| ad80a wrote:
> I don't understand why changing control rate and sampling rate I've
> differences in timbre and amplitude values.
> I'm working with an instrument that has white noise filtered by a bank of
> resonant filters and a waveguide reverb with a lot of delay lines (with
> delay opcode because I don't need to change the delay at kr).
> Using kr 441 sr 44100 I obtain a sound I like (this is the strangest
> thing!), but with kr equal to sr (44100/44100), I have some resonance peaks,
> a slightly different timbre, and greater amplitude values...I don't
> understand why! I DON'T use modulating delay lines! And I don't use any
> krate variables! Why changing kr influences timbre and amplitude? Same thing
> if i try with sr 96000, timbre changes (and it's natural because there are
> more high frequencies and a cleaner timbre), but amplitudes are about TWICE
> great!
> Thanks for your help and sorry for this newbie question.
>
I've seen some csound instruments that accumulate a signal, i.e. summing
subsequent samples, to have a quick and dirty way to amplify low
frequencies. The problem with this is that the result is dependent on sr
or kr (whether it is an a-rate or k-rate signal). This is because when
the rate is higher, the samples are closer so you add up more values per
second, resulting in a higher amplitude.
The same thing happens when you use the delay1 opcode, to have a quick
and dirty way to amplify high frequencies (by taking the difference of
two subsequent samples). In this case when the samples are closer, the
difference of two subsequent samples is smaller, resulting in lower
amplitudes.
Are you sure that the instrument doesn't use delay1, and doesn't
accumulate? There may be other opcodes with the same problem.
If this is the problem, I think it could be corrected by using the value
kr or sr in the calculation, or by using the integ and diff opcodes.
--
Mark
_________________________________________
When you get lemons, you make lemonade.
When you get hardware, you make software. |