ORIGINAL: RnRmaChine
The sample rate which alot of people tend to disregard as secondary... is defined by a computer in "dot-to-dot" format. (how many samples it takes per second.) It's not a perfect flowing wave like we all have seen on waveform graphs and such.
It
is after the reconstruction filter!
Here is a "join the dots" representation of a 20Khz sine wave (curtousy of Sound Forge):
And here is a reconstructed representation of the same sine wave (curtousy of Audition):
Before I blabbler on I will post a link to a good read on this subject. Good for lamen but probably a lil too basic for someone partially educated in the field.
Anyone really should read this before thinking samples rates only matter if you want to hear over 20kHz, there are also well documented attributes to acoustical environments that aren't actually audible in the "human hearing" range. If you are working with mostly samples and adding verbs and such then 44.1 is probably more then adequate. BUT if you are recording an orchestra in the Vienna State Opera you can't possibly think that 44.1 is professional or would get you asked back to record again... do ya?
At least scroll down to the graphs of a square wave and how well defined it becomes as you raise the sample rate... Future Proof Recording Explained
Well f*ck Korg for misleading the unsuspecting public to sell their pointless products.
Their claim that it is a "notoriously difficult “torture testâ€," is bogus. Removing inaudible harmonics is a practical application of sampling theory unhampered by marketing BS.
When you filter out the inaudible harmonics of a square wave, you end up with a sine wave.
Check out this little graph:
http://williams.comp.ncat.edu/Networks/modulate.htm Start with 64 harmonics, it looks close to a square wave. Lower the number of harmonics untill you end up with a sinewave. That is what the anti-imaging filters in ADCs do. They remove the inaudible frequencies to prevent aliasing fold-back. (Reguardless of wether this happens in the analogue or digital domain).
Korg chose a 20Khz square wave for their "demonstration" because the 20Khz figure will mislead uninformed readers into thinking that it is all in the audible range. In reality only the fundamental is in the audible range (for young people with no hearing damage). All those harmonics are beyond 20Khz.
If they would have chosen a 2Mhz square wave, their graphs would have shown a 2Mhz sine wave after sampling with their product for exactly the same reasons that a 44.1Khz sampling rate will only show a 20Khz sine wave after sampling a 20Khz square wave.
And note, this is very important, that our ears also work as low-pass filters. Even if you play back those inaudible harmonics, they never reach our brains.
1bit (5.6448MHz) recording... It took me by surprise too when I first read about.
Marketing bla bla. High-end converters have moved on from 1-bit sampling due to issues they have. They now use multi-bit oversampling. (4-5 bits at 64 to 128 the base rate). Check out the last graph. It shows how they (Korg) go down to various base rates by using a decimation filter. That is
exactly how other converters work except that they have the decimation filter built in to directly hand over at base rates. Other converters have an advantage over Korg's product because they avoid the 1-bit issues by using multi-bit sampling.
Also note in the last graph that they use interpolation to achieve 48Khz sampling rates and multiples of that. That is also
exactly what happens in sample rate converters.
Don't believe the marketing hype.
UnderTow