AETHERPHON, global theremin family

I wrote:

> I am researching the breath controller specs, but so far the best I
> can
> find is 0v = 0 pressure, and I am not sure about that.  It seems to
> be
> a dc voltage proportionate to pressure input, but I can't find a
> spec,
> yet.
> 
> See if the manual for your keyboard indicates the breath controller
> input voltage range.  My guess is the cv out from theremax/epro and
> breath controller input are compatible, but that is a just a guess at
> this point.

I downloaded the manual for the Kurzweil, and don't see a spec for
breath controller.  I do see that the input jack for breath controller
can also accepts a cc pedal.

Remember a cc pedal or a breath controller is an analog device.  It is
either a resistor, or a voltage source.

The kurzweil cc pedal has a tip, ring, sleeve (trs) connector.  This is
the same scheme used in the roland EV-5L pedal, that I have.  These trs
cc pedals are a pedal controlled potentiometer.  

I believe both are nominally 10k pots, but I know the roland has an
adjustment pot on the side to vary from about 8k to 50K (just measured
it).

The tip seems to be the wiper on the pot.  What some companies do is to
use this as a voltage divider.  The sleeve is ground, the ring is the
input voltage, the tip is output voltage.  The suggestion that kurzweil
does this is indicated here, regarding the k2500:

http://sonikmatter.com/wiki/Kurzweil:Dead_Letters_1996c
----------------------
(snip)

The rest of this document details more measurements on the Kurzweil
K2500.

I enabled the "Cped1" transmit (PitchBend) on the "Cpedal" page under
Setup and turned on "MIDI View Mode" under the Master Page to view the
MIDI values sent out during testing.

We've seen on this list that the connections for the pot are:

    Ring = One end of pot 
    Sleeve = other end of pot 
    Tip = Wiper 

I've been told by kurzweil@... (I think that's David Fox), that a
"standard" (is there one? :-)) 10K CV pedal will work on the K2500.

I used the previously-mentioned part from Radio Shack.

With 10K linear pot:

    Vts @ MIDI value 127 = 5V; It = 5uA 
    Vts @ MIDI value 0 = 0V; It = 0uA 

Ir was constant at about .6mA (as expected)

For grins, I tried a 100K linear pot. The results were the same as for
the 10K pot.

    Vts @ MIDI value 127 = 5V; It = 5uA 
    Vts @ MIDI value 0 = 0V; It = 0uA 

Ir was as expected (I didn't get an accurate reading, but it was just
over 50uA).

Additionally, varying the load on Ring to Sleeve from 10K to 100K does
not change Vrs.

Note the K2500 appears to prefer a full voltage swing on the Tip. That
is, for full MIDI value swing from 0-127, the Tip should go all the way
from the Sleeve voltage to the Ring voltage. Scaling using the K2500
firmware (Setup:Cped1:Scale/Add values) seems possible if the voltage
on the Tip is not full scale. 
--------------
end of clip

Kevin,

I believe the input voltage (from breath controller) to the k2600 is
the tip on the k2600 cc input.  I think that if you take a 3 conductor
(trs) cable, and plug it into the cv output  of the epro or theremax
(should be a 2 conductor jack), plug the other end into the k2600
breath controller/cc input, and assign that cc controller on the synth,
it will work.  

What this does is connect sleeve to sleeve, tip to tip.  Since the cv
output of the theremax and epro is a 2 conductor jack, there is no
ring, thus the k2600 ring is not connected (the supply voltage from the
k2600 to the breath controller or passive cc pedal).

It Must be a 3 conductor 1/4" cable (male to male), NOT 2 conductor
(that would connect the k2600 ring to sleeve, there is likely
protection for that, though) so that you have a ring on both ends.

Since I can't verify with a kurzweil here, I cannot 100% guarantee this
is correct, but the spock in me says that the probability of this being
correct is 99.77%.  Try at your own risk, or email/call kurzweil to
ask.

If you want to check things further, get a trs plug (radio shack) and
measure the voltages from tip to sleeve, and ring to sleeve to get a
better idea.  

I think you will see (as described above) the sleeve is ground, and the
ring is 5v dc.  Thus, the tip responds to the voltage connected (from
cc pedal or breath controller, or your theremin cv).

Email me directly if you need some assistance.  Let me know if you have
questions.   You can do this without going around your elbow with cv to
midi to synth midi cc.  Midi only has 128 levels, and has latency. 
Analog is continuous and immediate.

BTW, have you read this interview with Ray Kurzweil?  He is quite an
amazing thinker, and manages to make his thoughts into reality.

http://www.smart-publications.com/articles/MOM-kurzweil.php

bret





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