Classe Audio CP-500 Manuale Utente

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rotary The rotary knob on the front panel does not directly control the volume. 
Instead, it controls circuitry that does so with greater fidelity and precision than 
traditional volume potentiometers could ever achieve. 
Since the volume control circuitry is under software control, it is possible to 
customize its behavior under various conditions. To better understand why this 
is so valuable, consider two scenarios: 
Person A places a high value on precision in achieving exactly the 
volume setting that makes the music most realistic; being able to 
easily change volume setting by a fraction of a decibel is critical to his 
enjoyment of the system.
Person B just wants to jump easily from low volumes to a reasonable 
listening level, and is less concerned with the finer points of precision 
than with getting what he wants with a quick twist of the knob.
You can see the problem in these scenarios: Person A wants extremely fine 
gradations on the volume control, which will require many rotations to go from 
extremely low setting to normal listening levels; Person B wants to get from one 
to the other with a “quick twist” of the knob, requiring coarse gradations in 
order to cover so much range in so little space. What happens when Persons A 
and B live in the same house? Or if Person C wants to have both, depending on 
their mood at the moment? (In fact, most of us are probably like Person C.)
Classé solves this dilemma by altering the response of the volume control, based 
on several factors.
Since it is rare to listen at extremely low (barely audible) volumes, the low range 
adjustment of the volume control allows for faster response to knob input when 
the volume setting values are low. When activated, you will get from extremely 
low to middle volume control settings a bit faster than you would otherwise. 
This effect can be subtle, and may not even be desirable when the speakers used 
have extremely high sensitivity (since this results in using the lowest part of the 
range more than you would otherwise). 
The most significant factor in the perceived responsiveness of the volume control 
is the speed at which the knob is being turned. We all naturally tend to move 
volume knobs more quickly when we need to make a bigger change, and we 
tend to slow down as we approach our desired volume. Thus, if the CP-500 sees 
the knob moving relatively quickly, it uses coarse steps to effectively accelerate 
the action of the circuitry. As the knob begins to turn more slowly, the CP-500 
will actually increase the resolution of the steps, which slows down the action 
of the volume control and yields greater precision in choosing an appropriate 
setting.