A while back, I was talking to a young electrical engineering student about how DACs do not produce the stairstep pattern that many textbooks and audiophile forums would lead you to believe. As the video in the link shows, you can create a sine wave with analog equipment, measure it on an analog oscilloscope, put it through a computer for ADC and then DAC, and measure the output on another analog oscilloscope. The sine wave you get on the output will be exactly the same as the input, excepting whatever line noise is introduced in the process. No stairstep at all.
In fact, if the stairstep were true, then square waves should come out perfect, not sine waves. It’s just the opposite; square waves come out as a messy combination of sine waves. This is generally fine, as square waves don’t really exist in nature, anyway.
Then the followup question came: DACs are built with a combination of voltage dividers (also known as a resistor ladder), which should produce just such a stairstep pattern. Why wouldn’t it be a stairstep?
I couldn’t remember what the hell the answer to that was at the moment, and probably came off like an idiot. The answer is that there’s a low pass filter that takes care of that, but I’ll be damned if I remembered that at the time.
I feel that so hard.
A while back, I was talking to a young electrical engineering student about how DACs do not produce the stairstep pattern that many textbooks and audiophile forums would lead you to believe. As the video in the link shows, you can create a sine wave with analog equipment, measure it on an analog oscilloscope, put it through a computer for ADC and then DAC, and measure the output on another analog oscilloscope. The sine wave you get on the output will be exactly the same as the input, excepting whatever line noise is introduced in the process. No stairstep at all.
In fact, if the stairstep were true, then square waves should come out perfect, not sine waves. It’s just the opposite; square waves come out as a messy combination of sine waves. This is generally fine, as square waves don’t really exist in nature, anyway.
Then the followup question came: DACs are built with a combination of voltage dividers (also known as a resistor ladder), which should produce just such a stairstep pattern. Why wouldn’t it be a stairstep?
I couldn’t remember what the hell the answer to that was at the moment, and probably came off like an idiot. The answer is that there’s a low pass filter that takes care of that, but I’ll be damned if I remembered that at the time.