[sdiy] Analog bandwidth

[cheater00 .]

The link you provided shows a guy explain aliasing - it is unrelated
to what we've been talking about. We're talking about signals which
are above the threshold of hearing, not above the nyquist frequency.
It's only a coincidence that both are at roughly the same frequency in
your video. Don't confuse them. You can have nyquist frequency as high
as 500 MHz or as low as 1 kHz and neither of them are related to being
able to hear above that pitch. Then you can have hearing that gives up
sooner or later. (cue David's old-man-complaining routine ;-) )

D.

On Sat, Feb 22, 2014 at 7:47 PM, Kylee Kennedy <kmkennedy at gmail.com> wrote:
> http://www.wired.com/underwire/2014/02/monome-ingmob/
>
> Check out the video at the top, he specifically makes a Max patch that goes
> well above hearing. See what happens.
>
>
> K
>
>
> On Saturday, February 22, 2014, cheater00 . <cheater00 at gmail.com> wrote:
>>
>> The theory is that if you multiply noise which is just above 20 kHz
>> (that's your noise), by something that has spectrum between 0 and 20
>> kHz (that's the envelope), then you get sum and difference. The
>> difference is at frequency, say, 20 kHz - (something between 0 and 20
>> kHz), and therefore ends up in the audio band again.
>>
>> Cheers,
>> D.
>>
>> On Sat, Feb 22, 2014 at 5:46 PM, Tom Wiltshire <tom at electricdruid.net>
>> wrote:
>> >
>> > On 22 Feb 2014, at 13:45, cheater00 . <cheater00 at gmail.com> wrote:
>> >
>> >> On Sat, Feb 22, 2014 at 1:47 PM, Michael Zacherl
>> >> <sdiy-mz01 at blauwurf.info> wrote:
>> >>>
>> >>> On 22 Feb, 2014, at 1:33 PM, cheater00 . <cheater00 at gmail.com> wrote:
>> >>>
>> >>>> I believe adding shaped, ultrasonic noise before a VCA is a way to
>> >>>> shape transients during fast A/D/R stages. It should also work in a
>> >>>> compressor (you must not add the noise to the sidechain, though).
>> >>>
>> >>> I wonder if this also applies when using programming environments,
>> >>> like
>> >>> SuperCollider, Max/PSP, Puredata, Csound etc. In theory it should,
>> >>> given
>> >>> that the basic elements used are pure and 'un-shaped'.
>> >>>
>> >>> Michael.
>> >>
>> >> Yes, but when doing multiplication or non-linearities or IMD in
>> >> digital the typical rules for oversampling apply. So you'd have to
>> >> take, say, a signal that goes up to say 100 kHz, and then oversample
>> >> it quite a bit.. that's computationally expensive. Why 100 kHz? For
>> >> example in multiplication you obviously get sum and difference
>> >> components. So depending on the frequency content of the envelope of
>> >> your VCA, you'll at most push the noise (which is at 20 kHz - 100 kHz)
>> >> down by that much. If you want a nice thump you'll make the envelope
>> >> push down the noise by those 20 kHz or more. As the envelope goes
>> >> faster, I imagine you would get typical "overdrive" type effects
>> >> happening on the noise.
>> >>
>> >> Andy said he was going to check whether adding some ultrasonic noise
>> >> makes sense for fast attack settings in his Glue VST but I don't
>> >> recollect if we spoke about that afterwards.
>> >
>> > Sorry, I'm missing something. Why is ultrasonic noise supposed to help
>> > with a fast attack?
>> >
>> > Thanks,
>> > Tom
>> >
>> >
>> >
>> >
>> >
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at dropmix.xs4all.nl
>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy