Re: AUParametricEq Q parameter?
Re: AUParametricEq Q parameter?
- Subject: Re: AUParametricEq Q parameter?
- From: "James Chandler Jr" <email@hidden>
- Date: Tue, 4 Jan 2005 23:43:20 -0500
Hi Felipe
Sorry to say, I've not messed with audiounits or the Apple audiounits. The only
OSX Mac music programming I've had time to do was MIDI only.
IF the Apple 'Parametric EQ' is one of those basic little one-band EQ's, you can
probably get satisfactory performance by wiring three of them in series. In
analog, one wouldn't typically wire EQ sections in series because of noise
build-up, but in digital this isn't a huge problem.
Wiring the sections in series, will give pretty low inter-band interaction (a
good thing). Parallel filter structures are subject to inter-band phase
cancellation, which is a big contributor to inter-band interaction.
Many of the little minimal single-band-parametric plugins also offer filter
shape choices of Low Shelf (bass control) or High Shelf (treble control), in
addition to the BandPass shape.
For a three-band tone control, IF the Apple Para EQ is simple single band, and
IF it offers Low Shelf and HiShelf options, I would try three EQ's in series,
one Lo Shelf with an FC about 100 Hz (some folks use 50 Hz, but IMO that's too
low for general use), one BandPass with either a fixed FC or user-adjustable
midband frequency knob, and one Hi Shelf with the FC somewhere around 5000 to
8000 Hz.
If the Apple plugin only offers Bandpass shape, you could still get something
pretty passable.
As a point of reference, typical analog mixers with three-band non-sweepable
tone controls, either have a mid-band FC around 400 Hz, or 2500 Hz.
A four-band tone control, with 100 Hz Lo Shelf, 400 Hz Bandpass, 2500 Hz
Bandpass, and 8000 Hz Hi Shelf, would be pretty flexible, and implemented with
only four simple boost/cut knobs. There are a lot of
'sound reinforcement' analog mixers with four-fixed-band EQ's. Sweepable EQ's
are nice, but fixed-frequency tone controls are very quick, simple and
intuitive. For starters, I'd try a Q of 0.707 for all bands.
Sorry if the reply is way off-mark. Maybe somebody else has better suggestions.
JCJR
----- Original Message -----
From: "Felipe Baytelman" <email@hidden>
To: <email@hidden>
Sent: Tuesday, January 04, 2005 3:08 PM
Subject: Re: AUParametricEq Q parameter?
What Kevin said. A higher Q has a longer ring-time.
If this Q parameter is the typical EE definition, 'musically useful'
parametric
equalization is in the range of 0.5 to 10. Once Q gets above about 5 or 10,
the
ring time can get annoyingly long, and it sounds real artificial except for
special FX.
...
A multiband parametric (depending on its design) will not necessarily have
the
frequency response you would guess just by looking at the knob settings. The
bands interact, and various equalizer designs have different behavior of
interband interactions.
JCJR
Thanks very much...
What I'm trying to do, is to have a 3-band (low-mid-high) equaliser, because
the 31-band Apple eq eats the processor!!
So, in this case, can I use parametric EQ? Your definitions are way too
difficult for a non music related guy :D
How can I build a 3-band equaliser based on Apple free effects?
Thanks!
--
Felipe Baytelman
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