Hello, Jonathan, To keep things in perspective, most motors and other devices that use electromagnetism keep most of it inside in order to improve efficiency. If I recall correctly, the DC magnetism of the earth is 0.5 Gauss. The best reference I'm aware of is here: http://home.flash.net/~mrltapes/field-strength-for-partial-erasure.pdf And if you wish a quick refresher on magnetic units, please see http://www.irm.umn.edu/hg2m/hg2m_a/hg2m_a.html I hope that helps. Cheers, Richard At 04:32 PM 2008-08-26, you wrote: >Hi all, > >We have most of our audio collections housed in powered mobile storage >units (Spacesaver Eclipse EC300). A colleague from another institution >recently mentioned that they had chosen manual mobile storage due to the >potential interference from the motor on magnetic-based audiotape. The >EC300 uses a 90VDC motor, 1/6HP, 5 amp max, 120VAC 60Hz. There is >approx. 3-4" between the motor and the lowest storage shelf. Is that >enough to cause interference with the audio signal? > >Many thanks, >Jonathan > >Jonathan Wise >Audiovisual Archives >Canadian Museum of Civilization Richard L. Hess email: [log in to unmask] 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.