Implementing a 1/3 Octave Filter
Hi All,
I'm trying to simulate room reverberation using third-octave RT60 measurements (actual results are taken using RT30/20) and i was just wondering if anyone had much lucky implementing a third-octave (32 band) filter using MaxMSP?
I know it's possible to replicate third-octaves using the FFT~ object, but FFT isn't an option as for one it delays the signal chain etc.
Cheers all!
The [fffb~] object implements a chain of [reson~]-like band-pass filters. It might be worth a look.
lh
take a look at Elsea's tutorial on the third octave filter:
Visibleman wrote on Thu, 26 February 2009 10:22Hi All,
I'm trying to simulate room reverberation using third-octave RT60 measurements (actual results are taken using RT30/20) and i was just wondering if anyone had much lucky implementing a third-octave (32 band) filter using MaxMSP?
I know it's possible to replicate third-octaves using the FFT~ object, but FFT isn't an option as for one it delays the signal chain etc.
Cheers all!
I made one using CNMAT's peqbank~. Download the CNMAT Max/MSP/Jitter Depot and the peqbank~ object here:
And search for:
+peqbank~_overview.maxpat
mz
Cheers all, but unfortunately FFT isn't an option due to it being linear.
Mzed - I had a look at using the biquad as i have third-octave coefficients, so i'll have a look into peqbank~. But not be a pain, have you got a direct link to the peqbank maxpatch? Had a look on here as well as CNMAT but couldn't find a thing, cheers.
Visibleman wrote on Sun, 01 March 2009 14:57Cheers all, but unfortunately FFT isn't an option due to it being linear.
Mzed - I had a look at using the biquad as i have third-octave coefficients, so i'll have a look into peqbank~. But not be a pain, have you got a direct link to the peqbank maxpatch? Had a look on here as well as CNMAT but couldn't find a thing, cheers.
Download this:
Search in there for "+peqbank~_overview.maxpat" in .../tutors/object-tutors/peqbank~/
I don't know what platform you're on, or I'd send a link to the object. Scroll down to peqbank~ here:
and you'll find links or either platform.
mz
Hi,
To make good 1/3oct filters for measurement, you should comply to IEC1260, this document tells you what the specs are. Hint: use three biquads in bandpass mode per filter, two with q=6, one with q=10 for flattop behaviour
greets,
Kessito
Hi all,
mzed - cheers for the link, been playing around with Peqbank all afternoon, but do you know if there is a performance hit using Peqbank~ over Biquad~?
Kessito - Yeah, IEC1260 is what i'm trying to design the filters to. But is the following patch about right?
Also, does anyone know where i might be able to get hold of 1/3 octave biquad coefficients? The coefficients i have currently are IIR Filter (ie: you have a/b[0] to a/b[6] instead of biquad a0, a1, a2, b1, b2 etc).
Cheers for the help so far, it's appreciated greatly!
ComfortableInClouds wrote on Thu, 26 February 2009 12:29take a look at Elsea's tutorial on the third octave filter:
Great !
Thanks !