good thing.
I haven’t tried to putting it on anything else but for £100 I would have it over a powerline as it without doubt makes a bigger improvement to my ears.
Many dealers will let you try one on sale or return so I thought it was worth a try.
I would like to try one on my pre but I’m not sure about power amplifiers as it has a maximum load of 4amps.

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If you are using a distro of any description, put a single one before that and it will serve all your units.

Yes ! Sorry

I would be slightly concerned by the claim that:
it also contains a high-performance audio class filtering circuit that removes RFI/EMI contaminants from the mains supply. This is effective in reducing both differential-mode noise (exacerbated by cheap switch-mode power supplies used by many home appliances) and common-mode noise (aggravated by airborne interference from phones, Wi-Fi networks, and Bluetooth).

Many (but by no means all!) implementations of this type of filtering don’t work too well with Naim equipment.

I wish they just did a DC blocker without the extra filtering

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Look at ATL Audio then, they do… and inexpensive.


I believe Isotek or was it Isol8 do, but it’s a lot more expensive.

Mike-B and I have both built our own, in his case no filtering, in my case a particular type of filtering circuit very specifically designed to work with Naim equipment.

Update… OK, now you have three suggestions (+DIY).

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The choices seem to be “IsoTek EVO3 Syncro Uni DC Blocker” $ £595 or IFI DC Blocker @£129, or the ATL Audio. The first two would be able to be purchased on a return basis in the UK. Personally I’m still investigating a dedicated mains, but one of these might be a fallback option if that isnt possible

Thanks for the clarification.

Just a note: a dedicated mains spur and a DC blocker solve completely different issues. Using either one will give absolutely no benefit toward fixing the issues that are fixed by the other!


I use Supra DC blocker. Works like a charm. Silence.

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As I understand it, a dedicated mains is a boost in SQ and has been reported to resolve many humming issues, which is my issue. So that would be my first point of call, but that would always leave the option of a DC blocker if still needed. My problem will be getting a 10mm thick armoured cable from one side of the house to the other, without too much disruption.

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A separate mains spur might not necessarily remove the DC problem, and certainly wouldn’t if it is on the incoming mains supply.

If you have a DC offset on your mains then I’m not sure a dedicated spur would help. The issue is an offset between neutral and earth and that’s probably endemic in the mains for the whole house. I had it in my last house, ISTR it was about 2V and I only found out when one day I stripped a neutral wire whilst touching earth… I could feel it! The house before that, I never measured it but I never sensed it so I’m assuming it wasn’t present, or very small. Anyway I fitted a Supra DC blocker… I’ll be honest I couldn’t hear any music improvement though, perhaps, there was a slight drop in transformer hum on my SN2.

I’m not sure if the problem is a poor earth at the house end or at the local electricity boards drop transformer… to my mind earth should be the same at both ends and since neutral is earth at the electricity boards drop transformer then there shouldn’t be a DC offset. However, I agree, I don’t really know what I’m talking about.

I wonder if a worthwhile test would be to measure the offset of your house earth wrt the earth in the ground outside (earth rod driven into damp soil). If there’s an offset there then does that mean the problem is the earth for your house is rubbish? I don’t know.

I’ve not measured the offset (neutral to earth) at our new house but, interestingly there is actually an incoming earth wire from the overhead mains feed… I assume that feeds back to the primary drop feed. If so then I assume there would be a much lower DC/Earth offset.

Or am I being simplistic here? Perhaps someone can explain better? :slight_smile:

Actually now I think back that offset might have been 0.2V not 2V. 2V does sound a lot!

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This so called DC is not actually DC at all, its a distortion in the AC wave form, in very simple language it’s a shift or difference between one half (180 degrees) of the sine wave compared to the other. It causes current flow in that instance to behave like DC in an inductive load.
Its on L (live) only, it has no relation to N or E.

If its present on the local supply, a separate (dedicated) radial will not help.
If it’s from something in your property, normally something with half wave rectification used for speed or heat control, a separate radial might help.

If you do have a voltage difference between N & E, its normal to have low single number volts & its caused by the circuit resistance difference between the two circuits back to their common point.
If you have concerns, consult a qualified Part P approved electrician.