Homebrew expression pedals for Helix

[Verne Bunsen]

Hello all,

I've been looking for a couple of external expression pedals to augment my Helix and had almost come to terms with paying the $130 each for a couple of Mission pedals when I came across a thread on the Line 6 forum where some folks were discussing modifying an old wah pedal to serve as an expression pedal. This intrigued me, as I do enjoy tinkering. It requires very little in terms of parts, just a pot and a jack. Line 6 spec is a 10k ohm linear pot. Dunlop ECB078, $10 a pop.

I have two very eligible donors in the form of an old BYOC wah that I built years ago and an old Dunlop Roto-Vibe. The wah has been collecting dust since I acquired my Fulltone Clyde a few years ago and the Roto-VIbe hasn't worked right in about a decade.

After gutting the enclosures, I installed the new pots in the brackets and used a multimeter to position the gears so I got a full 0-10k on the sweep. Line 6 expression pedals run Tip/Sleeve as opposed to TRS. Wiper and CCW are joined and run to the jack sleeve, CW runs to tip.

Simple! Hooked them up and they work flawlessly!

Saved myself about $240 and had a pretty good time doing it. The wah will serve wah duty (go figure) and the Roto-Vibe will handle modulation rate and depth parameters. I've been using the onboard expression pedal for volume, gain, or reverb/delay thickness. The only bummer here is that the floor controller doesn't have any support for actually toggling an effect on/off with an external expression pedal. It's something I'm hoping to see come around in a future firmware update.

:icon_thumright:

 

[stratamania]

Cool idea if you have the enclosures hanging around.

 

[Volitions Advocate]

Pretty awesome.

I've been having trouble with the midi data I'm receiving into the computer from my FC 300.  I'm wondering if the board is somehow messed up or of I just don't know jack about  MIDI (I don't).
Homebrew expression pedals were my next idea, but I wasn't sure how to go about making them.  My main thought was going to be an arduino or something using an ultrasonic or infrared sensor, easier than the mechanical part of hooking up a pot, but rife with other hurdles.  I've always been partial to the Ernie ball designs though,  How does it feel as far as range of motion?  I always thought my dunlop wah would be terrible for an expression pedal, unless I was using it for a wah, because it doesn't really rock that far back and forth.

 

[Timmsie95]

That's awesome! I believe Mission also sells kits to turn a wah into an expression pedal, but I haven't looked at the site in a while, so I could be wrong.

 

[Cagey]

[snip] Homebrew expression pedals were my next idea, but I wasn't sure how to go about making them.  My main thought was going to be an arduino or something using an ultrasonic or infrared sensor, easier than the mechanical part of hooking up a pot, but rife with other hurdles.  I've always been partial to the Ernie ball designs though,  How does it feel as far as range of motion?  I always thought my dunlop wah would be terrible for an expression pedal, unless I was using it for a wah, because it doesn't really rock that far back and forth.

Have you seen the new Fractal Audio EV-1 pedals yet?

More throw than most pedals (comparable to a Morley, I would guess), planetary gears instead of rack & pinion to drive the pot, expression or volume control operation, linear output, high quality and reasonably priced. I haven't tried one yet as I already have a pile of Mission Engineering pedals, but by all reports they're really nice. They're analog out, though, not MIDI. You'd have to have an analog input on a MIDI device, or devise some sort of analog-to-MIDI converter. But, if  you're considering tinkering with an Arduino board, one of these would solve a lotta problems on the input side. $140, when you can get them.

Speaking of Morley, they have a long throw volume pedal, too, called the EOV. Less than $80 just about everywhere.

They encode pedal position optically using a shuttered LDR instead of a pot, and are also a high-quality unit.

Finally, there's the DOD FX-17.

It uses a variable capacitor to encode pedal position. It can do volume control, wah, and has a 0-5vdc out that tracks the pedal position. You can't buy them new anymore, but you can still find them on the used market. But, if you don't care for the traditional Dunlop pedal travel, you may not like the size or throw of this one. It's a small unit with a short throw. I suspect that's why the market shied away from it. I know it's why I sold mine. But, a self-contained variable 0-5vdc out might be a handy thing to use with your own converter circuit.

 

[Verne Bunsen]

Cool idea if you have the enclosures hanging around.

Yeah! And really, an empty enclosure can be purchased new for around $30, so if someone were inclined to take this approach it could still be done at a big savings.

How does it feel as far as range of motion?  I always thought my dunlop wah would be terrible for an expression pedal, unless I was using it for a wah, because it doesn't really rock that far back and forth.

That's actually what started me on this path: I didn't like the movement of the onboard expression pedal at all for wah, felt all wrong. So for me, the wah enclosure was a perfect solution. I also use that one for pitch shifting (Whammy) and I like the feel for that application as well. The travel on the Roto-Vibe is pretty much identical to the wah, works nicely for modulation effect speeds. Like vibe for instance... The onboard expression pedal travels a lot like an Ernie Ball, which is great as a volume pedal or reverb settings, which is what I mostly use that one for.

 

[stratamania]

I'll revise then, cool idea if you have or can obtain an enclosure for a reasonable price.

@Cagey, I've seen those Fractal EV-1s and I like the look of them. I'm on a wait list for an FX8 Mk 2 so if I can resist the urge to build a pedalboard in the meantime I might be getting a pair of those too.

 

[Volitions Advocate]

if I can resist the urge

:sad1:

In the same situation.

 

[stratamania]

if I can resist the urge

:sad1:

In the same situation.

All you need to do is design a pedalboard that will cost about £  2500 - 3000 or more to put together and the resistance gets easier...

 

[Verne Bunsen]

I've re-visited my home brew expression pedal in an attempt to solve what has been a conundrum for me: switching the darn thing on and off when using it for wah! The existing options are to use a Helix footswitch or to use a position based "auto-on" that engages when you come off of heel-down and dis-engages when you return to heel-down. Both of those are functional for some things, but a bit clunky for wah. For me anyway. Helix supports 2 external expression pedals, so I decided to see about putting them both to work to make a single functional toe-switched expression pedal. I have posted this on the Line 6 forum, I know there are a couple of Helixers here so I thought I'd post it here as well.

Stuff you need: An expression pedal with a spot for a toe switch, a 3PDT switch (standard "true-bypass" style guitar pedal switch), a jack (not pictured, whoops! It's just a regular old mono guitar jack...) and a 10k resistor. In this case I used a 15k resistor because it's what I had in my parts bin, it's fine for this purpose.

The Helix sees an open circuit as "No Pedal Present", a dead short from tip to sleeve as 0% on the expression pedal position, and 10k ohms between tip and sleeve as 100%. So what I want is for one position of the switch to jump straight from tip to sleeve and for the other position to put the resistor in the between. In a 3PDT switch the middle row of lugs is common and connects to the left or right row depending on the switch position. That makes it a pretty easy configuration to wire up:

The black and white wires on the center row go to the jack tip and sleeve respectively, the black jumper on the left connects them directly in position 1 and the resistor on the right connects them with 15k ohms resistance in position 2. Again, 10k is spec for 100%, 15k still registers as 100%.

Testing it on the meter:

Looking good! Now testing it with Helix. For this I hooked it up to EXP2 and loaded a wah, then assigned both the position and bypass to it so that I could see it functioning. I set the bypass threshold at 20% (could be anything bigger than 0%, really) and no delay. What I want to see is OFF at position 0% and ON at position 100%.

Frickin' sweet. Hook it up and stuff it in the enclosure. I marked the jacks externally so I'd remember which goes where....

I connected the switch to EXP2 and the Expression pot to EXP3, so by assigning bypass to EXP2 and position control to EXP3 I've got a toe-switchable external expression pedal!

It works just like it should, I really like it. You can still use the expression pedal to control other things as long as you remember that if any of them are ON when you go to use the wah you'll be manipulating both of them. The only downside to this arrangement for me is that I've been running two external expression pedals, one of which was assigned to vibe with auto-on. Auto-on works wonderfully for that application. I can still use the external expression pedal to control it but I'll have to toggle it with a Helix footswitch. Nothings free....

Anyway, I hope someone finds this useful, or at least of interest!

 

[Cagey]

Nice work on a handy feature!

I'm surprised Line 6 didn't put a little more thought into the "auto engage" feature in order to preclude the need for such work. On the Axe Fx, you can auto-engage on pedal position, rate of change or amount of change, and set a response delay time. Makes operation intuitive, saves you an external switch input to use for other things, and keeps the thing from nuisance switching.

 

[stratamania]

Nice work...

@Cagey, I think a few Helix users have been requesting that feature similar to the Axe FX for a while. Perhaps it may appear at some point...time will tell.

 

[Cagey]

What I'd like to see is some of these companies get shamed by Fractal's practice of bug-swatting/upgrading on a regular basis into a similar behavior.

 

[stratamania]

Well to be fair to Line 6, they have put out quite a few updates since the release of the Helix, so its looking promising.

I remember when I had my Axe FXII sometimes the upgrades were coming thick and fast so I know what you mean.

 

[Verne Bunsen]

Thanks guys!

The current implementation of the auto-engage function does allow some tweaking. You can set the point that it triggers and set a delay before it dis-engages after traveling back, and with some creativity you can make it a toe-down function instead of a heel-down function. To be fair there are plenty of folks for whom it works perfectly. I'm just not one of them. Maybe it's my technique, I dunno. I could not eliminate nuisance switching (excellent term for it, by the way) while operating the wah. The "rate of change' or 'amount of change' that you describe from the Fractal function is more in line with what I had imagined. Perhaps they'll refine it with future firmware updates.

As far as more frequent updates, I'd personally like them to spend some time with the update process first. The current procedure is rather crude and problem prone. The idea of doing it more frequently gives me heartburn.....

 

[Cagey]

I think maybe some of them make the update procedure deliberately obfuscated so as to prevent entering into the process inadvertently and bricking the device. I know it can be done more easily because I recently did a BIOS upgrade on an ASUS motherboard and it was essentially a non-event. I actually tried to do it twice because it was so easy I wasn't sure I had actually done anything the first time. Then, it was smart enough to abort the unnecessary update.

 

[Verne Bunsen]

Good analogy. The feeling I get when updating Helix is very much reminiscent of the feeling I get when doing major OS updates. Please don's screw everything up, please don't screw everything up, please don't screw everything up.... DANGIT!