Forums > MaxMSP

Filtering adc and dac for live-gigs. help me.

February 9, 2006 | 2:53 am

guys, i have a gig coming up,
and I do not want the dac to go above 1.
I am planning to filter any hz that does not need to be there.
have a mic and some synth-like stuff connected to the interface.
Should I cut below 10hz and above ?khz.
Low=10hz High=?khz ???
I do not have a clue.

Any advice would greatly appriciated.

snif


February 9, 2006 | 11:06 am

Highcut won’t help you much, since high frequencies have little energy
compared to low ones. 10hz is really low, and not even perceived as a
tone but LFO (good for modulation but not something you want as a frequency
in a music signal). You can easily cut below 40 or maybe even 60. After your
lowcut filter you should insert a limiter at the end stage. Synths typically
don’t have a very dynamic output, but for your mic source, an additional
compressor is probably useful.

T_


February 9, 2006 | 1:16 pm

It’s difficult to say how you should treat the sound from the microphone without knowing what kind if sound you are trying to capture and what you want to do with that sound in Max. Some people would say filter out any frequencies that are not present in the source material others would filter off the very low end with a hi-pass filter. A notch filter might be useful to reduce feedback if this is an issue. With out a doubt you should test your entire setup before the gig.

to keep the sound from going over 1 (or under -1 this is called clipping) you can use a limiter. You can make a very basic hard limiter by using the clip~ object or a better solution may be to use the new omx.PeakLim~ object that comes with Max. Check out the OMX Tutorials folder!

good luck,

john.


February 11, 2006 | 3:39 am

Quote: thijskoerselman@gmail wrote on Thu, 09 February 2006 20:06
—————————————————-

> compressor is probably useful.

thx, mate.
I have used the limiter at the end and it is working like a charm.
Will you please recommend me any cpu-freindly compresser, or highpass filters ?


February 11, 2006 | 3:45 am

Quote: Leafcutter John wrote on Thu, 09 February 2006 22:16
—————————————————-
> It’s difficult to say how you should treat the sound from the microphone without knowing what kind if sound you are trying to capture and what you want to do with that sound in Max.

Exactly. You really know your stuff.

>others would filter off the very low end with a hi-pass filter. A notch filter might be useful to reduce feedback if this is an issue.

Will you please tell me where I could find the notch filter is ??
As mate above said, I am planning to cutoff around 10-60HZ.
I checked the tutorials and msp externals, but could not find any notch filter or highpass filter.
If you know any cpu-friendly highpass filter, please inform me. I really appriciate for your great advice.

> to keep the sound from going over 1 (or under -1 this is called clipping) you can use a limiter. You can make a very basic hard limiter by using the clip~ object or a better solution may be to use the new omx.PeakLim~ object that comes with Max. Check out the OMX Tutorials folder!

Thank you so much with the omx.PeakLim.
I would not have come up with this if it wasn’t for you.
And it is working like a charm.
Thank you so much with your big help, john.
It’s always nice to see you in the forum+mailing list.
>
> good luck,
>

thx
—————————————————-


February 11, 2006 | 6:36 am

I’d try using either biquad~ or cascade~, with a filtergraph feeding it the
desired parameters. If you look at the help files and/or the tutorials for
those two filter objects (sorry, not on the right computer now to double
check for you,) there should be a sample patch with a menu object connected
that feeds sets up filter object for a variety of different responses: high
pass, low pass band pass, band reject (notch), etc.

Cheers,

*V*I*R*G*O*


February 11, 2006 | 1:51 pm

You could use the cascade~ like this….

#P window setfont "Sans Serif" 9.;
#P window linecount 1;
#P newex 50 362 548 196617 cascade~ 0.997458 -1.994915 0.997458 -1.994906 0.994924 0.925489 -0.748145 0.858128 -0.748145 0.783617;
#P window linecount 2;
#P message 149 244 253 196617 0.997458 -1.994915 0.997458 -1.994906 0.994924 0.925489 -0.748145 0.858128 -0.748145 0.783617;
#P window linecount 1;
#P newex 149 221 62 196617 prepend set;
#P user umenu 89 63 70 196647 1 64 79 0;
#X add display;
#X add lowpass;
#X add highpass;
#X add bandpass;
#X add bandstop;
#X add peaknotch;
#X add lowshelf;
#X add highshelf;
#X add resonant;
#X add allpass;
#P newex 51 269 51 196617 cascade~;
#P user filtergraph~ 149 86 255 124 3 9 0. 22050. 0.0625 16. 1 1 1 0 0 1 1;
#X frgb 193 193 255;
#X brgb 233 233 255;
#X rgb2 0 0 0;
#X rgb3 130 130 130;
#X rgb4 0 0 0;
#X rgb5 118 121 166;
#X rgb6 210 74 54;
#X rgb7 255 22 22;
#X linmarkers 5512.5 11025. 16537.5;
#X logmarkers 10. 100. 1000. 10000.;
#X nfilters 2;
#X setfilter 1 5 0 0 0 7986.987305 0.311301 6.705589 0. 0. 0. 0. 0. 0.;
#X setfilter 0 2 0 0 0 30.063284 1. 0.841762 0.0001 22050. 0.0001 16. 0.5 25.;
#X done;
#P comment 59 381 526 196617 Use all the wanted filtercoeffs as arguments , to free the filtergraph and other (in this situation useless) stuff;
#P connect 1 0 2 1;
#P connect 1 0 4 0;
#P connect 4 0 5 0;
#P connect 3 1 1 0;
#P window clipboard copycount 7;


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