Ladder 4 Pole LP Filter

[Frankbeat]

I‘m pretty happy with the sound of the 4pole LP – when I tested it, I didn’t recognize there’s a Moog LP to choose. So, judging by my ears, I already found a moogish filter

[DanH]

I think in general the filter selection could use a freshen up. @Lindon mentioned a while back that I'd need to find the code for new filters and then implement them into Hise.

So a) where does one find the code for filters, and b) how would you get them into Hise? (I'm assuming through SNEX).

[Lindon]

@DanH - you'd probably need to do it with C++ there are several well respected books on filter design - google it.

Alternatively you could look at the filters in Faust.

[DanH]

@Lindon Thanks - another issue is being able to update / create new filter displays for the UI. Any ideas on that anyone? Aside from drawing it all in PR

[DanH]

@DabDab how do I get the Faust Moog? Can't see it on https://faustide.grame.fr/ but maybe I'm in the wrong place!

[sletz]

Possibly here: https://faustdoc.grame.fr/examples/filtering/#mooghalfladder and next ones.

[DanH]

@sletz Thank you! :)

[DabDab]

@sletz said in Ladder 4 Pole LP Filter:

Possibly here: https://faustdoc.grame.fr/examples/filtering/#mooghalfladder and next ones.

@DanH here is an example

process = dm.moog_vcf_demo;

Click here to know more about moog faust library.

ve.moogLadder (4th Order)

Usage..

_ : moogLadder(normFreq,Q) : _

[DanH]

Ok finally trying the Faust Moog - It's mono lol... but has stereo in and out... Can make it work tho

[DanH]

@DanH ok no I can't

It only takes the left channel - is there a node I can use to get the right input channel and switch it over to the left input?!

[Christoph Hart]

@DanH I recommend spending 1-2 hours learning the absolute basics of Faust signal routing - turning a single channel processing module into a stereo module is super trivial if you now how it works. Just learn the basic operators and you should be able to do this (and many other simple things) yourself.

[DanH]

@Christoph-Hart ah ok... Will do!

[DanH]

@Christoph-Hart ok I found the bit to edit... I guess I'm confused as it's a parallel combination (2 ins, 2 outs) but only takes the left channel?

process = inputSignal : ve.moogLadder(normFreq,Q) <:_,_;

[d.healey]

@DanH

I don't have an answer because it's been a long time since I played with FAUST. But if you haven't seen this already you should check it out - https://www.kadenze.com/courses/real-time-audio-signal-processing-in-faust/info

[DanH]

Are we allowed to use the Moog name to describe the moog style filter on our UI?

[DanH]

@Christoph-Hart just digging into Juce.... Is there a reason all these Ladder filter options aren't included in Hise? And if it's possible to include them, please can you? Pretty please

namespace juce
{
namespace dsp
{

enum class LadderFilterMode
{
    LPF12,  // low-pass  12 dB/octave
    HPF12,  // high-pass 12 dB/octave
    BPF12,  // band-pass 12 dB/octave
    LPF24,  // low-pass  24 dB/octave
    HPF24,  // high-pass 24 dB/octave
    BPF24   // band-pass 24 dB/octave
};

/**
    Multi-mode filter based on the Moog ladder filter.

    @tags{DSP}

[d.healey]

@DanH I think if you called it Moog style you should be ok. Basically it comes down to trademark fair use. You are allowed to use trademarks as descriptors under certain circumstances, for instance if that's the only way to refer to a product.

If you run a phone repair shop you would obviously need to say somewhere in your advertising that you repair both iPhone and Android phones. Those are both trademarks but referencing them in this way wouldn't violate the trademark as it doesn't imply an affiliation with those brands or an endorsement from the brand owners.

So if you say your plugin contains a Moog filter that might be confusing - does that mean it was created by Moog specifically for you... so I think using Moog style would be the safe option because it's clear that it is not Moog. You could also include a disclaimer in your user manual/marketing material, etc.

Or talk to a trademark lawyer, or send Moog an email and ask them.

[DanH]

@d-healey Thanks, sensible thoughts! I can't think of an example of another dev using 'Moog-style' on their UI so maybe I'll avoid it :)