How to install outdoor speakers?

I have a brick row house (or terrace house for those of you more familiar with UK English) in a tough neighborhood. Sometimes people trespass in my backyard. I would like to install a bluetooth receiver and outdoor speaker on my rear wall. I am trying to figure out the best solution and would appreciate your ideas.

There is a junction box near the location where I want to install the speakers. Could I install an in-wall bluetooth receiver (like this: https://www.amazon.com/Pyle-Bluetooth-Receiver-Amplifier-Microphone/dp/B010U5EGKE) and connect it to two speakers (like this: RetroSound TS42 4" 2-way surface-mount speakers at Crutchfield)? I would put the in-wall receiver in a weatherproof electrical box that I would attached to the rear wall (like this: Amazon.com)

Any thoughts? Is there a better way to do this?

So you’re wanting to sooth the trespassers with some subtle music? The Speaker of the NZ House of Parliament tried this to much derision LOL Covid-19 Omicron convoy Parliament protest: The songs the NZ Govt has used to repel anti-mandate protesters - NZ Herald

Your solution looks OK to me, but you’ll need to run speaker wires, which will be vulnerable to trespassers. Maybe inside some conduit?

EDIT: and do some experimentation first. Is bluetooth doable through that wall?

Thanks @nickrout. Yes, I think the question is whether I can get a bluetooth signal from my raspberry Pi 4 which runs Home Assistant to the bluetooth receiver. It is about 5 meters away, but through 25 cm of brick.

Yes you can

You can go 10 meters line if sight, no obstruction. I actual use bluetooth over 5 meters through brick without issue (iPhone >> alexa speaker connected to audio amp)

I would say that you are on the threshold of working/not-working.
Don’t you have fences in England?
And what would the outdoor speaker be saying to the intruder? “Intruder Alert”, “Smile for the camera”?
I would experiment with a Wemos D1 Mini and a DFRobot sound board. Maybe a PIR motion sensor, then everything would be outside. Control through Home Assistant, if you want, could be by switching GPIO outputs on the Wemos to the DFRobot board.

The operative word is experiment, because I haven’t done something like this before.

Back to your original question: Will your BLE receiver connect reliably to the Raspberry?
Here’s an idea. Install a Bluetooth Scanner on your phone and see what the Raspberry Bluetooth signal strength is at your target location. If it’s -90 or weaker, you may not be able to connect.

@stevemann Thank you for the brilliant suggestion about the bluetooth scanner :+1:

After researching this issue some more, I think the following might be a better solution but more expensive.

All I need to do is drill two holes through my brick wall to run passive speaker wire to the outside where I’ll mount each speaker. Then I’ll connect each speaker to a wifi amplifier that I’ll place in the rear bedroom where I’ve drilled the two holes. Of course, I’ll need to spray foam the hole to keep it insulated. And I’ll install speaker outlets on the inside.

Arylic makes a wifi amplifier that I think works with Home Assistant:

Here’s the model I’m thinking of using:

I have the same A50, and really like , also an integration within HA… The speakers itself are cheap outdoor ones with speaker cable, so cheap to replace