Quote:
Originally Posted by Lupo  I don't really know, but I think it goes like this:
Clipping creates fast changes. Fast changes are high frequency. If this is done purely digital, those high frequencies have no where to go but to alias into the audio range. That's why clipping at higher sample rates often sounds better - less alias.
If the sampler clips prior to the antialias filter, the extraneous high frequency information will be removed and the clipping will sound cleaner.
Andreas Nordenstam |
You're right that the square waves created from clipping changes the frequency spectrum and that this causes severe aliasing back into the audible spectrum. The problem with clipping at higher sampling rates in studios and mastering is that as soon as it is made into a 16/44.1 file all the problems will surface.
The theory of digital sampling dictates that the frequency range going out of a D/A has to be the same as that coming in through the A/D - clipping changes this. It is because of the antialias/low pass filter that aliasing distortion and +dBFS signals are created. When this filter is moved up to 40kHz the aliasing will no longer be as audible but the +dBFS issue will still be there.
Unfortunately for most of the listeners all the studios and mastering studios have converters that can handle some amount of +dBFS signals - this means that even if you guys can't hear the distortion the people buying the CD will - and it's not subtle either.
It is without exeption a huge dissapointment to buy any new CD - this is why I have spent most of my money on buying CD's of the music I listened to in the 70's and 80's. I bought the Madonna (confessions of a dance floor), the two latest U2 CD's, No Doubt, Justin Currie, and they are unlistenable on any high-resolution loudspeaker system. They are only good for background music. Old CD's like Yello (Baby), Police (Syncronicity), Fleetwood Mac (Rumours) - you can really play them loud without obnoxious distortion
threatening to tear your ears off - and the soundstage: there is DEPTH and the instruments has life.
I notised someone mentioned "inexperienced engineers" earlier in this thread but in my experience it goes like this: The higher profile artist the worse the sound. What's the explanation?
I also noticed someone talking about "radio ready" - that myth really should have died a long time ago. Bob Katz, Orban and TC Electronics all have written books and documents on this.
Because of the issues with digital sampling digital clipping should not be used at all - especially not to the extent you can find it on CD's today where the clip indicator is on all the time.
It is obvious that the record companies will NEVER be successfull in selling DVD-A and/or SACD if they don't get their priorities right - audio quality needs to come back on that list.
My opinion is that some of the
classics like dark side of the moon, ziggy stardust, rumours, thriller, bad, HiStory, Baby are classics not only because of the music but for a large part also because of audio quality. People still buy these CD's - who will buy todays horrible sounding CD's in 30 years?
H