Shure Phonograph TTR-103 User Guide
2 2 2 HARTREY AVE.. EVANSTON. IL. 6 0 2 0 4 U.S.A. |
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Model TTR-103 |
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AREA CODE 3 1 2 1 8 6 6 . 2 2 0 0 |
CABLE: S H U R E M l c R o |
SHEET Trackability Test Record |
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TWX: 9 1 0 - 2 3 1 - 0 0 4 8 |
TELEX. 7 2 - 4 3 8 1 |
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The T T R - 1 0 3 contains three trackability" tests:
1. 10.8 kHz pulsed high-frequency test with a 270 Hz repetition rate trackability and distortion test.
2.The 1000 Hz plus 1500 Hz mid-frequency trackability and distortion test.
3.The 400 Hz plus 4000 Hz low-frequency trackability and distortion test. These tests aDDear. . on the record as shown in the table below:
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M A X I M U M PEAK |
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VELOCITY |
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FREQUENCY |
B A N D |
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( C M / SEC) |
Turntable Speed 45 rpm** |
(Side 1) |
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Pulsed |
10.8 kHz |
Left Channel |
1 |
15 |
Pulsed |
10.8 kHz |
Left Channel |
2 |
19 |
Pulsed |
10.8 kHz |
Left Channel |
3 |
24 |
Pulsed |
10.8 kHz |
Left Channel |
4 |
30 |
1000 |
+ 1500 Hz |
Lateral |
5 |
20 |
1000 |
+ 1500 Hz |
Lateral |
6 |
25 |
1000 |
+ 1500 Hz |
Lateral |
7 |
31.5 |
1000 |
+ 1500 Hz |
Lateral |
8 |
40 |
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(Side 2) |
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Pulsed |
10.8 kHz |
Right Channel |
1 |
15 |
Pulsed |
10.8 kHz |
Right Channel |
2 |
19 |
Pulsed |
10.8 kHz |
Right Channel |
3 |
24 |
Pulsed |
10.8 kHz |
Right Channel |
4 |
30 |
400 |
+ 4000 Hz |
Lateral |
5 |
15 |
400 |
-+ 4000 Hz |
Lateral |
6 |
19 |
400 |
-t4000 Hz |
Lateral |
7 |
24 |
400 |
+4000 Hz |
Lateral |
8 |
30 |
The ability of a pickup to track can be determined three ways: distortion measurements, visually on an oscilloscope, and audibly by listening. For best results, it is suggested that all three means be employed.
DISTORTION M E A S U R E M E N T S
If a pickup mistracks any of these tests, distortion components are generated and distortion percentages can be defined.
A.10.8 kHz Pulsed High-Frequency Test
The distortion component of this test appears at the repetition rate (270 Hz), and a distortion percentage can be defined as:
Voltage at 270 Hz x
100%
DHlciH = Voltage at 10.8 kHz The necessary voltages are obtained with a wave analyzer.***
The bandpass width settings for the 10.8 kHz and 270 Hz voltages should be 1000 Hz and 30 Hz, respectively.
B.1 kHz + 1.5 kHz Mid-Frequency Test
The distortion components of this test appear at the sum (2500 Hz) and difference (500 Hz) frequencies of the signal component frequencies. A distortion percentage is defined as:
Voltage at 2500 Hz f Voltage at 500 Hz
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Voltage at 1000 Hz IVoltage at 1500 Hz The necessary voltages are obtained with a wave analyzer.***
The bandpass width setting for the 500 Hz, 1000 Hz, 1500 Hz, and 2500 Hz voltages is 100 Hz.
C. 400 Hz 1 4 kHz Test
The distortion of the 400 - f - 4000 Hz low-frequency test is best determined using an Amplitude Intermodulation Distortion Analyzer, as it adheres to the SMPTE* * * * intermodulation distortion input requirements.
THE DISTORTION PERCENTAGES VERSUS RECORDED VELOCITIES MAY BE PLOTTED TO PROVIDE A GRAPHIC PRESENTATION FOR EASY COMPARISONS.
VISUAL DETERMINATION OF MISTRACKING
Mistracking of a pickup for the high-frequency test can be determined by first passing the pickup output through a narrow-band filter centered at 270 Hz then displaying the filtered output on an oscilloscope. Any sudden change in the level of this output indicates mistracking.
The midand low-frequency tests are best presented in a Lissajous display. Any sudden change in the output at right angles to the display (vertical modulation) indicates mistracking.
AUDIBLE DETERMINATION OF MISTRACKING
A tonal change will occur in each of these tests when the pickup mistracks.
'The term"trackability" |
refers to the ability of a phono pickup to reproduce |
h ~ g h - |
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level program material |
The trackabil~tylimit of a plckup at any glven tracking force |
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and frequency |
is d e f ~ n e das the m o d u l a t ~ o nvelocity |
(measured in c m l s e c ) at which |
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the stylus tip |
loses contact wlth one or both of the |
groove walls. T h ~ sloss of |
con- |
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tact results ~nsevere d ~ s t o r t i o nof the recorded program m a t e r ~ a l . |
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C O P Y R I G H T 1979, |
S H U R E B R O T H E R S INC. |
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2 7 A 9 9 8 ( S E ) |
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*'This record has been |
recorded for 45 rpm playback in order |
to |
minimize the |
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s ~ d u a ld ~ s t o r t i o nlevsl |
of the test signals due to tracing |
inaccuracies. |
pre- |
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* * * C a r e must be taken not to clip the input of the wave |
analyzer |
or |
associated |
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a m p i ~ f ~ e r . |
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* * * * S o c ~ e t yof Motion Picture &Television Engineers |
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P R I N T E D I N U . S . A .
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