Up2Stream I2S connection to Wondom amp - audio heavily distorted when in WiFi mode

I have connected anUp2Stream mini to the I2S port of a Wondom AA-AB32256 Amp. When I stream from bluetooth, I have good sound quality, but very heavy distortion when I use the Wifi mode. Also the automatic voice is heavily distorted. The distortion is on both channels and can also be heard when listening to the line output on the Up2Stream mini board.

Thinking that the problem was something to do with grounding or the power supply I physically disconnected the amp from the power supply. I still got a distorted sound on the line output.

However, when I disconnected the i2s cables to the - powered down - amp, the distortion disappeared (cable was still connected to the Up2Stream board). Reconnecting the cable brought back the distortion.

I am now totally flummoxed and have no idea how to proceed. Can anybody help here?

I have managed to solve the problem.

Eventually I suspected that the I2S inputs on the Wondom amp were capacitively loading the output from the Arylic board too much (better said the output from the wifi module).

I inserted a 74HC126 (powered with 3.3 V) between the Arylic board and the Wondom amp to buffer the I2S signals (including MCLK) and I was able to stream undistorted audio.

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Thanks. I will bookmark this solution.

hello adoble,
can you share how you connect 74hc126 with arylic i2s?
with the schematic maybe, thanks a lot.

Hi,

I did it like this:

I’ve since extended the circuit to function as an I2S multiplexer so that I can select a number of I2S sources and route them to the amplifier. If you’re interested you can find the details on GitHub.

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hello adoble,
thank’s for your reply and thank you for sharing the project,
so with this configuration the BT and WIFI plays with normal, and no more distortion?
btw that multiplexer is very cool project.

regards.
Peter

Hello Peter,

It worked for me.

But remember that was only for my particular situation with the Wondom amp and only with the Airlink mode ( bluetooth always worked). The Up2Stream board probably works OK with other amps without using a buffer and I would advise trying that first. However, if you do have a distortion problem with other amps this may be a cheap and quick fix, but I can’t guarantee it.

Cheers, Andrew

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Thank’s Andrew,
i will try it.

Hi Peter,

As I said the solution worked for me, but @Densagined has recently posted that it did not work for him. As the SNHC126 solution is quite cheap though, perhaps it is worthwhile trying that out first, but you may have to resort to a another solution.

Cheers, Andrew

Hi Andrew,
after trying everything i can eliminate the arylic i2s distortion
believe it or not, it not about the isolation or anything else
but it is about the android phone version, before i am using an old android 6.0 phone
and then i change into newer android 11 phone distortion go away forever
very clean and no more distortion with my new phone.
so my conclusion is arylic up2stream can not work with an old android phone.
i am happy with the sound now, with i2s into external DAC, much much better sounding now.

hope this can help another user too, at least try to connect with newer android phone,

regards,
Peter