Hi community.

I have 3 filters that I need to design and need some help just implementing them in Pd. Two are boundary loss filters and one is a DC killer (implementation within a waveguide model).

Here's the details of the filters:

1. 0.376/1-.6^z-1 (low-pass)
2. 1.8417+ z^-1/1 (low-pass)
3. 1-z^1/ 1-.995z^1 (dc block)

Any help would be grateful, but any form of walk through to implement these filters in pd would be great. Attached is the image of the waveguide being created.

Cheers!

http://www.pdpatchrepo.info/hurleur/Screen_shot_2013-07-03_at_14.04.30.png

You probably want the rzero~, rzero_rev~, and rpole~ objects for this. here is a guess of what I think the first one is

http://www.pdpatchrepo.info/hurleur/lowpassrpole~.pd

Sweet, thanks for the input. Any ideas for the others?

Maelstorm, any ideas?

Take a look at this tutorial I wrote, if you haven't already. It's meant to make it easier to figure out filters you come across as difference equations or their z-transforms (as is the case here) and implement them in Pd:

http://puredata.hurleur.com/sujet-7001-building-filters-difference-equations-using-raw-filters

These are all first-order filters, which makes them nice and easy for Pd since Pd's raw filters are all first-order. All three of these can be done using only [rzero~] and/or [rpole~].

[*~ .376]
|
[rpole~ .6]

[*~ 1.8417]
|
[rzero~ -1]

[rzero~]
|
[rpole~ .995]

That's great, thanks Maelstorm. Life saver.

Hello guys.

Sorry to bring an old topic back from the dead, but is it possible, in particularly for the low pass filters (1 and 2) to derive the cut-off frequency/3db point for each or is that something you have to take from drawing the function?