I was hoping to get some guidance as to the feasibility of using (some kind of?) Shelly relay switch to switch between 2 different inputs going into one subwoofer. The subwoofer require a single RCA cable.
I’ve read through this post (linked below) which suggests this is solvable with a relay- but I am hoping I can use a Shelly device, as it has the built in compatibility with HA.
I’m just not sure which would be the right product to get? And could use some wisdom if anyone has the time.
Okay this is positive. And do you think it will be the case that only one device is ever connected at a time. I would hate to accidentally pass both signals into the subwoofer simultaneously. I need it to be reliably only ever one or the other. Forgive me for not fully comprehending the nature of such relays.
Careful. The Shelly might not be suitable for your needs.
Only the Shelly 1 has dry contacts (no voltage passing through the relay side). All the other Shellies will pass up to mains voltage on the relays and will fry your sub.
Unfortunately, the Shelly 1 only has 1 output, so you’re need two of them to switch inputs, and have to do an interlock in software.
You might be able to use a Shelly Uni which is marketed for such purposes. However, double check whether the outputs on it can be configured to interlock with each other.
Since you need two Shelly devices and there is still risk to feed them simultaneously, I suggest you to use normal relay instead.
RCA input goes to COM, one output connects to NC and other to NO. There is no way to have them both on at the same time, since it’s a physical switch. You can drive the relay with Esphome dev board or with single Shelly.
I’ve been unable to verify if the Uni is able to be configured with interlocking- but admittedly that’s the first time I’ve heard the term (rather novice over here, please bear with me)
I might just have to opt for the relay approach just to be safe and try work out how to hook it up with HA
The only thing is, I’m going the other way: 1 RCA IN, 2 RCA out. I assume this is fine and I just invert your instruction. And I also assume it’s the positives that follow your guide. What do I do with the negatives?
In or out doesn’t matter. I have no experience on audio field, if there are interferences leaving negatives connected, sound quality etc…
Use 2-CH relay module, one relay for each (+/-). And share the trigger.
I’ve decided to go down the ‘traditional relay’ route. I read in your thread that you had success combining the grounds. So could you confirm for a mono RCA, all I would need is a single relay and then connect all 3 ground wires together separate to the relay.
Or in total novice speak:
So my relay has 3 positive wires connected (2 sources, 1 to sub), and I join all the negative wires together (eg with a wago), completely seperate to the relay device… and it should work just fine?
