HiLetgo 3pcs M18 Wireless Bluetooth MP3 Audio Receiver Board BLT 4.2 mp3 Lossless decoder Bluetooth 4.2 Audio Receiver Board Wireless Stereo Sound Module

First, I want to point out that I've tried many bluetooth modules lately in a quest to add unobtrusive bluetooth audio pairing to some vintage (1980s) radios. But most importantly - these boards have the most pleasant chime when ready to pair, and upon successfully pairing. It's not a human voice. It's not an incredibly loud sound. It's pleasant and subtle.One of the big reasons I wanted this board was to be able to map media buttons. This has a really fascinating approach (in my opinion) by having one single "KEY" pin which, when grounded with varying levels of resistance, produces different results. This works very well, though you may have to dig deep to find some of the resistors mentioned (although you can also put resistors in series to achieve the same result; i.e. 30k + 3k = 33k). But don't forget to order resistors if you're ordering these, should you not have ones you need and want to use the button function!At first I tried using female header pins and pluggable cables with this board. Instructions elsewhere on the internet state very clearly that the wire's shouldn't be plugged, and should be welded (soldered) - in particular the Ground cable should be sturdy and short. This is to reduce ground isolation noise, which i definitely experienced. It can be alleviated by soldering everything, or putting a B0505S-1W between the power supply and this unit to help isolate the noise.You'll also want to make sure the 5v fed to this module is on it's own power rail as much as possible, and not shared off of some borrowed component of another device. In my case, I spliced the 120v AC just inside the radio and tapped it into cheap AC-DC converters (like a USB phone charger wall wart) to provide a stable 5v without signal interference.And having the buttons is great. There's even an indicator when you've hit max volume (for what it's worth, it starts at max volume, and since it's not amped, this is ideal). The volume that can be changed on here is independent of your Bluetooth device (phone) volume level.Anyway, like the title says, if you know what you're doing or willing to learn a little, these are great boards for the money. And they're the size of a postage stamp so you can add them to practically any project or existing stereo/radio.

Okay, the good first, obviously.The pairing and power-on sounds are simply the best I've come across so far on my years long Bluetooth module experiments and sampling. The ON-sound is a low volume four note ascent with swell; I find it to be very pleasant overall. The pairing/paired sound is like a digital star twinkle sound, also very quiet in volume.This low volume, unobtrusive sound set this unit has is THE BEST. In my search for the best Bluetooth module, I've found most sounds they make to be obnoxious and sobering. There should be a pad set on all Bluetooth modules that one can short out to cancel all power-up / pair sounds; isn't the LED enough??The Key functions are pretty cool. Try not to overlook the V+ / V- piggy backed on the track advance and back features. They are not kidding about the resistor values. I really like this unit a lot.Now for the bad elements, and there is only one I have found...-The overall output volume is weak. Like, very weak. As an example - if you plug a 1/8" to 1/8" male-male cable into your lap-top and play a 100hz test tone on Spotify and measure the AC voltage at the other end of the cable (level produced by comp) you're likely going to see something near 1VAC. The majority of "good sounding" Bluetooth modules will produce something around ~0.200mv AC when playing the 100hz Spotify test tone. ~0.200mv is a usable and strong signal strength; I would submit even ideal. The MH-M18 outputs ~0.068mv AC. This is mighty low and will require some means of amplification. The MH-M28 seems to be outfitted with a jack and I would assume it has a more robust output, but it is also outfitted with the USB hardware, a pity.If the volume were 3/4 stronger the unit would be an absolute knockout - 10 out 0f 10. I would say it's a strong buy though, even with its low output level.

I used them for two different projects so far, and they sound really good once they are going. They can be a bit static-y at times, but that may have been the way they were wired (when testing with another chip a different way I had no issue whatsoever).

I like these simple cheap bluetooth audio receivers. I bought them for the first time in 2020. They had a nice bluetooth connected tone that was quiet an unintrusive. I recently bought another set of these, and now they have a loud, annoying, voice announcement that says 'bluetooth connected'. It ruins the product.I still need to use something for my audio project, so I'm going mute my amplifier until the LED is on steady. This adds a few extra components to my project, and some tricky soldering to read if the LED is on or not. Pretty annoying.This went from 5 stars to 1 star.

For the money these can’t be beat. Works best on a 5v power source. As others have noted, remove the diode if you want to use a battery….but mine still cuts out at probably 3.7 volts, so It’ll really only work on a mostly charged battery. Bangood sells these and has a real instruction manual, so google it and there is some decent advice about its operation.

bought this because there was supposed to just be a beep sound effect that plays when you connect, disconnect, etc. Here to tell everyone, maybe they changed the manufacturer or programming - there is no beep sound effect, it is indeed a Chinese lady saying, "the bluetooth device is connected", etc, like every other bluetooth module. Other than that it works well.