Measurement techniques
Absolute and comparative criteria. Relative output level. Instrument
limitations. Standards. Method of establishing equipment accuracy.
Voltage comparisons. Waveform effects. Invalidation of reading due
to waveform change. Loading. Spurious effects. Invalidation of read-
ings. Faults in making audio measurements. Avoiding ground loops
and spurious effects.

Test equipment
Audio oscillators. Heterodyne or beat-frequency audio oscillator. Zero
beat. R-C feedback oscillators. Characteristics of various types of
audio generators. Vacuum-tube voltmeters. Scales. Audio wattmeter.
Calibrated attenuators. Oscilloscopes. Square-wave generators. Har-
monic-distortion meters. Intermodulation test meters. Wave ana-
lyzers. Bridge circuits. Flutter and wow meters.

Basic measurements
Frequency. Instrument calibration. Voltage and current. Phase. Re-
sistance and impedance. Commonly used ac bridges. Drysdale, Hay
and Maxwell bridges. Wheatstone bridge. Direct-reading capacitance
checker. Direct-reading impedance meter. Impedance-admittance
bridge. Acoustic velocity and pressure. Groove velocity. Disc com-
pliance and viscosity. Tape magnetization. Tube and transistor
dynamic characteristics.

Basic amplifiers
Frequency response. Audio-oscillator comparator techniques. Gain.
Power output characteristic. Power response. Harmonic distortion.
Intermodulation distortion. Intermodulation tests. Hum and noise.
Measuring input impedance characteristics. Output impedance. Im-
pedance reflection. Effect of supply variation.

Output transformers
Specifying transformer performance. Efficiency factors. Insertion loss
of an output transformer. Measurement of core loss. Frequency
response. Low-frequency performance. High-frequency performance.
Measuring magnetizing current and waveform. Leakage inductance.
Checking winding capacitance. Notch in transformer response.

Preamplifiers
Frequency response. Method for checking equalization characteristics.
Automatic plotting of response'curves. Interaction between bass and
treble tone controls. Variable-slope controls. Loudness contours. In-
correct loudness compensation. Gain and sensitivity. Distortion.
Noise. Dynamic range. Cross-talk termination. Microphony. Supply
changes.

Pickups and arms
Arm resonance. Frequency response. Pickup performance. Frequency
discrimination. Stylus compliance. Measuring the response of a
pickup. Shadowgraph techniques. Sensitivity. Impedance. Compli-
ance and dynamic mass. Checking arm mechanicaf impedance char-
acteristic. Stylus force. Distortion. A-N IM test. Utilization features.
Counterbalanced arms.

Turntables and changers
Speed constancy. Cyclic changes. Flutter and wow. Test with strobo-
scope for speed fluctuation. Frequency test discs. Flutter and wow
meter. Relative sensitivity of human hearing. Frequency response
of weighting network. Rumble. Setup for testing for rumble. Vibra-
tion pickup. Hum radiation. Measuring motor field radiation. Meas-
uring drag produced by a tone arm.

Tape recorders
Speed constancy. Varying tape tension. Flutter and wow. Method of
preparing a standard tape for a speed constancy test. Tape handling.
Setup for measuring start and stop times electronically. Incorrect
alignment. Response of a good head. Frequency response. Distortion
characteristic for a typical tape. High-frequency bias. Maximum
density levels of different tapes. Dynamic range.

Microphones
Acoustic properties. Using the Rayleigh disc. Deducing microphone
response. Reciprocal test method. Using a calibrated microphone.
Anechoic chamber for testing. Taking microphone response auto-
matically. Adding a warble tone to heterodyne-type audio oscillator.
Proximity of microphones. Symmetrical placement. Directivity.
Transient response. Phase response. Impedance. Distortion and noise
Vibration isolation. Effect of housing.