Solutions for interference issues

[nuyorican]

Morning all.

I have two separate issues with interference into my Hi-Fi audio. Thought I’d post up both of them and see if anyone has any ideas on how to best deal with them.

The first is my beer fridge/freezer in my music room. When its motor kicks in, or off, it causes a ‘blip’ in the audio. I know I could just get rid of the freezer but any other solutions?

The second is related to laptop power supply. I have a windows laptop (doesn’t happen with Mac, different kind of PSU apparently). That whilst the charger is plugged in, will cause significant noise into the audio stream. Fine when on battery.

Historically, in a pinch, one could disconnect the ground in the plug or cover the earth prong with tape. But looking for something a bit less, well, I dunno, safer? I’m no electrician, but disconnecting earth wires doesn’t seem very practical in the long term.

[Lucid_AV]

Beer fridge - you need a suppressor (a capacitor) fitted across the power connection to suppress the mains spike.

With main fridges, they come with one fitted. Over time they lose their effectiveness, and so a replacement restores silence.

A beer fridge should be built to the same standard, but, you know. Check first if it has a suppressor capacitor fitted. If so, look at replacing it.

Alternatively, Russ Andrews (I know, I know) has a kit. This is I think the only time I've ever seen something sold on their site cheaper than the going rate. £12 according to the Web page. You also get to return it if it doesn't work, I think.

https://www.russandrews.com/vdr-contact-suppressor...


For the switch mode power supply on the laptop, it's radiating RFI, and that's being picked up by the line level interconnects which have inadequate shielding. Because this is low frequency noise the cable shielding needs to be better than just foil. Also, any cable just listed as 'shielded' will have the bare minimum which isn't enough to deal with the noise from your PSU.

Tge gold standard for shielding is this RCA lead non eBay. Item number 233923936822. Forget your fancy Audio Quest or Van Den Hul and even QED. This one is the daddy.

Have a think about replacing the PSU if the one you've already got is an aftermarket item. But if it's the genuine article, then those eBay leads will give the best interference protection.

[OutInTheShed]

As above, you can filter the mains both at the fridge and at the hifi.

Radiated pick up can be improved by better shielded interconnects, moving things, different PSUs etc etc.
At one point I found using optical output from my PC was the answer, now it's fine on wired output!

RF interference can also get into some amps via the speaker wiring.
I have two supposedly identical Arcam amps, one has RF suppression caps on the speaker terminals inside.
You could try ferrite beads on the speaker wires?
Maybe move them to see if the effect changes?
Twisting the speaker cables can help.

Unfortunately a lot of 'classic' hifi was designed before the days of EMC standards and the world being awash with noise.
I have worked with getting products through approval, sometimes it takes a bit of work to understand how problems occur.

Dark Art sometimes!
(Some engineers would like their customers to believe that!)

[nuyorican]

Thank you chaps.

[FMOB]

OP, if you aren't familiar with mains electricity the last thing you should be doing is modifying the mains input of something like fridge.

There are no reviews for the kit, one can only assume no one lived to tell the tale.

[nuyorican]

Indeed.

I did look at the kit but decided it was beyond my skill level to install. So for now I've plugged the fridge into an extension and plugged it into another room which has fixed the issue.