Can you transpose Key with a CP-251??

[Acid Wash]

So I am about to purchase a Little Phatty for a project that I am playing in. The only catch is that guy who is writing all the Synth for this project is Transposing everything into the key of C when he writes his material. So when I learn the stuff on my Korg MS200 I am generally Transposing the songs +4, -1, ect. Long story short, in a live setting every song has to be transposed on the fly steps up/ steps down.

I know that there is no Key Transposition function on the Little phatty, but upon reading the manual I discovered this.

Additional CV control:

The PITCH jack on the side-panel is a CV input for external control of the oscillator pitch. This input controls
the frequencies of both oscillators. A 1-volt change of this voltage will change the pitch by NOMINALLY
one octave. The jack accepts -5 to +5 volts, or an expression pedal like the EP-1.

PERFORMANCE TIP: A steady control voltage applied to the PITCH jack will offset the base
pitch of both oscillators. You can use this feature to transpose the keyboard to any desired
interval applying the appropriate steady-state CV. See Appendix E for more information on
how to configure this.




Appendix E - Using the CP-251 with the Little Phatty

Pitch Transposition:
Using an Expression Pedal (like the Moog EP-1), you can program the CP-251 to transpose the LP’s pitch to
any interval desired and have it ready any time you need it. Here’s the connection:
- Connect the EP-1 to an Attenuator Input.
- With another 1/4’ patch cable, connect the Attenuator Output to the LP’s Pitch CV jack.
Appendix E - Using the CP-251 with the Little Phatty


LP User’s Manual - Appendices
To set the transposition interval, press the EP-1footpedal all the way down and slowly adjust the Attenuator
on the CP-251 while striking a note on the LP. The pitch will go up as you raise the Attenuator level. Rock
the EP-1 pedal between full up and full down positions to hear the difference in pitch, and adjust the Attenuator
until the desired interval is reached. This gives you a foot-controlled transposition device you can use at
any time during a performance!

So my question is can the CP-251 act as a Key Transposer on the fly for each song?

[jeepo]

I believe so (I don't have a 251), but you will have to retune it for each key, I recommend plugging a tunner into the headphone jack to speed the process. If you, or a friend has modest soldering skills, or wants to learn you should be able to build something with a switch for every key (or a few presettable keys). Let me know if you want help building such a device.

[Klopfgeist]

Transposing by using a voltage from the CP-251 will probably not cut it in a live situation; you would need to change the voltage very carefully (not something you would want to do in between songs). You could have a tuner connected, but I don't know how much the voltage will drift. You may just want to use a pitch shifting pedal, such as a Digitech Whammy or an Electro-Harmonix HOG. A key transpose function on the LP is probably doable, maybe you should kindly ask Amos.

[sine]

Acid Wash,

Before you consider adding a CP-251--which is a cool addition for many other reasons--if you have a MIDI expression pedal, try plugging it into the LP's Pitch CV input and see if both oscillators track pitch together when you move the pedal up and down.

On my LP, the oscillators went further and further out of tune with each other as the pedal was pressed. Normally, scaling discrepancies such as these are managed by the LP's Look Up Tables. It is a brilliant solution, as the oscillators are fed a stored voltage amount for every single note. The result is perfecting scaling. If the offset is changed, however, via Pitch CV input the Look Up Tables have no way of knowing, and you're at the mercy of each oscillator's individual scaling behavior, which of course varies from one to another. On your LP, maybe you'll be lucky and both oscillators will track together under external Pitch CV control. In my case, I had Moog install trimmers.

Sorry to be long winded, but hope to spare you possible frustration.

[qbaseden]

I have the same problem, my solution isn't great but here goes nothing: I set the pitchbend max values to -12 and +12 and connect my soundcard into the LP's Midi input. Then, each of my live sets start with a pitchbend midi message which turns the pitch up or down to any desired value, effectively transposing the keyboard as desired. The main downside is that any contact with the pitch wheel itself will reset the pitch to normal

Hope this helps somehow...that'll teach me not to cut corners when learning a new instrument

[ldtregent]

I use the CP-251 with my LP but you should be able to transpose the Phatty internally with your tuning settings. Otherwise you might consider using that Midi/CV pedal Moog has. The CP-251 is better used for other twisted things! I do recommend one as the Noise and Sample and Hold curcuit alone are reason to have it!

Cheers
LDT