Zitat:I always felt that companies in the 90's focused too much on particle subtlety, the detail and clarity of the sound improved, the treble response improved, but the overall performance and dynamics were worse than in the old models of audio cassettes....I don't think so, dynamics got better and better til the early 90s. What got worse in my opinion is the durability of the tape, probably due to more heavy calendering to get a smoother surface with lower noise.
And in the mid 90's there were still some developments, for example SONY UXS was able to increase MOL even more, but at time time the market was shrinking and the prices were down, so the makers had to cost cut everywhere and the overall quality went downhill. So the the better formulations the lab invented were coated not under the same strict quality control like before and also after around 1992 the shells had to be cheaper and the quality declined.
I don't like these post 1992 Sony tapes, even they are very capable when you measure them for MOL/SOL they are flimsy prone to drop-outs and fragile.
Zitat:I wonder if TDK continued to develop the tape and shrink the particles, since that picture is until 1990.
I don't think the shrinking went on after around 1990, at least not to a relevant amount like before.
But some developments were surely made, for example a new binder in the 1992 SA/SA-X series.
Zitat:TDK as well as almost all brands probably had a quality peak for me in 1988 or so.I agree with that, that was the prime of cassete tape technology, the biggest developments were made and the production quality was still on a high level.
My favorite TDK tapes are from 1988-90, same for Sony with exeption of UX-Pro and Metal ES wich both debuted in 1985 and were far ahead of any other tape of that time.
Maxell topped their previous products with the early 90s Black Magnetite tapes, but it seems to me these tapes beyond their very nice perfomnce levels were getting more fragile.
These Black Magnetite tapes, to my knowledge, don't use Fe3O4 instead of γ-Fe2O3, only some portion of the γ-Fe2O3 is replaced with the Magntite.
Magnetite is cheaper because one processing step could be saved, Fe3O4 is the pre stage in processing γ-Fe2O3.
But in earlier tapes, TDK AUDUA, Agfa FDXI-S Magnetite had it's shortcommings, so I'm sure Maxell had to find a different approach to add it to their tapes,because they clearly topped the performance of their eptaxial tapes.
I still wonder if Sony UX-S tapes (the black ones after 1987) also used some Fe3O4 (Magnetite) their behaviour is somewhat close to the later Maxell BM tapes.
Zitat:I also read somewhere here on the forum or Tapeheads that the magnetic pigment was purchased from big companies, why then is there so much talk about custom formulations and in-house manufacturing and technology?
A question I still have no answer for, Wilhelm stated that they all got their pigments from Pfizer. But I also know that Wilhelm sometimes confuses things and sometimes writes things out of context wich are art least misleading, especially when it comes to information about non CrO2 Type II tapes.
I still don't know if they got the ready for production FeCo pigment, or just the raw materials Gamma Hemmatit and Cobalt... Also possible is that Pfizer was the mass producer and made the FeCo particles specifically to the different receipes of the the different customers.
Maybe Pfizer also had (at least later) when the technology was very common, their own standard process and this ready for production pigments were sold to customers that were not that big like TDK or Maxell with their own big labs?
I still believe the different approaches to adsorb cobalt into the surface of the ferric particles, Avilyn, Epitaxial, Uniaxial are real and were done inhouse.
Zitat:But our dilemma regarding the TDK AR model was probably not about non porous, but about whether it contained cobalt or not, similar to the Sony HF-S models where cobalt was first mentioned in 1990, similarly it could have been the case with the HF-ES or AHF, but this information is almost untraceable.
Also hard to tell at what point of performance Cobalt was needed in the formulation of Type I tapes. For Type II it's clear they have to be CrO2, or they have to use the Cobalt adsorbtion technique otherwise the high coercivity to fit the high bias slot cannot be achieved.
HF-ES surely does contain cobalt, same for XLI-S or AR-X, all these top TypeI tapes with the oustanding HF perfomance are not only made with cobalt, they all use the Cobalt adsorbed Fe2O3 pigments. Maybe some of the not high end Superferrics are only using some cobalt added to te mix in an other way. AR for example has oustanding LF MOL but LF permomance is not really ahead of TDK D.
The early and also the lower grade superferrics were mostly just better refined and packed pure Fe2O3 pigments. TDK AD at up to 1982 is most probably just better Fe2O3 pigment. But TDK AD 1992... my gues is, it also contains cobalt to some degree, but maybe not the cobalt adsorbed technique.
Again no real knowledge... have to do much more research.