Based on a highly reliable circuit, the Model 378 Audio Generator produces a very low distortion sine wave signal over a very wide range of frequencies and is ideal for use in testing audio amplifiers for gain and frequency response, as a signal source for various bridge measuring circuits, for modulation of RF signal generators, or any other application where a stable, accurate audio sine wave must be used. Unlike most other audio generators that require interpretation of a dial setting with possible error, the frequency-determining elements of the Model 378 are not continuously variable, but are set by positive-setting detent switches that selects combinations of 1% resistors and 2% capacitors that make up the frequency-selecting network. This method of tuning enables repeatable accurate setting to any individual cycle between 1 cps and HOkc. The output level of this instrument can be set with great accuracy between 0 and 10 volts RMS (or between -70 and +22db) ön a 4-1/2 inch, 2% full-scale accuracy meter. Below 1 volt RMS output, the instrument is provided with a switch-selected internal 600Ω load that can be disconnected as desired.