Hi everyone, happy new year!
It’s been a while since my last post, but considering comments on using dedicated access point it seems like a perfect time to share my findings. First, a bit of context…
I had a total rollercoaster with my WR902AC and wifi streaming setup. There was lots of joy, but also lots of anger and despair! I had two WR902ACs, one as an Access Point (stock firmware) and one as the client (openwrt) with Eric’s isolator and a throttle cable 3, feeding my PS audio junior DAC/streamer. The client WR902AC was powered by a xiaomi battery and streaming is done via a Roon ROCK NUC which is connected to ethernet in a room 15m away from the audio equipment. When everything was good, it was simply unbelievable how much of an improvement it was over an etherregen/network acoustics Eno combo…. the soundstage, the depth, the silence, the explosive dynamics and most of all a massive reduction of glare (Thank you Eric!).
BUT, there were hours when everything was just sublime and then suddenly it would become a disaster, the glare comes back, everything starts sounding brittle, and sometimes I would get stutters and dropouts. It was very discouraging, but after many months of tweaking and testing I have solved the issue and am posting it as it might be helpful for other forum members with similar symptoms.
If you sometimes have issues streaming high-res (192/24) content due to stuttering or drops, or feel that the sound changes while streaming to your WR902AC then read on …if not, go grab a beer and know that I am extremely jealous of you because you have a perfect wifi setup😊
Few months ago, I was listening to music and had the web interface of the access point WR902AC open. I was playing around with the access point signal strength and quite easily heard a change in sound. Originally, I had everything at the lowest setting but noticed that increasing the power made everything calmer and improved the bass response. I thought I was going crazy, but repeated the test the next day and noticed the same change in sound. Combining this experience with fluctuations in sound quality I assumed that a bad or an inadequate signal is making the client WR902AC work overtime causing additional noise in the signal. After switching through various 2,4GHz channels on certain days it was better and on others it was worse so I downloaded a WIFI Analyzer app for my phone. To my surprise, I realised that my living room is in a WIFI warzone! Only in the 2,4GHz spectrum I have 8 strong signals out of which 2 use 40 mhz channel width!
Considering this wifi chaos I decided to get a higher quality access point to be able to manouver through all this wifi chaos. Searching around the net I found the dejitterit web page (https://dejitterit.com/SwitchX/WiFiX.htm) where substantial work seems to have been done on identifying a quality access point for audio environment. Based on what I read on the page I decide to order a refurbished Aruba IAP 325. This access point has a steep learning curve as nothing is preset and it has tons of settings. After spending many hours on Aruba and Cisco forums I managed to get it to work properly.
The biggest benefit of this Aruba AP was that one can monitor the quality of the wifi transmission in much more detail than the standard signal strength and noise floor. What you can track is: frame per second THROUGHTPUT in both directions, frame per second RETRIES in both directions, frame per second DROPS, and frame per second ERRORS.
This was an eye opener as I saw a correlation between the RETRIES, DROPS and finally ERRORS with the sound fluctuations and stream dropouts. Even though, in the IT sector up to 20% frame per second (FPS) retries is considered normal, when it comes to audio streaming, trouble starts already at 5% retries rate where the sound starts becoming brittle and eventually leads to errors and stream dropouts. This makes perfect sense as Tidal, Qobuz, Roon all use TCP protocol as the transmission backbone and this protocol has zero error tolerance (no buffering like in Netflix or similar). I am not and IT person, but my assumption is that the sound fluctuates as the TP link is working overtime to put an error free stream together and eventually fails due to all the packet delays.
Since this revelation, I have only the TP link connected via wifi to the Aruba AP, have bought a fritxtender directioinal antenna, connected it to the TP link, found a 5 GHz channel that nobody uses in close proximity and with many, many tweaks in the Aruba AP, placement of both pieces for optimal signal, I managed to get zero RETRIES when streaming 44.1kHz/16bit, and less than 1% when streming 192 kHz/24bit (Tidal via Roon). Keep in mind that when streaming via Roon the files are uncompressed so it uses around 20% more bandwidth then when streaming direct from Tidal. To reduce interference, I am using a 20 MHz channel width and it gives more than enough speed for streaming. I did try the 40 MHz, and yes, it increased the speed, but it also made the signal slightly less stable. I even bought a second directional antenna to use in tandem with the existing one. It bought an extra 3db, but made it much harder to set proper orientation. Also, my conclusion is that the best sound comes from the channel with least interference. It does not matter whether it is 2,4 or 5 Ghz (the antenna power setting on my TP link is 6db on a 5ghz channel)
In summary, if you sometimes have issues streaming high-res (192/24) content due to stuttering or drops, or feel that the sound changes while streaming, my suggestion is:
1. Get a wifi analiser on your phone and find a channel nobody is using
2. Connect only the TP link client wirelessly to your AP (which should be on the channel not used by anybody)
If you live in an area without too much interference, these two steps could solve all the issues.
Hope this helps! And if there are any WFI/network engineers reading this, please chip in… this is all based on trial and error and hours reading up on workings of wifi.
Now I can finally start focusing on the power supply😊