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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Cassette tape speed adjustment
Assuming my test tape is stretched (I doubt it , as it would have to be even
stretch the whole length). I normally test speed monaurally so the beats are unmistakable. That is 1KHz test tape output and floating accurate 1KHz sine signal both fed into one headphone cup. Easily gives 0.1 percent resolution (assuming test tape is ok). If I record accurate 1KHz tone onto a blank tape for exactly ( to human reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or so and output lasts for 100 seconds +/- reaction time then is the speed correct? I suspect that repeating this process with the speed regulator changed , say 5 percent, would also give "correct" speed, that time also Does anyone know how much effect types and thickness (play duration C30 to C90) have on replay speed perhaps in conjunction with too soft or too hard pinch wheel rubber ? |
#2
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Cassette tape speed adjustment
On Tue, 8 Dec 2009 16:32:52 -0000, N_Cook wrote:
Assuming my test tape is stretched (I doubt it , as it would have to be even stretch the whole length). I normally test speed monaurally so the beats are unmistakable. That is 1KHz test tape output and floating accurate 1KHz sine signal both fed into one headphone cup. Easily gives 0.1 percent resolution (assuming test tape is ok). If I record accurate 1KHz tone onto a blank tape for exactly ( to human reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or so and output lasts for 100 seconds +/- reaction time then is the speed correct? I suspect that repeating this process with the speed regulator changed , say 5 percent, would also give "correct" speed, that time also Does anyone know how much effect types and thickness (play duration C30 to C90) have on replay speed perhaps in conjunction with too soft or too hard pinch wheel rubber ? none at all. |
#3
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Cassette tape speed adjustment
AZ Nomad wrote:
On Tue, 8 Dec 2009 16:32:52 -0000, N_Cook wrote: Assuming my test tape is stretched (I doubt it , as it would have to be even stretch the whole length). I normally test speed monaurally so the beats are unmistakable. That is 1KHz test tape output and floating accurate 1KHz sine signal both fed into one headphone cup. Easily gives 0.1 percent resolution (assuming test tape is ok). If I record accurate 1KHz tone onto a blank tape for exactly ( to human reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or so and output lasts for 100 seconds +/- reaction time then is the speed correct? I suspect that repeating this process with the speed regulator changed , say 5 percent, would also give "correct" speed, that time also Does anyone know how much effect types and thickness (play duration C30 to C90) have on replay speed perhaps in conjunction with too soft or too hard pinch wheel rubber ? none at all. Tape speed depends on the rotational speed and diameter of the capstan. On a properly maintained deck all other factors are irrelevant. Ron(UK) |
#4
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Cassette tape speed adjustment
"N_Cook" wrote in message ... Assuming my test tape is stretched (I doubt it , as it would have to be even stretch the whole length). I normally test speed monaurally so the beats are unmistakable. That is 1KHz test tape output and floating accurate 1KHz sine signal both fed into one headphone cup. Easily gives 0.1 percent resolution (assuming test tape is ok). If I record accurate 1KHz tone onto a blank tape for exactly ( to human reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or so and output lasts for 100 seconds +/- reaction time then is the speed correct? I suspect that repeating this process with the speed regulator changed , say 5 percent, would also give "correct" speed, that time also Does anyone know how much effect types and thickness (play duration C30 to C90) have on replay speed perhaps in conjunction with too soft or too hard pinch wheel rubber ? I just use a speed test tape from Konig. It has a strobe wheel behind what would normally be the tape viewing window. Very easy to see an accurate setting for the speed, and virtually instant comparison between forward and reverse. Also easy to see any cyclic variations in speed, or long term drift. Arfa |
#5
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Cassette tape speed adjustment
Arfa Daily wrote in message
... "N_Cook" wrote in message ... Assuming my test tape is stretched (I doubt it , as it would have to be even stretch the whole length). I normally test speed monaurally so the beats are unmistakable. That is 1KHz test tape output and floating accurate 1KHz sine signal both fed into one headphone cup. Easily gives 0.1 percent resolution (assuming test tape is ok). If I record accurate 1KHz tone onto a blank tape for exactly ( to human reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or so and output lasts for 100 seconds +/- reaction time then is the speed correct? I suspect that repeating this process with the speed regulator changed , say 5 percent, would also give "correct" speed, that time also Does anyone know how much effect types and thickness (play duration C30 to C90) have on replay speed perhaps in conjunction with too soft or too hard pinch wheel rubber ? I just use a speed test tape from Konig. It has a strobe wheel behind what would normally be the tape viewing window. Very easy to see an accurate setting for the speed, and virtually instant comparison between forward and reverse. Also easy to see any cyclic variations in speed, or long term drift. Arfa Strobing of what rotational part against what reference? How do you know if the tape is stretched? |
#6
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Cassette tape speed adjustment
N_Cook wrote:
Arfa Daily wrote in message ... "N_Cook" wrote in message ... Assuming my test tape is stretched (I doubt it , as it would have to be even stretch the whole length). I normally test speed monaurally so the beats are unmistakable. That is 1KHz test tape output and floating accurate 1KHz sine signal both fed into one headphone cup. Easily gives 0.1 percent resolution (assuming test tape is ok). If I record accurate 1KHz tone onto a blank tape for exactly ( to human reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or so and output lasts for 100 seconds +/- reaction time then is the speed correct? I suspect that repeating this process with the speed regulator changed , say 5 percent, would also give "correct" speed, that time also Does anyone know how much effect types and thickness (play duration C30 to C90) have on replay speed perhaps in conjunction with too soft or too hard pinch wheel rubber ? I just use a speed test tape from Konig. It has a strobe wheel behind what would normally be the tape viewing window. Very easy to see an accurate setting for the speed, and virtually instant comparison between forward and reverse. Also easy to see any cyclic variations in speed, or long term drift. Arfa Strobing of what rotational part against what reference? How do you know if the tape is stretched? It doesn't matter if the tape is stretched, the tape speed is governed by the rotational speed of the capstan. If the tape were stretched you would have to adjust the capstan speed to get the right playback pitch on that particular tape tho I doubt it would be very noticable. Somewhere I still have a cassette with 100 hz on one side and 8k on the other, plus a strobe disk visible through the window on the 100 hz side. You set the capstan speed by measuring the 100 hz on playback. The 8k is for head alignment. The strobe disk is driven by the capstan. Quite often the playback speed would be adjusted to be correct, followed by complaints from the customer that all his tapes now seem to play at the wrong speed! Ron(UK) |
#7
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Cassette tape speed adjustment
Ron wrote in message
... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Assuming my test tape is stretched (I doubt it , as it would have to be even stretch the whole length). I normally test speed monaurally so the beats are unmistakable. That is 1KHz test tape output and floating accurate 1KHz sine signal both fed into one headphone cup. Easily gives 0.1 percent resolution (assuming test tape is ok). If I record accurate 1KHz tone onto a blank tape for exactly ( to human reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or so and output lasts for 100 seconds +/- reaction time then is the speed correct? I suspect that repeating this process with the speed regulator changed , say 5 percent, would also give "correct" speed, that time also Does anyone know how much effect types and thickness (play duration C30 to C90) have on replay speed perhaps in conjunction with too soft or too hard pinch wheel rubber ? I just use a speed test tape from Konig. It has a strobe wheel behind what would normally be the tape viewing window. Very easy to see an accurate setting for the speed, and virtually instant comparison between forward and reverse. Also easy to see any cyclic variations in speed, or long term drift. Arfa Strobing of what rotational part against what reference? How do you know if the tape is stretched? It doesn't matter if the tape is stretched, the tape speed is governed by the rotational speed of the capstan. If the tape were stretched you would have to adjust the capstan speed to get the right playback pitch on that particular tape tho I doubt it would be very noticable. Somewhere I still have a cassette with 100 hz on one side and 8k on the other, plus a strobe disk visible through the window on the 100 hz side. You set the capstan speed by measuring the 100 hz on playback. The 8k is for head alignment. The strobe disk is driven by the capstan. Quite often the playback speed would be adjusted to be correct, followed by complaints from the customer that all his tapes now seem to play at the wrong speed! Ron(UK) Whatever touches the capstan spindle could wear and if the reference source for stobing is a mains lamp, that is only set for (UK) 50x60x60 cycles per hour (for synchronous clocks) and short term only +/-0.5 percent targetted frequency. I have the related problem of someone who says he has perfect pitch. |
#8
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Cassette tape speed adjustment
N_Cook wrote:
Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Assuming my test tape is stretched (I doubt it , as it would have to be even stretch the whole length). I normally test speed monaurally so the beats are unmistakable. That is 1KHz test tape output and floating accurate 1KHz sine signal both fed into one headphone cup. Easily gives 0.1 percent resolution (assuming test tape is ok). If I record accurate 1KHz tone onto a blank tape for exactly ( to human reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or so and output lasts for 100 seconds +/- reaction time then is the speed correct? I suspect that repeating this process with the speed regulator changed , say 5 percent, would also give "correct" speed, that time also Does anyone know how much effect types and thickness (play duration C30 to C90) have on replay speed perhaps in conjunction with too soft or too hard pinch wheel rubber ? I just use a speed test tape from Konig. It has a strobe wheel behind what would normally be the tape viewing window. Very easy to see an accurate setting for the speed, and virtually instant comparison between forward and reverse. Also easy to see any cyclic variations in speed, or long term drift. Arfa Strobing of what rotational part against what reference? How do you know if the tape is stretched? It doesn't matter if the tape is stretched, the tape speed is governed by the rotational speed of the capstan. If the tape were stretched you would have to adjust the capstan speed to get the right playback pitch on that particular tape tho I doubt it would be very noticable. Somewhere I still have a cassette with 100 hz on one side and 8k on the other, plus a strobe disk visible through the window on the 100 hz side. You set the capstan speed by measuring the 100 hz on playback. The 8k is for head alignment. The strobe disk is driven by the capstan. Quite often the playback speed would be adjusted to be correct, followed by complaints from the customer that all his tapes now seem to play at the wrong speed! Ron(UK) Whatever touches the capstan spindle could wear and if the reference source for stobing is a mains lamp, that is only set for (UK) 50x60x60 cycles per hour (for synchronous clocks) and short term only +/-0.5 percent targetted frequency. I have the related problem of someone who says he has perfect pitch. Set up a sig genny and test him out |
#9
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Cassette tape speed adjustment
Ron wrote in message
... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones How come I cannot google the rpm of an audio cassette capstan? A calibrated strobe and tipex mark on the capstan periphery should give a definite answer (assuming the spindle is clean and not worn). It should be determinable from tape speed of 1 7/8 in per sec and spindle diameter, that is about 1.9mm, but what should it be to 0.1 percent accuracy? |
#10
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Cassette tape speed adjustment
On Wed, 9 Dec 2009 15:42:00 -0000, N_Cook wrote:
Ron wrote in message ... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones Has anyone ever heard of a tape stretching enough to be detectable? I find that very hard to believe. Far more likely that the motor's speed control is off. Do you have another deck you can use? Record 5 minutes on the reference deck and then compare the time to play the same on the test deck. I've used a CD recording and then played the CD at the same time as playing the tape on the test deck. If they fall out of sync then the test deck is running at a rate different than the reference deck. |
#11
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Cassette tape speed adjustment
In message , AZ
Nomad writes On Wed, 9 Dec 2009 15:42:00 -0000, N_Cook wrote: Ron wrote in message .. . N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones Has anyone ever heard of a tape stretching enough to be detectable? I find that very hard to believe. Far more likely that the motor's speed control is off. Do you have another deck you can use? Record 5 minutes on the reference deck and then compare the time to play the same on the test deck. I've used a CD recording and then played the CD at the same time as playing the tape on the test deck. If they fall out of sync then the test deck is running at a rate different than the reference deck. That's exactly the way I have (occasionally) adjusted the speed of a tape deck. Record a CD track on a known (or hopefully) good deck, and play it back on the suspect deck, while simultaneously re-playing the CD. A bit of skilful nudging of the tape deck 'pause' and 'fast-forward' buttons will be needed to get the audio adequately synchronised. As you tweak the tape speed control, you will may get the two tracks in almost perfect synchronism (producing a pleasant echo effect!). However, this condition will probably hold for maybe only 10 or 20 seconds, after which the tape audio will start to creep either 'early' or 'late', and may even wander between the two. At the end of a typical 3 minute track, the audio may be a a few seconds out, and no matter hard you try, you are never going to do better. But not even the most ardent audiophile with perfect pitch could ever detect that the speed was incorrect. -- Ian |
#12
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Cassette tape speed adjustment
Ian Jackson wrote:
In message , AZ Nomad writes On Wed, 9 Dec 2009 15:42:00 -0000, N_Cook wrote: Ron wrote in message ... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones Has anyone ever heard of a tape stretching enough to be detectable? I find that very hard to believe. Far more likely that the motor's speed control is off. Do you have another deck you can use? Record 5 minutes on the reference deck and then compare the time to play the same on the test deck. I've used a CD recording and then played the CD at the same time as playing the tape on the test deck. If they fall out of sync then the test deck is running at a rate different than the reference deck. That's exactly the way I have (occasionally) adjusted the speed of a tape deck. Record a CD track on a known (or hopefully) good deck, and play it back on the suspect deck, while simultaneously re-playing the CD. A bit of skilful nudging of the tape deck 'pause' and 'fast-forward' buttons will be needed to get the audio adequately synchronised. As you tweak the tape speed control, you will may get the two tracks in almost perfect synchronism (producing a pleasant echo effect!). However, this condition will probably hold for maybe only 10 or 20 seconds, after which the tape audio will start to creep either 'early' or 'late', and may even wander between the two. At the end of a typical 3 minute track, the audio may be a a few seconds out, and no matter hard you try, you are never going to do better. But not even the most ardent audiophile with perfect pitch could ever detect that the speed was incorrect. You underestimate audiophiles sir! |
#13
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Cassette tape speed adjustment
N_Cook wrote in message ... Ron wrote in message ... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones How come I cannot google the rpm of an audio cassette capstan? A calibrated strobe and tipex mark on the capstan periphery should give a definite answer (assuming the spindle is clean and not worn). It should be determinable from tape speed of 1 7/8 in per sec and spindle diameter, that is about 1.9mm, but what should it be to 0.1 percent accuracy? pi times diameter gives the circumference of the capstan. 1 7/8 ips divided by circumference gives the required revolutions per second. You can measure the RPS of the flywheel, but that does not guarantee that the tape is traveling at 1 and 7/8. The bottom line is that you need a calibration tape and a frequency counter. You can measure the frequency at several spots on the tape to see if the tape pack and such, has any effect on speed. BASF used to make an excellent calibration tape. I do not know if they are still available, and they are not cheap. |
#14
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Cassette tape speed adjustment
"N_Cook" wrote in message ... Ron wrote in message ... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones How come I cannot google the rpm of an audio cassette capstan? A calibrated strobe and tipex mark on the capstan periphery should give a definite answer (assuming the spindle is clean and not worn). It should be determinable from tape speed of 1 7/8 in per sec and spindle diameter, that is about 1.9mm, but what should it be to 0.1 percent accuracy? The rotational speed of a cassette capstan is not a fixed given. The diameter of capstans vary from machine to machine, and the correct speed of tape transport is then a function of how fast you drive the capstan round. The reference in my strobe tape, is indeed the mains. I have been using this tape for many many years, and I have //never// had anyone complain that the speed of their machine is off, after I have used it to set one up. Konig must think that the mains is a good enough reference, otherwise, there would be no point in them marketing the tape for the purpose of setting up speed. Exception to this. As Ron said, very occasionally, when an owner has recorded tapes when the machine was running at the 'wrong' speed ... Arfa Arfa |
#15
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Cassette tape speed adjustment
"N_Cook" wrote in message ... Ron wrote in message ... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones How come I cannot google the rpm of an audio cassette capstan? A calibrated strobe and tipex mark on the capstan periphery should give a definite answer (assuming the spindle is clean and not worn). It should be determinable from tape speed of 1 7/8 in per sec and spindle diameter, that is about 1.9mm, but what should it be to 0.1 percent accuracy? The rotational speed of a cassette capstan is not a fixed given. The diameter of capstans vary from machine to machine, and the correct speed of tape transport is then a function of how fast you drive the capstan round. The reference in my strobe tape, is indeed the mains. I have been using this tape for many many years, and I have //never// had anyone complain that the speed of their machine is off, after I have used it to set one up. Konig must think that the mains is a good enough reference, otherwise, there would be no point in them marketing the tape for the purpose of setting up speed. Exception to this. As Ron said, very occasionally, when an owner has recorded tapes when the machine was running at the 'wrong' speed ... Arfa Arfa |
#16
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Cassette tape speed adjustment
Arfa Daily wrote in message
... "N_Cook" wrote in message ... Ron wrote in message ... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones How come I cannot google the rpm of an audio cassette capstan? A calibrated strobe and tipex mark on the capstan periphery should give a definite answer (assuming the spindle is clean and not worn). It should be determinable from tape speed of 1 7/8 in per sec and spindle diameter, that is about 1.9mm, but what should it be to 0.1 percent accuracy? The rotational speed of a cassette capstan is not a fixed given. The diameter of capstans vary from machine to machine, and the correct speed of tape transport is then a function of how fast you drive the capstan round. The reference in my strobe tape, is indeed the mains. I have been using this tape for many many years, and I have file://never// had anyone complain that the speed of their machine is off, after I have used it to set one up. Konig must think that the mains is a good enough reference, otherwise, there would be no point in them marketing the tape for the purpose of setting up speed. Exception to this. As Ron said, very occasionally, when an owner has recorded tapes when the machine was running at the 'wrong' speed ... Arfa Arfa http://www.dynamicdemand.co.uk/grid.htm Wokingham, Surrey, UK monitored mains frequency, is instructive, try it in the middle of a national televised football match or similar spindle consistency Not from my random sample of 8 audio cassette capstan spindles, all were 1.9mm or a bit lower say 1.89, with no cleaning etc, just as found. If 1.9mm then rotational speed of 478.72 rpm and if the specified diameter (cannot even find that) is 0.075 inches (bit less than 1.9mm) then speed is 477.46 rpm for 15/7 ips. Googling including "478" or "477" throws up nothing, googling on rev/sec not possible in like manner -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#17
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Cassette tape speed adjustment
N_Cook wrote:
Arfa Daily wrote in message ... "N_Cook" wrote in message ... Ron wrote in message ... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones How come I cannot google the rpm of an audio cassette capstan? A calibrated strobe and tipex mark on the capstan periphery should give a definite answer (assuming the spindle is clean and not worn). It should be determinable from tape speed of 1 7/8 in per sec and spindle diameter, that is about 1.9mm, but what should it be to 0.1 percent accuracy? The rotational speed of a cassette capstan is not a fixed given. The diameter of capstans vary from machine to machine, and the correct speed of tape transport is then a function of how fast you drive the capstan round. The reference in my strobe tape, is indeed the mains. I have been using this tape for many many years, and I have file://never// had anyone complain that the speed of their machine is off, after I have used it to set one up. Konig must think that the mains is a good enough reference, otherwise, there would be no point in them marketing the tape for the purpose of setting up speed. Exception to this. As Ron said, very occasionally, when an owner has recorded tapes when the machine was running at the 'wrong' speed ... Arfa Arfa http://www.dynamicdemand.co.uk/grid.htm Wokingham, Surrey, UK monitored mains frequency, is instructive, try it in the middle of a national televised football match or similar spindle consistency Not from my random sample of 8 audio cassette capstan spindles, all were 1.9mm or a bit lower say 1.89, with no cleaning etc, just as found. If 1.9mm then rotational speed of 478.72 rpm and if the specified diameter (cannot even find that) is 0.075 inches (bit less than 1.9mm) then speed is 477.46 rpm for 15/7 ips. Googling including "478" or "477" throws up nothing, googling on rev/sec not possible in like manner But compact cassette was never intended to be a precise method of recording, almost everything about the system is inexact - the recording medium itself is hardly a precision piece of engineering. The whole system was designed for convenience over performance. Admittedly, there are/were some very very good machines available which I`m sure way outstripped the original design specs. Cassette machines intended for 'homestudio' quality recording generally run the tape at a faster speed and have a facility for varying that speed. they still tend to use a crappy brushed dc motor and rubber belt drives though. Ron |
#18
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Cassette tape speed adjustment
Arfa Daily wrote in message
... "N_Cook" wrote in message ... Ron wrote in message ... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones How come I cannot google the rpm of an audio cassette capstan? A calibrated strobe and tipex mark on the capstan periphery should give a definite answer (assuming the spindle is clean and not worn). It should be determinable from tape speed of 1 7/8 in per sec and spindle diameter, that is about 1.9mm, but what should it be to 0.1 percent accuracy? The rotational speed of a cassette capstan is not a fixed given. The diameter of capstans vary from machine to machine, and the correct speed of tape transport is then a function of how fast you drive the capstan round. The reference in my strobe tape, is indeed the mains. I have been using this tape for many many years, and I have file://never// had anyone complain that the speed of their machine is off, after I have used it to set one up. Konig must think that the mains is a good enough reference, otherwise, there would be no point in them marketing the tape for the purpose of setting up speed. Exception to this. As Ron said, very occasionally, when an owner has recorded tapes when the machine was running at the 'wrong' speed ... Arfa Arfa I've since found 2 capstan spindles of 2.4mm diameterm so no fixed specification for cassette tape dynamics. Another possibility as a test tape - record some constant tone, any f, on a few minutes of tape, pull out a long length and pass a magnet over two parts a measured distance apart. retract, and then time the interval between dips in play mode |
#19
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Cassette tape speed adjustment
Arfa Daily wrote in message
... "N_Cook" wrote in message ... Ron wrote in message ... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones How come I cannot google the rpm of an audio cassette capstan? A calibrated strobe and tipex mark on the capstan periphery should give a definite answer (assuming the spindle is clean and not worn). It should be determinable from tape speed of 1 7/8 in per sec and spindle diameter, that is about 1.9mm, but what should it be to 0.1 percent accuracy? The rotational speed of a cassette capstan is not a fixed given. The diameter of capstans vary from machine to machine, and the correct speed of tape transport is then a function of how fast you drive the capstan round. The reference in my strobe tape, is indeed the mains. I have been using this tape for many many years, and I have file://never// had anyone complain that the speed of their machine is off, after I have used it to set one up. Konig must think that the mains is a good enough reference, otherwise, there would be no point in them marketing the tape for the purpose of setting up speed. Exception to this. As Ron said, very occasionally, when an owner has recorded tapes when the machine was running at the 'wrong' speed ... Arfa Arfa I've since found 2 capstan spindles of 2.4mm diameterm so no fixed specification for cassette tape dynamics. Another possibility as a test tape - record some constant tone, any f, on a few minutes of tape, pull out a long length and pass a magnet over two parts a measured distance apart. retract, and then time the interval between dips in play mode |
#20
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Cassette tape speed adjustment
N_Cook wrote:
Arfa Daily wrote in message ... "N_Cook" wrote in message ... Ron wrote in message ... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones How come I cannot google the rpm of an audio cassette capstan? A calibrated strobe and tipex mark on the capstan periphery should give a definite answer (assuming the spindle is clean and not worn). It should be determinable from tape speed of 1 7/8 in per sec and spindle diameter, that is about 1.9mm, but what should it be to 0.1 percent accuracy? The rotational speed of a cassette capstan is not a fixed given. The diameter of capstans vary from machine to machine, and the correct speed of tape transport is then a function of how fast you drive the capstan round. The reference in my strobe tape, is indeed the mains. I have been using this tape for many many years, and I have file://never// had anyone complain that the speed of their machine is off, after I have used it to set one up. Konig must think that the mains is a good enough reference, otherwise, there would be no point in them marketing the tape for the purpose of setting up speed. Exception to this. As Ron said, very occasionally, when an owner has recorded tapes when the machine was running at the 'wrong' speed ... Arfa Arfa I've since found 2 capstan spindles of 2.4mm diameterm so no fixed specification for cassette tape dynamics. Another possibility as a test tape - record some constant tone, any f, on a few minutes of tape, pull out a long length and pass a magnet over two parts a measured distance apart. retract, and then time the interval between dips in play mode Far simpler, find a known good machine - your chum with perfect pitch will help here - record a known frequency on a tape which you know to be good. Play said tape back on customers machine with freq counter hooked up to the headphone socket and adjust for same frequency - sorted. My test tape is 100hz, I spose the higher the frequency, the better accuracy you can get. Don't expect miracles. |
#21
Posted to sci.electronics.repair
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Cassette tape speed adjustment
Ron wrote in message
... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Ron wrote in message ... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones How come I cannot google the rpm of an audio cassette capstan? A calibrated strobe and tipex mark on the capstan periphery should give a definite answer (assuming the spindle is clean and not worn). It should be determinable from tape speed of 1 7/8 in per sec and spindle diameter, that is about 1.9mm, but what should it be to 0.1 percent accuracy? The rotational speed of a cassette capstan is not a fixed given. The diameter of capstans vary from machine to machine, and the correct speed of tape transport is then a function of how fast you drive the capstan round. The reference in my strobe tape, is indeed the mains. I have been using this tape for many many years, and I have file://never// had anyone complain that the speed of their machine is off, after I have used it to set one up. Konig must think that the mains is a good enough reference, otherwise, there would be no point in them marketing the tape for the purpose of setting up speed. Exception to this. As Ron said, very occasionally, when an owner has recorded tapes when the machine was running at the 'wrong' speed ... Arfa Arfa I've since found 2 capstan spindles of 2.4mm diameterm so no fixed specification for cassette tape dynamics. Another possibility as a test tape - record some constant tone, any f, on a few minutes of tape, pull out a long length and pass a magnet over two parts a measured distance apart. retract, and then time the interval between dips in play mode Far simpler, find a known good machine - your chum with perfect pitch will help here - record a known frequency on a tape which you know to be good. Play said tape back on customers machine with freq counter hooked up to the headphone socket and adjust for same frequency - sorted. My test tape is 100hz, I spose the higher the frequency, the better accuracy you can get. Don't expect miracles. Things counldn't be easier with a "known good machine " . My 3 test tapes were created on what was supposed to be such a machine in a pro AV studio. One tape got knackered at one point but rest of tape agrees with the second one. The third remains unused while first 2 agree with one another, using any old speed consistent machine for cross-comparison, in relative rather than absolute terms. |
#22
Posted to sci.electronics.repair
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Cassette tape speed adjustment
N_Cook wrote:
Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Ron wrote in message ... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones How come I cannot google the rpm of an audio cassette capstan? A calibrated strobe and tipex mark on the capstan periphery should give a definite answer (assuming the spindle is clean and not worn). It should be determinable from tape speed of 1 7/8 in per sec and spindle diameter, that is about 1.9mm, but what should it be to 0.1 percent accuracy? The rotational speed of a cassette capstan is not a fixed given. The diameter of capstans vary from machine to machine, and the correct speed of tape transport is then a function of how fast you drive the capstan round. The reference in my strobe tape, is indeed the mains. I have been using this tape for many many years, and I have file://never// had anyone complain that the speed of their machine is off, after I have used it to set one up. Konig must think that the mains is a good enough reference, otherwise, there would be no point in them marketing the tape for the purpose of setting up speed. Exception to this. As Ron said, very occasionally, when an owner has recorded tapes when the machine was running at the 'wrong' speed ... Arfa Arfa I've since found 2 capstan spindles of 2.4mm diameterm so no fixed specification for cassette tape dynamics. Another possibility as a test tape - record some constant tone, any f, on a few minutes of tape, pull out a long length and pass a magnet over two parts a measured distance apart. retract, and then time the interval between dips in play mode Far simpler, find a known good machine - your chum with perfect pitch will help here - record a known frequency on a tape which you know to be good. Play said tape back on customers machine with freq counter hooked up to the headphone socket and adjust for same frequency - sorted. My test tape is 100hz, I spose the higher the frequency, the better accuracy you can get. Don't expect miracles. Things counldn't be easier with a "known good machine " . My 3 test tapes were created on what was supposed to be such a machine in a pro AV studio. One tape got knackered at one point but rest of tape agrees with the second one. The third remains unused while first 2 agree with one another, using any old speed consistent machine for cross-comparison, in relative rather than absolute terms. So you are saying that you already have a test cassette? |
#23
Posted to sci.electronics.repair
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Cassette tape speed adjustment
Ron wrote in message
... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Ron wrote in message ... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones How come I cannot google the rpm of an audio cassette capstan? A calibrated strobe and tipex mark on the capstan periphery should give a definite answer (assuming the spindle is clean and not worn). It should be determinable from tape speed of 1 7/8 in per sec and spindle diameter, that is about 1.9mm, but what should it be to 0.1 percent accuracy? The rotational speed of a cassette capstan is not a fixed given. The diameter of capstans vary from machine to machine, and the correct speed of tape transport is then a function of how fast you drive the capstan round. The reference in my strobe tape, is indeed the mains. I have been using this tape for many many years, and I have file://never// had anyone complain that the speed of their machine is off, after I have used it to set one up. Konig must think that the mains is a good enough reference, otherwise, there would be no point in them marketing the tape for the purpose of setting up speed. Exception to this. As Ron said, very occasionally, when an owner has recorded tapes when the machine was running at the 'wrong' speed ... Arfa Arfa I've since found 2 capstan spindles of 2.4mm diameterm so no fixed specification for cassette tape dynamics. Another possibility as a test tape - record some constant tone, any f, on a few minutes of tape, pull out a long length and pass a magnet over two parts a measured distance apart. retract, and then time the interval between dips in play mode Far simpler, find a known good machine - your chum with perfect pitch will help here - record a known frequency on a tape which you know to be good. Play said tape back on customers machine with freq counter hooked up to the headphone socket and adjust for same frequency - sorted. My test tape is 100hz, I spose the higher the frequency, the better accuracy you can get. Don't expect miracles. Things counldn't be easier with a "known good machine " . My 3 test tapes were created on what was supposed to be such a machine in a pro AV studio. One tape got knackered at one point but rest of tape agrees with the second one. The third remains unused while first 2 agree with one another, using any old speed consistent machine for cross-comparison, in relative rather than absolute terms. So you are saying that you already have a test cassette? 3 of them made on the same batch of tape and on the same machine but more than 15 years ago. As they are all stored in the same environment they could theoretically all have chemically degraded/stretched to the same degree. I'm trying to find some process that gives an independent verification that does not require a know good machine. eg quartz controlled (so low tens ppm) f-meter coupled strobe fed to rotating capstan if diameter/s of the spindles are manufactured to specific dimensions of precisely known tolerances. Perhaps 1.9 +/- 0.002 mm and 2.4 +/- 0.002mm say, no such data found googling. I can only measure to +/-0.02 mm and no slip gauges for absolute calibration. +/-2 in 200 or so, is not accurate enough |
#24
Posted to sci.electronics.repair
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Cassette tape speed adjustment
"N_Cook" wrote in
: 3 of them made on the same batch of tape and on the same machine but more than 15 years ago. As they are all stored in the same environment they could theoretically all have chemically degraded/stretched to the same degree. I'm trying to find some process that gives an independent verification that does not require a know good machine. eg quartz controlled (so low tens ppm) f-meter coupled strobe fed to rotating capstan if diameter/s of the spindles are manufactured to specific dimensions of precisely known tolerances. Perhaps 1.9 +/- 0.002 mm and 2.4 +/- 0.002mm say, no such data found googling. I can only measure to +/-0.02 mm and no slip gauges for absolute calibration. +/-2 in 200 or so, is not accurate enough Suggestion: Google for guitar tuning meter There are meters available for ~20 bux and even some 'on line' meters. Record a known good 'string note' frequency and use it for your standard. Should get you close enough for any audiophile's ears -- bz 73 de N5BZ k please pardon my infinite ignorance, the set-of-things-I-do-not-know is an infinite set. |
#25
Posted to sci.electronics.repair
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Cassette tape speed adjustment
N_Cook wrote in message ... Arfa Daily wrote in message ... "N_Cook" wrote in message ... Ron wrote in message ... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones How come I cannot google the rpm of an audio cassette capstan? A calibrated strobe and tipex mark on the capstan periphery should give a definite answer (assuming the spindle is clean and not worn). It should be determinable from tape speed of 1 7/8 in per sec and spindle diameter, that is about 1.9mm, but what should it be to 0.1 percent accuracy? The rotational speed of a cassette capstan is not a fixed given. The diameter of capstans vary from machine to machine, and the correct speed of tape transport is then a function of how fast you drive the capstan round. The reference in my strobe tape, is indeed the mains. I have been using this tape for many many years, and I have file://never// had anyone complain that the speed of their machine is off, after I have used it to set one up. Konig must think that the mains is a good enough reference, otherwise, there would be no point in them marketing the tape for the purpose of setting up speed. Exception to this. As Ron said, very occasionally, when an owner has recorded tapes when the machine was running at the 'wrong' speed ... Arfa Arfa I've since found 2 capstan spindles of 2.4mm diameterm so no fixed specification for cassette tape dynamics. Another possibility as a test tape - record some constant tone, any f, on a few minutes of tape, pull out a long length and pass a magnet over two parts a measured distance apart. retract, and then time the interval between dips in play mode You are assuming that if the capstan rotates at the correct RPM , that the tape speed will be correct. The proper way to do this is to measure the playback frequency of the tape which gives you the tape speed. Obviuosly, the accuracy of the test tape, the accuracy of the counter, etc all come into play to add errors. The industry standard is to use a wow and flutter meter in conjunction with a test tape. The test tape is recorded at 3000hz on a reel to reel recorder and then loaded into a cassette shell because there is no cassette recorder on earth that can produce a test tape with the 10x or 5x accuracy needed as a standard. Wow and flutter meters are basically frequency meters. They are like guitar tuners, but the output is weighted to breakup the frequency variations into long and short term changes. If you can find a calibrated wow and flutter meter with a test tape, I'm sure the cost will far exceed what your client is willing to pay. The technology is at least 20 years old, and there really isn't a market for anyone to make this equipment available. The bottom line -------- Even if you go through the time and expense to do this right, what good is it if your client's tapes are not recorded at the same precision? You and he will be better off if you add a front panel speed control so that he can dial in the speed to match the tape being played |
#26
Posted to sci.electronics.repair
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Cassette tape speed adjustment
bg wrote in message ...
N_Cook wrote in message ... Arfa Daily wrote in message ... "N_Cook" wrote in message ... Ron wrote in message ... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones How come I cannot google the rpm of an audio cassette capstan? A calibrated strobe and tipex mark on the capstan periphery should give a definite answer (assuming the spindle is clean and not worn). It should be determinable from tape speed of 1 7/8 in per sec and spindle diameter, that is about 1.9mm, but what should it be to 0.1 percent accuracy? The rotational speed of a cassette capstan is not a fixed given. The diameter of capstans vary from machine to machine, and the correct speed of tape transport is then a function of how fast you drive the capstan round. The reference in my strobe tape, is indeed the mains. I have been using this tape for many many years, and I have file://never// had anyone complain that the speed of their machine is off, after I have used it to set one up. Konig must think that the mains is a good enough reference, otherwise, there would be no point in them marketing the tape for the purpose of setting up speed. Exception to this. As Ron said, very occasionally, when an owner has recorded tapes when the machine was running at the 'wrong' speed ... Arfa Arfa I've since found 2 capstan spindles of 2.4mm diameterm so no fixed specification for cassette tape dynamics. Another possibility as a test tape - record some constant tone, any f, on a few minutes of tape, pull out a long length and pass a magnet over two parts a measured distance apart. retract, and then time the interval between dips in play mode You are assuming that if the capstan rotates at the correct RPM , that the tape speed will be correct. The proper way to do this is to measure the playback frequency of the tape which gives you the tape speed. Obviuosly, the accuracy of the test tape, the accuracy of the counter, etc all come into play to add errors. The industry standard is to use a wow and flutter meter in conjunction with a test tape. The test tape is recorded at 3000hz on a reel to reel recorder and then loaded into a cassette shell because there is no cassette recorder on earth that can produce a test tape with the 10x or 5x accuracy needed as a standard. Wow and flutter meters are basically frequency meters. They are like guitar tuners, but the output is weighted to breakup the frequency variations into long and short term changes. If you can find a calibrated wow and flutter meter with a test tape, I'm sure the cost will far exceed what your client is willing to pay. The technology is at least 20 years old, and there really isn't a market for anyone to make this equipment available. The bottom line -------- Even if you go through the time and expense to do this right, what good is it if your client's tapes are not recorded at the same precision? You and he will be better off if you add a front panel speed control so that he can dial in the speed to match the tape being played I found a large quantity of salvaged capstans+spindles. 26 off on my mike (rather than callipers before) measure 1.99 +/-0.01 of reading accuracy and 2 nearer 2.00 5 off measure 1.79mm 1 at 2.19mm 9 measure 2.49mm So I will give a few to my engineer mate and ask him what they measure and the temperature at the time. The machine in question uses 2.49. Assuming it is actually 2.5mm then doing the maths and strobing with quartz f-meter calibrated strobe then my test tapes are 0.4 percent out from calculation via 15/8 ips etc. spindle rotation speed of 6.05 rev per second with an error of about 0.4 percent , needs longer gate time or repeating more times to bring that accuracy up (rounding errors? so probably longer gate time required than my meter has). If 2.49 diameter then 0.6 percent out |
#27
Posted to sci.electronics.repair
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Cassette tape speed adjustment
"N_Cook" wrote in message ... bg wrote in message ... N_Cook wrote in message ... Arfa Daily wrote in message ... "N_Cook" wrote in message ... Ron wrote in message ... N_Cook wrote: Ron wrote in message ... N_Cook wrote: Arfa Daily wrote in message ... "N_Cook" wrote in message ... Set up a sig genny and test him out Much easier to say the test tape is stretched. Perhaps perfect pitch testing would only work by playing the likes of JSB Tocatta and Fugue in D major, not pure tones How come I cannot google the rpm of an audio cassette capstan? A calibrated strobe and tipex mark on the capstan periphery should give a definite answer (assuming the spindle is clean and not worn). It should be determinable from tape speed of 1 7/8 in per sec and spindle diameter, that is about 1.9mm, but what should it be to 0.1 percent accuracy? The rotational speed of a cassette capstan is not a fixed given. The diameter of capstans vary from machine to machine, and the correct speed of tape transport is then a function of how fast you drive the capstan round. The reference in my strobe tape, is indeed the mains. I have been using this tape for many many years, and I have file://never// had anyone complain that the speed of their machine is off, after I have used it to set one up. Konig must think that the mains is a good enough reference, otherwise, there would be no point in them marketing the tape for the purpose of setting up speed. Exception to this. As Ron said, very occasionally, when an owner has recorded tapes when the machine was running at the 'wrong' speed ... Arfa Arfa I've since found 2 capstan spindles of 2.4mm diameterm so no fixed specification for cassette tape dynamics. Another possibility as a test tape - record some constant tone, any f, on a few minutes of tape, pull out a long length and pass a magnet over two parts a measured distance apart. retract, and then time the interval between dips in play mode You are assuming that if the capstan rotates at the correct RPM , that the tape speed will be correct. The proper way to do this is to measure the playback frequency of the tape which gives you the tape speed. Obviuosly, the accuracy of the test tape, the accuracy of the counter, etc all come into play to add errors. The industry standard is to use a wow and flutter meter in conjunction with a test tape. The test tape is recorded at 3000hz on a reel to reel recorder and then loaded into a cassette shell because there is no cassette recorder on earth that can produce a test tape with the 10x or 5x accuracy needed as a standard. Wow and flutter meters are basically frequency meters. They are like guitar tuners, but the output is weighted to breakup the frequency variations into long and short term changes. If you can find a calibrated wow and flutter meter with a test tape, I'm sure the cost will far exceed what your client is willing to pay. The technology is at least 20 years old, and there really isn't a market for anyone to make this equipment available. The bottom line -------- Even if you go through the time and expense to do this right, what good is it if your client's tapes are not recorded at the same precision? You and he will be better off if you add a front panel speed control so that he can dial in the speed to match the tape being played I found a large quantity of salvaged capstans+spindles. 26 off on my mike (rather than callipers before) measure 1.99 +/-0.01 of reading accuracy and 2 nearer 2.00 5 off measure 1.79mm 1 at 2.19mm 9 measure 2.49mm So I will give a few to my engineer mate and ask him what they measure and the temperature at the time. The machine in question uses 2.49. Assuming it is actually 2.5mm then doing the maths and strobing with quartz f-meter calibrated strobe then my test tapes are 0.4 percent out from calculation via 15/8 ips etc. spindle rotation speed of 6.05 rev per second with an error of about 0.4 percent , needs longer gate time or repeating more times to bring that accuracy up (rounding errors? so probably longer gate time required than my meter has). If 2.49 diameter then 0.6 percent out This is becoming bizarre ... Konig strobe test tape. Good enough. End of. If not good enough for your very discerning customer with "perfect pitch", then it is he who is at fault, for believing that the cassette medium is sufficiently good to serve his needs, and you for allowing him to continue believing this ... Arfa |
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