. Are there any 8 tracks that allow that?
I'm pretty sure there aren't. Remember the width would be roughly half of the 4 tracks, so I guess the quality would really suffer if they let you run 8 tracks at normal (1 7/8 ips) speed on cassette. I've only ever seen double (3 3/4ips) on the 8 track cassette recorders.
with the 4 tracks it would be cool to have a list of the ones that gave the options of the two speeds - I'll be in the market one day to archive old tapes also, and I've got some recorded at both speeds. keep in mind also that you'll want to find a deck with the same noise reduction as was used on your old tapes.
the one model that really disappoints me regarding the 2 speeds is the Tascam Syncasset 234. If it had the two speeds, I'd definitely be after one of these, but as I understand it (and from looking at spec sheets) it only offers 3 3/4ips.
now, the similar looking Syncasset 134(B) DID offer both speeds
however it uses Dolby B & C noise reduction which renders it useless to me. If I were rich or maladjusted I'd have someone frankenstein one of these to use dbx...
so... I'd be happy if I missed some model somewhere, but i believe that there does not exist a rack mount style (not portastudio style) 4-track cassette deck that offers both 1 7/8 and 3 3/4 ips AND dbx noise reduction.
(any here know of any?) sometimes people believe the Syncasset 234 has two speeds, but from my investigations I've found this not to be true, (unless somehow there were various models, anyone have a 234 that runs both speeds???!!!)
so the models that have both speeds are mostly portastudio style:
424, 424 mkii and many others of which someone with more first hand knowledge than I could gather together the names of and make a list,
if they felt so inclined......