Will a simple matrix like this work? What else does it need?


2018-08-09 11:06 am
Hi, totally clueless here. I don't really have any business trying to build something like this, but a multiroom amp is a few 1000 dollars and I'd still be stuck with their horrible proprietary web interface.

  • 4 zones: zone 1 and zone 2 each have 4 speakers. Zone 3 and 4 each have 2 speakers.
  • I plan to use ebay amps for each of the channels. https://www.ebay.co.uk/i/281787604166
  • I have 4 stereo inputs (probably).

I did see online some matrix chip. I really prefer through hole, but I am ok with soic, and e.g. MT8816 | Microsemi MT8816 looks really nice but I couldn't find any schematics of using it. I figured relays are safe. I attached the quick design to this message.

I have some questions.

  1. Will it work? If not, how can I make it work, please?
  2. What, if anything do I need between the outputs of the matrix and the speaker amps? I'd most like to have digital volume control. What chips would you recommend? I'm not going for audiophile, but at the same time, I'm happy to pay for chips that save me hassle of playing with op-amps (sorry too clueless)
  3. How do I prevent the thing backflowing when all the things are connected? Is there a kind of component that ensures that the audio travels correctly around the matrix?

Thanks for any help you can give me

I'd first worry about ground loops and hum - differential signalling is normally used for this kind of setup to allow for different ground potentials in different parts of the building. Transformer isolation can be added to a single-ended system if necessary, but they cost.

If you never route more than one signal to each amp, there's no issue with "backflowing" as no sources are shorted to other sources (you definitely don't want this). An audio source can drive several/many audio inputs so long as its a normal low-impedance source (not something with valves/tubes!).