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New FIFO buffer for RPI/SBCs

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S

Skip Pack

Member
Joined 2004
I want to be very sure I'm powering my newly arrived Isolator correctly. Is there a difference other than connectors between the power jack input and the battery input pins. I expect to use either batteries or a supply with greater than 5 volts and want it to power the Isolator board and the Boss DAC. I'll leave my current linear supply on the RPi2.

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DonVK

DonVK

Member
Joined 2017
I'm using Volumio2 because seems to have better support for configuring the Piano2.1. I can't comment on other setups.

I have used DAC#0 with ALSA equalizer, but unfortunately it's only a 1 octave 10 band equalizer and configures via command line. There are some projects trying to add equalizers and convolution engines and make them configurable from Volumio's web intf. They are on my list, in the link listed below.

Yes you can access all 4 channels.

I have a TI PurePath GDE licence now, I'm trying some programming examples : Raspberry Pi with Piano2.1 DAC DSP and Volumio2
 
S

soundcheck

Member
Joined 2005
soundcheck-audio.blogspot.com
CharlieLaub said:
I have a couple of implementation and capability questions:

  • Will the Piano DAC work under Raspbian?
  • Do I need to install a driver and/or configure a device tree overlay?
  • Can I use the Piano DAC as 4 output channels without DSP (no EQ or crossover functions)?
  • Can I access all four Piano DAC channels via ALSA?

Thanks, this looks interesting.
Click to expand...

1. Kernel 4.9.36 onwards is required for final functionality.
As ususal it doesn't depened on the OS if a DAC is working, it'll depend
on the kernel first of all. You need to check what kernels your OS supports.
e.g. Arch is already on 4.9.36
2. In /boot/config.txt
dtoverlay=allo-piano-dac-plus-pcm512x-audio
With Kali master clock:
dtoverlay=allo-piano-dac-plus-pcm512x-audio,glb_mclk
3. The Piano 2.1 is 2 in / 4 out
Following modes are supported from kernel 4.9.36 onwards:
Standard-Modes: Dual-Mono, Dual-Stereo, DSP-Modes: 2.2, 2.1 (requires firmware for lowpass!)
Note: I played around with the DSP stuff. It's pretty basic and offers some fixed crossover frequencies via alsamixer. And that's about it. Pretty useless to me.
Beside that I experienced very strange behavior (phase issues etc.) when using the
early stage Dual-Mode firmware. Dual-Mode via DSP firmware is no longer supported.

The modes can be selected through amixer/alsamixer.

4. See 3

I'm currently running the DAC in Dual-Mono mode.
The outer jacks will be active. The inner jacks are muted.

Note: Dual-Mono mode doesn't mean that there are two outputs running in parallel per channel, as we know it from e.g. a lot of Sabre 9018 implementations!
Two channels just get muted by the driver. This approach might improve the crosstalk. But wouldn't e.g. lower the output impedance.

Allo is trying hard to get the documentation properly done. I'm in close contact to them ( some might call it "bugging them" ) about this and the driver updates.

In "Dual Mode" operation 384k will be possible to bypass the internal DAC filters as we know it from the Boss DAC.
When using the DSP for subwoofer operation 192k is the limit. (DAC restriction)

Moode will soon show up with all this integrated.


Note: Allo is trying to confuse us with terminologies around the DAC. E.g. there's no DAC Plus as the driver name suggests. Perhaps they'll manage to get that straight one day.
( You bet -- I mentioned that towards them more then once ;) )

Enjoy.
 
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S

soundcheck

Member
Joined 2005
soundcheck-audio.blogspot.com
While testing the latest Piano21 drivers, we're facing pretty weird behavior of the driver under certain conditions.

Obviously releasing the new kernels - respectively Piano21 support- with these problems still in, won't happen!!


Sorry CDSGAMES. I hope you'll get that fixed soon. I don't have to tell you that you guys are slowing down the process once again.
And.
By doing so , you cause us huge delays and long hours extra work to do design and sales support for your product only!

PS:
(I still have the impression you're not listening to the feedback I'm giving you in private!!! )
 
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