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Richard Hess:

> I've found 96/24 at 7.5 in/s is adequate for 15/32 logging tapes.
> If you start with 40 kHz bandwidth and take that down 16 X you
> end up with 2500 Hz bandwidth which is probably optimistic for
> most 15/32 logging tapes. Comms channels are brick walled at
> 3000 or 3200 Hz.

Yes, you have 40 kHz bandwidth from the A/D conversion ONLY.

What will the gap losses do when replaying 15/32" tapes ?

And since I like to use a flux loop to understand what happens above 20 kHz
electrically in the playback electronics I can tell you that almost every
tape machine I have looked at they intentionally drop off very fast above 20
kHz.

The intent here is to avoid having the erase/bias frequency getting out of
the machine.

Even the Ampex ATR 102, when the input damping potentiometer in the replay
amplifier is correctly set as per the manual, rolls off swiftly above 20 kHz
electrically.

Unless you have replay heads having very narrow gaps with gap loss
correction and replay electronics designed for greater than 60 kHz response
and the replay head has sufficiently low inductance AND very low capacitive
loading you just will not have 40 kHz all the way from tape to A/D input.

Thus you may have in practice nothing better than a few hundred Hz in actual
bandwidth due to restrictions before the A/D when you replay 15/32 tapes at
7.5" speed.



-- 
Best regards,

Goran Finnberg
The Mastering Room AB
Goteborg
Sweden

E-mail: [log in to unmask]

Learn from the mistakes of others, you can never live long enough to
make them all yourself.    -   John Luther

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