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AA-51A Audio Analyzer
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DESCRIPTION

The AA-51A is a multi-purpose, precision audio analyzer that helps to automate proof-of-performance measurements and equipment maintenance. Unique features of the AA-51A make it the ideal instrument for engineers, and service professionals. Excellent RFI shielding enables measurements to be made within the high-level RF environments of commercial broadcast transmitter facilities.

Total harmonic distortion measurements are made by simply setting the Mode Switch to THD and reading the meter. The AA-51A automatically accomplishes nulling and tuning to the inputfrequency. This enables the operator to accurately measure the harmonic distortion at various discrete frequencies and different power levels much faster than using conventional distortion analyzers.

Intermodulation distortion measurements are performed with equal simplicity. Utilizing the SMPTE Standard intermodulation signal the AA-51A displays percent of IM. Measurements are completely automatic over a wide dynamic range.

Accurate frequency response measurements are facilitated by a wideband voltmeter which exhibits a flat response (+ or - 0.1dB) from 20 Hz to 100 kHz. Input level range is 1 mV to 100 V full scale. The average responding meter is calibrated to the rms value of a sinewave. For Signal + Noise/Noise measurements the voltmeter bandwidth may be restricted to 20 kHz by placing the mode switch in the NOISE position.

Incidental frequency modulation -- "Wow and Flutter" -- usually associated with tape decks, cart machines and turntables is measured automatically. The AA-51A measure weighted peak flutter as specified by IEEE Standard 193.

Stereo signals and mono signals derived from a stereo source are often degraded by phase errors and differential gain variation between left and right channels of a given audio system. The AA-51A contains both phase and ratio measuring circuitry which enables the operator to evaluate these characteristics quickly and accurately throughout the complete audio spectrum, and over a wide dynamic range. Phase angle is displayed with a zero center scale indication and a full scale, switch selected sensitivity of either + or - 180 degrees. The ratio meter is also a zero center scale device with a + or - 6dB full scale deflection.

The Phase and Ratio measurement features of the AA-51A are particularly useful for line equalization measurements, azimuth alignment of stereo tape heads, and trouble shooting of audio consoles, amplifiers, and networks.

AA-51A SPECIFICATIONS
Input:
  Impedance
  Maximum AC
  Maximum DC
  Common-mode rejection
  Cable connector
  MON SCOPE output
  MON PHONES output
  HIGH LED on when:
  LOW LED on when:

Balanced 80 k ohms+100 pF, each pin to ground
220 Vrms, each pin to ground
250 Vdc, each pin to ground
greater than 60dB
Switchcraft p/n 05CL3M
5.6 Vp-p for inputs from 40 mVrms to 90 Vrms, typical
Set to 70mVRMS, internal adj.
Input less than 80 Vrms (except for VM and NOISE)
Input less than 100 mVrms, (except for VM and NOISE)
THD Meter:
  Input frequency range
  Measurement passband
  Notch attenuation
  Ranges

  Accuracy
  Input level ranges
  Internal THD + noise

  Filters

  METER MON output
  Nulling time

20 Hz to 20 kHz, fundamental
1.7 to 12.5X input frequency at -3dB
greater than 100 dB
6 ranges, 0.03% to 10% full scale, -20 dB to -70 dB full scale
± 15% (± 1.5 dB)
100 mV to 80 V
0.01% max, 0.006% typical, 20 Hz-5 kHz 0.02% max,
0.012% typical at 20 kHz
22 kHz low-pass at input, switch selected
400 Hz high-pass, switch selected
100 mVp-p, meter at full scale
2 seconds approximately
IMD Meter:
  Input signal required
  Full scale ranges
  Accuracy
  Input level range
  Internal IMD + noise
  METER MON output

60 Hz + 7 kHz, 4:1 voltage ratio
6 ranges, 0.03% to 10% full scale
± 10%
100 mV to 80 V
less than 0.015%
100 mVp-p, meter at full scale
AC Voltmeter:
  Frequency response
  Ranges

  Accuracy
  METER MON output
  Internal noise
  Filter
  REF SET range

10 Hz to 100 kHz, + or - 0.1dB max.variation
11 ranges, 0.3 mV to 30 V full scale,
-68 dBm to +32 dBm full scale
± 3%
100 mVp-p, meter at full scale
20 uV(-92 dBm) maximum
400 Hz (at -3 dB) high-pass, switch selected
greater than 10 dB
Noise Meter:
  Frequency response
  Ranges
  Accuracy
  METER MON output
  Internal noise
  Filter
  REF SET range

20 Hz to 20 kHz at -3 dB
11 ranges, 0.3 mV to 30 V full scale
± 3%
100 mVp-p, meter at full scale
15 uV (-94 dBm) max.
400 Hz (at -3 dB) high-pass, switch selected
greater than 10 dB
Phase Meter:
  Measurement ranges
  Accuracy
  Polarity
  Input frequency range
  Input level range
  METER MON output


± 54 degrees and + or - 180 degrees full scale
± 3 degrees
Positive angle means L leads R
20 Hz to 20 kHz
100 mV to 80 V
Rectangular wave at input frequency, duty cycle proportional to angle
Ratio Meter:
  Measurement ranges
  Accuracy
  Polarity
  Input frequency range
  Input level range
  METER MON output

± 6 dB
± 0.2 dB
Positive ratio means R greater than L
20 Hz to 20 kHZ
100 mV to 80 V
dc voltage proportional to ratio
Wow & Flutter Meter:
  Measurement ranges
  Input frequency
  Accuracy
  Input level range
  Internal Noise
  METER MON output

0.1% and 0.3% full scale
3.15 kHz ± 10%
± 10%
100 mV to 80 V
less than 0.01%
500 mVp-p at full scale, passband 0.2Hz-200Hz
Frequency Counter:
  Frequency range
  Resolution



  Accuracy
  Input level range

10 Hz to 200 kHz
less than 900 Hz (approx.), 0.1 Hz
900 Hz to 9000 Hz (approx.), 1.0 Hz
9 kHz to 24 kHz (approx.), 0.01 kHz
greater than 24 kHz (approx.), 0.1 kHz
-1 to 0 count error in RH digit (LSD)
1 mV to 80V
Power:
  117 Vac
  (230 Vac option)

50/60 Hz, 10 W
Weight, lb (kg): 5.44 (12)
Dimensions, in. (cm):

  Optional Rack Mount
15.25 (38.74) W; 5.25 (13.34) H;
10.125 (25.72) D
5.25 (13.34) Rack space rqd.

Specifications subject to change without notice.

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AA-51A Audio Analyzer
enlarged view


KEY FEATURES
  • Shielded, Balanced Inputs
  • Auto-Null THD
  • Frequency Readout
  • Compatibility with NAB Test CD's
  • Stereo Measurements
  • Measures:
    • THD, IMD, Volts
    • Signal + Noise/Noise
    • Stereo Phase
    • Stereo Ratio
    • Wow and Flutter
    • Frequency