AETHERPHON, global theremin family

Bret,

Thank you very much for taking the time to research the breath  
controller specs.

I expected to read +5v on the ring however I am reading -12v!  Not  
sure what to make of it.   When I apply a voltage to the tip, the  
K2600 does, indeed, generate midi CC messages -- however only a narrow  
voltage range (that I haven't been able to measure).

As you pointed out, the resolution of this input is only 0 thru 127,  
so would have limited utility.

Perhaps I should rephrase my question to the list:  how do you use  
your Theremin to control your MIDI devices?

-- Kevin

Quoting Bret <echoplex@...>:

> 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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