Home of the Squeezebox™ & Transporter® network music players.
Page 1 of 3 123 LastLast
Results 1 to 10 of 24
  1. #1
    Senior Member chill's Avatar
    Join Date
    Mar 2007
    Location
    Nottingham, UK
    Posts
    1,358

    A Pi-based whole house system

    I've been making up a system to go into a house where the previous owner has fitted ceiling speakers into most rooms and has conveniently routed all the speaker wires into a single location. I thought this setup lent itself to a system based on multiple Raspberry Pi players with attached amplifiers.

    A Pi Zero W with a JustBoom Amp Zero pHat, fitted inside the JustBoom case and running piCorePlayer, makes a nice compact amplified player. The speaker terminals on the Amp Zero are a touch small for comfort, so I added some chocolate block connectors. Using just the official USB power supply, the JustBoom Amp will make 1.5W into 8 Ohm speakers. I don't yet know the specs of the ceiling speakers so I'm going to see how they perform with that amount of power. If more is needed the JustBoom amp can take an external supply which also then back-powers the RPi.



    For the server I've gone with a 3B+, again running piCorePlayer. I had previously made a button board that fits inside the standard RPi case, so this will give some physical buttons for ON/OFF, PLAY/PAUSE, NEXT/PREV, VOL+/- etc. I made two versions, one that fits entirely within the case and one that has an expansion tab on the side that allows additional devices to be daisy-chained onto the GPIO connector. I had designed it such that the button board can use configurable GPIO pins, so this gave me a chance to try that out, since the JustBoom Amp uses a number of GPIO pins that I had to avoid. My button board allows for an easy choice of 2 GPIO pins for each button via jumpers, and I was able to find a set of GPIO pins that did not clash with the JustBoom.



    The expansion tab on the button board was intended to take a box header for a ribbon cable, but in fact, since it flips the connector over, I was able to mount the JustBoom amp directly onto this connector by soldering in a set of header pins rather than a box header, and it still fits the case.





    I made a case to go around the amp to support it and protect it.







    I added some chocolate block connector for the speaker wires, and that's the first two 'zones' sorted. Further zones will just use the Pi Zero W+Amp Zero. I'm including a Joggler as a remote display/controller.


  2. #2
    Senior Member Apesbrain's Avatar
    Join Date
    Jun 2005
    Location
    East Coast, USA
    Posts
    1,383
    Nice job. I'd be surprised if 1.5W cuts it, but 40W with the bigger power supply should be fine.

  3. #3
    Senior Member chill's Avatar
    Join Date
    Mar 2007
    Location
    Nottingham, UK
    Posts
    1,358
    Quote Originally Posted by Apesbrain View Post
    Nice job. I'd be surprised if 1.5W cuts it, but 40W with the bigger power supply should be fine.
    I suspect it'll need something between those two extremes - I don't think they are big speakers. That figure of 1.5W is the rms figure - 3W is the peak figure. The Amp Zero can do a maximum of 15W rms (into 8 Ohms) with a 15V 3A supply.

    I noticed that the Amp Zero can only back-feed 0.5A to the RPi - enough for the Zero W I think, but not enough for the 3B+, so the server/player might need two supplies.

  4. #4
    Babelfish's Best Boy mherger's Avatar
    Join Date
    Apr 2005
    Location
    Switzerland
    Posts
    20,324

    A Pi-based whole house system

    > Nice job. I'd be surprised if 1.5W cuts it, but 40W with the bigger
    > power supply should be fine.


    TBH I'm very much surprised how much I get out of that little power
    using the same amp...


    --

    Michael

  5. #5
    Senior Member chill's Avatar
    Join Date
    Mar 2007
    Location
    Nottingham, UK
    Posts
    1,358
    Quote Originally Posted by mherger View Post

    TBH I'm very much surprised how much I get out of that little power
    using the same amp...
    That's good to know. Did you configure the Alsamixer Volume to -8dB (92%) as advised in JustBoom's technical guide? I assume that's to limit the output power to what the USB power supply can keep up with, and therefore avoid distortion. There's also a couple of other options:

    * Toggle a 6dB increase on analog output level
    * Toggle a 0.80dB increase on analog output level

    I've disabled both of those for now. Not sure what those are all about, especially that 0.8dB increase, which seems like it could be achieved with a combination of the +6dB option and a bit of attenuation on the Alsamixer volume.

  6. #6
    Senior Member chill's Avatar
    Join Date
    Mar 2007
    Location
    Nottingham, UK
    Posts
    1,358
    Quote Originally Posted by chill View Post
    There's also a couple of other options:

    * Toggle a 6dB increase on analog output level
    * Toggle a 0.80dB increase on analog output level
    I've found a FAQ on the JustBoom website (here) that explains those two settings a little. It seems like those options mimic the ALSA sliders referred to in that FAQ. One goes from -6dB to 0dB, and one goes from 0dB to +0.8dB, and they make it possible to "to set the gain to -6dB, -5.2dB, 0dB or 0.8dB". So I think the wording of those two options in the pCP driver seems misleading. I think the 6dB option ought to be labelled a *de*crease (and the toggle should perhaps be inverted?).

    So to limit the output to exactly -8dB I would want to disable the 6dB decrease (is that the same as enabling the 6dB increase?) and disable the 0.8dB increase, then set the mixer slider to 92%. I guess a quick test with some connected speakers will confirm how that 6dB option works.

  7. #7
    Senior Member Greg Erskine's Avatar
    Join Date
    Sep 2006
    Location
    Sydney, Australia
    Posts
    1,719
    Great work!

    What are you doing with the IR?

    I have taken note of your comments about the dB settings.
    Last edited by Greg Erskine; 2018-12-23 at 01:12.

  8. #8
    Senior Member chill's Avatar
    Join Date
    Mar 2007
    Location
    Nottingham, UK
    Posts
    1,358
    Quote Originally Posted by chill View Post

    So to limit the output to exactly -8dB I would want to disable the 6dB decrease (is that the same as enabling the 6dB increase?) and disable the 0.8dB increase, then set the mixer slider to 92%. I guess a quick test with some connected speakers will confirm how that 6dB option works.
    The 6dB option does toggle the way it's described, i.e. with a tick next to the 'increase' option, the sound is louder. But I do suspect it should actually be described as a 'decrease' and the toggle should be inverted, since that FAQ suggests 0dB is obtained with both output options disabled.

    Anyway, with the existing 6dB option enabled, the 0.8dB option disabled, and the ALSA volume set to 92%, the sound is surprisingly loud through a 6 Ohm, 91dB Tannoy 611. I'll wait to find out how they sound through the ceiling speakers before rushing to get external supplies.

  9. #9
    Senior Member chill's Avatar
    Join Date
    Mar 2007
    Location
    Nottingham, UK
    Posts
    1,358
    Quote Originally Posted by Greg Erskine View Post
    What are you doing with the IR?
    I've enabled LIRC on GPIO17, and my original SB3 remote seems to work perfectly. The IR signal seems unaffected by the PLA of the panel around the buttons. But this system is going into a house where there are no native Slim Devices or Logitech products, hence no compatible remotes, so I think the IR feature will not be used.

  10. #10
    Senior Member
    Join Date
    Apr 2005
    Location
    UK/London
    Posts
    1,887
    The IR support is not limited to working with native remotes.
    Getting it to work with others usually just requires working out the mapping for the preferred remote.
    Sometimes easier to hit pause on a remote that is sitting on the desk than finding a touchscreen or asking Alexa to stop it.
    Paul Webster
    http://dabdig.blogspot.com
    Author Radio France (FIP etc) plugin

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •