WhitakerAudio JC Whitaker 20 W Stereo Integrated Audio Amplifier, Manual

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5) Move the generator input to the left channel Line input and move the audio voltmeter input
to the left channel speaker terminals. The left channel response should closely match the
right channel response.
6) Loosen the Bass control knob set screw and reposition the knob so the white line faces
straight up. Tighten the set screw.
7) Set the generator to produce 1 kHz at 1 V rms. Set the Bass control to the flat position (as
just identified). Adjust the Volume control to produce 1.5 V rms at the speaker terminals. Set
the audio voltmeter to read 0 dB. Note that for this measurement it is necessary to reduce the
output of the amplifier to avoid overdriving the output stage, which would result in an
incorrect reading.
8) Change the generator setting to produce 20 Hz. With the Bass control set to the flat position,
the meter should still read 0 dB (within about 1 dB). Turn the Bass control to the full “cut”
position (counterclockwise). The observed output on the audio voltmeter should drop by
about 12 db. Move the Bass control to the full “boost” position (clockwise). The observed
output on the audio voltmeter should increase by about 12 dB. Return the Bass control to the
flat position.
9) Repeat the previous Bass cut/boost measurement on the right channel. The performance of
the two channels should be identical, or at least very close.
10) With the audio voltmeter and generator connected to the right channel, set the generator to
begin a sweep at about 1 kHz and end the sweep at about 20 kHz. Adjust the Volume control
to produce 2.8 V rms at the speaker terminals. Set the audio voltmeter to read 0 dB. Begin a
repetitive linear sweep of about 1 second duration.
11) Slowly adjust the Treble control for the flattest response, which should be in the range of +/
–1 dB.
12) Move the generator input to the left channel Line input and move the audio voltmeter input
to the left channel speaker terminals. The left channel response should closely match the
right channel response.
13) Loosen the Treble control knob set screw and reposition the knob so the white line faces
straight up. Tighten the set screw.