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[Amp100 + DSP Add-on] TOSLINK Input Results in Hi-Pitch Noise

hftsai256

December 22, 2021 15:21

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Hifiberry OS Version: 20211105
Pi Model: 3B
Sound Card: Amp 100 + DSP Module
Sound Card ID: 0
Features: pi pi3orlater arm7 dsp spdifnoclock toslink localui

SPDI/F Input Source: TV
DSP Profile: DSP Add-On v11 (no audio)/13 (hi-pitch noise)

Logs from spdifclockgen:
systemd[1]: Started SPDIF clock generator.
spdifclockgen[9589]: DEBUG: root - SPDIF lock, playing silence

There is no audio output when I run DSP profile v11, or plays hi-pitch noise with DSP profile v13.

I believe SPDI/F input stream is received on the DSP side somehow, so I downloaded dsp-addon-v11.dspproj from repository and hooked it up. What I found is that register ERR_DM0B3 is set: does this mean the DSP doesn't POST due to an hardware error? Could this be the smoking gun on the noise I have?

Also there are sparks whenever I plug in the barrel power connector from HiFiBerry 24V/180W power supply. I wonder if that destroyed the RAM bank. Isn't there a surge protection circuit on board? I ended up plug in the barrel connector first, and then plug in the live power, but is there a better way to prevent this?

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4 comments

• 0
  
  hftsai256 December 22, 2021 15:55

  A few workarounds:

  * Mask out register DM0_BANK3 so that it won't report an error
  * Run DSP profile v13
  * Turn sensitivity to low

  I'm not sure where the sensitivity parameter is referenced in genclock.py. It seems only checking the SPDIF locking register, but it turns out to be a critical parameter to avoid turning stream into hi-pitch noise, especially when the audio stream from TV is not continuous.

  On the other hand, I checked the build on v11 and the memory footprint is 58% on DM0 (occupying 3 banks out of 4). I wonder if I could replace the RAM chip on my soldering station as a cheaper solution, or just order several backups. I can't say for sure what is causing it to fail, but definitely watch out for the spark when plugging in the barrel connector.

  Edited by hftsai256 December 22, 2021 23:42
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  hftsai256 December 22, 2021 23:47

  One more note: The mechanic to stop spdifclockgen is not yet implemented, so once it is switched to optical input, no other player can reclaim the device, unless, as I mentioned in another thread, putting in a dmix layer.

  Edited by hftsai256 January 08, 2022 04:09
• 0
  
  HiFiBerry team December 23, 2021 07:00

  > Also there are sparks whenever I plug in the barrel power connector from HiFiBerry 24V/180W power supply. I wonder if that destroyed the RAM bank. Isn't there a surge protection circuit on board? I ended up plug in the barrel connector first, and then plug in the live power, but is there a better way to prevent this?
  
  No, that can't "destroy a RAM bank" and it's absolutely normal. Limiting the current would mean limiting the performance of the amplifier. The right way to connect power it to connect the power connector to the board before adding mains power.
  
  >  I wonder if I could replace the RAM chip on my soldering station as a cheaper solution, or just order several backups.
  There is no "RAM chip" as the RAM is internal. 

• 0
  
  Steve BUrke February 25, 2022 21:15

  Those sparks are the result of empty capacitors on the amp 100 filter bank. So when you plug in the power supply - its looking at a momentary short circuit. At first I thought it was a loose connection but found out I just needed to push it in all the way. My system still works fine so I dont think your problem is a surge issue.

  I have yet to connect the controller card up yet to my system but that will prevent potential light shows from happening. One thing you could try is just disconnect the amp 100 from the pi to see if the pi boots up under normal conditions. the pi memory chip you can find on this link https://support.thepihut.com/hc/en-us/articles/360006049318-Which-Raspberry-Pi-4-RAM-option-do-I-have-

  these chips are surface mounted so you will need a hot air soldering system to change out the memory chips. and I'm not sure if the pi people have made a custom controller chip that would also need replacing. the Arms chip sets Im not quite familiar with as compared to amd or intel.