How to make working AC3 (from mp3) for Adobe Encore?

[PatPowerMan]

Adobe Encore let me import my *.AC3 (BeSweet-converted mp3's).

(Reason why I do that:
If I import the mp3 directly, Encore needs a lot more time to "transcode" it.)

But If I try to make a timeline with this *.AC3, Encore will hang forever.

Could someone tell me, which encoding options I need to adjust in BeSweet to create working *.AC3?

Are there other mp3 to ac3-converter that I could use?

[PatPowerMan]

FYI:
I have successfully imported *.AC3-File (converted from mp3) by ffmpegGUI https://www.videohelp.com/tools?tool=434#comments.

No fancy screens, but it works I'm happy

P.S. The quality of ffmpegGUI-AC3-Files are much better then from BeSweet. Give it a try!