Introduction
This continues my evaluation of old cassette tapes, this time a bunch of TDK premium and super ferrics. All tapes were erased in a Weircliffe BKE200 prior to testing.The details of the test methods are here.
Maxell UR C90 (1994) (what the deck was calibrated for)
Relative sensitivity: (reference)
THD @ Dolby level: 0.42%
MOL400(THD=1%): +3.4dB
MOL400(THD=3%): +5.3dB
MOL1k(THD=3%): +2.9dB
SOL10k: -1.3dB
SOL15k: -7.3dB
Bias noise: -49.5dB, -52.5dB(A)
Dynamic range: 57.8dB
TDK OD (1979)
Relative sensitivity: +0.6dB
THD at Dolby level: 0.55%
MOL400(1%): +3.3dB
MOL400(3%): +5.8dB
MOL1k(3%): +2.3dB
SOL10k: -1.4dB
Bias noise: -48.0dB, -51.2dB(A)
Dynamic range: 57.0dB
This is a bit of a rarity, TDK's first super-ferric, slotting in above AD. In terms of compatibility and performance it is roughly equivalent to 1977 Maxell UD-XLI.
TDK AD (1979)
Relative sensitivity: 0dB
THD at Dolby level: 0.33%
MOL400(1%): +3.0dB
MOL400(3%): +5.3dB
MOL1k(3%): +3.5dB
SOL10k: -0.8dB
Bias noise: -49.7dB, -53.0dB(A)
Dynamic range: 58.3dB
The OD should have been the superior product, but this AD beats it in nearly every respect. But we should not forget that the AD required a, for the 1970s, rather high bias.
TDK AD (1982)
Relative sensitivity: -0.2dB
THD at Dolby level: 0.57%
MOL400(1%): +1.9dB
MOL400(3%): +5.1dB
MOL1k(3%): +4.1dB
SOL10k: -0.8dB
Bias noise: -50.0dB, -53.5dB(A)
Dynamic range: 58.6dB
This cassette has a 1983 manufacturing date code. It came in a small lot I got from Japan, with a commercial after-market j-card as was en vogue there for a while. According to the notes its date of recording was 58/12/28. That would be 28 December 1984 in Showa period notation ...
TDK AD (1984)
Relative bias: +2.5
Relative sensitivity: +0.2dB
THD at Dolby level: 0.45%
MOL400(1%): +3.6dB
MOL400(3%): +6.5dB
MOL1k(3%): +5.0dB
SOL10k: -0.6dB
Bias noise: -50.7dB, -54.3dB(A)
Dynamic range: 60.8dB
TDK AD (1986)
Relative bias: +1
Relative sensitivity: +0.6dB
THD at Dolby level: 0.45%
MOL400(1%): +4.1dB
MOL400(3%): +6.7dB
MOL1k(3%): +4.0dB
SOL10k: -0.1dB
Bias noise: -51.0dB, -54.6dB(A)
Dynamic range: 61.3dB
This type is supposed to cover the 1984-1987 era. My sample was from 1986.
TDK AD (1988)
Relative sensitivity: +0.1dB
THD at Dolby level: 0.51%
MOL400(1%): +4.0dB
MOL400(3%): +6.8dB
MOL1k(3%): +5.8dB
SOL10k: +0.1dB
Bias noise: -50.2dB, -53.9dB(A)
Dynamic range: 60.7dB
Together with Maxell UDI-CD (1996) this is the tape in my collection that demands the highest bias for type I. MOL, SOL, and compression are excellent.
TDK AD (1990)
Relative sensitivity: +1.0dB
THD at Dolby level: 0.52%
MOL400(1%): +5.5dB
MOL400(3%): +6.8dB
MOL1k(3%): +4.6dB (see remark)
SOL10k: -dB (no reading, see remark)
Bias noise: -51dB, -54.8dB(A)
Dynamic range: 61.6dB
Sadly, this sample was dirty and badly worn, with railroading all over. Consequently the signal stability during testing was poor, especially with higher frequencies. MOL1k is but an estimate, both channels differed wildly, and my patience was not up to the task of assessing SOL. But given the low noise and the very high 1% MOL this must have been a stellar tape.
TDK AD (1994)
Relative sensitivity: +0.9dB
MOL400(3%): +6.9dB
SOL10k: -3.1dB
Bias noise: -51.5dB, -55.3dB(A)
Dynamic range: 62.2dB
Even better than the 1990 version, but SOL seems low. This is the highest dynamic range I've ever seen for a type I. Remember that this is with 120 us equalisation. To put things in context, type II/IV 70 us equalisation would give a 4dB noise advantage. Under this regime TDK AD would reach 66.2dB(A) dynamic range, which is entirely equivalent to the 1990 SA-X!
TDK AD-X (1985)
Relative sensitivity: +0.5 dB
THD at Dolby level: 0.79%
MOL400(1%): +3.7dB
MOL400(3%): > +7.0 dB
MOL1k(3%): +3.5dB
SOL10k: -0.7dB
Bias noise: -49.8dB, -53.0dB(A)
Dynamic range: > 60.0dB
MOL is so high that it clipped the input of my ADC slightly before the 3% THD point was reached.
TDK AR (1988)
Relative bias: 0
Relative sensitivity: +1.7dB
THD @ Dolby level: 0.9%
MOL400(1%): +1.6dB
MOL400(3%): +8.8dB
MOL1k(3%): +5.2dB
SOL10k: -0.3dB
Bias noise: -49.1dB, -52.9dB(A)
Dynamic range: 61.7dB
TDK AR (1992)
Relative sensitivity: +1.5dB
THD @ Dolby level: 0.6%
MOL400(3%): +6.7dB
SOL10k: -1.1dB
Bias noise: -50.8dB, -54.3dB(A)
Dynamic range: 61.0dB
TDK AR-X (1988)
Relative sensitivity: +2.0dB
THD @ Dolby level: 0.55%
MOL400(1%): +6.0dB
MOL400(3%): +8.4dB
MOL1k(3%): +4.1dB
SOL10k: +1.3dB
Bias noise: -50.8dB, -54.6dB(A)
Dynamic range: 63.0dB
Despite still being underbiased in the BX-300 MOL400 is gigantic. SOL is in metal territory. MOL1k, on the other hand, is not stellar, but with increased bias it would probably grow a bit. 63dB dynamic range with a type I!!! I should try this tape in the CR-7 ...
INDEX OF ALL CASSETTES