[PD] bugs with [hip~] and [bp~]

Alexandre Torres Porres porres at gmail.com
Fri Jan 30 06:21:38 CET 2015


> This message of mine was intended to be a bug report

I see, but my point is that it's not much of a "bug", so if you want to see
how these filters work more deeply, you may check my stuff.

You can see how I made versions of the filters as [fexpr~] or [biquad~] and
the raw filters. I made [vcf~] out of [cpole~], for example. And you can
check the plot of magnitude/phase.

> I know (and enjoy very much) yours
*> Computer Music With Examples In Pd*.

Thanks. That got old though... I translated from portuguese what I had for
a workshop at the last pd convention in 2011, but it's mostly FFT. My
current portuguese version is way bigger, up to 250 examples in the next
release I'm planning for next month. These patches I'm sharing is from my
newest releases.

> Probably it would be better then to warn users
> about this limit of ~12 kHz in the help-files then.

Yeah, it'd be good to point out a bit of its characteristics. I learned a
lot by checking on my own.

I could realize how [bp~] is quite similar to the resonant lowpass from
[lores~] for example. Its just a matter of setting up the gain. If you set
[bp~]'s Q to 1, you'll also see how it behaves much like a lowpass filter
like [lop~]. The [vcf~] filter has similar characteristics.

cheers

2015-01-30 0:19 GMT-02:00 Gilberto Agostinho <gilbertohasnofb at googlemail.com
>:

>  Hi Alexandre, thanks for your reply.
>
> On 30/01/15 02:39, Alexandre Torres Porres wrote:
>
> it's how the filters were designed, they're not perfect throughout the
> spectrum
>
>
> Probably it would be better then to warn users about this limit of ~12 kHz
> in the help-files then.
>
> you'll need to use/build other filters for that purpose of working with
> that higher portion of the spectrum (in which I can hardly still hear, by
> the way)/
>
>
> Hmm, I can clearly hear the difference between feeding a high frequency to
> [vcf~] and to [bp~] using a large enough Q (~100 for instance). With that
> Q, try sweeping from 12kHz until 14kHz in both filters, and you'll hear
> that [vcf~] behaves as expected, while [bp~] does not change the frequency
> but only affects the amplitude of the output for some reason.
>
> a few of patches of mine that describe the behaviour of vanilla and some
> extended filters
>
>
> Thanks a lot for the patches, but I am actually aware of [vcf~] and
> [biquad~]. This message of mine was intended to be a bug report rather than
> a cry for help as I have no particular problem with filters needing a
> solution right now. But in any case I will check your patches, as I know
> (and enjoy very much) yours *Computer Music With Examples In Pd*.
>
> Take care,
> Gilberto Agostinho
>
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