Midi MuRF in patchbay

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PHC
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Midi MuRF in patchbay

Post by PHC » Sun Aug 14, 2011 4:18 pm

Hi

I've just put my 105M in a rack and connected it to a TRS patchbay (with a TRS cable) and there is a problem.
All my other racked foogers (101, 102, 103, 107) behave correctly (knobs work full range as if there were no cables pluged into the foogers - except some normalling that had to be done in the 102 and 103), but 105M is different.

When I plug the cables the knobs stop functioning or function in a very narrow (low) range. I guess it's like I've plugged an "empty" expression pedal, but it doesn't add to the knob setting, it just drops the value of the knob to the low range. When I plug somthing into the patchbay (eg. lfo) it controls the 105M correctly, it's just the empty patch cable into patch bay that causes problems. Any solution?

jeepo
Posts: 282
Joined: Fri Jul 31, 2009 11:38 pm

Re: Midi MuRF in patchbay

Post by jeepo » Sun Aug 14, 2011 11:18 pm

You could try using jacks normalled such that when nothing is plugged in they send a couple volts to the tip.
Stage II, MF-102, MF-105m, MF-107, paia theremin, akai s2000, yamaha pss 680, yamaha cp 25, and other stuff

PHC
Posts: 307
Joined: Thu Dec 14, 2006 1:05 pm
Location: Warsaw
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Re: Midi MuRF in patchbay

Post by PHC » Mon Aug 15, 2011 3:44 am

Now how do I do that?

I understand that it will fool the murf that an expression pedal in the heel position is plugged in?

jeepo
Posts: 282
Joined: Fri Jul 31, 2009 11:38 pm

Re: Midi MuRF in patchbay

Post by jeepo » Tue Aug 16, 2011 1:03 am

I think your unit is functioning as though it has a expression pedal plugged in. If I plug an expression pedal in its heal position into the rate jack of my murf it slows down. To counter this I would normal the jack to a voltage divider so that it acts like an expression pedal is plugged into the jack somewhere within its range when nothing is plugged in. I would start by using two 25k-ish resistors to build the following circuit (I was gonna attach it, but I don't know how, PM me if you want me to email it to you) then increase or decrease the resistor connected to ground to adjust the voltage.
Stage II, MF-102, MF-105m, MF-107, paia theremin, akai s2000, yamaha pss 680, yamaha cp 25, and other stuff

PHC
Posts: 307
Joined: Thu Dec 14, 2006 1:05 pm
Location: Warsaw
Contact:

Re: Midi MuRF in patchbay

Post by PHC » Fri Aug 19, 2011 3:26 am

Why am I having no issues like that with my other MFs? How is the MuRF different? (I guess something about how it handles the knob values to make it MIDI comaptibile).


PHC
Posts: 307
Joined: Thu Dec 14, 2006 1:05 pm
Location: Warsaw
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Re: Midi MuRF in patchbay

Post by PHC » Fri Aug 19, 2011 12:19 pm

Thanx. I must say that's really a bad solution. They should put some jumpers inside that might change the behaviour. Many people rack their foogers and it's really not up their alley. So I guess there is no solution (I don't know if a 2.5V normalling in the patchbay would solve this?)

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