[AudioI] "Tck" sound between tracks

[Matt Flax]

Referring to the ALSA SoC driver for the Pro and Isolated Audio Injector 
soundcards : 
https://github.com/raspberrypi/linux/blob/rpi-6.1.y/sound/soc/bcm/audioinjector-isolated-soundcard.c#L57-L75

The mute relay is operated as part of the _trigger ALSA function calls. 
it is possible to find a better place to put them. Perhaps digital_mute ?

That would require some experimentation.

What is absolutely fundamentally important is that the mute relay 
remains off, while the dirver loads - otherwise there is spurious 
startup noise which can be absolutely terrible.

About pops and clicks ...

In the XLR preamplifier hardware there are no AC coupling caps. This 
means that any DC voltage on the input from any of your sources can make 
their way through the system to the output.

Out of interest, how loud is the pop or click on playback start ?

Matt

On 15/2/24 01:16, Iain Mott via People wrote:
>
> There doesn't seem to be an option to disable auto-mute in alsamixer, 
> unfortunately. A box would be to reduce the noise made by the relay 
> itself (acoustic noise), not the noise in the speakers.
>
> Iain
>
> Em 14/02/2024 08:41, jr52884--- via People escreveu:
>> Matt,
>>
>> Isn't there an option to disable that in alsamixer? I don't remember. 
>> I don't have one in use to check.
>>
>> Iain,
>>
>> I doubt putting it in an enclosure would help as the relay transient 
>> is present on your audio line. There may be an option to disable the 
>> auto mute in alsamixer, but I don't remember.
>>
>> Jonathan
>>
>> On Tuesday, February 13, 2024 at 03:52:40 PM EST, mott via People 
>> <people at lists.audioinjector.net> wrote:
>>
>>
>> Ah, so it is. But there is also a transient heard in the speakers. 
>> Not so loud and more of a pop sound. I'll look into boxing the 
>> pi/audio injector to reduce the relay noise.
>>
>> Iain
>>
>>
>>
>>
>>
>>
>>
>> Enviado do meu Galaxy
>>
>>
>> -------- Mensagem original --------
>> De : mott via People <people at lists.audioinjector.net>
>> Data: 13/02/2024 16:54 (GMT-03:00)
>> Para: people at lists.audioinjector.net
>> Assunto: [AudioI] "Tck" sound between tracks
>>
>>
>> Hi,
>>
>> I've been using the Pro card with the XLR preamp on a Pi 3b to listen 
>> to Qobuz and Tidal streaming services by way of the Logitech Media 
>> Server (LMS) running on the same computer. My system has never 
>> sounded better. There's a quiet but noticeable "tck" sound, however, 
>> when a track starts,  when "stop" is pressed on the LMS interface and 
>> sometimes two tcks are sounded between tracks.
>>
>> It's not a big problem, but I thought I'd mention it. It never 
>> happened with the old audio injector stereo card. I've tested the 
>> streaming with LMS's standard web interface and also with an Android 
>> app called Squeezer.
>>
>> Cheers,
>>
>> Iain
>>
>>
>>
>>
>>
>>
>>
>> Enviado do meu Galaxy
>>
>>
>> -- 
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>>
> -- 
> _______
> Iain Mott
> https://escuta.org
>
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