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well, whatever they did, it sure sounds great.i love my SL900.
To clarify, class D consists of elements of analog and digital methods. Rather than have the statement above that was clipped from the owner's manual taken out of context let me provide a bit more detail about the blurring between digital and analog in the class D process. It's a little easier to explain what's happening borrowing examples from the digital world but this is not absolutely accurate without the context (hence the "similar" qualifier rather than "exactly")
1. Class D is not purely analog, but it's not digital either. It's a hybrid that consists specifically of NONLINEAR ANALOG SIGNAL PROCESSING TECHNIQUES.
2. The signal is NOT represented as a series of digital words that can be stored or processed, or that consist of zeros and ones. The analog signal is converted to a continuous stream PWM signal that has no start or end other than when the power switch is turned on or off.
3. A PWM signal merely represents the analog signal in a series of non-linear samples whose varying pulse width represents the varying amplitude of the analog signal. There are no ones or zeros, just varying pulse widths. The varying pulse width is not a binary or digital function, it's an analog parameter embedded in what is essentially a clocked pulse stream or a hybrid type of signal... has both analog and digital properties.
4. The level shifter is a "simple" transistor/FET switch bridge. It's either on or off and merely follows the PWM signal which is not "digital" nor is it "analog". Note that I quoted the word simple because while it appears simple in theory, in practice is very, very difficult to do with the necessary precision and timing. Recent introduction of a variety of dedicated integrated circuit chipsets has made this more commercially viable at the high speeds necessary (~500kHz) and the amp can be switching as much as 200 volts and 50 amps at these freqencies too. Hardly simple or trivial in practice.
5. The integration filter is a high power analog integrator that integrates the high level PWM signal, stripping off the "pulse" portion and integrates the "width" portion back into a purely analog signal. It is nothing more than an analog low pass filter, usually 2 pole for audio amps... but again while seemingly simple, it's low passing a high voltage, high current signal.
6. The term "D" in class D has nothing at all to do with "digital", it's just the letter that was available to catagorize the operational type of amplifier, the same way that class G or H describe switched rails (G came before H because IIRC, Hitachi described class G before H was described) Class D has been around in theory since before the 1950's, and there were a few experimental class D tube amps too, just that it took the invention of the power MOS FET to make it commercially practical.
So before folks go off on a tangent comparing class D to digital circuits, or A/D and D/A converters, or memory, or DSP, let's understand the technology so that we don't further the myths and misconceptions. Class D is a very interesting, and really cool (no pun intended) technology, it's simple on the surface but extremely difficult to get right. Almost right doesn't cut it in class D, there's too much happening way too fast to be sloppy.
There are others here who are in this stuff up to their eyeballs as well, I encourage participation as this is a good learning opportunity IMO.
I would (with genuine curiosity) ask in what way you felt some loss of control? And as support, could you describe the exact circumstances (the rig, the gig, the volume, how you were playing, how long into the night's show were you, what sounded or felt "off")?bryanspkr said:
