I have a small, portable, battery-powered Bluetooth speaker (has aux input) and an XLR microphone (Shure SM57). I was wondering if there is anything I could use to convert the microphone signal to 3.5mm so I can use the speaker as a mini amplification system, without needing to use a power cord. I know there are XLR-to-3.5mm adapters, but I'd also like an adjustable amplification knob or something so I can get the volume loud enough.

Is this possible, or would I need a mixer that needs to be plugged into a wall? I really don't need to "mix" anything--just amplify it enough to be at a good, standard signal strength for the Bluetooth speaker. Preferably, it would be something very compact. Is there any device like this I could use?

3 Answers 3


The microphone signal level will typically not be strong enough to produce acceptable quality at the AUX (line level) input. You need a pre-amplifier to convert the signal from one to the other. Most mixers have one or more; you can also use a standalone pre-amp, and some of them can run on batteries. There are also microphones with built-in pre-amps, but the SM57 is not one of them.

  • I am not aware of any microphone that has a preamp built in.. I could definitely put one to use if you can give me the make and model? Aug 11, 2018 at 5:40

An SM57 is an odd choice to be starting out with. It's not really a vocal mic without an added pop-shield [though you didn't actually say what it would be used for - as an instrument mic, they're lovely].

Anyway, by the time you've got a mic preamp, then [again you didn't actually specify] something capable of converting that to transmit bluetooth - without significant delay being introduced...

...you'd be better off spending your money on some budget, entry-level portable PA system, like this Behringer* which can be up-scaled into a wireless system without the delays inherent in bluetooth.

*Random shop found on internet, no actual recommendation.
Note: Behringer's entire raison d'être appears to be price point, rather than quality. I haven't tried this device, but I assume it will be adequate, though no more.
I'd recommend 'try before buy' for any audio product.

  • A 57 was my first mic and they have been used for vocals many times. Foam pop filters are cheap and with one of those, you can do almost anything with a 57. And it's like $10 cheaper than a 58 and doesn't have the presence bump. Aug 10, 2018 at 15:58

What you can do is use something like an iRig Pre that plugs into your phone and then use the headphone output to plug into the speaker.

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