[AudioI] "Tck" sound between tracks

[Iain Mott]

My apologies. Yesterday, I had ssh'd to the wrong Raspberry Pi, so I was 
actually looking at the audio-injector stereo card on a different device 
and not the Pro/XLR. It's too early in the morning to test, but if 
auto-mute is disabled in alsamixer, does this mean that the start up 
noise you mention will be heard as the driver is loaded?

The pop in the signal is not loud. It's less loud than the relay "tck", 
but it's audible. I actually purchased the RCA pre in addition to the 
XLR pre and will use the former with my stereo system (will use the XLR 
board for other things), however the RCA board is stuck in customs and 
that's why I'm using the XLR. There are no devices attached to the XLR 
board's inputs. I can't see a way to mute the inputs in alsamixer. The 
master control seems to be shared by playback and capture.

Iain



Em 14/02/2024 21:47, Matt Flax escreveu:
> 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
>>>
>>>
>>> -- 
>>> People mailing list
>>> People at lists.audioinjector.net
>>> https://lists.audioinjector.net/mailman/listinfo/people
>>>
>> -- 
>> _______
>> Iain Mott
>> https://escuta.org
>>
-- 
_______
Iain Mott
https://escuta.org