Hi just moved into a new house which seems to have in wall speakers (I didn’t even realize when I bought the house) but they look to be pretty old. I found where the speak wires are in a closet they all are retrofitted with spades on the end. I tried hooking these into an old Yamaha receiver I dug out of my basement then hooking a CD player into that. No luck with any sound at all, not even static in any room. Any ideas? I am thinking maybe it’s a bad connection with the twist speaker wire connectors in my Yamaha and the spades but would think if that was the case I would at least hear something.
It's possible that the system is set up as a 25 or 70v PA system. There will be a small step down transformer mounted at each speaker if this is the case.
If there are only 4 conductors at the closet rather then 4 for each room that also indicates this. That type of setup allows for each speaker to be connected in parallel without home runs and with thin wire.
Two of these https://www.parts-express.com/70v-200w-high-power-speaker-line-matching-transformer--300-226
would allow you to drive them with the Yamaha.
Unless there is a volume control in each room you won't be able to adjust volume for each room independently.
You can't easily modernize this type of set up. Usually requires all new wiring. You might be able to disconnect the transformer at each speaker but this type of speaker is usually not very good quality.