Andy McFadden wrote:
Using something other than a 15-year-old boom box and the "line in" on the PC motherboard audio might improve things as well, but a careful examination of the non-working tapes suggested that most of them were too tweaked for recovery.
As I wrote, I got good results with a Commodore Datasette attached to the PC's parallel port, and Markus Brenner's "mtap" program (Google for "mtap36.zip"). The Datasette is built for zero crossing detection, it has internal triggers for that.
-- Linards Ticmanis