[PD] [biquad~] as cyclone's [allpass~]?

[Alexandre Torres Porres]

on curtis roads' computer music tutorial, page 418, it shows the same
formula, but the figure of the design seems to contradict it. I'm confused.
I don't seem to get the same result with one delay line. maybe if you send
me a patch that sounds the same as cyclone's allpass I can check it.

cheers


2013/10/5 Alexandre Torres Porres <porres at gmail.com>

> i dont think there is one way or proper way of doing this, and it is a
> general form, from an equation you can find in other references. So, I
> don't know why, but Max/Cyclone's allpass use this one: y(n) = -g x(n) +
> x(n)-(DR/1000) + g y(n)-(DR/1000)
>
>
> 2013/10/5 Chris Clepper <cgclepper at gmail.com>
>
>> That means cyclone's allpass~ is not done properly.  Why not do it the
>> standard and more efficient way?  When it comes time to do dozens of
>> allpasses it will make a difference.
>>
>>
>>
>>
>> On Sat, Oct 5, 2013 at 1:00 PM, Alexandre Torres Porres <porres at gmail.com
>> > wrote:
>>
>>> but this way it won't be the same as cyclone's [allpass~], the way I did
>>> it is equivalent to it (and max's).
>>>
>>> cheers
>>>
>>>
>>> 2013/10/3 Chris Clepper <cgclepper at gmail.com>
>>>
>>>> You only need one delay line for the allpass.
>>>>
>>>> feedforward = input * -gain
>>>> feedback = delayout * gain
>>>> delayin = input + feedback
>>>> output = delayout + feedforward
>>>>
>>>> http://www.spinsemi.com/knowledge_base/effects.html#Reverberation
>>>>
>>>>
>>>> On Thu, Oct 3, 2013 at 11:29 AM, Alexandre Torres Porres <
>>>> porres at gmail.com> wrote:
>>>>
>>>>> i hope i guess i figured it out on how to implement it with delay
>>>>> lines. see attachment. And I realize you can't do this with [fexpr~] or
>>>>> [biquad~] because the sample delay length is kinda big for that, right?
>>>>>
>>>>> cheers
>>>>>
>>>>>
>>>>> 2013/10/3 Alexandre Torres Porres <porres at gmail.com>
>>>>>
>>>>>> cool, but do you know how to implement cyclone's [allpass~] with it?
>>>>>>
>>>>>> It's really unclear to me what is the relation of this pass filter
>>>>>> with the one you can generate with biquad coefficients, or with raw
>>>>>> poles/zeros objects for that matter.
>>>>>>
>>>>>> Well, one way or another, it's also unclear to me how to do it with
>>>>>> delay lines.
>>>>>>
>>>>>> seems that it is related to a comb filter, right?
>>>>>>
>>>>>> cheers
>>>>>>
>>>>>>
>>>>>> 2013/10/2 Chris Clepper <cgclepper at gmail.com>
>>>>>>
>>>>>>> Allpass for reverb is easy to do with delwrite~ and vd~.  I used 32
>>>>>>> of them today to recreate a famous 'deep space' reverb.
>>>>>>>
>>>>>>>
>>>>>>> On Wed, Oct 2, 2013 at 1:53 AM, Alexandre Torres Porres <
>>>>>>> porres at gmail.com> wrote:
>>>>>>>
>>>>>>>> hi there, i see the biquad's coefficients can be set as an allpass
>>>>>>>> filter, generated by frequency and "Q" parameters. But can it do the same
>>>>>>>> as cyclone's [allpass~] filer? If yes, them how since the parameters for
>>>>>>>> [allpass~] are different (delaytime and such).
>>>>>>>>
>>>>>>>> One way or another, I guess that my real question is: how to
>>>>>>>> implement [allpass~] from vanilla objects?
>>>>>>>>
>>>>>>>> thanks
>>>>>>>>
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>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
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