Note on the top half of this picture the black sine wave, then the red constant triangle wave and in the lower picture, the on and off length of the modulator output.
It's kind of easy to see that there's a direct relationship between the time the triangle wave is on - and where the sine wave is - resulting in our longer and shorter output. But also note that as soon as the sine wave drops below the red triangle wave the output goes away.
The sine wave is our music - and, if you put this sine wave into your loudspeaker, you will hear sound. Funny thing is, if you put the modulator output into the loudspeaker you will also hear sound.
For those of you following along in my posts you may recognize a similar pattern to this statement - yes, it's the same as DSD. Remember that DSD can be placed directly into a speaker (ignoring the watts it takes for the speaker to move) as can a sine wave as can a PWM or Class D signal. In fact, Sony's SACD process is very close to PWD or class D. Digital audio, on the other hand (known as PCM) cannot be placed directly into a loudspeaker - for if you do you'll only get noise.
So, we'll cover more tomorrow, but to sum up - Class D is an analog process and not one that requires conversion to a discrete numeric representation like digital audio - and Class D is as close to DSD and analog as you will ever get.
There are a number of shortcoming for Class D and we'll start to understand these soon, but at least now you get an idea how Class D should maybe be called Class DSD.
Class DSD
Note on the top half of this picture the black sine wave, then the red constant triangle wave and in the lower picture, the on and off length of the modulator output.
It's kind of easy to see that there's a direct relationship between the time the triangle wave is on - and where the sine wave is - resulting in our longer and shorter output. But also note that as soon as the sine wave drops below the red triangle wave the output goes away.
The sine wave is our music - and, if you put this sine wave into your loudspeaker, you will hear sound. Funny thing is, if you put the modulator output into the loudspeaker you will also hear sound.
For those of you following along in my posts you may recognize a similar pattern to this statement - yes, it's the same as DSD. Remember that DSD can be placed directly into a speaker (ignoring the watts it takes for the speaker to move) as can a sine wave as can a PWM or Class D signal. In fact, Sony's SACD process is very close to PWD or class D. Digital audio, on the other hand (known as PCM) cannot be placed directly into a loudspeaker - for if you do you'll only get noise.
So, we'll cover more tomorrow, but to sum up - Class D is an analog process and not one that requires conversion to a discrete numeric representation like digital audio - and Class D is as close to DSD and analog as you will ever get.
There are a number of shortcoming for Class D and we'll start to understand these soon, but at least now you get an idea how Class D should maybe be called Class DSD.
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