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Strange volume drops when source is moved

Spat
#1

Hi,

I’m using spat in Max MSP for a quadraphonic live, and I noticed something odd. I have setup the speakers positions in SPAT as they are in my studio, with approximately the same ratio as the concert room I’m playing the live at the end. I’m using stereo sources ( up to 8 ). I noticed that at a few points when I move a source, the volume suddenly drops or raises without any apparent reason (like if there was an ‘edge’). So the movement is not really smooth anymore and has some irregularities.

But when I go back to the default settings for speaker positions (given by the ‘source quad’ exemple) which is “loudspeakers az -45 45 135 -135”, the problem disappears. I’m placing the speakers individually using xy and not az (so : speaker 1 xyz -3 5 0 ).

Am I doing it right ?

Thank you

#2

Hi,

Could you please send your patch (at least the relevant part of it), so that I can better understand the issue.

Thanks,
T.

#3

Here’s the patch, cut down to the necessary. I used pink noise as a source in the 1st source of spat.spat~.

I’ve left comments on the patcher. The drop in frequency/volume is even visible in the vu-meters, and it is really one increment that causes the change to happen.

It seems that it only happens near speaker 1. As said earlier it only happens with my speaker position and not with the default one.

Thanks

Krake_SPAT.maxpat (152 KB)

#4

I’d recommend not to use ‘panr’, as there are some caveats.
Try instead to use ‘angular’ or ‘vbap2d’ for your panning type.
Hopefully that should work.

I’d also recommend to upgrade to spat5 !

Cheers,
T.