This will explain how to get the Master of the Beats achievement in a bit more detail for those that do not get it to trigger.
How to Obtain Master of the Beats Achievement
Setting It All Up
This achievement is actually a lot easier then most people think, let me show you how.
You start by starting a solo assignment (this is crucial, you cannot do this in multiplayer).
Pick either Zero-G Therapy or Gravity Drive (these maps both have a Zero-G environment).
My preference was Zero-G Pure and simple because it's smaller and the radio is way easier to find. Because from the moment you start the map, you can spot the radio from where you stand.
Grab the radio and go over to the Bin Dispenser Machine.
Hold down the left mouse button and fiddle the radio until you are holding it face forward but rotated so it's almost sideways, then shove it inside the Dispenser like this:
Getting the Achievement
Now we can make the magic happen, before we start let's turn on the radio and see if it stays where it is!
As you can see, it's at max volume and On and it's not going anywhere. This is what we want.
Now for the other part: if turning it On and Off does not trigger the achievement, open the in-game options and make sure your Master and Music volume are not lowered.
For the sake of the achievement I did the overkill thing and cranked everything up to 150%, after turning off my Speakers cuz i didn't wanna go deaf.
When you have done this, Go back to your game, Turn ON the radio, Turn if Off and Boom achievement should pop up!