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Hence, possibly, the Play Trim knob on NAD decks which put a variably vicious lift in the top octave to improve replay on Dolby cassettes? ----- Original Message ----- From: "Richard L. Hess" <[log in to unmask]> To: <[log in to unmask]> Sent: Friday, January 14, 2011 5:00 PM Subject: Re: [ARSCLIST] Association for Recorded Sound Discussion List <[log in to unmask]> > Hello, Goran, > > A friend of mine (who would rather not be dragged into more conversations > about this) who worked in the Ampex Standard Tape Lab, and who is not part > of this list, reported to me that no one could explain why, but some > cassettes that were recorded would lose high frequencies if stored for > about a year. The loss was substantial. While Don no longer has any notes > on this, I have generally found his memory and knowledge to be reliable. > His recollection is that the 15 kHz loss was in the neighbourhood of 10 dB > in the worst examples. > > I have grilled him on this, and he is convinced that it happened and it > was not due to external magnetic fields. > > One theory that was proposed at the time was magnetostriction due to the > relatively small radii of the guides in the cassettes. > > He used Dragons and other top-end cassette machines in the lab. He was > responsible for a while for manufacturing Ampex standard "test" > [calibration] tapes for audio and video. > > Cheers, > > Richard > > On 2011-01-14 11:43 AM, Goran Finnberg wrote: >> None of the high speed duplicated cassettes I still have, several 100, >> and >> none of my approx 60 BASF, Nakamichi and RCA test cassette tapes show any >> change in level or frequency response either objectively or subjectively >> IF >> the azimuth is very carefully adjusted on my Dragon, 582 or 682 Nakamichi >> decks. > > -- > Richard L. Hess email: [log in to unmask] > Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX > http://www.richardhess.com/tape/contact.htm > Quality tape transfers -- even from hard-to-play tapes.