Accessing individual channels through MOST bus?

Hi everyone,

@rhys_m Thank you for putting together all the great resources on this topic! I came across MOST and your PiMost a few months ago while researching the inputs and outputs of the audio amplifier from the Jaguar XF.

I have a few questions if that’s alright. I am a researcher at the University of Southampton and our current project involves the perception of spatial audio in automotive environments. We will be conducting several listening experiments in a Jaguar XF (most probably 2012, B&W system). For that, we need to be able to access the individual audio channels. The main question is. Is it possible to do that, either through the amplifier (are there any physical individual inputs?) or through the MOST bus with your PiMost? Do you have any information on how the channels are processed/upmixed and where exactly? Or is the amplifier just taking a stereo input and sending it to the Left/Right sides with minimal processing? Any guidance/thoughts/pointers will be greatly appreciated.

TL;DR: Is there a way to send a 7.1 audio signal through the XF’s audio amplifier, or do we have to use our own amplifiers/processing?

Best,
Bogdan

Hi Bogdan,

Thanks for joining! Unfortunately it’s not possible to do this with JLR (from what I have found) Audio streams are all sent as stereo streams, and the amplifier then creates the dynamic sound stage. The only slight exception to this that I have seen is for parking sensors. It still seems that this audio is created by the amplifier, however the control MOST messages seem to control which speaker plays audio. I am guessing the amplifier itself generates the sound and frequency of the parking beeps based upon the messages received.

I am unsure if you could programmatically control balance/fader to achieve some spacial audio? The update rate could be pretty fast!

Please keep me updated! It is interesting stuff

Hi Rhys,

Thank you very much for your answer, this is very helpful. This would indeed be a very interesting idea to pursue, however, given the complexity of the problem and the lack of transparency from JRL in terms of what kind of processing is done and where, it may not be feasible to pursue for now. In our experiments, we just need a way to drive the loudspeakers, but we do need discrete control of each one. This does indeed make things a bit easier for us because we will just bypass the amp and use our amplifiers and processing instead.

Seeing that things are slowly moving towards spatial audio (especially with the recent announcement of Dolby Atmos being supported in cars) I am sure that we will soon see more on this subject.

Best,
Bogdan

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Hi @rhys_m,

I’m sorry, this may be a noob question but I’ve looked everywhere and I’m not quite sure where to look anymore. But I’m interested in purchasing a couple of connectors similar to the ones found on the amplifier of the 2011 XF with the B&W (1200W) system. The ones which are connected to the loudspeakers.

Would you happen to know the connector types (either names or part numbers) or do you know if they can be purchased separately? The alternative would be to purchase a second amplifier and stripping them from there but I would rather not go down that avenue if at all possible.

Best,
Bogdan

Hi @bogdanbacila I’m afraid I don’t know the part number or connector type, they can likely be gained from rs components or similar.

On the subject of your original post, I may have mislead you a bit. There is an amplifier function 0x46D called speaker levels, which may give you the option to experiment with spatial audio!