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Re: Fw: EDP Oversampling
I think Jesse is making a good point there. I had not understood he
was asking about the HalfSpeed feature. Since the EDP does it by
lowering the sample rate of the D/A it may sound less clean than with
interpolation at full sample rate. And its not so wrong to call this
process Oversampling.
I dont quite understand the thing about the older sampler though,
since it needs to change the sample rate for each note you play
simultaneously, so its not possible adapt the D/A convertor rate as
the EDP does. Probably they use a simple interpolation in the old
model.
>The Echoplex and the old sampler pitch change by really changing the
>sample rate on the D/A convertors. The newer sampler probably does
>it digitally by interpolation techniques or other DSP pitch-shift
>techniques, and maintains the same sample rate on the convertor. I
>don't think oversampling or the anti-alias filtering would have
>anything to do with the effect you are hearing.
>
>Oversampling isn't "smoothing out" the waveform. It is a
>mathematical technique that spreads out the aliased frequency bands
>so they aren't right next to each other. That makes it simpler to
>filter out the aliased bands with a less-complex low-pass filter
>with a gentler slope.
>
>kim
>
>At 02:39 AM 6/24/2004, Jesse Ray Lucas wrote:
>>I was just curious since comparing the sound of an older Akai S2000
>sampler
>>against the sound of a newer S5000 sampler. Although both are 16-bit
>>samplers, the older model sounds "grittier" when you pitch samples down
>or
>>resample to a lower bandwidth. The EDP sounds gritty, too, when you
>shift
>>into halfspeed.
>>
>>As I understood that article it was saying that during the D-A conversion
>>the oversampling process was the interpolation of in-between samples into
>>the signal to smooth the waveform out.
>>
>>Just trying to figure out what makes that sound sound the way it does.
>If
>>you say it's the anti-aliasing filters that matter, then I believe you.
>>Thanks for the info.
>>
>>-J
>>
>
>______________________________________________________________________
>Kim Flint | Looper's Delight
>kflint@loopers-delight.com | http://www.loopers-delight.com
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