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Re: Estimation of the time used on *partially-full* open-reel audio tapes - seeking good reference

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Sat, 27 Oct 2018 10:50:17 +1300

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 Hello Nick, This is simple calculation: Tape length L =Pi /4 /t*(D+d)*(D-d) Where Pi =3.14, t = tape thickness, d =hub diameter, D =tape-pack Diameter In your example t =1.5 mil =0.0015 inch, d =2.25 inch, D =4.5 inch So, L =3.14/4/0.0015*(4.5+2.25)*(4.5-2.25) =7948.125 inch Duration T =L/S Where S =Tape Speed. In your example S =7.5 ips. So, T =7948.125/7.5 =1059.75 sec =17.6625 min =17 min 39.75 sec This calculation is correct for tight tape winding. Best regards, Gennady Lyskin G e n n L a b http://www.gennlab.com [log in to unmask] Tel: +64 21 238 3056 New Zealand ----- Original Message ----- From: "Nick Patterson" <[log in to unmask]> To: <[log in to unmask]> Sent: Friday, October 26, 2018 7:54 AM Subject: [ARSCLIST] Estimation of the time used on *partially-full* open-reel audio tapes - seeking good reference > Dear collective ARSC wisdom, > > I'm looking for reference resources for the estimation of the time used on > *partially-full* open-reel audio tapes. > > I'm aware of resources that calculate timings (based on various factors) > for *full* audio tape reels, such as: > > https://www.weareavp.com/open-reel-audio-duration-calculator/ > > But, I'm wondering if anyone might be able to point me towards a stable > and > authoritative reference for similar calculations for *partially* full > reels. > > So, a sample problem would be: > > What is the duration on a reel which is 7", 1.5 mil tape, recorded at 7.5 > ips, and has a tape-pack diameter of 4.5 inches on the reel (assuming a > 2.25 inch center hub)? > > We have a working estimation method in place, for the project I'm current > working on, but I'd like to find an authoritative reference in the > community, that documents this. > > If anyone knows of such a resource, I'd appreciate any info! > > P.S. the engineers amongst you may scoff that this is simply math, but, > math is not my strongest suit, hence my search for a stable reference, > rather than back-of-the-napkin calculation - please don't judge too > harshly > :-) > > best regards, /Nick > > > Nick Patterson, Music Librarian > Music & Arts Library, Columbia University > 701 Dodge, 2960 Broadway > New York, NY 10027 > 212-854-8523