Power supply hum

[tarantina5555]

good morning everyone. First of all I wanted to wish a happy Easter to the friends of the forum who are always available and friendly.
I have an annoying problem with my naim power supplies, XPS/2 DR, and HICAP DR. Both emit an annoying buzz.
They tell me to try various solutions, one of them is the DCblocker in the plus version. What do you think? cordially

[CliveB]

Have you read the post on transformer hum in the FAQ topic?

[tarantina5555]

no where can I find it? sorry but I’m not very familiar with the forum

[Steve57]

Transformer hum

From the Naim Amplifier manual: A hi-fi system usually shares a mains circuit with other household equipment some of which can cause distortion of the mains waveform. This distortion can in turn lead to mechanical hum from mains transformers. Some Naim transformers are large in size, making them relatively sensitive to such distortion, and it may be necessary to take account of transformer hum when siting your equipment. Transformer hum is not transmitted through the speakers and has no effect…

Hi, this should assist in finding a cause / possible mitigation factors. There are several similar posts on the forum. Good luck!

Alternatively “Transformer hum” in the forum search bar will open up a fair few discussions.

[Mike-B]

Hi @tarantina5555

Does your hum vary in tone or volume at different times of day.
It it does, it’s most probably caused by so called DC on the power supply (actually it’s asymmetric AC wave form distortion). A DC block filter will probably help in that case.

If it’s a constant and unchanging hum, it most likely a naturally noisy transformer, maybe not helped by a high AC voltage. A DC filter might help, maybe bring a subtle change in wave form, but no guarantee.

[DiggyGun]

I have previously used the iFI DC Blocker to great effect without it being detrimental to the SQ.

DG…

[Thegreatroberto]

I use the iFI DC blockers too on my 555psu and Supercap. Never noticed any drop in SQ.

[Blythe]

I’ve nearly always experienced transformer hum in all 4 UK houses I’ve lived in since owning Naim equipment.
All power amps and power supplies always hum, some times changing in note in my current house, (in a remote rural area) so I guess DC is the most likely cause.
I guess I’d need to buy one DC blocker for each noisy component - 6 in total; XPS2, Supercapx2, 250x3 is that right?

[Thegreatroberto]

Id start by buying one and see if it helps.
There are often a few on sale on ebay. Think i paid £85 for my last one.

[Blythe]

Thanks - good idea to try one first!

[bruss]

I use an ATL dc blocker with two outlets. I then run power blocks from these outlets.

[DiggyGun]

One option is to use an extension block, with a DC Blocker on that plug.

DG…