Roland EV-5 Pedal

[WeAreAs1 at aol.com]

Hello Paul and others,

Here's a crummy asciimatic of the inside of the Roland EV-5 expression pedal:
(display with a mono-spaced font)

  |----------------------------- Ring
  |
  >
 <
  ><----------------------------- Tip
 <   10K (special taper)
  >   Volume pedal pot           
  |                              Sleeve
  |                                |
  |                                |
  >                                |
 <                                 |
  ><---- 50K lin.                  |
 <     | (sets minimum volume)     |
  >    |                           |
  |    |                           |
  |---------------------------------
  |
-----
 ---
  -

The synth (or other Roland device) provides +5 volts to the pedal through the 
ring.  The Sleeve connects to the synthesizer's ground, and the tip carries 
the attentuated 5 volts back to the synth, in most cases to be read by an 
ADC.  The 50k linear pot (on the side of the pedal) limits the minimum volume 
that the pedal can be brought down to, since some people prefer to not have 
their volume pedal go all the way to zero.  The pot that's actuated by the 
pedal has a special modified audio taper that tries to maximize its effect 
over the usable mechanical range of the pedal (since the pedal can't actually 
get full rotation out of the pot, which explains the odd 8.8K resistance).

If you want to use it as a straight CV pedal, you just need to provide a 
reference CV at the ring, and take the CV output at the tip.  Alternatively, 
I guess you could put a 9 volt battery inside and connect its plus side to 
the top of the 10K pot (maybe via a 1K or 10K series resistor).  This would 
give you a regular 0 to 9 volt CV pedal.  However, you'd also have to 
disconnect that +9v wire from the ring connection, so the battery wouldn't 
get shunted directly to ground when you plugged it into a non-Roland mono 
1/4" CV input jack.

BTW, there are similar expresssion pedals (with ring/tip/sleeve 1/4" 
connections) made by a couple of other manufacturers that have the same 
circuit, but have the wiring of the Ring and Tip reversed.  The Kawai 
expression pedal is this way, and maybe the Yamaha FC7, also.  Yamaha made 
two different expresssion pedals, one with a light bulb and photoresistor 
(FC5? - made for the original DX7), and one with a regular old pot (the FC7, 
made for the DX7II and later).  You can simply reverse the ring/tip wires on 
the Kawai pedal to use it on Roland gear - maybe this will also work on the 
Yamaha pedals.

As Juergen said, the Yamaha pedals feel very nice.  However, I disagree with 
him about their ruggedness.  I've owned four of them (two of the FC5 and two 
FC7), and I have already destroyed three of them from using them on live 
gigs.  The metal footpads just bend and buckle, under my feet, at least.  
(No, I don't stand on them, and I weigh in at just 145 pounds.  I sit down 
while playing, but I play a lot of organ patches, so I keep my right foot on 
a pedal almost all the time)  These same feet have been stomping on a couple 
of the "cheap fragile plastic" EV-5's for about 5 years, with no problems 
whatsoever.  They don't feel nearly as nice as those Yamaha pedals, though.

Michael Bacich