Let's start with chrome tapes, which are the ones I use the most. And the SA from the '92 goes the first:
As it can be seen, the SA from the '92 has a pretty plain response with less than 1 dB of deviation from almost 30 to 20,000 Hz. The oscillation present between 20 and 100 Hz is something completely normal that almost every tape shows, so it cannot be considered an issue. Only a light falloff of about 1-2 dB at 20Hz can be seen, which in real life will be hardly heard.
The response at -10 dB is the most plain while at 0 dB a small treble falloff appears and at -20 dB a very light rise does appear. All-in-all, an excellent response, which confirms both the quality of the tape and the deck.
With the TDK SA, hardly any 'coloration' of the sound can be felt in the K909ES.
Let's see a start-of-the-art chrome tape: the magnificient UX-Pro from the '96. This tape is almost the same as the UX-ES (which is excellent too) with a small additions like the ceramic tape guide. This tape represents the best technology that was available for type II tapes, so I think it's pretty interesting to see how it performs in this Top-Of-The-Line deck.
As everyone can expect, the UX Pro performs admirablily, with a very plain response. The entire audible range from 20-20,000 Hz is almost plain at all three volume levels, showing just a very light deviation of +/- 0.5 dB.
There is a slight tendency of the treble to falloff at 0 dB and to rise at -20 dB while at -10 dB is the most plain of all three. Excellent performance indeed, especially at -10 dB which is almost perfect.
Although not widely known -at least in my country, Spain- there were high perfomance type I tapes, beside the famous TDK D and the SONY HF. Yes, they existed. One of them was the AR, and the AR-X which was the top ferric tape. This one I'm testing is a special version of the AR, which probably has the same performance but a different case. I never got the point of limited editions of a particular tape but nowadays it's a cool thing to collect.
With this high performance ferric tape some interesting things appear at -10 dB: a small rise like a narrow 'mountain' at the top of the audible range, from 15 kHz and up. This doesn't present a problem to many of us that were born in the 70s because once you reach 40 years-old, your ears barely hear anything above 15 kHz. Yes, from an analythic point of view there's an issue but in the real life there isn't. If you're under 30 you probably will hear something but with that age you probably can't afford such a deck. Ironies of life, isn't it?
At the bottom end there's also a slight loss of bass power but with just 2 dB or less under 50 Hz is hard to notice.
At -20 dB the performance is more or less the same, but at 0 dB the high frequencies start to show the weak points of ferrics: the treble, which starts to go downhill from 5 kHz and above. This makes this tape good for music genres without a lot of treble, so you better avoid disco or rock...
Also, given the more background hiss of these ferrics, a noise reduction system is very welcomed. Dolby S -or even better, dbx- would be perfect for this matter.
Now let's jump to BASF. This tape was one of the best ones in the brand's type II range of that year. Regarding the design I find it quite different although IMHO is a bit ugly design.
I inmediately realized that something was wrong when I started calibrating this tape. I had to push the Rec cal level to the maximum, and even with that it didn't reach the necessary level. It either has a very low sensitivity or it is not compatible with this deck. I've read that some pure chrome tapes looses it's properties after years but I have to confirm.
Update: After posting this question at Tapeheads, Wilhelm (an old BASF engineer) explained that these tapes tend to loose some signal after years, but it normally goes about 1 dB, which is not my case (about 3-4 dB). I did some testing and found that in my Tandberg 3014 is works perfectly fine. Not only the sensitivity is spot on, the linearity is absolutely perfect. So it looks that BASF chrome tapes are definitely NOT meant to be recorded on this SONY (and probably most japanese decks), but european decks.
The linearity is quite bad, with a big rise of the midrange and the treble, making it not recommendable at all with this K909ES. However, I've tested this very same tape in my Tandberg 3014 and the performance is absolutely perfect, in pair with the UX-Pro or even better.
Let's move on to an excellent SONY MetalXR from the early 90s.