John T
Goddard
My "Surprise!" statement was in response to what that blogger wrote here (about super-high frequency IM):
But be careful of designers who go for super-sonic sampling rates and set their filters too high. If you include too much super-sonic information in the signal it becomes likely that you will introduce super-high frequency “intermodulation distortion” on playback.
(Lavry's papers do refer to such high converter "modulator" sampling frequencies but I suspect the facestious scientist has no idea how converters actually operate)
So if I'm reading you right, you seem to concede that he at least is reporting the information he has correctly, but because you suspect his knowledge doesn't extend to point X, you're dismissing him. But not because you think he's wrong. That's kind of odd.
You've misunderstood. A converter is actually sampling its input at a far higher frequency (in the MHz "low radio frequency" band) than "ultrasonic". Yet remarkably, no reports yet of heterodyning artifacts showing up in recorded digital audio.
And "super-sonic" usually refers to the speed of sound (or an NBA team), not sampling frequency.
Btw, 44.1kHz is "ultrasonic" territory too. If a converter's anti-aliasing LPF isn't designed or working properly, well then... Fido will inform.
John T
Goddard
And my "Another surprise" above was in reply to what the blogger wrote here:
Now in 2013, the 16/44.1 converter of a Mac laptop can have better specs and real sound quality than most professional converters from a generation ago, not to mention a cassette deck or a consumer turntable. There’s always room for improvement, but the question now is where and how much?
(last time I looked inside a Macbook (several years ago), it used a 192kHz-capable Realtek chip in its "Intel HDA" componentry, but I suspect the facetious scientist really has no clue of what "the 16/44.1 converter of a Mac laptop" is actually capable)
Same thing, really. His point stands regardless. He's talking about it being better than tape decks or turntables even operating at fairly low rates. That's correct. You're dismissing him because he doesn't seem aware that it can run at higher rates. That's a gap in his knowledge, sure, but not one that undermines his point.
No, he's saying a current laptop's converter is better (at CD audio sampling rate and bit-depth) than earlier generation pro converters, without grasping that the very same laptop about which he's talking is, thanks to its cheap little codec chip, well and truly capable of handling multi-channel 24-bit/192kHz digital audio (e.g. when playing a Bluray disc) without suffering any of the "problems" to which he later points for justifying not sampling at 192kHz. If there's a gap in his knowledge (and there appear to be many) it's that he can't recognize that the example he posits (the capability of that laptop's measly little codec chip's converter) actually disproves a lot of the baloney he later foists as being problematic of 192k sampling.