KVR Audio

Deep Purple · Post by **Deep Purple** » Fri Aug 21, 2015 4:04 pm

I have wanted to buy a MIDI expression pedal for a while so I can control various amp sim software, but funds are a little tight right now. I have a few volume pedals and keyboard expression pedals kicking around, and seem to remember that there's a piece of hardware that can do the conversion.

Google yields a ton of results, but can't seem to find the one I was thinking of. Anyone aware of a product or products that fit the description?

knockman · Post by **knockman** » Fri Aug 21, 2015 9:06 pm

This one, perhaps?
http://www.audiofront.net/MIDIExpression.php

GaryG · Post by **GaryG** » Fri Aug 21, 2015 9:45 pm

Are you into DIY at all? It's pretty simple nowadays to build your own converter with one of the cheap microcontoller boards around at the moment (arduino, teensy etc)

I did exactly this a while back, wired a few pots and sockets to an arduino board I had lying around so I have a simple midi controller that you can plug a couple of footswitches and a volume pedal into.

Even simpler would be to use a Teensy LC which can function as a class compliant usb midi device (ie. no drivers or separate midi cables needed). Obviously some programming is involved if you're up for that. I think they go for ~$10 in the US.

BertKoor · Post by **BertKoor** » Mon Aug 24, 2015 7:19 am

The old SoundBlaster cards also featured an analog joystick connector (or two) which were basically A/D converters for two potmeters on each joystick. This allowed me for nearly zero costs to convert a scrapheaped RadioShack 4-channel audio mixer to a fader + buttons controller. Software needed: Joy2Midi I think it was called. Some extra 1/4" inputs allowed me to plug in volume pedals.
Fun DIY project for the days, gathering dust now... If I wanted to do it again, an Arduino or maybe Raspberry Pi would probably be the way to go.

Deep Purple · Post by **Deep Purple** » Mon Aug 24, 2015 2:24 pm

OK, that's a few good ideas there. Thanks guys.

Deep Purple · Post by **Deep Purple** » Wed Aug 26, 2015 2:52 pm

Actually, while I'm at it - does anyone know of a good cheap USB expression pedal? As conversion isn't so straightforward, what about budget MIDI pedals? I know of a few expensive ones, but I'll leave that until some future time.

knockman · Post by **knockman** » Wed Aug 26, 2015 8:34 pm

Do you have a MIDI keyboard or controller with a expression pedal input? That way you could use one of your existing analog pedals to do this at no further cost.

Deep Purple · Post by **Deep Purple** » Thu Aug 27, 2015 12:55 pm

I hadn't actually thought of that - I have other controller, but I just didn't think about connecting to them. DOH!

thecontrolcentre · Post by **thecontrolcentre** » Thu Aug 27, 2015 1:23 pm

knockman wrote:Do you have a MIDI keyboard or controller with a expression pedal input?

This. I use 2 midi pedal controllers connected to a ReMOTE SL ... PUSH has similar connections too.

Deep Purple · Post by **Deep Purple** » Thu Aug 27, 2015 6:46 pm

Been looking online. Seems I need a CV output on the pedal for it to work and not sure that mine have that capability. However, there do seem to be a few relatively cheap and rugged ones online that do.

Looks like I can pick up a Behringer FCV100 (yes, I know...but I don't have the funds for anything more expensive right now...) for $30 and that appears to have a CV mode. Anyone used one of these or anything else that is switchable to CV mode like this?

BertKoor · Post by **BertKoor** » Fri Aug 28, 2015 9:34 am

What controller needs CV on the input of an expression pedal? Because that's quite rare...

You can convert any expression pedal to send out a CV if needed with a DC power source (9V battery or 3 AA's get you close to the required 5V) and maybe some resistors.

Deep Purple · Post by **Deep Purple** » Fri Aug 28, 2015 12:39 pm

Not CV on the input, but on the output. Just wondering if all controllers that have a 1/4" jack for the expression pedal input use CV so that I just need to worry about whether or not the pedal can output CV.

None of my existing pedals have CV output so I can't use them.

BertKoor · Post by **BertKoor** » Wed Sep 02, 2015 8:44 am

Well it usually works like this: the expression pedal jack has 3 conductors: tip, ring & sleeve. The keyboard supplies a steady voltage on say ring & sleeve. The pot (controlled by you foot) then gives back a lower voltage between the tip & sleeve. Maybe I swapped the tip & ring, but that's just technical details.

Anyway, what if you connect a pedal that outputs a CV by itself? Well, if it's on the proper conductors (say tip & sleeve) then the keyboard senses a voltage, just as it expects. There might be some tiny details though. What if the keyboard sends out 5V and receives maximally not 5 but 4 or 6V? Calibration of either the pedal or by the keyboard could be the answer.

Another thing: if the connector of the pedal is just tip & sleeve without ring (a mono plug instead of stereo) it could short-cirquit the current supplied by the keyboard. If the keyboard is properly designed (you could by accident plug in a mono lead into the expression pedal jack) it would not do any harm. But whether it's good on the long term I wouldn't know. If the keyboard is badlt designed you could fry it's power supply.

That was the scenario where the pedal outputs a CV. But I don't know of any keyboard that expects a CV to be fed by the pedal, because that would require a battery or power supply on the pedal. Very unusual... Conventionally expression pedals are passive devices: just containing a foot-controlled pot meter wired to a "stereo" lead.

So my question to you: what is the make & model of your keyboard controller? We could then look up the tech specs for the expression pedal.

Deep Purple · Post by **Deep Purple** » Wed Sep 02, 2015 4:55 pm

This expression pedal has CV output - I'll probably just buy one as they're not too expensive:

http://www.behringer.com/EN/Products/FCV100.aspx

Covert volume pedal to USB/MIDI