At 12:46 PM 2010-04-29, Mike Gray wrote: >What a simple and elegant idea - use the bias signal as a clock; >wow+flutter=jitter; heterodyne - same as recovering audio modulation >from an RF signal. Congratulations to all involved. > >One criticism I heard when I mentioned this technique to someone in >the restoration community - is the bias signal sufficiently stable >to ensure that the derived signal is accurate? Hi, Mike, There are many different "windows" of perturbations in tape systems. Bias would generally be stable enough to correct for wow and flutter. Where it might fail us is in certain circumstances over the length of a recording. As you may have noted, David mentioned that Jamie suggested transferring on a song-by-song basis, recalibrating the Plangent bias recovery for each song. Once we have the wow and flutter filtered out via Plangent, we can apply long-term speed drift compensation using a variety of tools (although some of the "autotune" tools might have too much of an acoustic signature). Cheers, Richard 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.