DOD FX-17 MOD to Expression pedal for M9

[vhollund]

Hello

I just bought an line6 M9 and I want to control it with the FX-17
Googling it i found there's already been some experiments with it but no conclusive information, except that the mod would be but a simple change of two resistors.
The values of the build in voltage divider.

Can this information in anyway be confirmed ?
And if so can you point me to the 2 resistors to change on the photo (sorry about the quality)




Better Resolution :
http://www.flickr.com/photos/psopho/5180694857/in/photostream/lightbox/

Thanks.

If you plug a cable into the exp input without any pedal it measures around 3.15V without any load. A reducing resistive load will reduce the voltage progressively down to 0V.

Within limits, the EXP input is not critical about the range of operation - it appears to learn the range of resistance/voltage swing and calibrates its position dynamically.

But... if you exceed a certain resistance (and therefore voltage) the M13 seems to get confused about the pedal connected and it stops operating as a controller even in the sweep range which worked Ok before the resistance/voltage limit was reached.

I found this out with an Ernie Ball 250K pedal - it works heel down but as you increase the resistance towards toe down it gets to a certain point where the calibration gets screwed and thereafter returning to heel down no longer works. This is an odd quirk but my guess would be if you apply a voltage of greater than say 2.3V or whatever the exact threshold is, you will suffer the same problem.

If my calculations and assumtions are correct - with the L6 pedal max being only 10K, the max voltage seen across the EXP input in that case will only be 1.5V - so you should be able to reduce your controller voltage to 0-1.5V max and still get it to work OK.

I'd be pleasantly surprised if any M9/M13 product expert is prepared to give you their blessing regarding connecting any active device into an expression pedal input - but would be interesting to hear their opinion on this.

BTW - here's a tip for any Ernie Ball (or other) 250K pedal owners - I made up a special jack lead with a 33K resistor between tip and screen in one of the plugs so I could use this pedal without the problem - although the taper is not 100% linear it becomes quite useable with the M13 with this simple custom cable...

DOD FX-17 Scematics:

http://www.diyguitarist.com/Schematics/FX17-Schem.pdf

[vhollund]

This article talk about using a stereo jack/jack ?

...Yes they do. I just tried it. It works. I also figured out how to use mine for my HOG. At first mine was adjusted so that at max it was only putting out 3V, and so I adjusted it with my DMM and a screwdriver to put out 5v. When looking down at it, the trimpot on the left controls minimum and trimpot on the right controls maximum.

female stereo 1/4" to male stereo 1/8" with a mono 1/4" cable plugged in.

This grounds out the ring (which is the supply voltage from the pedal.)



Holy shit! This is great! I wondered if the trim pots would control the cv.

AMAZING. NO MODS REQUIRED!!!!

http://acapella.harmony-central.com/archive/index.php/t-2551070.html

More about cv voltage to M9 :
http://www.talkbass.com/forum/f36/moog-mp-201-line-6-m9-729610/

[vhollund]

Hey
I've tried simple mono connection jack-jack
And the Stereo with the ring grounded

It doesnt work for me
Any clues why ?