krell

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  • 20. November 2020 at 20:41 #50295

    Thinking about this application further, assuming the clocking issue is resolved, it would be nice to have the option for a low-latency path between the ADC and the DAC similar to the bluetooth input path. Operating through Slim introduces tons of latency as well as transcoding, and if I’m not trying to bounce the sound to another room, it would be nice to have a more direct path for local playing of records.

    17. November 2020 at 20:52 #50275

    So, I got it limping along, but with issues…

    Since the U/I does not know about the overlay for hifiberry-dacplusadcpro.dtbo, I went in and instantiated a copy of DAC+ADC, calling it DAC+ADC Pro, in /var/www/max2play/application/plugins/hifiberry/controller/Setup.php, and having it configure the dtoverlay to hifiberry-dacplusadcpro. Verified that config.txt was set to the appropriate driver, added some amixer settings to override input defaults (input selection, gains, turn off mic bias, etc.) rebooted and the interfaces came up as expected. I also did an apt update and upgrade to ensure I had the latest (along with all the other patches and security upgrades that have been neglected up to this point).

    With this, card Input works as expected, the input LED comes on, audio is captured, and I can fine-adjust input gains with alsamixer.

    Now, what is happening, is nominally every 90sec (varies from 2sec to 2min) I get a single sample full-scale ‚POP‘ at random on either the right or left channel (never both at the same time). I’ve cross-posted this issue with Hifiberry as well. Since it is a single-sample, the tweeters are the only speaker taking the hit. I’ve since switched back to the DAC+PRO driver and the popping is gone, but input is not working either.

    Thanks

    UPDATE: Chatting with the Hifiberry folks, the principal difference between DAC+ADC and DAC+ADC PRO has to do with clocking. Apparently the PRO model uses an internal clock, so the RPi must slave from this clock. I do not yet know if this difference applies to DAC+PRO and DAC+ADC PRO.

    CORRECTION and confirmation from Hifiberry: DAC+ADC uses the RPi clock. DAC+ADC PRO uses a clock generated on the hat.

    • This reply was modified 3 years, 6 months ago by krell. Reason: add update and additional information
    • This reply was modified 3 years, 6 months ago by krell.
    15. November 2020 at 3:36 #50219

    Hi-

    I, too, am having issues with the DAC + ADC PRO. This model has a different dtoverlay, for this one it should be dtoverlay=hifiberry-dacplusadcpro
    There are a number of differences in the chip used on this model, which include customized amixer settings and a PGA for the input gain.

    Since M2P does not know about this card, it forces you to use hifiberry-dacplusadc, and the PGA settings get set to maximum and the amixer settings are inaccessible which results in unrecognizably distorted input when used with line level inputs from a phono preamp. In fact, the gain is so high, even direct cartridge connection to the input is still too high (let alone missing the RIAA equalization curve).

    So, basically, we need a specific output device entry for this card so it sets the correct dtoverlay on boot. The custom amixer settings for input, bias, and gain could be left to /boot/config.txt because for me these are ’set once and forget‘ parameters.

    Thanks

    • This reply was modified 3 years, 6 months ago by krell. Reason: expand issue/resoluion
    23. Mai 2019 at 9:39 #45476

    Side note on point 6 (multisqueeze): If you create an instance player name containing a space, the instance crashes.

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