Downgraded Airport Express firmware to 7.6.9, simultaneous multi-room audio still works

[EugW]

I have a few A1392 Airport Express units which I bought used to get multi-room simultaneous audio support. I updated them all to 7.8.1 immediately when I received them. In my home office I play from iMac to the AE at the stereo for background music, but when manually switching tracks I often get a split second crackle and then it plays fine after that. As long as I don't manually switch to another track I don't get the crackle. It only happens when I switch it myself in the iMac's Music app. I tried analogue, and it's still there, not just over optical.

I read online this was introduced at 7.8 and not fixed in 7.8.1 and that downgrading to 7.6.9 fixes this. So, I decided to give up multi-room to get rid of the crackle and guess what? The crackle is gone AND simultaneous multi-room still works. I had thought this latter feature was restricted to AirPlay 2, no?

Note that the "Office Stereo" has a red notification, which means it has an available firmware update, because it's now on 7.6.9, but you can also see that it's playing simultaneously with another 7.8.1 AirPort Express (South Speakers) and with my iMac (Computer).

So far so good. I haven't heard the crackle anymore. If it makes any difference, my iMac is on Big Sur. The other difference is at east with my Computer and Office Stereo, with this setup there is no instance so far where the audio has gone out of sync. That's happened before when Office Stereo was on 7.8.1. Also, I had the old A1084 AirPort Express and I could definitely not do multi-room with those. I could only select them individually from the Music application.

I read on reddit that AirPlay 1 is a real-time streaming protocol whereas AirPlay 2 is a file-transfer protocol. I don't know how this affects things.

WWDC17 - Videos - Apple Developer

developer.apple.com

 

[EugW]

Hmmm...

This may be old news to some of you. According to that reddit thread, if you play from iTunes (or Music), it was mentioned by one member that multi-room audio already worked fine on recent AirPort Expresses with AirPlay 1. However, I had tried this with my original A1084 AirPort Express units and it simply didn't work. The Music application never let me choose more than one of them at a time. However, I had never tried this with my last gen A1392 AirPort Express units with older firmwares. As mentioned, I had immediately updated the firmware when I received them.

I've been doing more testing and I can confirm the multi-room audio support with the 7.6.9 AE only works with the iMac's Music app. If I try to do this from iOS 14, it doesn't work. The other 7.8.1 AE units will play together simultaneously, but won't work with this 7.6.9 AE. When I choose that 7.6.9 AE, it shuts off the other AE units.

So, I guess the advantage of AirPlay 2 is not that it supports simultaneous multi-room audio. It's that it supports simultaneous multi-room audio when you are playing from a mobile iOS/iPadOS device.

BTW, in the linked video the explanation of the AirPlay version differences starts at 7:28.

AirPlay 1: Real-time stream, with a few seconds of buffer.
AirPlay 2: Faster than real-time streaming to speakers to create minutes worth of buffer.

The touted advantage is that AirPlay 2 reduces the chance of audio dropouts due to network stalls and it also allows for quicker restarts of paused music. The thing is though with my usage for playback from my Computer to my Office Stereo, it's rare for me to get audio dropouts on AirPlay 1, probably because my AirPort Express units are hardwired via Ethernet. Furthermore, when starting new tracks, it appears to be a bit faster to start on AirPlay 1 than with AirPlay 2.

So, what I will do will be to leave those other AE units at 7.8.1. They supply the in-ceiling speakers in the house. Low quality, but fine for the radio or quiet background music when guests are over. However, I'll keep this one Office Stereo AE at 7.6.9 for when I work. I can play music from the iMac's Music app with no crackles at the beginning of a stream and even simultaneously play music from the Computer and the Office Stereo if I want, with good audio sync.

tl;dr:

AirPlay 1: With some hardware it already supports multi-room simultaneous audio, but only if you play from a Mac. No crackles. Audio sync seems to work well. This doesn't work from an iOS device however.

AirPlay 2: You can have multi-room simultaneous audio, even from an iOS device, but you may get audio glitches when starting a track (at least in my case from my Mac). Audio sync may be problematic.

 

[oryan_dunn]

I recently picked up a couple of these A1392 for Airplay 2. I immediately reset and upgraded to 7.8.1 and all seemed to be working fine. However, I streamed some relaxing piano music while I was working today, and that's when I heard the crackling. I started looking for what the issue could be, and eventually wound up on the AEs. I tested both the analog and digital out, and it happened on both. Some searching later, I found numerous complaints, and that downgrading to 7.6.x would fix it (at the cost of Airplay 2). I downgraded, and they sound fantastic now. But, I'd like to still have Airplay 2. On some other threads, it seems that maybe later builds don't have an issue with Airplay 2, since some people didn't seem to have the issue. I'd love to get a late built model to test.

Since it's been almost 2 years since 7.8.1 was released, probably no hope that Apple will address this issue. It's a shame, as I suspect that as time goes on, more and more of these units are essentially used as a Chromecast Audio of the Apple world, so it'd be nice if that feature could at least work correctly.

 

[Arctic Moose]

I have a total of ten (plus two spare) AE units that I use exclusively for Airplay 2, with both analog and digital outputs. Networking is disabled, i.e. they are only audio receivers, and in most cases wifi is disabled altogether since they are connected through Ethernet.

I have never noticed any crackling noise. Is it so obvious that you couldn't possibly miss it if you have this issue?

 

[oryan_dunn]

I have a total of ten (plus two spare) AE units that I use exclusively for Airplay 2, with both analog and digital outputs. Networking is disabled, i.e. they are only audio receivers, and in most cases wifi is disabled altogether since they are connected through Ethernet.

I have never noticed any crackling noise. Is it so obvious that you couldn't possibly miss it if you have this issue?

Mine are setup as audio only receivers via wifi. I didn't notice the issue until I played a solo piano track. But it was there every time, in the exact same spots, and is super noticeable.

I noticed right away on the first song of Apple's "Piano Chill" playlist, which is "Wrecking Ball (Solo Piano Version) by Stephan Moccio".

With rock or pop via speakers, you probably wouldn't notice. Solo piano via headphones, can't miss it.

 

[EugW]

I’ve read about the crackling noise but had not noticed that (yet). I’d probably have to do more critical listening via headphones because most of my listening was as background music via inexpensive speakers while I’m doing work at my desk.

My issue with the 7.8.1 firmware is different, a pop at the beginning of the track, when switching tracks. This likely indicates a loss of sync with the signal when switching tracks. Note though I hear this both with optical and analogue so it is not an incompatibility issue with my receiver. It’s appears to be a signal link issue with the 7.8.1 AirPort.

 

[Arctic Moose]

I noticed right away on the first song of Apple's "Piano Chill" playlist, which is "Wrecking Ball (Solo Piano Version) by Stephan Moccio".

I was scared to try. I can hear a slight pop once in a while when switching tracks, but not during normal playback.

 

[oryan_dunn]

I didn't mean to hijack this thread, but I'd like to try to figure out what's different. It could be a silent hardware revision, I'll get the date codes for mine when I get a chance. I'll also try connecting mine via ethernet. My source was an iPhone 12 Mini on 14.4.1 using Apple Music. I'll try iTunes on my Windows PC, and Spotify on my phone to see if either of those behave different. Notably I don't have a pop when I change tracks.

What sources are you guys using?

 

[EugW]

I was scared to try. I can hear a slight pop once in a while when switching tracks, but not during normal playback.

This disappears if I downgrade to 7.6.9.

Do you need the multi-room support controllable from iOS? If not, you may consider downgrading.

I didn't mean to hijack this thread, but I'd like to try to figure out what's different. It could be a silent hardware revision, I'll get the date codes for mine when I get a chance. I'll also try connecting mine via ethernet. My source was an iPhone 12 Mini on 14.4.1 using Apple Music. I'll try iTunes on my Windows PC, and Spotify on my phone to see if either of those behave different. Notably I don't have a pop when I change tracks.

What sources are you guys using?

Using my serial number, according to this page, my A1392 was manufactured November 2014.

WiFi turned off, running off Ethernet, and playing from networked iMac from Music application (formerly known as iTunes) in Big Sur. I think it happens with purchased AAC, self-encoded AAC, and with MP3, but I'd have to check more closely. A1392 firmware 7.8.1 gives pops, A1392 firmware 7.6.9 does not. Happens whether I use optical or analogue stereo to the receiver.

 

[oryan_dunn]

Ok, back with a few more test results.
My units were made in June 2014 and September 2015, so probably can rule that out.
I connected mine via ethernet, same exact behavior as on WiFi.

Now, here's where it gets interesting. I tried streaming the same songs via iTunes on my Windows computer. It was much much cleaner, and if I didn't know what I was listening for, I would miss it. I did find that I can hear the same crackling noise if I quickly fling the volume slider up and down in iTunes.

On the phone, it didn't matter if I used Apple Music or Spotify, both had the same crackling and it was very noticable... but only on some music. Some of the pop and synthwave I normally listen to, even with very critical listening, I don't detect any crackling. But solo piano, it's very noticeable. That particular piece I mentioned before isn't on Spotify, but "Natalie's Song by Wayne Gratz" (on an album called Whisperings - Solo Piano Vol 1) is on both, and also has plenty of crackling via both services. I also tested with my iPad which is also on 14.4.1 and it behaved the same as my iPhone.

If you have access to Apple Music or Spotify on an iOS device, try out streaming Natalie's Song.

This is a really strange issue, I looked in iTunes, and the songs that have issues and the ones that don't are all AAC 256kbps at 44.1kHz. Maybe there's something about the piano that brings out this issue, and far worse on iOS devices than iTunes.

Edit: Just to satisfy my curiosity, I tried airplaying these tracks to my Apple TV. No crackling at all.
Another test, playing this video via Youtube on my iphone and airplay to the AE, there's noticable crackling at the 50-52s mark, but also throughout on the louder piano notes

 

[Arctic Moose]

Interesting. Would you mind recording the crackling on Wrecking Ball and posting it?

This disappears if I downgrade to 7.6.9.

Do you need the multi-room support controllable from iOS? If not, you may consider downgrading.

Yes, and I also “need” the improved robustness of Airplay 2. I don’t switch tracks manually very often, and when I do this has never bothered me in the past. (Of course, now I’ll hear it.)

 

[oryan_dunn]

Interesting. Would you mind recording the crackling on Wrecking Ball and posting it?

I'll see if I can get something setup to record that. I tried using audacity once, and was quickly overwhelmed.

 

[oryan_dunn]

Edit: see updated post below for my recordings.

 

[Arctic Moose]

Wow, ambitious! I was thinking something along the lines of holding your iPhone up to the speaker.

I’ll listen to it tomorrow when there’s no offspring around.

 

[oryan_dunn]

Here are updated recordings. These were made using AE->Schiit Magni 2 uber (for analog volume control using the pre-outs) -> line in on my motherboard. I hope you're able to download these from OneDrive.
I had issues with the AE overloading the input to my motherboard, so once I fixed that, these recordings are what I hear. First is the song played via 7.6.9

Microsoft OneDrive

1drv.ms

And the second is the same song played via 7.8.1

Microsoft OneDrive

1drv.ms

This song is played via Apple Music on an iPad Pro 10.5 with iPadOS 14.4.1 and iPad's digital volume set to 100%.
Direct link to the song if you have Apple Music

Here is the clip from iTunes 12.11.0.26 on Windows 10, far less crackling, but it's still there

Microsoft OneDrive

1drv.ms

Inspecting the new recording in Audacity, I don't see the tell-tale signs of clipping, even in the 7.8.1 release, but you can definitely hear static. If it were clipping, I'd have expected the digital volume control to fix it, but even dropping it very low, and turning up my headphone amp, I still hear the static.

 

[oryan_dunn]

Wow, ambitious! I was thinking something along the lines of holding your iPhone up to the speaker.

I’ll listen to it tomorrow when there’s no offspring around.

I'm an engineer afflicted with the condition to go a bit overboard on simple things like this...

 

[oryan_dunn]

My normal use case would be to just start a playlist or album and not really jump around. To do this testing, I had been jumping around, and there are times I hear that loud pop. I think it's the last few bit of the previous song that's still in the buffer that play before the new track starts. It's like the buffer doesn't get cleared out correctly. It's not every time I jump to a new track, but it's more often than not. I'll leave mine on 7.6.9 for a while. I've not heard the crackling or the pop when switching tracks with the older firmware.

 

[Arctic Moose]

My normal use case would be to just start a playlist or album and not really jump around. To do this testing, I had been jumping around, and there are times I hear that loud pop. I think it's the last few bit of the previous song that's still in the buffer that play before the new track starts. It's like the buffer doesn't get cleared out correctly. It's not every time I jump to a new track, but it's more often than not. I'll leave mine on 7.6.9 for a while. I've not heard the crackling or the pop when switching tracks with the older firmware.

I finally got around to looking into this, sorry about the delay!

I could definitely provoke the pop you have at the beginning of ae_fw7.8.1_1.flac. Now that I am actively hearing it I am pretty sure it has been subconsciously annoying me, but I think I was attributing it to Apple Music, and not the Airport Express.

Now I will definitely scowl every time it happens, but Airplay 2 is worth enough to me that it is worth it, and besides, I do not skip around all that often, and when I do a pop after the skip isn't all that intrusive anyhow.