CHA/V User Guide

[this guide is a work in progress and will be updated regularly]

Congrats! If you made it here, you probably have a completed CHA/V that you’d like to test. Here’s a general overview of the controls:

IMG_6822.jpeg

To turn it on, plug a 12v center-positive power supply. Center positive means that the sleeve of the jack is negative (in most cases it’s just ground) and the inside is the positive voltage. Anything above 500mA is more than adequate, and you can probably get away with even half of that.

Unknown.png

dig through your box of old wall-warts and find a 12v one with this symbol, which means center positive.

If the power LED turns on and nothing explodes, you’re probably in business. If you have the CHA/V connected to a monitor with a VGA cable and you see color bars, you’ve passed the first test. Hit the background cycle button a few times and make sure it cycles though the colors. Hit the resolution cycle a few times and make sure it cycles through the resolutions.

All good? Cycle the background color to black.

Screen Shot 2019-11-27 at 12.59.02 PM.png

Before any of the oscillators can be used, we’ll have to put in some jumpers. It’s doubtful any of them will do much without jumpers.

First, let’s look at the vactrol headers on the VCOs:

Screen Shot 2019-11-27 at 1.03.09 PM.png

As-is, there’s no jumper, and because of that, the VCO circuit is not complete (it won’t do anything).

If you place a jumper connecting the [off] pin and the center-pin (the triangle), the circuit will be complete, but the vactrol frequency modulation will be off. Here’s the off jumper position:

Screen Shot 2019-11-27 at 1.03.21 PM.png

If you want frequency modulation to be on, place a jumper connecting [on] and the center (triangle) pin. Like so:

Screen Shot 2019-11-27 at 1.03.32 PM.png

In this position, the LDR will be inserted into the VCO circuit and it (in addition to the potentiometer) will change the frequency of the VCO. Once we get this fired up, if you wave your hands around over it, it will change the amount of light that the LDR sees, and in turn change the frequency (pitch). For now, put the vactrol headers of both VCOs in [off] position.

Ok, now we have to place jumpers on all the sync headers. Each oscillator has a sync header like the one pictured below. They are all identical.

The pins on the right (in the red box) are the sync inputs for each oscillator. There are 3 pins, but you should only connect one of them at a time. 

The pins along the left are:

horizontal video sync pulses from the VGA tester [H]

vertical sync pulses from the VGA tester [V]

and ground [G] which allows the oscillator to free-run

Below are some oscillators with jumpers in place.

OSC 2 is synced to V

LFO 2 is free-running

VCO 2 is synced to H

Initialize the CHA/V for some basic tests by setting the jumpers and switches like this:

This is the most basic configuration. The VCOs should make vertical lines, the OSCs should make horizontal lines, and the LFOs are ready to animate the VCOs.

Here are some basic patches to start with:

VCO 1 > RED, GREEN or BLUE = Vertical red, green or blue lines

OSC 1 > RED, GREEN or BLUE = Horizontal red, green or blue lines

See what you can come up with just by patching both VCOs and OSCs to RED, GREEN and BLUE and playing with the frequencies. Because each oscillator has multiple outputs, and each color has multiple inputs, you can experiment with sending one oscillator to multiple colors, multiple oscillators to one color, or any combination. Play with the coupling toggles to change the line thickness. Some combinations will work as expected, and others will have unexpected results, especially when lots of oscillators or colors are patched together.

Next step: Frequency Modulation

Patch one VCO 1 to a color. Turn the VCO 1 vactrol on. If you cover the LDR of VCO 1 with your hand, now you should see the frequency change. Try shining a light on it.

Set LFO1 back to free-running and set to low/low if you changed it. Now patch LFO 1 into the FM pin on the VCO 1 vactrol header. The LED should now be flashing and animating VCO 1.

Change the frequencies of VCO 1 and LFO 1 and watch what happens.

Try syncing LFO 1 to V or H and see what happens.

Coming SOON: HOW TO VIDEOS !

Also, more topics such as:

JACKS

  • RGB audio out
  • RGB audio in
  • Audio Modulation
  • Eurorack in
  • Sync out

MIXER COOKBOOK

  • variable resistor
  • attenuator for brightness
  • attenuator for volume
  • attenuator for CV
  • crossfader
  • colorfader
  • sync router

EXPERIMENTAL PATCHES

  • vactrol vca
  • background automation

“IT’S A FEATURE NOT A BUG”

  • creative applications of crosstalk
  • sync jitter
  • raw output
  • working with blanking
  • still higher resolution than composite video, lol

TIPS:

  • Although all of the oscillators have specialties, all of them are able to produce relatively high or low frequencies. Try playing to their strengths, and also AGAINST them. The rules were made to be broken.
  • Try leaving some jumpers off and see what happens when the oscillators “float”. You can also use your finger as a temporary jumper for sync or on the vactrol header.
  • Change the resolution if something is acting weird or not synching the way you want it to. This sometimes fixes things. It also sometimes clears up weirdness that occurs along the edges of the screen.
  • Change the background to white and all the colors will be inverted.