#1943224 - 05/16/08 07:32 PM
FUZZY MATH? / Botnick transfer of The Doors' master tape
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AppolloRecords
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Registered: 05/16/08
Posts: 1
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May 8, 2008
Dear Editor,
I just got around to reading the article in your October 2007 issue, where Bruce Botnick talks about transferring the master tape of The Doors’ first LP to ProTools. Something he said confused me: “When the Scully 4-track machine it was mixed on neared the end of a full roll of tape, it would slow down because of the tension. . . the speed was pretty much normal at the beginning, but. . . “Light My Fire” is a quarter-tone off by the end. . .”
Now, this scenario presents a mother of a calculus textbook “word problem” -- something like this!:
A 2,500’ spool of 1.5MIL-thick audio tape weighing 3 lbs. plays at 15 i.p.s at its head, but by the time it reaches its tail it has slowed by a musical quarter-tone. Assuming a uniform resistance against the tape machine’s capstan, pinch roller, heads, tension arms and internal motors and spindle-brakes; a uniform tape drag; and that the aluminum takeup reel is exactly the weight of the spool’s reel when empty, determine the following:
a. the tape’s playback speed at its tail;
b. whether the rate of speed change from head to tail is constant or curved; and
c. the speed change algorithm, if curved.
Any takers? Without knowing the answer, and without having access to the original un-corrected Scully for transfer, I don’t see how it’s possible to correct the problem in ProTools or in any other way, though I suppose a very sophisticated auto-tune program might be able to fix the ever-changing pitch sample-by-sample!?
And why 4-track for mastering?
Thanks,
Christian Matthews, Appollo Records
Pleasant Hill, California
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#1956159 - 06/11/08 02:51 AM
Re: FUZZY MATH? / Botnick transfer of The Doors' master tape
[Re: AppolloRecords]
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Anderton
MP Hall of Fame Member
Registered: 01/28/00
Posts: 7346
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I can't speak for Bruce Botnick, but I think I can address your questions.
If a reel slows down by 25 cents over, say, 30 minutes of tape, that's less than 1 cent per minute. So for a three minute song, the delta from start to finish would be three cents - hardly notcieable at all. You could simply speed up the entire tune by, say, 2 cents and be pretty much in the ballpark.
As to four-track mastering, I knew some engineers who preferred mixing down each channel on two tracks, thus giving the equivalent of more track width because four-track machines usually handled wider tape than equivalent two-track machines.
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