Hammond XB-2 pedal [was Re: Pedals for Clones]

["Mark Longo" <longo@zk3.dec.com>]

> While we're on the subject, is the pedal for the XB2 worth the extra cash?  I 
> didn't buy one because the price seemed steep, I just used my Ernie Ball 
pedal 
> and it seems fine.  Any comments?

        The XB-2 pedal is really a different animal than your Ernie Ball pedal, 
since the XB-2 Hammond expression pedal is NOT a volume pedal.  Hammond calls 
it an expression pedal and I'm pretty sure that the XB-2 does not send any 
audio to the pedal at all.   Instead the XB-2 sends a voltage level which the 
pedal attenuates and returns.  Based on the return voltage the XB-2 sets the 
audio send levels.  BUT, the audio send levels are not attenuated evenly across 
the tone spectrum.  From past discussions I believe the XB-2 pedal-driven level 
changes model a B-3 pedal, which drops the midrange 30db over it's full sweep 
while dropping the bass only 10db.  The timbre change roughly follows the 
loudness curve of human hearing.  The result is said to be that as the 
expression pedal is backed off the tonality of the organ remains constant, 
whereas when a volume pedal is backed off the human perception is of a thinning 
tone accompanying the volume reduction.

        Of course the $64 questions is: is there any REAL world audible 
difference between the expression and volume pedals?  Unfortunately, I don't 
know, never having used a volume pedal.  Anyone used both who cares to venture 
an opinion?

        One potential negative of the expression pedal, though, is that when 
backed off all the way, you can still hear the organ a bit (though not much) 
which makes fade-to-black endings impossible.  I find this to be a little 
annoying in live settings but it isn't hard to work around, just slightly 
limiting.  In recording situations you could simply fade the channel to black.  
One other thing about the expression pedal annoys me a bit: the last 30% or so 
of the pedal travel has little or no effect.  You hit minimium attenuation when 
the pedal is 2/3 of the way forward and also the pedal moves very easily and is 
very sensitive to movement.  Maybe this is an attempt to model a B-3 pedal, I 
don't know, and you quickly adjust to this, but it is a very tiny bit of a pain 
in the butt to me.

        The Hammond expression pedal seemed pretty pricey to me, I seem to 
recall it costing something around $100 US.  It might be easy to make one from 
a volume pedal, but I've never seen a wiring diagram for the XB-2 pedal around.

        Mark

=======================================================================
  Mark Longo                                    Digital Equipment Corp. 
  longo@zk3.dec.com                             Nashua, NH
  88 8200 030