any favourite bluetooth audio modules for retrofits?

[gardner]

I've been retrofitting different audio gear with bluetooth receivers and I've mostly been using cheap ones based on the Jieli AC6925A.  These are a pretty mixed bag with varying features and quality.  It looks like the Jieli chip is a general purpose MCU and there's no telling what features may have been programmed into it by the manufacturer.  All the cheap modules seem to suffer from huge PSU noise issues requiring an isolated PS and I've been using small DC-DC converters for this with good results.

I would like to at least have the ability to change the BT module's name and have a contact closure to place it into pairing mode.  Ideally it would be great to have a full set of wireable control inputs that you can use or leave out depending on your needs.  Maybe settable output levels would be nice.

I'm wondering if anyone has identified a source of BT modules with more consistent features than the cheapies from Amazon?

[DavidAlfa]

I've played with Cambridge Silicon Radio modules (Now owned by Qualcomm) like csra64215, csr8635, adding bluetooth to mine and some friends's cars.

Try to get aptX modules, that's the best quality you can get (lossless audio).

Since it became Qualcomm, a lot of previously freely available software became NDA or for customer-only.
You can still find them in the >web<...

Programming them is a bit messy, you need a specific CSR USB-SPI adapter, and the software is a bit tricky.
Someone made >bluemagic<, based on a stm32f103 bluepill, emulating the CSR programmer, but the bluepill only "talks" 3.3V, while most of these bluetooth SOCs work at 1.8V, using resistor dividers didn't work.
Ended using a TXS108e logic level translator, then it worked.

However, these modules get bricked extremely easy, beyond recovery!
They feature a 1.8V-only SPI flash, backup its contents before anything else, so on the event something goes wrong you can restore it.
Use another TXS108e if your programmer doesn't support 1.8V, I did that way to interface my CH341A.
Once you have a backup, there's no fear!
I probably bricked it 20 times .

On the first try, I changed the bluetooth name, worked nicely... but then touched something else and killed the module, had to buy a second one to dump the flash contents and recover the first one!