On Sunday, 14 January 2018 16:49:17 GMT Andrew wrote:
> Ideally you want a balanced audio output. I would give you a link to the
> USB to XLR audio device I bought many years ago, but I can't seem to
> find them any more! There's lots around with a single input but the one
> I got has two inputs and two outputs.
> There is this for the Raspberry Pi, however I'm not sure if you can have
> more than one on the same machine:
>
> https://www.hifiberry.com/shop/boards/hifiberry-dac-pro-xlr/
>
> Then you'd need a balanced amplifier and cables, and that should get rid
> of any hum at all.
We looked at these devices before we went with the solution that we chose.
The problem is that they cost significantly more than the Raspberry Pi itself
and an order of magnitude more than the USB Audio Adaptors. Also, we're not
looking for HiFi, just a reasonable rendition of organ music and bells.
I haven't given up with the hum problem, but the two USB adaptors solve the
problem perfectly; as long as someone is there to iteratively discover which
adaptor has been attached to which channel. Not a practical proposition of
course in a system runs 24/7 and has to cope with the odd power cut.
> I think you want 'aplay -L', not 'aplay -l'. Then you'll see the device
> names, something like "plughw:CARD=Device,DEV=0".
>
> From the man page:
>
> -l, --list-devices
> List all soundcards and digital audio devices
>
> -L, --list-pcms
> List all PCMs defined
>
> -D, --device=NAME
> Select PCM by name
I have used both aplay -l and aplay -L, but neither help. Here is a couple of
segments from the relevant output for the two devices:
<Start>
<First>
sysdefault:CARD=Device
USB PnP Sound Device, USB Audio
Default Audio Device
......
plughw:CARD=Device,DEV=0
USB PnP Sound Device, USB Audio
Hardware device with all software conversions
<Second>
sysdefault:CARD=Device_1
USB PnP Sound Device, USB Audio
Default Audio Device
front:CARD=Device_1,DEV=0
....
plughw:CARD=Device_1,DEV=0
USB PnP Sound Device, USB Audio
Hardware device with all software conversions
<End>
As you can see, the only difference between the two entries is the _1 after
Card=Device. That doesn't tie up with the ID Numbers in lsusb either.
Of course, if I knew the name of the device that was connected to the channel
that I wanted, then aplay -D might be useful..... :-)
--
Terry Coles
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