| At 12:47 AM -0600 4/9/97, Pablo Silva wrote:
>Hello, CSounders:
>
>On April 8, 1997 Tobias Kunze wrote:
>
>>The
>>signal is clean at kr = sr only. I get ~20dB sidelobes at
>>ksmps = 100.
>
>Does this mean we would need to have a kr of the
>same value as the sr to get truly clean results?
The issue is very much dependent on instrument specifics. If you
are just running a-rate oscil's with a-rate envelopes, ksmps doesn't
have an influence on noise. If you use k-rate envelopes, you'll get
noise except at ksmps=1. If you run a ugen like foscil where k-rate
parameters directly affect the signal and you vary the parameters during
a note, you'll get noise except at ksmps=1. A k-rate signal used to vary
a low-frequency signal (e.g., a randomizer on a vibrato) is usually OK.
Some ugen's like gain or balance multiply everything by a constant
which is fixed during a k-frame but changes from frame to frame. They
only work properly at ksmps=1. Some other things such as home-grown
recursive (IIR) filters or pulse-width modulation only work at ksmps=1.
Everything tends to work better but more slowly at ksmps=1, but it is
not always necessary for noise reduction. I hope that clarifies things.
-----------------------------------------------------------------------------
Erik Spjut (rhymes with cute) - Associate Professor of Engineering and/or
Associate Director for Engineering Computing in the Engineering Design Center
Harvey Mudd College, Claremont, CA 91711 USA
Erik_Spjut@hmc.edu Ph & Voice mail (909) 607-3890 Fax (909) 621-8967
|