Wi-Fi Interference

[springwood64]

I recently encountered an issue that I'm now surprised I've never come across before.

To summarise, my Amplifi mesh point or router generated interference that was audible through the system when set to high volume. It was a pulsing hum that is mostly in the low frequencies. I've seen it described as a motorboat or helicopter noise, and I think that's quite apt.

It was intermittent in intensity, most of the time very hard to hear, but caught my attention when it was suddenly loud. I thought initially it was a fault with the phono preamp, but later established it could be picked up by an amplifier alone.

At the time, the Amplifi mesh point was 20cm from the phono preamplifier, on the same rack but a couple of shelves below.

I have reduced the level of the interference to below audible by moving the mesh point off the rack, and now it's about 0.5m from the phono preamp.

[matthias]

Pete,
just for clarification:
You heard it only via LP12 and not via Källa?

[springwood64]

With Boazu as amp and Slipsik as phono, I heard it only via Slipsik. It was not audible on any other input. It was also not audible with zero connected to Boazu.

However when I swapped Boazu for an Arcam Alpha 6 integrated amp, I heard it on all inputs, even with nothing connected, and loudest on the Arcam's MM phono stage.

[matthias]

I have reduced the level of the interference to below audible by moving the mesh point off the rack, and now it's about 0.5m from the phono preamp.

So it seemed to be caused by electrical interferences with the Amplifi and not by the wifi radio per se.

[tokenbrit]

I have reduced the level of the interference to below audible by moving the mesh point off the rack, and now it's about 0.5m from the phono preamp.

So it seemed to be caused by electrical interferences with the Amplifi and not by the wifi radio per se.

They're both electromagnetic, aren't they, whether intended (wifi) or unintended (interference)? Moving the mesh point off the rack only eliminates electrical interference if you change where the mesh point is plugged in with respect to the hifi...

[matthias]

Just from my gut feeling I would use the 2.5m lenght of the ethernet cable to have some distance of the mesh point to the devices in my hifi rack.

[springwood64]

I didn't change where the router is plugged in - I just changed its location. Note that I get the same effect with both Amplifi HD and Amplifi Alien meshpoints/routers

My rack is in an alcove, so that limits how far away I can place the meshpoint.

[tokenbrit]

I didn't change where the router is plugged in - I just changed its location. Note that I get the same effect with both Amplifi HD and Amplifi Alien meshpoints/routers

My rack is in an alcove, so that limits how far away I can place the meshpoint.

I expect things sound (much) better having managed the wi-fi interference. Curious if you feel you lost anything from moving the Amplifi off the hi-fi rack; whether the Amplifi is (particularly) sensitive to the surface it's on to perform at its best? Maybe your Boazu upgrade sounds too good to notice :)

[springwood64]

I expect things sound (much) better having managed the wi-fi interference. Curious if you feel you lost anything from moving the Amplifi off the hi-fi rack; whether the Amplifi is (particularly) sensitive to the surface it's on to perform at its best? Maybe your Boazu upgrade sounds too good to notice :)

Too many changes at the same time to make that assessment, unfortunately. The Alien that replaced the Amplifi HD is too bulky to fit on the rack so I can't test it. You are right in that the Boazu upgrade is the dominant effect.

[tokenbrit]

Too many changes at the same time to make that assessment... You are right in that the Boazu upgrade is the dominant effect.

Thanks for advising of the potential problem & fix - something to listen out for. Congrats on the upgrade.

[springwood64]

I encountered another form of interference.

I was experiencing frequent interruptions to the music with the Aliens in place. I have 3 5GHz WiFi networks, so I configured the Aliens to use the DFS channels (see below) and increased the bandwidth to 160MHz. This eliminated overlap between the 3 network's groups of channels.

Screenshot_20250222-175551.png

However, I noticed a significant harshness, making anything above moderate volumes quite unpleasant to listen to.

This harshness affected all inputs: Källa, LP12 and TV.

In the end I eliminated one of the other 5GHz networks, returned the Aliens to lower channels and split the two 5GHz networks evenly with bandwidth of 40MHz each. I also moved the Alien mesh point as far from the hifi rack as possible. This seems to have eliminated the harshness and solved the drop outs.

[matthias]

One question:
Why is "Automatic" enabled for 5GHz but not for 2.4GHz?
Thanks

[springwood64]

I had to select the channels for 2.4GHz to stop the different networks from overlapping channels. The 5GHz band seems to successfully auto select to avoid conflicts

[matthias]

IMO, a high MCS Index is a good parameter for optimising the Wi-Fi transfer.
My Macbook gives info about some parameters:

TuneDem2204:
PHY Mode: 802.11n
BSSID: 8c:6a:8d:7f:c0:c8
Channel: 11
Country Code: DE
Network Type: Infrastructure
Security: WPA2 Personal
Signal / Noise: -61 dBm / -91 dBm
Transmit Rate: 145
MCS Index: 15

The MCS Index is quite high (15), maybe the Alien is able to show MCS Index as well.

[springwood64]

These are the values for the two 5GHz networks. The Aliens are 'hifi':

Screenshot_20250224-074626.png

Screenshot_20250224-074646.png

[springwood64]

This is how the channels are distributed:

2.4GHz

Screenshot_20250224-074729.png

5GHz

Screenshot_20250224-074737.png