Classe Audio CP-500 owner manual rotary

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.

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