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Sound on the pi-top

I have no experience with sound on the pi-top. Before I start, I would therefore like to ask some questions. A bluetooth speaker would certainly be an option, but as far as I can see the internal bluetooth of the rpi is not yet working without problems.


1. The pi-topPROTO board has a pin labelled SPDIF. I don't see any signal there, but as far as I understand the HDMI audio signal is SPDIF. Does anybody know anything about that pin?


2. What audio does the pi-top speaker use? The raspi analog audio output, or the hdmi audio?


3. What are the dimensions of the pi-top speaker? Will it fit in between a pi-topPROTO board and the Raspberry Pi? If yes, will it cover up the sd card slot? How does it sound if the cover is closed?



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Unlike a laptop the Pi-Top v1 has simply neglected to bring the basic RPi connectons to the outside leaving a typically British heath-robinson affair. AKA a development environment. Not the sort of thing to win credibility points in Italy where style and comfort are everything. We just don't get it so we teach untidiness and live oblivious to untidiness. Our designs are not out there on the world stage and we just don't get it unless we pay some consultant a huge sum of money to tell us why. Meanwhile I guess we must get some kind of benefit because it would be insane otherwise. Use chewing-gum to hold the speaker on the back of the screen. That'll save on the expense of screws.

Difficult to say much about the pi-top speaker since it is not available yet but it would appear that it plugs directly into the pihub breakout socket just like the pitopPROTO board.  It therefore takes its audio output from the SPDIF pin and is thus HDMI output (ie digital).  At a guess I would think access to the sd slot would be difficult with both a speaker and PROTO board installed.    


I created my own speaker set up working off the audio jack which is an analogue signal.  The audio jack does not provide enough power to drive the speaker directly and so I needed to use a small amplifier as well. I bought the speaker and amplifier from Jaycar in Australia (think Maplin in the UK).   The setup works well but as with any small speaker system the sound is a little tinny.






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Thanks, Norman, for your helpful hints. Using the analogue audio jack is a meaningful option. Have you put your speaker inside the pi-top? If yes, a picture would be intersting. If I find the time I will try to get some high quality stereo out of the SPDIF pin. Maybe something is wrong with my Raspian configuration, but even if I switch to hdmi audio I cannot see any signal there.

Hi Rene Yes my speaker is inside the pi-top.  I have attached a jpeg photo for info.  At the moment the amp which is inside a tic-tac box to the right of the speaker is powered from the pi-top hub breakout connection (5v and gnd).  The speaker model number is AS3030 in the jaycar catalogue and is described as a full range speaker.   I also got a simple case from jaycar with mounting posts that were exactly right for mounting the speaker.  The case has a mounting lug which allowed the case to be mounted to the pitop mounting slot.   


I agree that HDMI is the way to go but I am not how to do the signal processing.  I am will be ordering a pitop speaker when it is available to compare the sound quality.


Regards

  

Very nice work! I think the pi-top speaker or the analogue output of the pi together with a small amplifier is the way to go for a speaker inside the pi-top. The conversion from SPDIF could be done with a "digital to analogue audio converter". These are normally quite expensive. I have one from a project I did a few years ago. It is in a little box of roughly 2 x 4 x 6 cm. I think it will not fit inside the pi-top with the connectors at both ends, but I will open it to see how big the board in the box is. But maybe that would be the way to go with large external speakers for a high quality sound system.

Sorry uploading a large jpeg photo does not seem to work  so have converted it into pdf format to see if that will work.   Are you using an oscilliscope to check the signal output from the SPDIF pin?

regards


pdf
Actually uploading the picture did work, but one needs to click the link next to the small image to look at it. Unfortunately this forum software is not very user friendly. Yes, I have used an oscilloscope. I will try again.
Why not just plug in a PC powered speaker either through the analogue 3.5mm jack or source a USB audio driver to find how Microsoft delivered audio this way? No harm in asking them I guess?
Thanks Alexandra, to plug in a powered speaker is certainly a very good idea. Many of those get their power using an USB connector, and the Raspberry Pi does provide 5V on the USB ports. But you should not draw more than 100 mA per USB port. This translates to 500 mW per USB port of the Raspberry Pi. One could draw more than 100 mA when taking the 5V from the pt-hub-controller connector or the pi-topPROTO. According to specs the limit is 3A or 15W there (including rpi). The disadvantage of using the analogue jack of the raspberry pi as the audio source is the limited quality. For a cheap speaker in a laptop that is probably ok, but not if you want to play high quality sound on an external sound system. As many makers I would just like to learn new things and make make nice gadgets. That' why I am interested to try to use the SPDIV output of the pi-top-hub-controller.

Hi Rene

I agree with you, the audio jack is useful but HDMI provides a quality sound with the right speakers.  I look forward with interest to see how you progress with using the SPDIF (Sony Phillips Digital Interface Format) for audio output.  I am not sure if you have seen the pi-top youtube promo on the pi-top speakers, so I have attached a screen capture from the video for your interest. The white button on the right of screen in the top photo is to set up the speaker for right, left or mono sound.

BTW, thank you for your very useful software in Github

Norman

pdf

SPDIF AUDIO WORKS


Hi Norman,

Thanks for the pictures. I will order a pi-top speaker as a nice little internal speaker.


I just got the SPDIF to work using the latest Raspbian, but believe that this should also work on pi-topOS.


I had to do 2 things:

-/boot/config.txt: Uncomment #hdmi_drive=2. After a reboot, "noise" appeared on the SPDIF output.

-call omxplayer as follows:  omxplayer -o hdmi filename

 where filename is the name of the file to play


Just right-clicking on the speaker icon and selecting HDMI did not do the job. I guess omxplayer ignores this setting or needs to be called properly to look at it.


I hooked up the SPDIF pin of the pi-topPROTO to my little "Digital to Analog Audio Converter" from goobay (AVW 7), and the output of that device to an amplifier and speaker. The sound was very good. Of course one could also hook the SPDIF directly to a suitable amplifier with SPDIF input.


If I find the time I will do some tinkering and fix that all up for nice high quality audio player, maybe drilling a hole somewhere for a SPDIF output with the proper jack.

Hi Rene

Great work, glad to know that you have sorted out how to get sound from HDMI.  I have a look at the AVW7 of the net and it looks very impressive.  You might also want to have a look at the HiFiBerry DAC+ as sold by ModMyPi as it fits directly on top of the Pi GPIO.

best wishes


DACs seems to be the standard solution for High Quality Audio out here.
Mounted a Pimoroni Phat DAC on my Pi-Top PDB. Nice Sound & FormFactor, too :)

 

Is the pi-TOP Speaker out yet

 

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