Clarion XC7420 Handbuch für Besitzer und Installation - Seite 4
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GENERAL FUNCTION EXPLANATION
Setting Mixer/Gain Settings in XC-Tune
This adjustment is provided for each channel in order to adjust the amplifi er sensitivity
so that it will produce maximum power given a variety of different input signal voltages.
Setting this control correctly will ensure that you get maximum performance from your
amplifi er and is critical to ensuring that minimal noise and distortion is produced.
Clarion recommends the use of an Oscilloscope or distortion detecting device such as the
SMD DD-1 or DD-1+ Distortion Detector to properly set amplifi er sensitivity. A headroom
setting of approximately 10dB will help to ensure that music that is recorded at low levels
can still be reproduced at high volume levels. With this setting, it is the responsibility of the
operator to use the amplifi er in a manner that will not produce audible distortion.
Procedure (Oscilloscope) Method:
1.
Obtain a test disc with a selection of Sine Waves recorded at -5dB and -10dB.
2.
Turn the gain all the way down on the amplifi er (to the left).
3.
Connect the ground terminal of the scope lead to the shield of the RCA cable
coming from the source unit. Do no connect the scope lead to the speaker output
terminals.
4.
Connect the scope probe to a speaker terminal on the channel you want to adjust.
5.
Select a Sine wave frequency that is well away from the chosen crossover frequency.
For midrange speakers use 1kHz at -5dB, use 40Hz at -10dB for subwoofers.
6.
Turn the source unit up as high as possible without distortion.
7.
Monitor the output waveform of the amp on the scope.
8.
Increase the sensitivity of the amplifi er until the scope waveform shows a small fl at
spot on the top or bottom of the waveform. See Figure 2 for an example of what to
look for.
Fig 1 - Sine Wave at different Levels
SMD DD-1 Method:
1.
Following the instructions provided with the DD-1, use the 0dB track to confi rm the
output of the audio signal source is unclipped.
2.
Connect the DD-1 to the output of the amplifi er and use an appropriate -5dB or -10dB
track. Increase the gain on the amplifi er until the Distortion LED illuminates
You should be able to turn the volume up to almost full (or wherever your source unit clips/
distorts) without hearing distortion. If you can't turn the volume up most of the way without
distortion, the sensitivity control is not adjusted properly.
4
Fig 2 - Close-Up of waveforms
Clipped Sine wave
Sine wave unclipped
Sine wave well bellow clipping