Solution for patchbay problems with the 104 and the MuRF

[latigid on]

Hey again

Have you considered the fact that CV jacks in the MuRF are wired differently?

Most of the MFs "expression" inputs will add voltage to whatever is set on the knob, so a knob set to zero and swept with an expression pedal will increase from something like 0 to +5V and back. But, with the knob set to 5, the same sweep will go from, say, +2.5 to +7.5V and back. Thus the position of the knob, if static, will essentially act as an offset voltage for the expression pedal (or other dynamic CV).

The MuRFs CV inputs will use the knob position as the centre of the sweep. So, a knob set at 5 and swept with the pedal will change from 0 to +5V! A knob set at 0 will change from -2.5 to +2.5V! (Possibility of longer envelopes on the MuRF with negative Env. voltage??)

While this sweep is useful for the envelope control (which is bipolar), it makes no sense (to me) to control the other knobs like this, considering none of the other MFs work this way. Why confuse yourself?

Again, I haven't quite tried it yet, but I am planning to wire the MuRF CV differently. Something like swapping the Tip and Sleeve wires around (but not for Envelope).

[Michael Glaviano]

I spent several hours this weekend experimenting with my Fooger array. As part of this, I tried various "dummy plug configurations":

jumper between tip & sleeve on a TRS plug
jumper between tip & sleeve on a TS plug
jumper between ring & sleeve on a TRS plug
jumper between tip & ring on a TRS plug

This latter made some of the parameters go wild, which makes sense since it's a lot like turning the knob all they way to the right... or perhaps beyond. This got me thinking, so using a multimeter, I measured the resistance between the tip & ring of an expression pedal. I did this with the pedal all the way "open", all the way "closed", and about the middle. I also set some control knobs at noon and experimented with expression pedal positions until the parameter had the same behavior whether or not the pedal was plugged into the jack... and then I measured this resistance. It seemed to be in the 30kOhms range.

So I ended up making a half dozen plugs with a resistance of around this soldered between the tip and ring. It was snowing most of yesterday so I ended up pawing through a pile of old, inexpensive resistors that I had on-hand. The plugs all ended up with a resistance of about 25kOhms.

These work great when I plug them into the Murf's CV inputs. By "work great" I mean that the other CV inputs now respond to an expression pedal, while the knob controlling the parameter whose CV input has the resistance plugged into it continues to work.

It also helped in one of the CV jacks on the 103 (Phaser); although I don't recall which. I don't have a 104, but I think that this is a good fix in general.

And, perhaps best of all, I connected the CV jacks for the 103 and 105 to the back of a TRS patch bay and put these plugs into the front panel, and it made the MF's work just as I had hoped. I guess this just makes sense, right? I mean I am essentially plugging in a resistance that's about like my expression pedal set somewhere in the middle.

I hope that this helps; it doesn't seem as though it could hurt.

Regards,

[CTRLSHFT]

I spent several hours this weekend experimenting with my Fooger array. As part of this, I tried various "dummy plug configurations":

jumper between tip & sleeve on a TRS plug
jumper between tip & sleeve on a TS plug
jumper between ring & sleeve on a TRS plug
jumper between tip & ring on a TRS plug

This latter made some of the parameters go wild, which makes sense since it's a lot like turning the knob all they way to the right... or perhaps beyond. This got me thinking, so using a multimeter, I measured the resistance between the tip & ring of an expression pedal. I did this with the pedal all the way "open", all the way "closed", and about the middle. I also set some control knobs at noon and experimented with expression pedal positions until the parameter had the same behavior whether or not the pedal was plugged into the jack... and then I measured this resistance. It seemed to be in the 30kOhms range.

So I ended up making a half dozen plugs with a resistance of around this soldered between the tip and ring. It was snowing most of yesterday so I ended up pawing through a pile of old, inexpensive resistors that I had on-hand. The plugs all ended up with a resistance of about 25kOhms.

These work great when I plug them into the Murf's CV inputs. By "work great" I mean that the other CV inputs now respond to an expression pedal, while the knob controlling the parameter whose CV input has the resistance plugged into it continues to work.

It also helped in one of the CV jacks on the 103 (Phaser); although I don't recall which. I don't have a 104, but I think that this is a good fix in general.

And, perhaps best of all, I connected the CV jacks for the 103 and 105 to the back of a TRS patch bay and put these plugs into the front panel, and it made the MF's work just as I had hoped. I guess this just makes sense, right? I mean I am essentially plugging in a resistance that's about like my expression pedal set somewhere in the middle.

I hope that this helps; it doesn't seem as though it could hurt.

Regards,

awesome information!! thanks for your hard work and experimentation.