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Author Topic: Info on tape length in min...  (Read 17891 times)

Offline rekloos

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Info on tape length in min...
« on: November 21, 2008, 09:42:46 PM »

 I dont seem to be able to find this anywhere, not even on wikipedia.
Anybody knows or has a link to where i can find out how long in minutes,
depending on their size [7", 10.5"] and thickness [1200'. 2400' etc.]and
depending on what speed [7.5ips, 15ips] they're been played/recorded at?
thx.
rek.

Offline reelnut

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Re: Info on tape length in min...
« Reply #1 on: November 21, 2008, 11:39:02 PM »
Hi rekloos-

Glad to help out here.

Firstoff let's consider speed:
You can record at whatever speed you like, but 7" reels usually have recordings at 3.75ips or 7.5ips. 10" reels are normally recorded at 7.5ips or 15ips, but again the speed is entirely up to you.

Now lets consider tape thickness and tape length:
Two variations are quite common: 1- The "standard" tape thickness is 1.5mil. This is your "toughest" tape in terms of resistance to breakage and print-through. 1.5mil tape is wound on 7" reels in lengths of 1200' or 1250', depending on the manufacturer, and wound on 10" reels in lengths of 2400' or 2500', depending on the manufacturer. 2- The "long-play" tape thickness is 1.0mil. A 7" reel will spool 1800' of 1mil tape and a 10" reel will spool 3600'. These two lengths are almost always what long-play tape is available in. There are also "double play" and "triple-play" tapes, which aren't common and aren't even being made anymore, to my knowledge. You really need a fine machine to safely handle these last two tape thicknesses because they are delicate and prone to stretching and breakage, so for our purpose we will only consider "standard" and "long-play" tapes.

Now consider recording time:
This is pretty easy to figure. For example, a 10" reel with 2500' of tape at 7.5ips: 2500' is 30,000in. And 30,000in/7.5ips = 4,000sec. And 4,000sec = 66.66 minutes. As you can see, what we did was convert feet to inches to get total number of inches. Then we divided speed (in this case 7.5) into total inches to get total seconds of recording time. Lastly we divided total seconds (4,000) by 60 to get recording time in minutes.

Here is a quick summary for you. I saw a really good table just the other day, but I'll need to look for it and get back to you on that:

7" reel
1200' @3.75ips = 64min.  @7.5ips = 32min.  @15ips = 16min.
1800' @3.75ips = 96min.  @7.5ips = 48min.  @15ips = 24min.

10" reel
2500' @3.75ips = 2hr, 13min, 20sec.  @7.5ips = 66min, 40sec.  @15ips = 33min, 20sec.
3600' @3.75ips = 3hr, 12min, 00sec.  @7.5ips = 96min, 00sec.  @15ips = 48min, 00sec.

I did have to work this out on the calculator, but after you live with these numbers for awhile and end up using one or two speeds and a couple of different tape lengths most of the time, you won't even have to think twice about this.

Cheers, and happy reeling!

« Last Edit: November 22, 2008, 12:48:41 PM by reelnut »
John Hanek (dedicated amateur)- A810, X2000R, X1000R, A3440, GX636. Played thru Yamaha CX1, MX1, YST-SW150 (2), S55 (2).

Offline ironbut

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Re: Info on tape length in min...
« Reply #2 on: November 22, 2008, 01:51:49 AM »
Here's a link to a table that should help. If you scroll down the index on the left and select "Tape Talk" you'll find the table.
http://www.angelfire.com/electronic2/vintagetx/
steve koto
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Offline reelnut

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Re: Info on tape length in min...
« Reply #3 on: November 22, 2008, 03:07:56 AM »
Yeah, I'm still surfin!
Here's one that's easy to read: http://www.richardhess.com/tape/timing.htm
John Hanek (dedicated amateur)- A810, X2000R, X1000R, A3440, GX636. Played thru Yamaha CX1, MX1, YST-SW150 (2), S55 (2).

Offline rekloos

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Re: Info on tape length in min...
« Reply #4 on: November 22, 2008, 10:02:49 AM »

 Thank you guys, that's exactly what i was looking for. I'm surprised this
info is not so easily available, it seems so basic.

Reelnut, i think your explanation was very well written, you should get on the
Wikipedia and write some stuff for the 'reel-to-reel tape' description.


rek.
rek.

Offline jcmusic

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Re: Info on tape length in min...
« Reply #5 on: November 22, 2008, 10:07:54 AM »
Someone should make this table a sticky.

Jay
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Offline ironbut

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Re: Info on tape length in min...
« Reply #6 on: November 22, 2008, 10:39:02 AM »
Someone should make this table a sticky.
Jay

Done,.. it's now in the "Tape Basics #4" in the Beginners Guide sticky (I meant to do this but just plum forgot).
steve koto
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Offline reelnut

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Re: Info on tape length in min...
« Reply #7 on: November 22, 2008, 12:25:29 PM »
thanx rekloos- that's really nice to hear!
John Hanek (dedicated amateur)- A810, X2000R, X1000R, A3440, GX636. Played thru Yamaha CX1, MX1, YST-SW150 (2), S55 (2).

Offline reelnut

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Re: Info on tape length in min...
« Reply #8 on: November 22, 2008, 12:44:34 PM »
Observation:

The tape counter on the A810 which I use is extremely accurate and:

I noticed when I bought (1 only) RMGI LPR35 tape on metal reel in a setup box that the tape length appeared to be EXACTLY 96min @7.5ips.

However, when I bought (2 cases- equals 40 tapes) pancakes of this same tape, the length of every single tape was ALWAYS 96min, 30sec @7.5ips.

Has anyone else had an experience like this?
« Last Edit: November 22, 2008, 12:46:13 PM by reelnut »
John Hanek (dedicated amateur)- A810, X2000R, X1000R, A3440, GX636. Played thru Yamaha CX1, MX1, YST-SW150 (2), S55 (2).

Offline sound signal

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Re: Info on tape length in min...
« Reply #9 on: November 23, 2008, 11:11:45 AM »
Greetings,

There are also "double play" and "triple-play" tapes, which aren't common and aren't even being made anymore, to my knowledge. You really need a fine machine to safely handle these last two tape thicknesses [...]

RMGI make the double-play PM975.  It is a non-backcoated tape and has the same characteristics as PM974 (long play) and PM973 (standard play).  Given the latest findings on the role of back coating in the cause of sticky shed syndrome, it seems non-backcoated tapes deserve consideration.

"Back in the day", double-play tape on 10 1/2" reels was considered borderline, and few brands made double play available on 10 1/2".  You could only get triple play on 7" or smaller.  In my experience, with good adjustment of the brakes and care in use (always use the same type of reel for supply and take up to match inertia, and have a care when switching into or out of fast wind modes) a good quality domestic or semi-pro machine should safely handle double-play and triple-play tape within the above limits on reel size.  Nowadays, the double-play PM975 is only available on reels up to 7".  This tape configuration was quite widely sold to domestic users from the mid-1960's on.  So you can't really get into any trouble unless your machine is rather primitive, or it needs service and/or adjustment.
George Karaolides
Nicosia, Cyprus

Offline ironbut

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Re: Info on tape length in min...
« Reply #10 on: November 23, 2008, 02:13:31 PM »
There's a good deal of controversy surrounding this research among preservationists and restoration experts. That's certainly not to say that the results aren't valid or useful, but as far as I know, I haven't heard of anything in the field that has offered any evidence that these results are applicable in the real world. I don't wish to imply that Mr. Richardson's research is somehow flawed of unworthy of consideration, but rather, I hope that it leads to a long term solution for SSS and these tapes will be able to be played for future generations of high resolution transfers.
steve koto
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Offline sound signal

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Re: Info on tape length in min...
« Reply #11 on: November 24, 2008, 06:56:29 AM »
Hi Steve,

The only half-important tape I have which has developed "sticky shed syndrome" is an MRL calibration tape I bought over fifteen years ago (I guess I'm lucky).  I was thinking of sending that to Mr. Richardson for treatment, just to see if it comes back "cured" and how long it stays "cured" for.  To my mind, it's worth spending the same as, or less than, the 120-odd dollars it would cost to buy a new MRL calibration tape today, to find out if that method works.  So I guess I'll be getting round to that pretty soon and will be reporting my experiences to the forum.

With best regards,
George Karaolides
Nicosia, Cyprus

Offline docb

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Re: Info on tape length in min...
« Reply #12 on: November 24, 2008, 10:21:36 AM »
Removes carbon black, no chemicals, no baking. That leaves only one possibility -

Pink Pearl eraser

man it would take some time to do a 2500' tape ;^)>
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline ironbut

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Re: Info on tape length in min...
« Reply #13 on: November 24, 2008, 09:58:46 PM »
That's a great idea George. An MRL tape would be an idea subject. Changes in levels was one of the drawbacks that Richardson has brought up of "baking when needed" (repeated baking) so if his process avoids that problem, it should be obvious.
steve koto
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Offline sound signal

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Re: Info on tape length in min...
« Reply #14 on: November 25, 2008, 02:51:42 AM »
Just got an emailed reply from Charles Richardson saying that Rezerex have not yet finished building the machine that can treat tapes on a commercial basis, and that he will notify me as soon as they are able to accept my tape for treatment.  His reply was prompt, courteous and quite informative.  He explained why I should not bake the tape, and why the old calibration tape would be worth treating and keeping, as well as getting a new one from MRL.

I agree with Steve.  Letting Richard try out his method on my old MRL tape is just about the best way to verify the claimed results.  I really look forward to being able to do this.

With best regards,
George Karaolides
Nicosia, Cyprus