At 05:54 PM 2/12/2006, Michael Shoshani wrote:
>Jeffrey Kane <[log in to unmask]> wrote:
>How does that affect the frequency response, though?
>I mean, theoretically...let's say you have a machine whose high end
>tops out at 25 kHz. You have a tape whose highest frequency is 22
>kHz. If you play that tape at twice its speed, I should think that the
>high frequency now tops out at 44 kHz while the machine itself is
>still limited to 25 kHz, rather destroying any nuances in that 22 kHz
>sound once it's been brought back down to normal playing speed.
>Or is my math severely off? (This is something I have wondered about
>for years concerning high-speed tape duplication...)
The original post was about spoken word recordings. I responded to
that with what I do with normal audio tape machines--that go out to
30-35 kHz at the higher speeds (a Sony APR-5000 test report that came
in one of my manuals shows -1.5 dB at 27 kHz at 30 in/s).
An instrumentation recorder can go out to 100 kHz or more.
Duplicators were designed to work at the higher frequencies. They
were not normal tape recorders. Sadly, most of them are now in
landfills. Few have been preserved as they're mostly recorders and
usually an oddball player (like a 1/2" tape or a bin loop.)
I was thinking of 2x reproduction to speed things along. For
voice-grade oral-history type recordings, 2x is certainly fine using
the machines we've been talking about, as there probably isn't much
information past 10 kHz on the original. I just checked a couple of
originals and there didn't seem to be much energy past 10 kHz and
what's there is often noise and noise modulation.
I have done some work at 4x where I had a 15/16 in/s 4-track cassette
and only a 3-3/4 in/s player...it worked OK. The transfer process
wasn't the worst that had already happened to the tape by a long shot.
Given good pro tape machines and oral-history content, you might be
able to go up to 4x, but that would be the limit. I was thinking 2x.
But if you ingest both sides in one pass, then that gains you another 2x.
An approach I'm working on is four transfers in real time for
cassettes with monitoring each cassette for audible problems out four
of the five identical speakers in my studio. I think this is
preferable to speeding up the process...and who wants to modify Dragons.
Richard L. Hess email: [log in to unmask]
Vignettes Media web: http://www.richardhess.com/tape/
Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX
Detailed contact information: http://www.richardhess.com/tape/contact.htm