DC Blocker for TV?

I have an all Naim system - I don’t have a dedicated Mains supply for it, and it’s hard to get one.

I used an Isol-8 mains unit for a while, but thought it impacted the sound of the Naim gear a bit. Not massively. But it also didn’t fit on my Fraim, so I’ve replaced it with a MusicWorks unit, which are back to basics no filter no Jiggery pokery type units. Sonic magic back.

On the same circuit - and into the same wall gang - I have my TV - a Sony 85” 8K job - and very nice it is too.

Whenever the TV is on - and especially on certain types of image (I haven’t quite worked out if it’s light, or movement, or something else - but anyway…) I get a buzz through the Naim that I never had when I had with the Isol-8 in place. So I’m almost certain the TV is the issue.

This leads me to believe that the ISOL-8 was doing something that’s the MusicWorks isn’t - and loath to back to a Mains solution for the Naim - I’ve wondered if the issue is DC - and getting a DC blocker to go in line on the TV power feed might do the trick.

Anybody have any experience of such things?

I think it would help to know what you mean by Buzz, and where is it coming from, e.g. speakers, Amp, etc. Does it change with the volume

As a test, are you able to use a long extension lead to a different circuit for your TV as a test. Does your TV have an external power transformer that may need moving somewhere different?

Thanks for the rapid response :blush:

So it’s not coming from the speakers - and it’s not volume dependant or impacted by the volume control (or the mute button) in any way. It’s primarily coming from the 555PS units I have feeding my streamer. And it’s a definite buzz rather than a hum. As far as I can make out it’s coming from both of them. I can switch off the 552PS and the 500PS with no change to the buzz levels - only when the 555PS’s are off does it stop.

The TV just had a standard IEC cable - with no external power supply.

The buzz stops immediately the TV is turned off.

Interesting point to try to lash the TV up onto a different circuit - I can do that I think. Will try that for sure.

If it is DC on your mains, a blocker may help but it will need have your 555ps on the output of the blocker so to speak.
It will not work connected to your TV.
The blocker will remove DC offset from the input and provide pure AC on the output. It won’t work the other way round.

I’ll admit I don’t really know what a DC blocker is :blush: …but I think you worked that out :relaxed::joy:

I was just basing this possible solution in the TV being the “prime suspect” and thinking that it was dumping DC back onto the mains (which seems to be a cause of buzzing - and is certainly something the “non buzz” ISOL-8 blocked) and that a DC blocker in-line might kill that.

I’m not up for putting anything on the Naim mains - so I’ll need to come up with another solution. Maybe moving the TV mains to another circuit will do it.

A blocker may well cure your problem.
I use one and it is excellent.
The blocker needs to be filtering power for the buzzing unit, not filtering from the suspect appliance.
Audiolab do a blocker for not too much money.
You could always order one, try it and return if it doesn’t work for you.

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Hi Matt,
I have a D.C. offset problem with my incoming mains supply. The cause being someone else on same phase running some noisy electrical item. I first noticed it when I had a XPS DR power supply and also on the power supply for the 300 DR. When I changed the XPS for a 555 DR power supply, the noise level increased to a level that was not acceptable. I sit very close to my Fraim, when listening to music. I already had a Musicworks distribution block, so fed this with a MCRU D.C blocker. That cured the excessive power supplies noise problem. The noise was reduced to a level which you could reasonably expect on two very big power supplies. As for the effect on the Naim pre and power units, well I could not detect any noticeable difference.
I have a 50” Sony LED and a 55” Panasonic OLED TV’s. The Sony runs on a external and the Panasonic runs on a internal power supply. I know neither of these produce any adverse effect on my mains. If the Sony runs on a external supply, is there any chance of swapping this out with another one?

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That’s super interesting - I know David Brook from MCRU - and the idea of having one inline into the MusicWorks is very appealing.

I’ll reach out to him and see if he has one I can perhaps try, both from a buzz point of view, but also of course from sonics, although it’s great to hear you detected no discernible difference so that bodes well.

I notice David also does a “proper” power supply for the Roon Nucleus, so I will likely try that in time too :blush:

It’s internal alas. I’m this weekend going to try a temporary lash up to see if that helps.

Try and get a white picture on the TV. This will be maximum video signal and could possibly lead to a different fault diagnosis.

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Yep - definitely worse when there is more white.

I’ve spoke to MCRU, they are made to order but they are happy to refund if it doesn’t do the job…but more testing to do on the TV Mains location, but chances are I’ll get one ordered tomorrow :+1:t2:

I would suspect the TV either has a design flaw or has developed a fault. I guess this would be hard to prove with a 80 inch TV by substitution, with a internal power supply. How long have you had it? Did this noise on the Naim exhibit itself from purchase of TV?

It’s 85 inches :woozy_face::joy:

The TV is quite new - maybe 18 months maximum. It’s odd that it has such a dramatic effect on the Naim buzz - so yes, it could be a fault, but I think more likely a design flaw with the power supply.

Hopefully just powering the TV from another circuit will sort it, failing that the DC blocker inline will be where I’ll go!

Oh Matt,
If I had a pound for every time a fault diagnosis turned out to be something else than the bleedin’ obvious. Well I might not have a 500 system, but would be well on the way to it. My experience with past Sony TV power supplies are they overly complex in there design, to the point of being over engineered. Had one power supply in a Sony TV which had developed a fault elsewhere in the circuitry. The power supply protection should have cut in, which eventually it did, when the power supply had half destroyed itself. :bomb:
Obviously, getting to test another TV in situ would not be easy. Could you take the 555 to someone else who has one or a local Sony retailer, especially if TV is still under guarantee. It is a pity you are not near me, as you could have borrowed and tried my MRCU DC Blocker.
What niggles me, is how the problem gets worse with a white picture. I would have expected Sony to pick this mains noise problem up in development of the TV. My gut feeling is that a slight fault has developed in the power supply or video card.
But then again, what do I know…………there goes another pound to my 500 fund :grinning:

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