posted 14 February 2008 10:38            

First off, I need to connect my cv signal to the Capybara. My signal comes out of a female mono jack (i.e. 2 wires). Please can you let me know the correct wiring for connecting to the Capy's XLR sockets.

Secondly, if possible, it would be helpful if you could upload a simple patch that registers cv input that I could then use as a starting point for building more complicated sounds. Would that be possible?

And finally, because it would be stupid not to ask, does anyone out there have experience of this sort of thing and have any useful words of advice, etc.

Many thanks,

posted 14 February 2008 17:17            

I think (but I could be totally wrong) that the capy inputs are not DC coupled. What this means is that if you put DC or CV on the input, you would get zero a split second after the CV had settled at a voltage and it would only deviate from zero if the CV changed value , but would go straight back to zero as soon as the CV settled to a steady voltage again.

If the capy is DC coupled all you would need is a live input module going to a sound to global controller module to monitor what was happening to the input on the VCS.

You would just need to wire the cold XLR pin 2 to ground XLR pin 1 and ground of the CV and feed your signal into the hot Pin3 XLR.

Depending on the arraignment of the CV supply you may find it works better if you connect the ground of the CV to cold XLR pin 2 and leave the ground XLR pin 1 un connected.

The first arraignment may give earth loops if the CV is tied to ground and the second may have a voltage offset that is outside the range of the input pins if the CV is floating , but one of the two should work ok.

You may find that you need an attenuator if the CV range is too high but a simple passive preset potentiometer of about 22 K ohms should do the job. You could then replace this with two fixed resistors when you know what setting works best.

hope this helps

Pete

posted 14 February 2008 17:34            

Also, there was a previous thread on going in the *opposite* direction that might be have some useful ideas.

posted 15 February 2008 16:09            

* Ground to pin 3
* CV signal to pin 2
If your cable has a shield, connect it to pin 1 (otherwise, leave pin 1 unconnected)

posted 17 February 2008 06:29            

The fluctuations are what you are hearing on the mini disc, but that's the problem. It's the fluctuations only that you are getting. If the CV rises you will get a positive spike that will settle back to zero volts after a split second and if the CV falls in voltage you will get a negative spike that will settle back to zero volts. All the constant levels are replaced by zero and all you get is the changes. This is what AC coupling does, it removes the DC content leaving only the AC part (Changes in level only not the level itself).

It may theoretically seem possible to undo what the AC coupled input is doing to the CV signal but you would first have to give it an assumed starting point and in the real world the accumulative error would put you out by at least full range within a few of seconds. You would stand a better chance prediction the wether on a certain day and time three years from now.

The simplest way (that I can think of) to get the full CV info through the AC coupled input is to keep switching it between a positive version of the CV and a negative version. This way the peak to peak level of the generated square wave equals two times the level of the CV voltage. The AC coupled input will still try to average the signal out to zero but as the square wave is already Zero on average, the signal will be unaffected.

It is then easy to turn it back into a DC control level once it's inside the capy. If the square wave was 3 Khz it would still recognize changes that were faster than or slower than the 3 Khz. The 3 khz modulating frequency would appear to be invisible.

The analogue circuit wouldn't need an expensive complicated VCA to achieve this amplitude modulated square wave, as diode type clipping could achieve the same thing.

Hope this makes sense

posted 17 February 2008 16:28            

All the best,