Hi all
I have a hicap dr feeding a supernait 3 and I get occasional but annoying humming from it. According to Ai, a cure might be inserting a ifi silent dc power blocker between the powerline and the back of the hicap. It also suggests an audiolab dc blocker or a puritan conditioning power block. Has anyone tried any of these options or can suggest other remedies to buzzing naim power supplies?
There are a number of threads on this topic so well worth doing a search. While these DC blocking devices can indeed âfixâ the hum/buzz they do also come with a cost, a performance hit, so while a good last resort itâs usually itâs best to first try fixing the issue at source, particularly if itâs being caused by a device in your own home (fridges, freezers, anything with a heating element etc..).
Itâs also worth reading the FAQ on the topic which also provides an excellent summary and links compiled by @GadgetMan ;
I had him from my NC250 so I bought an iFi DC blocker. It completely cured the hum with no detriment to performance. They are not expensive so definitely worth a go
Guyâs Iâm sorry to be a pain in the ⌠but quality of mains input is paramount. We are lucky to live in a very rural area in Pembrokeshire with two neighbours and our non DR Hi Cap ( CB 1984 & 250 DR do not hum.
Appreciate that we are all not in the same position but probably given a more populated area etc that this can be an issue.
We had the same at our old place and after a a check and upgraded fuse box the hum definitely disappeared.
Worked a treat on my old Supercap 2 tooâŚ(tutu?)
I tried both the iFi and Audiolab DC-blockers. Immediately killed the humming, but⌠like Richard also mentioned, it can (and in my situation sure did!) have a negative effect on the sound. (lowering dynamics and making the sound very soft/dull) 
Itâs worth giving them a try I guess. Most people have positive experience with these devices.
Ive used ifi blockers and they worked well. I coukd not detect any sound detriment on my , then set up.
I put in a 6mm dedicated mains and that was enough to no longer need the ifi. Yes, good clean mains is the key, but if you cant get that ifi is the next step. These are often on ebay, so no need to buy new.
My office located in a huge flat with 10 other companies share the same electrical network and no hum.
Only time âit humsâ was because of a tiny refrigerator in my place, just like what Richard said.
For amp having such performance I think it worths find out whatâs actually humming, hopefully eliminating through better solutions rather than using hum blockers.
Not sure that I would know what to do if say that I found out that it was the freezer that was causing the buzz. It is only occasionally, so I imagine itâs linked to something. I live rurally so not a busy city flat scenario. Prior to having naim equipment I didnât encounter this issue, which makes me wonder, given the price of naim gear why it is an issue at all and couldnât it be engineered out?
Replacing a fridge would be cheap compared to what some spend on audio accessories. If itâs in warranty you would probably have a valid claim, as emissions are limited by regulation in most countries.
Many white goods have suppressers built in. If you were to identify the culprit, adding such a device to stop the emissions at source might be a better option than connecting something directly to the HiFi.
Try hair driers as the worst culprit.
In my past apartment, the Ifi dc blocker on the NC 250 reduced notably the hum. As Richard said, you canât predict what it will do for you. But itâs easy to buy and return, on Amazon or elsewhere.
âŚor electric blankets, or just about anything with a heating element inside.
Have a look at Russ Andrews products; they specialise in curing all sorts of mains issues. Best option, a separate circuit for your kit, although, that said, my 250DR hums like a pollen-loaded bumble bee most of the time, as do the 200 and 250.2 on the standard ring.
Thinking of trying the ifi silent dc blocker, but has anyone used one with a powerline going into a hicap. I ask because although it will clearly take a kettle lead , the powerline has a mechanism that grips the hicap inlet. Would it be a big trade off if it gripped the dc blocker which then went into the hicap. Any experience of this?
Sorry, no.
yes old style hair dryers were guilty because they used simple diodes/basic thyristors to produce half power - ie they asymmetrically consumed power on one half of the mains cycle producing a pseudo DC on the mains effect.. More modern product are sometimes more sophisticated offering more control and use TRIACs instead which symmetrically draw the load on the AC which causes no issues or very minimal issues.
I guess itâs hard to determine what product uses what. If it only has simple half power control then it might use basic thyristors or diodes and an asymmetric power draw⌠and produce pseudo DC on the mains when on half power.
Some other legacy heated products used similar methods