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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 12th Jun 2017, 8:19 am   #21
'LIVEWIRE?'
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Default Re: Cassette death by take-up torque

Away back in post#6 Ben mentioned Tanashin Cassette Mechanisms. They, and clones thereof were used in a wide range of in-car cassette players, including some by leading brands such as Blaupunkt, Clarion, Philips, and Pioneer, who all fitted the TN303 to some of their products. I totally concur with Ben's description of the problems they caused. Decks like the TN303 are now to be found in some of those 'Fake Antique' Music Centres from China, so the problem hasn't gone away. A worse mechanism, fortunately now consigned to history, was the EDI Leader, later RIEL basic mech., which originally didn't have any kind of autostop, although later versions had an electronic 'pulse counting' one. I first came across them in the Radiomobile 301CS (made in Italy) back in the 70s.
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Old 12th Jun 2017, 11:17 pm   #22
TIMTAPE
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Default Re: Cassette death by take-up torque

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Originally Posted by Ted Kendall View Post
Analogue video recording was FM, so the question of bias in that sense didn't arise except for the audio/control tracks.
I'm no expert on video but I take it the tone that was frequency modulated was effectively "its own bias signal", ie: it removed the distortion you get without such a signal. I guess we could do the same with audio: record say a 10 kHZ tone with no bias signal added, and within a certain range of magnetisation it will record itself undistorted as if a separate bias signal was present.

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Originally Posted by Ted Kendall View Post
Plangent works, if you have the budget for it and can work with a bureau system. I use Cedar Respeed to good effect, according to the reviews. It doesn't need a clock signal to work - it's one clever algorithm which I don't pretend to understand, but it works.

No experience of Capstan, but judging by some ARSCLIST posts, it's a temperamental beast more akin to Autotune. You pays your money...
As apparently with Cedar Respeed neither does Capstan use a "clock signal" (bias tone) that Plagent uses, so perhaps both Cedar Respeed and Celemony Capstan work on the same principle?

In their advertising literature the makers of Celemony Capstan do not claim it works on mere speech, and in a discussion on another forum, a Celemony company representative stated he had tried but had no success removing Wow and Flutter from mere speech recordings. It only worked for him on music recordings and on the "polyphony" within it. I guess Capstan would appear to be "a temperamental beast" if an operator didnt understand this limitation. Perhaps this same limitation also applies to Cedar Respeed...

Last edited by TIMTAPE; 12th Jun 2017 at 11:29 pm.
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Old 3rd Jul 2017, 11:15 am   #23
IanNVJ35
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Default Re: Cassette death by take-up torque

Back on the original subject, how many cassette decks offered double capstan drive WITHOUT tension applied over the two by different capstan sizes? I have one sony deck from 1973 that does this and it goes a long way to preserve tapes. So many decks pull at the tape too strongly that it is a breath of fresh air to find one that is kind to the tape.
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Old 3rd Jul 2017, 4:19 pm   #24
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Default Re: Cassette death by take-up torque

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Originally Posted by McMurdo View Post
In the paper and textile industries, reel take-up is a very common problem, albeit on a bigger scale. DC Motors are the preferred option, at least on the less modern stuff. It's quite an art. The current is controlled/limited for torque control as you'd expect. It's not constant however but linked to a speed sensor on the take up motor. That way the circuitry can estimate both the torque and the diameter of the spool. As the spool fills, the speed decreases of course, but the current must increase to compensate for the 'moment' as the reel fills. As the reel approaches full capacity the winding tension must slowly decrease to prevent a layering/lapping error where the last few turns develop a tendency to go on the spool in an irregular way (also called telescoping).

The DC motor method overcomes the common problem of cassette clutches which is that they are very taught when the spool is empty but can slow and stop when the reel starts getting full.
Indeed. I worked at Thorn Automation and that was just the type of thing that we were doing with our DC drives (later, AC drives). The technique was used in the steel industry too. Sometimes there would be parts of the line that had many rolls, in a vertically offset row, 'one above the other' in a part of the line (I think they were called take up lines?) used to take up excess material in the event of problems or different feed and take up issues. It was all very complex to maintain tension throughout the line. The rollers would often be 'dancing' types that moved up and down to take up excess, or 'pay off' material as required. I just worked in the test department and worked to a spec. The actual setting up was done on site by the commissioning engineers.
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Old 4th Jul 2017, 3:49 am   #25
TIMTAPE
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Default Re: Cassette death by take-up torque

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Originally Posted by IanNVJ35 View Post
Back on the original subject, how many cassette decks offered double capstan drive WITHOUT tension applied over the two by different capstan sizes? I have one sony deck from 1973 that does this and it goes a long way to preserve tapes. So many decks pull at the tape too strongly that it is a breath of fresh air to find one that is kind to the tape.
I doubt any of them are designed to run both capstans at the same speed.
The slightly different speeds assume the tape is somewhat elastic and the tape's elasticity limits the tension. Thicker tapes which are less elastic get more tension, which they can stand. Thinner more fragile tape get less tension which is just as well. So with dual capstan the tape tension should self regulate. That's my understanding.

But badly regulated take up torque is no good for cassettes. Either too much or not enough can be a killer.

Another factor often not appreciated is that tapes need a controlled back tension upstream of the main capstan or upstream of both if it's dual capstan.
Without it the tape can ride up or down the capstan shaft/pinch roller and destroy itself. Some cheaper machines rely only on the back tension supplied by the small felt pressure pad but of course if that pad fails, the back tension is lost and the tape can chew itself at the capstan. Excessive take up tension brings this on earlier. That's been my experience.

Last edited by TIMTAPE; 4th Jul 2017 at 3:56 am.
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