LinuxMusicians

Hi! I'm trying to locate an opensource linear phase EQ plugin with no luck.

Those are particularly useful in mastering. With regular EQ, agressive cuts or boosts on such broadband and complicated signals as a whole mix, can cause audible phase shift artifacfs, like messing up transients and stereo image.

Does anybody feel like there's a need for such tool in the Linux pro audio world?

Anybody feels like making a linear phase version of existing EQ plugins?
I don't know the math and science behind this technology, are algorithms for linear phase filters freely available?

What are your thoughts?

I think there's definitely a need for one, I don't know if any either and I would love to find one. I think the mastering process is an area which is not well catered for in general in linux.

I would really like to see eq matching as well (applying an averaged eq curve from one source to another) but a linear phase eq would be a more important request.

Jamin sports "linear filters" I'm not sure if that means linear phase or not. http://jamin.sourceforge.net/en/about.html
If i have a second I'll look at the source and find out. EDIT: looked at it, it has some linear phase filters but also has some IIR filters which cannot be perfectly linear phase (but they can be designed to be close). I'm not sure which ones are used where in the 5 minute look over, but I've heard good things about JAMin, you might try it.
EDIT2:
Now that I look back I've heard some bad things about JAMin also. Its not perfect. see http://www.linuxmusicians.com/viewtopic ... &start=195 for some discussion.

Be aware that linear phase can smear transients.
For anyone interested, there's a nice video comparing linear phase and minimal phase eq-ing: https://www.youtube.com/watch?v=efKabAQQsPQ.

thanks for bringing that up. It makes sense. Here's a good discussion about it: https://www.gearslutz.com/board/masteri ... e-eqs.html (slightly more product agnostic than the video but saying the same thing).

Very interesting. I will add a linear phase filter to my list of plugins to develop (since we ought to have the option), but it's a fairly long list, so honestly me saying that isn't worth anything to you.

I've found more information about the topic recently and looks like there's a confusion between linear phase EQ and minimum phase EQ.

Looks like linear phase EQ has a bad impulse response, that can smear drum transients, while minimum phase EQ doesn't do that. I'm not educated in signal processing so I can't really tell, but maybe it's the minimal phase filters and EQ that'd be a better tool for sound engineering.

Here's a good read on the topic: http://theproaudiofiles.com/linear-phas ... -phase-eq/

Anyway, I'm still confused about this topic. Gotta stick to the Calf EQs anyway

well, one thing to be said on the topic is that linear phase filters are strictly digital. Analog filters can't be linear phase. So if you know of any good recordings that were made before digital mastering came around then there's still hope for us LA users.