Expression pedal for Resonator CV inputs

[jucas]

Well, having just ordered a resonator, I'm thinking I need an expression pedal for it to be worth the cash. My moogerfooger's expression pedal is passive, and expects the CV signal from the fooger to work whereas the resonator will need an expression pedal that supplies voltage. I was thinking about getting a volume pedal that I could mod up and possibly throw an internal switch on to have either function available. So, the question is ultimately... what volume pedals would have the room in them for a 9V (or 2) battery so that everything is secure and tidy? Should I stick with what I know, pay a little extra and get the VP Jr as I like the action, build, and there's definately space for easy modding?

Paul perry's initial suggestion is to just use any expression/volume pedal and wire a 9V into it, and says that anything from 10ohms to 100ohms will be fine (and to hit up 18V if I don't get enough range...) would this suggest that I ought to be able to get a useable result from simply using a 25ohm vp jr? I had tried one with the moogerfooger and didn't like the range that resulted, but the 'fooger was 5V (i think) so should I expect a different result as there's suddenly 9V pumping through it?

Thanks for any thoughts, and sorry about the long rambling posts... as usual, I have little of substance but take a long time to say it.

[bongomania]

Huh... I've never heard of an expression pedal with its own voltage source before. Certainly it can be built, but I'm surprised that it would be part of Frostwave's design. Do they list any off-the-shelf solutions, and if so is there a reason you wouldn't get one?

[jucas]

I probably used more than a little incorrect terminology there, but don't most expression pedals use a 9V battery as a source of voltage? I know that in conversing with paul perry I was told that there was no voltage send on the CV ins on his products, but is that actually uncommon?

And no, aside from his spacewave theramin/cv there wasn't really an off the shelf device listed or I'd be all over it. His suggestion was almost verbatim "solder a 9V to a guitar cable and plug that into the input on a volume/expression pedal... you can't hurt anything"

In retrospect as I type this, probably any old expression pedal would do, I've just gotten into the bad habit of looking for multiple functions from the things I use (and didn't see any ratings on the pots in the expression pedals)... yep... I've overthought my problem and asked a silly question... lets let this sink through the forum and never speak of it again!

[speak_onion]

CV pedals do exist, but they're usually 0-5V instead of 0-9V. There was recently a thread on the Behringer FCV100, which I use as a CV pedal. 5V max, though.

[squarewave]

Originally Posted by jucas

I've overthought my problem and asked a silly question... lets let this sink through the forum and never speak of it again!

This is not a silly question at all. There appears to be no industry standard for calling a pedal CV vs. expression when it comes to external control. Many manufacturers refer to a CV pedal when they really just mean a simple expression pedal. Of course, either way the pedal is modifying a control voltage, but it sure is confusing.

If the device being controlled does not provide the control voltage (which is the case here), you will indeed have to find/mod a pedal that does. Speaking Onion suggests that the cheap Behringer pedal outputs a CV, but I haven’t tried it yet. My Electrix Filter Factory has a CV input to control the cutoff frequency of the filter. I’ve been meaning to mod a pedal just as you suggested, but haven’t gotten around to it.

[bongomania]

Originally Posted by speak_onion

CV pedals do exist, but they're usually 0-5V instead of 0-9V. There was recently a thread on the Behringer FCV100, which I use as a CV pedal. 5V max, though.

OK, so are there any others on the market aside from the Behr? Again, it just seems weird to me that a manufacturer would design a pedal to require a DIY accessory, and I doubt they had Behringer in mind when they designing it.

[speak_onion]

Originally Posted by bongomania

OK, so are there any others on the market aside from the Behr? Again, it just seems weird to me that a manufacturer would design a pedal to require a DIY accessory, and I doubt they had Behringer in mind when they designing it.

Korg makes one as well. Or they made one, and you can find it; I'm not sure if they still do.

I doubt Frostwave had foot-controlled CV in mind at all when designing the Resonator. I don't think it was really intended to be part of a guitar/bass setup, more for modular synth or noise or keyboard stuff.

Also, most CV inputs that I've heard of are 0-5V, not 0-9V. I can't think of a single other example of needing more than 0-5V. Even the Frostwave MIDI-to-CV device in reverse mode takes a CV from 0-5V to generate MIDI. It kind of makes no sense no need 9V of CV.

[jucas]

Alright... a little more clarity here, I may have had a few beer in me and gotten easily confused last night...

Does an "expression pedal" not usually send a signal of its own? As in they tend to use a TRS jack and get their input from the device they are controlling... I think I was under the impression that they used a battery and could provided the signal as well. Yamaha also seems to make a "CV" expression pedal but in the end isn't it just variation on a pot in a "wah" housing and a different source of voltage?

As for the range, I don't think I need 0-9V, that was just the suggestion that was made as its easy to obtain in battery form. (although the ms-10 I was playing with the other night had an input for 0-8V... didn't take the time to really look at what it was for but maybe more range could be useful)Actually, 18V was the recomendation if I didn't get enough range out of the pedal I ended up with...

In the end, would there really be much difference between wiring a battery to the pot on an expression/volume pedal and finding an something designed for the job? It seems like a pretty straightforward thing to do as long as I didn't need to mount a different pot (or even just smallbear up the enclosure and pot value I need) and it might be worthwhile depending on how I feel about the "CV" expression pedals that are out there... I think I just need to hit up a music store and get a feel for the sweep on a few pedals and see what I can live with and what I can't and if I would gain any comfort/ease of use with a moded volume/expression pedal.

[bongomania]

Every expression pedal I've personally seen was passive, just a potentiometer in a pedal really. The fancier ones like the Alesis F2 I use just have passive options such as polarity reversal or adjustable range.

[jucas]

Thanks. I hadn't had much need for them before this and wasn't sure.

[squarewave]

Please update this thread when you mod or buy a pedal. I'd like to hear what you decide.

[jucas]

Well, probly more than I wanted to spend, but this seems pretty cool (and pretty ugly)

Otherwise, I'm not having much luck with finding stuff that appeals to me stock. Leaning towards a VP JR and smallbearing some craybaby parts. We'll see.

[niftydog]

Whacky. So... do Frostwave themselves even know what the CV voltage range should be?

If I were you, which I'm not () I'd be buying a VP Jr., working out the right voltage (perhaps by using a variable power supply), then making up a box with a 9V (or two) and a short cable with a jack plug. Or even just an adapter to take one plug of a daisy chain and feed it into the input. No modification of brand new equipment required!

However, DC voltages and potentiometers are generally a no-no because the voltage causes arcing as the wiper moves over the resistance track, which manifests as noise in the "signal" voltage. Still, it might not be a problem in this case - only one way to find out!

[jucas]

I'd wondered about the DC on the pots thing, but was hoping it wouldn't be an issue as this doesn't really seem to have much to do directly with the audio path...

The battery box/daisy chain idea is great, and might actually be the way I go... Honestly I'm ranging between just taping the batery in place and dealing with the issues and talking to someone about a custom expression pedal/LFO (or just finding a drill and doing that myself... DIY without some existing enclosure is difficult for me at the moment) WE'll see where I end up and how long it takes...

I would guess that they know what voltage levels to use, as they have a product that allegedly turns a volume pedal into a CV device with ranges from -5 to +5, 0 to +5 and 0 to 10 volts... which is a great idea in theory, but space that I don't want to waste.

[jucas]

Well, I'm off to look at some pedals today to see what's what. Right now I'm leaning towards modding a VP Jr as I think that looking at some pictures of the inside a pot swap wouldn't be to hard to get to a better value/taper... I'm pretty sure the guide on othe pot for the cable is removable, but I want to see one in person to be sure. Also, no facilities to really drill out a box as a voltage source, but I think that I could take the tuner out and just totally rearrange the thing to be volume or expression which would be cool.

Otherwise, in all my reading all I leaned was that I'm probably being silly using this for bass and should have just bought a keyboard/synth long ago... But, since I didn't I've found myself thinking about all the really entertaining possibilities that a CP-251 would bring about. I have an expression pedal that would work with it and allow for all kinds of wild configurations (especially with the MF-101), and really the biggest downside is that I couldn't just pick up the resonator and an expression pedal... any hope of simplicity would be long gone. (plus I like the idea of being able to control some of my synth players parameters and vice versa)

Seriously though (and greedy, self centered rambling aside), would it kill someone to throw a CV out with a switchable LFO into a crybaby shell?

[niftydog]

Re the VP Jr pots. They LOOK the same as commonly available pots, until you look a bit harder. They have a very long threaded portion, much longer than any pot I can buy down at my local electronics stores. Beware!

[jucas]

Ahhh... thanks for the tip... it turns out that I may have done some poor shopping while I was out and probably made some bad desicions... there was a used DOD volume pedal with some nice action, what appeared to be an alpha style 9mm pot, and an apparantly removable attatchment for the expressoin pedal portion. Unfortunately its less removable than I thought, so I might be looking to rig something up, but if not I have a nice (really nice) passive volume pedal that was cheap.

In other news, I may have also given in and found a CP-251 which is absolutely amazing. No more pedalboard in the cards here, but in I got out to jam with the moogerfooger, and the wooley mammoth and the new gear... It's amazing. I seriously am dying to do some crazy stuff with the trem and resonator added... honestly, the cp-251 was a phenomenal investment when I stop and add up what I would've spent on a volume pedal, LFO chips, and all the time it would have taken. The limited time I had with it was great, and if I get my bass and cables back soon (I might've drank until I forgot them at the jam space) I'll really dig into these features.

I know I may sound like a moog fanboy, but I'm pretty impressed and really liking the setup I have going right now. Even just using the fooger as a typical envelope was sounding beautiful while cranked.

Thanks for all the help guys... As of now I'm a very happy man.

[Sean S]

Originally Posted by jucas

...I know I may sound like a moog fanboy...

Anything is better than...well...yeah


I'm glad you're getting good use out of your gear.

[markjazzbassist]

hey jucas, how do you like that resonator? how well does it work with bass? review, clips? was it worth the money?

[Tecx]

You need a frostwave PVC:



Or build a +/- 5v into a volume pedal...