Major radio interference from Topping equipment

[AshleyC25]

Hi all, long-time lurker, first-time posting. I run a system heavily based on objective performance. Hypex amps, Topping A90D / D90LE etc. It's the D90LE that is giving me trouble. I have a DAB tuner in the system (I'm in the UK) and the D90LE seems to give off a huge amount of radio frequency interference, that completely kills the tuner signal on DAB, FM and AM. I've tried disabling Bluetooth, thinking that might be the cause, but nothing changes. Switching the power socket to which the tuner and DAC are connected does help somewhat, giving me some kind of signal on the tuner - but it's garbled and unlistenable. I've gone through everything in the system and confirmed that it's the DAC that is at fault. The A90D also gives off a reasonable amount of interference, though it's not enough to stop the tuner in its tracks.

Has anyone else experience this with Topping equipment? I note that they now use switch-mode power supplies, but I thought they were supposed to be decent modules from Meanwell which should have RFI under control. Perhaps this is a test that Amir could add to the standard suite of tests, to see if equipment is well guarded against injecting RFI into the power lines or just radiating it from the case. Any input, solutions or general thoughts very welcome, as this is driving me mad. I did reach out to Topping but I find their responses to be quite hit and miss, and I did buy the D90LE second-hand. It works great aside from this issue.

 

[Dunring]

I've had the Topping D90SE twice and didn't notice anything, and this office is loaded with stuff so it would have been obvious. One time I used a Faraday cloth on another project, and it really works, but it's laced with metal thread. It's conductive, and you have to be a little careful. Have you tried turning it on without anything except power to see if it does the same thing to narrow it down, and without the bluetooth antenna screwed on? If it's zapping the FM/AM bands there's an issue, in the U.S. that would never get FCC approval and the two I had didn't have it. I keep a clock radio here playing a lot to hear latest news and it would have messed with it for certain.

 

[RayDunzl]

I'd try some ferrite clamps on the power cord, since I have it in the junk box.

Recently. in my glider, a 12V to 5V USB power converter was making my handheld radio (118 to 136Mhz ) be almost unusable. I had to turn the squelch very high to stop idle noise.

Ferrite on the power wire cured the trouble. It reduces RF travelling from the noise source through the battery wiring - reducing the antenna effect.

Examples:

ferrite clamps - Google Shopping

www.google.com

 

[Speedskater]

Jim Brown is the retired AES go-to expert on interference. He has lots of interference papers and Power Points on his site:

Audio Systems Group, Inc. Publications

 

[usersky]

I bet these Topping radio interferences sound like music to @restorer-john

 

[Somafunk]

I have a DAB tuner in the system (I'm in the UK) and the D90LE seems to give off a huge amount of radio frequency interference, that completely kills the tuner signal on DAB, FM and AM. I've tried disabling Bluetooth, thinking that might be the cause, but nothing changes.

I fitted a garmin dash cam to my VW Tiguan and ran the power wire round the headlining and into a spare fuse box socket then found the Dab radio suffered from interference, bought a few ferrite cable chokes of different frequency specifications from Amazon (very cheap) and found one that totally cured the problem, for maximum benefit I clamped it round the cable as close as possible to the dash cam.

One of these, if the power cable feed to your topping is very thin then wrap it through the choke a few times