One other item, the original concept of the Magnetophon did not have the benefit of all of the later research about levels and overload and, to my ears, the early engineers would sometimes overload -- especially on some second-generation copies that I've transferred. It didn't happen all the time, but it certainly contributed.
In addition to the Engel-Hammar article I've referred to,
http://www.richardhess.com/tape/history/Engel_Hammar--Magnetic_Tape_History.pdf
You might also enjoy looking at my AES paper on the transfers of the first group of tapes.
http://www.aes.org/journal/suppmat/hess_2001_7.pdf
Cheers,
Richard
Richard L. Hess email: richard@xxxxxxxxxxxxxxx Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX Detailed contact information: http://www.richardhess.com/tape/contact.htm Quality tape transfers -- even from hard-to-play tapes.