[PD] What is that 4khz whine?

[William Huston]

Simple square wave patch into a [vcf~] and a [bp~].
Pass though 6-stage [lop~ 8000] to try to eliminate
harmonics > nyquist (22.5khz).
(attached).

Set the Q to about 3.
Now keep the frequency of the oscillator and the filter cutoff freq
below 100 hz.

Try [bp~] then try [vcf~].

No matter what the setting of either (as long as they are both below 100
hz),
I get I get a strong artifact at 4k, another at 12k, another at 17k.

This has been bugging me for months.
I can't figure it out.

I thought it was super-Nyquist foldover,
but the [lop~] didn't eliminate it,
and it does not seem dependent on the frequency of the oscillator.

Any ideas?

Sample rate=44100 hz. Delay= 80 ms. Blocksize=64.
*Pd 0.46.7 on Windows 7. *


-- 
--
May you, and all beings
be happy and free from suffering :)
-- ancient Buddhist Prayer (Metta)
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