WhitakerAudio 60 W Stereo Power Amplifier, Руководство пользователя и по сборке

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• Using the audio voltmeter, measure the residual signal, which will be a combination of
noise and crosstalk from the left channel into the right channel. A reading of –90 dB is
typical for this amplifier.
• Return the audio voltmeter sensitivity switch to the previous setting (30 W). Connect the
voltmeter to the left channel output. Adjust the meter to read 0 dB.
• Move the 1 kHz signal to the right channel input. Place a shorting plug in the left channel
input jack.
• Using the audio voltmeter, measure the residual signal, which will be a combination of
noise and crosstalk from the right channel into the left channel. A reading of –90 dB is
typical for this amplifier.
7.5 Square Wave Performance
The square wave response of the amplifier can be measured if desired.Typical square wave
performance of the amplifier is documented in Figure 7.1 for input frequencies of 100 Hz, 1 kHz,
and 10 kHz at power output levels of approximately 2 W, 15 W, and 30 W
3
. Measurements of the
right channel and left channel should be essentially identical. The following comments and
observations can be made:
• 2 W power output – a ) Tilt is observed at 100 Hz. b ) At 1 kHz response looks quite good.
c ) At 10 kHz some amount of ripple can be observed.
• 15 W power output – d ) Low frequency tilt is observed at 100 Hz, but not unexpected
given the measurement at 2 W. e ) The performance at 1 kHz looks quite good—almost
picture-perfect. f ) Considerable ripple at 10 kHz is found, but again not unexpected.
• 30 W power output – g ) Low frequency tilt is observed at 100 Hz, but for an amplifier
running at the edge of its capabilities, the performance is not bad. h ) At 1 kHz, with the
exception of some minor ringing on the leading edge, the waveform is perfect. i ) The
ripple at 10 kHz is not surprising, given the response at lower power levels.
It is important to note that a fundamental square wave test at 10 kHz will predict amplifier
performance with reasonable accuracy from 10 kHz up to 100 kHz or so. No audio source
material will approach that limit.
3. Power output was determined with a voltmeter, not with the oscilloscope.