Building an expression pedal for Line 6 units

[krankguitarist]

I recently picked up a line 6 M13.  I'd really like to get an expression pedal for it, but I'd like to do it on the cheap.  That, and I'd like it to be a bit more durable than the cheesy line 6 EX-1.

The line 6 unit uses a 10K pot.  I've got an old wah shell laying around with a 100K ICAR taper pot that I got from smallbear.  The 100K pot by itself didn't work,  so I put a 12k ohm resistor in parallel with it, which got it into the 10k range.

Problem is, It's jumpier than hell.  I'm assuming that this is due to the nature of the ICAR taper pot, as it's taper is none too smooth.  Or could the resistor in parallel with the pot be affecting it's sweep?  Any ideas?

Anyways...Does anybody know where I could get a 10k pot that I could use with the expression pedal shell?  Or should I just pick up the 200K wah pot from smallbear and wire a resistor in parallel to get it down to about 10k? Any suggestions would be greatly appreciated.

[Mark Hammer]

I recently picked up a line 6 M13. 

Urp!!  <insert choking on coffee sounds here>

How do <insert urgently cleaning up mess off keyboard with any available absorbent material here> you like it?

[Processaurus]

Sorry to break it to you but you're entering a world of pain  .  Using the parallel resistor does indeed make the overall impedance of the pedal 0- 10K, but imagine the two resistances in parallel as the varable resistor the of the 100K pot travels to from 100K to O ohms.  Let's even say it's linear taper rather than the weirdo icar taper for an easier time imagining it:  The line 6 wants to see 0 to 10K in a linear sweep (middle of the rocker pedal's travel should be ~5K).  The 100K wah pedal pot, in the middle of its travel, is 50K.  The parallel 10K resistor is in there too, so 50K in parallel with 10K is 8.33K.  The overall resistance of the wah pot and parallel resistor won't get to 5K (the line 6's middle point) until the wah pot is at 10K, which is after 9/10 of its travel.  Jumpy!

You need an honest to goodness 10K linear pot, I'm afraid, and as far as I know, they've never made one for crybabies.  I made a linear 100K pot work in a crybaby once and it ate my evening! Tale of Woe

The Boss ev-5 works for the line 6 stuff (even thought the line 6 won't work for boss) if you can find one of those.  I know what you mean though, it's highway robbery for any of those plastic POS's.

PS how do you like that M13 pedal?

[Hanglow]

Chicago Iron will sell you a 10k dual pot for their parapedal clone if you ask, I think they want about $25 for it though. At least they did when I emailed them ages ago. I ended up going with the resistor/pot combo in the end

[selectortone]

You need an honest to goodness 10K linear pot, I'm afraid, and as far as I know, they've never made one for crybabies.  I made a linear 100K pot work in a crybaby once and it ate my evening! Tale of Woe

Taking the gear off the existing pot and putting it onto the shaft of an ordinary 10k pot is about all you can do. Buy a pot with the flat on the shaft. It won't be sealed so it'll get noisy after a while but that's what Deoxit is for.

[selectortone]

oops

[Alien8]

MOOG EP2.

[krankguitarist]

Sorry to break it to you but you're entering a world of pain  .  Using the parallel resistor does indeed make the overall impedance of the pedal 0- 10K, but imagine the two resistances in parallel as the varable resistor the of the 100K pot travels to from 100K to O ohms.  Let's even say it's linear taper rather than the weirdo icar taper for an easier time imagining it:  The line 6 wants to see 0 to 10K in a linear sweep (middle of the rocker pedal's travel should be ~5K).  The 100K wah pedal pot, in the middle of its travel, is 50K.  The parallel 10K resistor is in there too, so 50K in parallel with 10K is 8.33K.  The overall resistance of the wah pot and parallel resistor won't get to 5K (the line 6's middle point) until the wah pot is at 10K, which is after 9/10 of its travel.  Jumpy!

You need an honest to goodness 10K linear pot, I'm afraid, and as far as I know, they've never made one for crybabies.  I made a linear 100K pot work in a crybaby once and it ate my evening! Tale of Woe

The Boss ev-5 works for the line 6 stuff (even thought the line 6 won't work for boss) if you can find one of those.  I know what you mean though, it's highway robbery for any of those plastic POS's.

PS how do you like that M13 pedal?

Dammit, I knew i wasn't figuring something right in my head here.  Thanks for the info .

I'm really diggin the M13 so far.  I used to have a big, 30 pound pedalboard that I lugged around with me to practice and gigs.  All the toe-tapping was driving me insane.  After that I had a brief fling with a TC Electronic G-force before I came to my senses, sold it, and pre-ordered the m13.  It's everything I coulda wanted in an FX board.  Instant access to patches, individual FX switching, easy as hell to use (no manual diving), and a plethora of great sounds.  I'm still keeping around a lot of my old FX for studio work and everything, but I couldn't have asked for anything better for live use.  Don't get me wrong though, it's gonna get plenty of time in the studio as well . 

I'll look into the Moog EP2 as well, for price vs value it looks like it might be a winner.  Some people on the line 6 forum report it working better than the EX-1, some people have said that they couldn't get it to work.  Might just have to take a chance.