Is there an easy way to convert .b1 files to .mp3 audio format?
Converting B1 Compressed Archives directly to MP3 Audio Files (.b1 to .mp3 conversion) is not possible.
You can, however, decompress your B1 archive using a software, such as B1 Free Archiver. If the B1 archive contains any MP3 audio data files, you will be able to extract those from the archive.
We are not aware of any media editing software or (online) conversion tool capable of converting B1 to MP3.
In a word, direct b1 to mp3 conversion is not possible.
So don't expect any so-called b1 to mp3 converter or b1 to mp3 free online conversion tool available.