Forums > MaxMSP

a really weird problem with [overdrive~]

September 9, 2008 | 12:44 pm

I just discovered a weird problem with overdrive~ in combination with a few things. The problem exists with the latest max 4 (mac and pc) and max 5 (I checked only pc) as well.

-if and only if the incoming signal contains clicks (or abrupt changes)
-if and only if the signal is routed through a [freqshift~ ] object (the shift itself is irrelevant, even shift 0 ‘works’)
-if and only if that signal is routed to an overdrive whose drive is controlled by a signal (not when it is controlled by a float)

–> then the output becomes really dirty, even with drive = 1.
i noticed the problem because this output can blowup biquads (resulting in a ‘nan’ output)

you can check this situation for yourself with the patch belowing and trying out the various situations, you will find out that it will only result in a dirty output when you have clicked all three green message boxes

placing a [bitsafe~] or [el.killdc~] object before or after the [freqshift~] doesn’t help

can somebody explain this to me? what is [freqshift~] doing to the signal (inaudibly) that causes an [overdrive~] to behave like this? does it mess up the phase for wideband (click) signals? And why is this only a problem when the [overdrive~ ] is controlled with a signal object?

max v2;
#N vpatcher 154 328 727 691;
#P origin -1 0;
#P window setfont "Sans Serif" 9.;
#P flonum 206 253 35 9 0 0 0 3 0 0 0 221 221 221 222 222 222 0 0 0;
#P comment 391 137 155 196617 < -- change the drive factor here;
#P comment 80 196 49 196617 no effect;
#P comment -1 216 133 196617 overdrive – float controlled;
#P flonum 353 136 35 9 1. 0 1 3 0 0 0 221 221 221 222 222 222 0 0 0;
#P flonum 312 114 35 9 0 0 0 3 0 0 0 221 221 221 222 222 222 0 0 0;
#P comment 35 129 117 196617 freqshift with zero shift;
#P comment 101 110 49 196617 no effect;
#P comment 51 73 100 196617 dirty sine with click;
#P newex 242 114 65 196617 freqshift~ 0;
#P message 153 127 14 196617 2;
#B color 6;
#P message 153 108 14 196617 1;
#P newex 182 150 71 196617 selector~ 2 1;
#P message 153 73 14 196617 2;
#B color 6;
#P message 153 54 14 196617 1;
#P newex 212 61 61 196617 cycle~ 400;
#P newex 182 89 71 196617 selector~ 2 1;
#P newex 162 253 41 196617 *~ 0.2;
#P message 133 232 14 196617 3;
#B color 6;
#P message 133 214 14 196617 2;
#P message 133 195 14 196617 1;
#P newex 202 178 73 196617 overdrive~ 1.;
#P newex 162 215 71 196617 selector~ 3 1;
#P newex 353 156 41 196617 sig~ 1.;
#P newex 290 178 73 196617 overdrive~ 1.;
#P user ezdac~ 162 305 206 338 0;
#P newex 327 38 44 196617 rect~ 1;
#P newex 276 61 61 196617 cycle~ 400;
#P comment -2 233 138 196617 overdrive – signal controlled;
#P comment 102 55 49 196617 clean sine;
#P comment 349 113 202 196617 < -- change the frequency shift amount here;
#P connect 12 0 8 0;
#P lcolor 7;
#P connect 11 0 8 0;
#P connect 10 0 8 0;
#P connect 8 0 13 0;
#P connect 13 0 5 0;
#P fasten 16 0 14 0 158 70 187 70;
#P connect 17 0 14 0;
#P fasten 19 0 18 0 158 124 187 124;
#P fasten 20 0 18 0 158 144 187 144;
#P fasten 18 0 8 1 187 191 187 191;
#P connect 30 0 13 1;
#P fasten 13 0 5 1 167 287 201 287;
#P fasten 18 0 9 0 187 172 207 172;
#P fasten 9 0 8 2 207 208 207 208;
#P connect 15 0 14 1;
#P fasten 14 0 18 1 187 110 217 110;
#P fasten 6 0 8 3 295 209 227 209;
#P fasten 3 0 14 2 281 83 247 83;
#P fasten 14 0 21 0 187 110 247 110;
#P connect 21 0 18 2;
#P fasten 26 0 9 1 358 153 270 153;
#P fasten 18 0 6 0 187 172 295 172;
#P connect 25 0 21 1;
#P connect 4 0 3 1;
#P connect 26 0 7 0;
#P connect 7 0 6 1;
#P pop;


September 9, 2008 | 3:06 pm

I can confirm with Max 4.6.3 on Mac OS X Intel, the output sound goes wild. Seems quite buggy to me.

Did you check in the latest version of Max 5 (currently 5.0.4)? Some msp stuff has changed there, recently.

Mattijs


September 9, 2008 | 4:14 pm

thanks for confirming

good point about the latest version, I still had to update to 5.0.4
I just did and… the problem remains (at least on a pc running xp)


September 9, 2008 | 9:31 pm

This should be fixed for the next incremental update.

-Ben


September 9, 2008 | 9:51 pm

thanks!


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