Headless Plexamp with DSP on RPI?

Plex Labs
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Hi,
I am looking at added some DSP ‘magic’ to a headless Plexamp running on a RPI. Has anyone tried this yet and can share their configuration?

Thanks

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what sort of “magic” are you looking to add?

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Well specifically I want to enable some room correction filters. These are typically FIR DSP filters (that are the room based equivalent of noise cancelling headphones) - Audyssey and Dirac used them but the specific values for the filters can be calculated use REW and applied to a Raspberry PI based DSP - e…g GitHub - HEnquist/camilladsp: A flexible cross-platform IIR and FIR engine for crossovers, room correction etc. - If you get the right filters configured the difference is pretty amazing (unlike most ‘audiophile’ enhancements).

Specifically they can get configured to cancel the secondary reflections of sound off walls, so they work in the time domain not just the frequency domain.

6 Likes
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huh, interesting

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Hi @elan looking forward to listening to your talk later in the week!

I had a couple of more thoughts on EQ and plexamp.

  1. AutoEQ support?
    GitHub - jaakkopasanen/AutoEq: Automatic headphone equalization from frequency responses - this is a fantastic resource with 1000’s of IEM and headphones normalised EQ settings (including 10 band EQ so perfect for the current EQ in PlexAmp). A UI to find a headphone and automatically set the EQ would be perfect (FusionDSP plugin in Volumio does this already). I think there is a maser list of Headphones and URL’s to download the EQ values.
  2. Multiple selectable custom EQ settings?
    So using AutoEQ above you can see that headphones vary wildly in EQ - so for example I use AirPods Pro sometimes but then some other IEM’s at other times. So the custom eg works well for Bluetooth but not for various IEMs!!
    I also use PlexAmp in my car with CarPlay and finally I do occasionally use Airplay from my iPhone to my Denon Speakers. So all possible more options around custom eg which are easily switchable? Possible even automatically e.g. turn off headphone EQ when using Airplay
  3. Virtual sound card in Headless RPI PlexAmp
    I am pretty sure I can write up a post explaining how to create a virtual sound card would could be feed from the output from the headless PlexAmp and which would then go through to CamillaDSP. I will try and write a script to configure this on a basic RPI image. Though I am looking at trying to setup both PlexAmp and CamillaDSP in separate Docker containers (possible with some other end points like SpotifyConnect and Shairport-sync for Airplay) as other containers - allowing people to pick’n’mix how they want their headless RPI setup for audio.
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We specifically tweaked the EQ so that it would allow entering profiles from AutoEQ, but yes, it would be nice to build them in.

Right now as you’ve noticed we allow custom profiles per output but we can’t tell the difference between plugging in different IEMs as these aren’t identified. Something we can improve on.

Should be able to do this with a loopback ALSA device.

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