On Jan 28, 2011, at 10:12 PM, Richard L. Hess wrote:

> ...One of my clients likes it that we can pitch the tapes for him  
> in the analog domain.

Dear Mr. Hess, et al.,

      I was wondering how much speed tolerance there is to a given  
pre-/de-emphasis EQ, even if a vari-speed oscillator is available.     
Say there is a 1 kHz tone at 990 Hz, and you know they had intended  
the EQ to be NAB...   Had the horse already left the barn (in terms  
of the emphasis's efficacy) when they were signaling a 1k sine, but  
the machine was turning a bit faster than 15 ips (say, 15.2 ips)  and  
turned the 1000 cycles per second into 990 cps when played back at  
the intended record speed?   Or, by speeding up the playback machine  
to 15.2 ips - enough to make the intended 1k tone actually play 1000  
cps - does the vari-sped playback (at the original record speed)  
magically de-emphasize the haunted pre-emphasis?  What is the point  
at which an alteration should be made to the pre- and/or de-emphasis  
EQ?  (Obviously, if the recorder is turning at 20 ips or higher, a  
different emphasis eq has to be set, whence the custom curves - let  
alone AES and AME.)

Thank you,