Hi , because i want to have my own filtermodule , i try to add 4x LP 6dB in chain. The goal was to build a 4Plole mission filter. I want to generate a addition of the 4 poles to realize a BP and also HP . I use for a basic filter 4x 6db standart - first and for test without 180 degree phase for each 6dB filter . The normal 24 dB works , but if i add a feedback path - 180 degree, the feedback works only from 50 up to 620 Hz. I thought that a CPU with 180 Mz can calculate a filter with 1..2 Samples latency, but it seems that it takes much longer to calculate 4 x 6dB LP. Any ideas ??
Hmm , i thought that the audio phat is quicker than 3000 HZ. Funny is , if i don't use the Feedback in a Filtermodule and build an external pot for Feedback , this seems to work.
In recent years, something called "zero-delay-feedback" (ZDF) filters have been all the rage in the KVR DSP forum. Maybe some of these structures could be useful for you?
Just digging up this topic for a bit, is there a particular reason there's no 4-pole filter? I am right in thinking that the VCF family of objects is still only 2-pole? A 24dB slope could be achieved by chaining 2 2-pole filters, but I have a feeling their response to resonance would be different from a true 4-pole object since it effectively represents two separate (internal) feedback paths (output of pole 2 back into pole 1 and output of pole 4 back into pole 3).
I'm prototyping a 4pole filter now, based on source code from Miller Puckette:
"Imitates a Moog resonant filter by Runge-Kutte numerical integration of a differential equation approximately describing the dynamics of the circuit."
Stay tuned - but don't go into self-oscillation yet
Ok, added a test patch to axoloti-contrib/patches/jt/devel/filter-4pole-test.axp You can fetch it from version 1.0.10, if you "sync libraries". It's not a dedicated object yet, not very optimized, consider it a preview. It does self-resonate but only if clip is set to on. Otherwise, the filter explodes at high resonance settings. It does not drift, no matter how hot the weather is.
Thanks you @johannes. I just compile the current version of axoloti from source and "sync libraries", but I can't find your patch on the axoloti-contrib repository. Is there something I did not understand ?
Im sorry but how do i use this filter? If i open the filter-4pole-test.axp as a patch in the axoloti patcher i get tons of errors. Using version 10 of the patcher by the way:)
works for me @the19thbear ... I assume you did a sync libraries to get the patch? (and also to update the libraries to 1.0.10)
what errors do you get?
@johannes , sounds really nice ... bit heavy on cpu (about 20% per filter) ,and for some reason compiler errors if i put it in a subpatch... not really spent to much seeing why (undefined reference to `_cxaguard_acquire'), but rings a bell from before.
anyway, very tasty for mono synths !
one thought, where are we on the opening up the other filters to 24k ? do you want to do this once the object lifecycle is 'resolved'? or go with the original suggestion of giving them different names? .... @DrJustice were you still up for doing this ? given the credit for finding and resolving this goes to you.
Axoloti version : 1.0.10-0-gf8ed51d build time : 10/05/2016 19:56:36 UTC Link to firmware CRC 3DB31696 Status: factory (1.0.10,anon) : OK ( 1.0.10,clean ) Status : home : OK Status: community (1.0.10,anon) : OK ( 1.0.10,clean ) USB device found connected Authentic Axoloti Core search path : /Users/TRJ/Documents/axoloti/axoloti-factory/objects Firmware version: 1.0.0.1, crc=0x3DB31696, entrypoint=0x20011000 search path : /Users/TRJ/Documents/axoloti/objects search path : /Users/TRJ/Documents/axoloti/axoloti-contrib/objects finished loading objects
also what errors do you get when you open the patch?
@johannes, just seen your v2 patch... something a bit odd... you have 2 connections going to pitch (on both filters) this shouldn't be allows (and doesn't work ... are you using an unreleased feature )
yes i also got errors: java.lang.ClassNotFoundException: is-copy-enabled loaded the file from directly github, because when i sync, console says org.eclipse.jgit.api.errors.WrongRepositoryStateException: Cannot pull into a repository with state: MERGING org.eclipse.jgit.api.errors.WrongRepositoryStateException: Cannot pull into a repository with state: MERGING
I experienced this 2 cable in one input, since 1.0.9 sometimes, in MAX its a feature.....
I suspect this is because you had outstanding changes when you upgraded... as it tried to merge the changes from 1.0.10 with changes you had locally, but found conflicts... which would need resolving and committing...
if you know, you don't have any changes you need to keep then you should use File->Preferences-> Reset All
if you do have changes that you need to keep, then you should copy the files that you need to keep before doing reset all, then you can put the copied files back. (just check they still are opening ok, PM me a copy of the affected files)
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