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logarithmic pots


Guest ricrawford
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Guest ricrawford

could someone give me an idea of what the behavior of the midi out would be if one wired logarithmic  potentiometers to a midibox64? through a failure of thoroughness, i bought audio pots and i'm wondering if the constant stream of control data has to do with this or some other wiring/ board construction issue- something i could work on as i wait for the replacement potentiometers...

thanks

ri

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Hi there

I'll go out on a limb here and suggest that the continuos stream is probably a fault in your board etc rather than the pots being log.

Thing is that the log pots still vary the resistance only they don't react on a linear scale.

That is the resistance does'nt change consistantly from one end to the other.

The resistance will tend to ramp up quickly towards one end..Not good for controlling stuff.

Y ;ou must check and recheck what you've done. :'(

It's happened to practically everyone on this community. ;) ;)

Have a good nose and you'll find it. ;D

All the best

Ian

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Hi

If you fitted log pots the midibox would be more prone to jitter caused by closer values at the top of the log scale.

Try to find out what pot the cc relates to and turn the pot right down this will increase the gap between resistance values and therefore stop the jitter.

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Or just try if the jitter is still there, if you pull all those Ins to ground (just use a big jumper row and solder the apropiate pins together). Then you can at least work on with all that other stuff.

It shouldnt be the pots. The pots will just result in a very slow value rising on the left and a very fast one on the right side.

Perhaps its just a shielding issue.

Are you using 10k pots? Using 100k or so can also cause big jitter. Is the jitter constant or just a wild big thing? Have you pulled all unused AINs to ground?

Hmmm... I think thats all I have for now. Hope that helps out somehow...

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Guest ricrawford

hey thanks guys for the responses. i'd had a suspicion that log pots would work as described in your replies. i was hoping for a simple explanation ;-----) it seems the data is in fact oscillating between 2 values (jittering). and it does stop as mark90 suggested. i reread the faq on the subject which, coupled with these responses, sheds some light on the subject. by the way, before i tied  the unused ins to ground the data stream included all types- control, program, note etc. now it is all volume- which is what i assigned the pots to. thanks again- this forum is way better than official tech support.  i'll be in touch

ri

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