> I have talked an evening with one of the
> magnetic tape experts at BASF while
> visiting an AES meeting in Germany in the 80´s.
His name is Diplom-Ingenieur (German equivalent of M.S.
degree) Günter Dreher coming from the Applications Engineering Department
Audio-Tape of BASF.
He was working out of the BASF WMA/ATA department in Mannheim.
We must have met or talked over the phone 100+ times over some 20 years at
Exceptionally knowledgable in everything analogue magnetic tape.
BTW, he claimed that the magnetic properties of ferric oxide remains
unchanged for at least 100,000 years! So, tapes made from ferric
oxide material will not show any degradation for a very long time indeed
unlesss abused in many ways.
Also BASF switched to CRO2, Crome, tape very early on in their Ferric Test
Tapes using 120 µS EQ since it was almost impossible to not get the high
frequency self erasure effect above 15 kHz using even the best BASF Ferric
tape at -20 dB rel. 200 nWb/m reference fluxivity.
Using Crome tape with its much higher high frequency self erasure point
compared to ferric tape made it possible with no problems getting the
frequency run at -20 dB.
P/S this problem is why only 1/4" and wider 15" and 30" test tapes have the
frequency response run at operating level while 7 1/2" test tapes is at -10
dB and 3 3/4" ones are at -20 dB.
This are for later productions.
Earlier test tape productions using older ferric oxide formulations can be
seen to have the frequency run at -10 or even -20 at 15" speed.
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