One thought strikes me (keep in mind I have no expertise here!)... If there is a tape machine available that has 3-3/4 and 7-1/2 speeds, would it be possible to play the 1-7/8 tape at 3-3/4 on one machine, thus hearing it a 2x speed, and dub that output onto the second machine recording at 7-1/2, resulting an a 2x-speed tape playing at 7-1/2...which, when played back at 3-3/4 would be half of twice the speed, or the proper sound. Is this practical?
Except for three wrong equalizations, it's quite practical. The result is, of course, a rather complex EQ-correction curve which may not be needed at all for some material.
Mike mrichter@xxxxxxx http://www.mrichter.com/