As part of my my consideration of possible solutions to my multi channel variable speaker number problem arising from my attempts to restore radio functionality to an old hotel intercom system (see previous post on the subject if interested) I have been considering how to distribute say three audio streams delivered to multiple locations (by way of three/four cores per location), where a switch at those locations can be used to select an audio line.
My inexperience is leaving me slightly unsure of what approach to take in terms of the big picture / over all design. Basically what I want to achieve is this...
BUT... I want it for many (10+) rooms (the room being the right hand side of the diagram, where the switch and speaker is).
The problem is this leads to a design that looks more like this:
That's three 'rooms', but with a maximum design consideration of 4 audio channels and 13 'rooms' this means over 50 amplifiers. Small amplifiers are cheap, but still, I can't help feel it's a bit of a mad design!
Trying to come up with something more sane, I considered this:
BUT... The system should obviously survive usage, and here the impedance of the load applied to the amplifiers will change dramatically as variable numbers of speakers are turned on and the audio lines tapped... Obviously it's going to halve just from a second speaker being brought online with the same channel, and whilst it's not a likely use case, what if someone went round turning on 10 or more speakers all on the same channel!? The impedance of the load is going to be REALLY low now, and I have no idea if it is allowable to have such a variable impedance load for an amplifier. I do realise it's not normal or ideal, but is it acceptable if the amplifier is big enough to handle it?
I'd really appreciate any comments and/or help with the above questions or any suggestions for an alternative approach. I'm obviously more than happy to put time and effort into researching and working to expand the ultimate solution, but it's not currently clear to me which direction to go in at the moment!