How to force Firefox to download mp3 file?

Somehow my Firefox reverted to old behaviour, and now it plays all mp3 files from URL in my browser. I want it to ask for download location.

I have tried several things such as:

• Firefox settings -> Programs -> ... no option for "save as" there. Edit: actually i see "save as" option there now, but when i select it, it still plays on the browser even after reopening firefox.
• about:config / media.windows-media-foundation.enabled -> false
• AppData\Roaming\Mozilla\Firefox\Profiles\n74u0loi.default\mimeTypes.rdf -> NC:saveToDisk="true"

But I cant get it to work.

Firefox version: 28.0 (newest)

Edit: yet not found the solution. still forced to right click every mp3 file...

Firefox Menu => Options => Applications

Choose "Save As" for (.mp3) (audio/mpeg) and also for (.mp3) (audio/x-mpeg)

Open about:config and change media.play-stand-alone to false. According to this answer on mozilla support, you should change media.windows-media-foundation.enabled back to the default value.

Edit: On older versions of Firefox media.windows-media-foundation.play-stand-alone helps.

A makeshift workaround is to mangle the address, like this:

data:text/html,<a href="http://www.example.com">bla</a>

Replacing http://www.example.com with your actual URL, of course. This results in a link being displayed where you can right click and use “Save Link As”.