If you don't have a specific reason to use ftp (the program), you could just as well use wget; it allows for recursive downloading and limiting to certain file extensions, for example .mp3 in your case. The man page of wget contains all you need, but probably you'll do fine with arguments for recursive downloading (-r) and accepting mp3 suffix (-A.mp3); if you need to, you can also restrict the download to given depth (of subdirs), tell it to (not to) create directories etc. I think the short way is
wget -r -A.mp3 ftp://address.to.the.site/somedir
see if it works..
By the way, what problems did you have using
with ftp (m
in the m
get as in "multiple")? Or did I get you wrong?