Sony Metal SELECT, Type IV, Metal Position, Metal Bias 70us - 90 MINUTES.
EXCELLENT SUPER METAL PERFORMANCE.
Comes with super useful EXTRAS.

This tape is in pristine condition. Recorded only once, then properly stored. 
Tape, case and inner sheet look like new. 
I tested its recording capabilities and the tape has performed as when it was new (tested using a Pioneer Elite CT-7). 
Please see the photos to realize the excellent shape of the listed item.

INCLUDES:

• SONY Metal SELECT 90 CASSETTE in mint condition.

• A rare copy of the 1988 AUDIO Magazine article comparing 88 tapes (PDF).

• A super rare copy of the 1983 High Fidelity Magazine - SPECIAL TAPE ISSUE (PDF).

• A super rare copy of the 1987 High Fidelity Magazine - 31 Tapes Tested (PDF).

• A SUPER COMPLETE TAPE RECORDING & Buying Guide from Stereo Review (PDF - 1982).

• A copy of Stereo Review, Issue March 1989 - The Tape Recording Special.

• A copy of AUDIO Magazine, September  1981 - Latest Tapes Tested + Cassette Shell Mechanics. 

• TDK Audio Cassettes Data Sheets & Product Guide.

• SONY Audio Cassettes Data Sheets & Product Guide.

• Tips & Tricks for the best analogue recordings (information gathered in the last 2 decades / PDF).


PINNACLE of Compact Cassette Performance:

Beyond contest, beyond any doubt, on of the best sounding cassettes of all time. 
The secret lies in the double layer of ultra fine EXTRALLOY particles. Coercivity is lifted to 1,100 Oersted by the upper later while in the lower layer the particles are tightly packed for increased M.O.L and enhanced low-frequency performance.

Metal SELECT also has a newly designed three plate, high precision shell for added rigidity and lowered vibration. 

This tape formula has extra fine EXTRALLOY particles in unique double coating magnetic layers for reduced noise and expanded performance.
So, it appears that Sony Metal ES was likely the first double coated metal tape produced, and that formula out-performed all the other premium metal cassettes to that date in 1987. 

FEATURES:

• EXTRALLOY Ultra high performing metal particles.
• Extremely high MOL for crystal clear sound.
• Sleek Ultra Precision Infinity-Shape Shell.
• Dynamic sound reproduction for digital or live music sources.
• Less Modulation noise for excellent sound.
• Streamlined advanced tape transport.
• SDC - Super Dispersion Control: for uniform particle dispersion.

NOTES:

This metal tape from Sony belongs to my personal collection. 
It has been kept in a controlled environment free of dust, sunlight or magnetic fields.

REVIEWS:

“As might be expected, Type 4 pure metal tape formulations attain the highest headroom, with Sony Metal SELECT leading the pack with an impressive 9 db”

TYPE IV / More About Metal Position Tapes:

Iron (not rusted) is used for the magnetic material, realizing strong magnetic flux density and coercive force. At the top of cassette tape evolution, it is a medium that can input a signal level as high as it can be said. Since it can be used all-round in terms of sound quality, it is the most easy-to-use tape in a sense, but unfortunately it is almost impossible to obtain at stores now ...

CASSETTES in the DIGITAL AGE:

Why are groups of people taking an increasing interest in audio cassettes as a means to preserve new sound recordings?

It’s generally harder, today, to appreciate the nuances of sound reproduction, because in many ways, the typical sound delivery system has gone backwards. Indeed, even the digital files themselves – MP3s or other compressed options, are simplified to facilitate better storage, and that compromises the quality. Worst of all, qualitative degradation in digital media is much less attractive than in analogue media such as tape.

The digital music reproduction we hear today is often way less stimulating and pleasurable a listening experience than we might have gained from an audio cassette and hi-fi system thirty years ago.

Additionally, cassettes colour a recording. The good ones add a sort of audible sugar, and every different product produces a different rendition of a sound. Us humans thrive on variety, and the nuances, the fluctuations, that audio cassettes add to our listening experience, accordingly have great value. Even though some of the nuances register subconsciously, we do miss them when we switch to digital media.

Happy eBaying!