[PD] What is that 4khz whine?

[William Huston]

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