Crackling Noise while Airplaying with Airport Express

The Airport Express frameware is up to date.

The later firmware is known to be buggy.. If you are on the Gen2 Express I would go back to 7.6.8 and see if that fixes the problem.

To downgrade firmware hold down the option key while you select the number on firmware.

It seems to me that the issue is more of an Airplay (or software issue) rather than hardware

That is why LaPastenague suggested rolling back the firmware (software) on the AirPort Express. If the problem were simply AirPlay in general, then all AirPlay devices would be affected, including the AppleTV as well......and we would have a flood of posts about the issue on the forum....which has not occurred.

Personally, I have experienced the same kind of "crackling" or "popping" sound on an AirPort Express here, and the issue was solved with a replacement AirPort Express.

To add a bit to the other excellent comments, I have observed that a "crackling" noise when streaming to an AirPort Express can sometimes occur if the Express is not well grounded ... or, as the others mentioned, the base station itself is defective.

AirPlay consists of a number of IP protocols for streaming. As such, they either work or streaming does not occur. Missing any one of these protocols would not lead to introducing this noise. However, poor connectivity between the host and the base station could reduce bandwidth and potentially cause data loss. The actual audio streaming is done over UDP, which is a connectionless protocol. UDP does not correct or recover from errors. Any error detection and recovery is the responsibility of the receiving application ... so poor bandwidth can lead to poor audio quality.

The most up to date firmware on the Express is 7.8.1. If you rolled back the firmware, that would have been back to 7.8, which has been more stable in my opinion than 7.8.1.

Are you saying that both 7.8.1 and 7.8 exhibit the noise issue?

Yes, the noise is subtle, but not hard to pick up with headphones plugged directly into the Express and the volume up to reference levels. I can't help but mention again that a replacement AirPort Express solved the noise issue here, but there are never any guarantees on issues like these.

For what its worth, my two AirPort Expresses(es) are wired back to the main router using Ethernet connections, so I'm not using WiFi with the Express devices.

But, I’m afraid that I should stick to Airplay 1, with the old firmware!

The Gen2 Express was released in 2012 long before Airplay 2. It was a major surprise when Apple released firmware to allow such an old device to be upgraded. However it was far from a success with most people reverting to earlier firmware and Airplay 1.

I am not sure where the problem lies.. your testing is interesting in your

My new Music streamer (Bluesound Node 2i) has the same crackling noise when using Airplay 2

why there is no noise with AppleTV when using Airplay 2?

Apple TV is NOT even related to the Airport.. it is iOS development using the iPhone A5 chip. The Express is based on NetBSD and is Atheros Qualcomm chipset with extra DAC etc. The bluesound device is outside my experience.. but interesting that issue is also there.

Apple abandoned the airport line and were not prepared to put more time and effort into fixing the issues.. the whole iOS line of products is far more important to Apple and their big money spinner.

Tesserax made interesting comment about the earthing.. I have to admit to being too old (too deaf) to worry overmuch about digital sound.. but as old analogue hifi guy who built amplifiers and speaker systems for 40 years.. earthing was one of our big hassles. Earth loops made everything difficult. The express of course is not grounded unless you use 3.5mm analogue stereo plug to a grounded amplifier. Do you use optical output to the Yamaha amp, or 3.5mm stereo. It would be interesting to swap whichever you use. I would put oscilloscope on the output and run it with a signal generator.. but I am clueless how they solve noise issues in digital systems.

Bob also seems to have found the Airport Express was actually faulty.. which is also interesting.. as they age the power supply will deteriorate and could cause issues. I have seen people use them with battery supply which will really help kill the noisy power supply issue.

Apple of course want you to buy an airpod so I expect it will have no issues with Airplay2. Considering the cost of the item with a 2" speaker.. perhaps you cannot hear the noise even if it was there.

For the sake of argument, let's say the issue is 7.8 or 7.81 firmware. How likely is it that Apple will ever issue another update for any of the AirPorts?

So, if you don't want to try another Express, or you are convinced that another Express will behave the same and you need AirPlay 2, then your only real option here would be to replace the Express with an AppleTV,,,,,.if your amplifier will accept an HDMI input. Or, maybe a HomePod, if it has an HDMI output jack.

The Apple TV uses a completely different operating system......(iOS11 last time I checked).....and different firmware.than the AirPorts, not to mention different hardware.

The hardware design on the AirPort Express is at least 9+ years old.

If the firmware rollback does not help, I'm afraid that the issue is that you simply have a defective AirPort Express.

New, refurbished and used Airport Express(es) are available on Ebay.