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. *
hello,
Le 15/06/2016 07:46, William Huston a écrit :
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).
This is not a good way to generate an aliased free waveform since all foldover frequency under 8KHz will not be removed. you should try using a real band limited square oscilator.
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.
i can see lot's of crap using your patch, but very few when using a good band limited oscilator.
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?
what did you use to record the sound?
cheers c
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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Thanks Cyrille!
It was my stupid soundcard.
My Asus/AMD motherboard uses an integrated VIA VT2020 audio chip. Utter crap.
I switched to my iMic USB interface, which has a Phillips UDA1325H/104 or /106 chip. *Clean as a whistle!! *
I can't believe I've been dealing with that for 4khz whine (under certain circumstances) for the last 5 years!
Thanks again, BH
On Wed, Jun 15, 2016 at 6:07 AM, cyrille henry ch@chnry.net wrote:
hello,
Le 15/06/2016 07:46, William Huston a écrit :
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).
This is not a good way to generate an aliased free waveform since all foldover frequency under 8KHz will not be removed. you should try using a real band limited square oscilator.
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.
i can see lot's of crap using your patch, but very few when using a good band limited oscilator.
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?
what did you use to record the sound?
cheers c
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)
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
-
cyrille henry -
William Huston