Re: [ARSCLIST] 1/4" audio tape digitizing

["Richard L. Hess" <arclists@xxxxxxxxxxxxxxx>]

At 05:54 PM 2/12/2006, Michael Shoshani wrote:
> Jeffrey Kane <jeffkane@xxxxxxxxxxxxxxx> 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.

Cheers,

Richard

Richard L. Hess                   email: richard@xxxxxxxxxxxxxxx
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