How to calibrate the TKB KV?

[Setherian]

My TKB KV is changing by 4 semitons instead of 1, anyone ever calibrated that thing? Which is the right trimmer?

[davemoog]

My impression of the KV is that it is not and cannot be trimmed to output 1 v/oct. It just puts out a voltage that increases from one side of the sequencer to the other. It is still can be very useful as it is, if you use it to scale the response of a filter or modulation depth. This would normally be done on the filter, etc. with the VC F knob (NTO, VQVCF). That being said I haven't used it very much, but have experimented a bit with it.

I'm pretty sure that the trimmers inside the TKB are to set the pressure and sensitivity response.

[Kopter]

From zthee's TKB DIY-thread:

There's a Keyboard Voltage output, which is anything but chromatic. I was just doing some calculations and it's possible to change the output to 1 step = 1 halftone and thus getting a bit over an octave out of the keyboard. It's just 5 resistors that has to be changed.

[widdly]

There is no trimmer. If you refer to this schematic...

http://machines.hyperreal.org/manufactu ... tkbpg2.gif

Top left there is a binary weighted dac with the 1M, 499k, 249k and 125k resistors into the opamp. The output is attenuated and inverted by the next opamp.

[widdly]

47k/1M x 12v = 0.564v
47k/87k x 0.564v =0.32326829268v

So the smallest step is 0.3232v

For 1v/Oct you want 1/12v = 0.083333v

47k/ A x 0.564v = 0.083333v

A = 318k

So you could swap the 82k resistor for something around 318k or better still something less than that and a trimmer in series.

[Setherian]

Wait a second, are you guys telling me its not supposed to change per semitone? Holly molly, i have been using it for almost 2 years absolutely assured that was the way it worked, sure i almost never used the KV but...humm ok, so its hot broken then, still i got a little sour taste it wont go out..it definitely makes less sense now, the KV..