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jamoma / jamoma2

A header-only C++ library for building dynamic and reflexive systems with an emphasis on audio and media.
MIT License
30 stars 6 forks source link

Should LowpassFourPole "q" really be named "resonance"? #27

Closed nwolek closed 9 years ago

nwolek commented 9 years ago

Most of the sources I reviewed for issue #12 called it resonance. It is not the same thing as Q, but I am having a hard time finding an online source that explains the difference/relationship clearly. Clearest thing was this discussion: https://www.native-instruments.com/forum/threads/filter-q-vs-resonance.234219/

The original Moog VCF panel has a resonance knob: Moog VCF panel

Just want to make sure @tap or others support renaming before I proceed.

tap commented 9 years ago

Please rename. I have a recollection now that I renamed it from resonance to q for the j.filter~ object so that it could be controlled using the same attribute as the others. But this was misleading and should never have been done.

Thanks, @nwolek !

lossius commented 9 years ago

In a thread at a NI forum, one of the NI techs gives the following conversion between resonance and quality:

1/Q=2(1-resonance)

https://www.native-instruments.com/forum/threads/filter-q-vs-resonance.234219/

lossius commented 9 years ago

(the previous post got posted prematurely, so if watching in mail, please check online)

lossius commented 9 years ago

The reason why we wanted all filters to have a Q parameter, was that they would share the same interface, and thus could be used interchangeably. But if a filter is a beast of a different colour I'd say that it does not make sense to force it to have a Q.