Vox Continental External Vibrato Control Modification

As you are probably aware the Vox Continental has but one external control for its vibrato, an on/off switch. However, not everyone knows that inside the Connie there are trimmer controls for the vibrato speed and depth. Needless to say it's pretty inconvenient having to remove the organ's lid to change these settings. So, the obvious solution is to move these controls to the outside of the organ. The modification is relatively simple and requires no permanent modification to the instrument. All that you really need to know is how to solder and drill holes in a box. Below I'll give the basic instructions for performing this very useful modification. Note that this mod is only described for Italian Continentals. While I'm sure the mad could be performed on UK and probably US Connies, Supers, II's, 300's, and Baroques, I don't have them available for reference. Basically if you can find the speed and depth trimmers or pots then you can probably figure it out from these instructions. The folowing are very basic instructions and skip over some steps that I feel are pretty obvious and possibly unique to the parts you use such as assmebling your DIN jack or how to mount the pots to the box, as well as things you can glean from the photos. I'm assuming that if you are attempting to do this mod then you have at least some basic experience in soldering and electronics. These instructions were written very quickly with that assumption and so some things I skipped intentionally and some I may have skipped accidentally. If this is so and you have any questions feel free to email me at sonicvi@mac.com

What you'll need:

1. Soldering tools and solder
2. 2 25K linear or audio taper pots
3. 1 DIN plug and jack with at least 6 pins
4. 1 6 conductor cable or six wires, approximately 24" in length
5. 1 plastic or metal box large enough to house two potentiometers and a 6 pin DIN jack
6. paint for the box (optional)

You can order all of these parts from Mouser or Digikey electronics suppliers.

The first step is to remove all the screws from the sides and back of the continental so that you can remove the top and allow the circuit board rack to swivel up. Once you have the top off and the bottoms of the circuit boards accesible you're ready to begin.

Locate the vibrato circuit board. it's the second board from the left if you're standing on the keyboard side of the organ. You'll see at the far side of the board two trim pots, the left one is the speed pot and the right is depth. The next step is to remove those trim pots. With the circuit board rack in an upright position it's easy to get your soldering iron to the solder pads of the trimpots. Melt the solder for each pad and preferably soak up the solder with a solder wick or vacuum pump. Once you have the trimpots out, hopefully in one piece, put them in a safe place in case you want to reverse the mod some day.

Next, you'll want to prepare your external box for mounting the pots and DIN jack. It's a good idea to drill the hole for the jack first so you'll be sure there's enough room for it with the pots mounted. Using mini-pots will give you a little more area to work with. Once you've drilled the hole for the jack you can drill the holes for the pots. Once the holes are drilled you can paint the box if you so desire. I used Rust-o-Leum's Hammered finish paint. You can use whatever you want.

Assembing the box. The first thing you'll want to do is solder wires to the jack. You'll need 6 wires, using at least two different colors, one for each pot will be helpful, or even 6 different colors. Solder each wire to one pin of the jack. Now, mount the jack into its hole and slip the nut over the wires and thumb tighten it. You need to consider the angle of your jack if you're using a right angle plug like I did, so that it sticks out at a good angle when it's plugged into the jack. Next mount the pots in the box and cut the wires down so that they reach the tabs of the pots with a little bit of slack to make moving them around easier. Strip and tin the ends of the wires and solder one to each of the tabs of the two pots. A systematic approach to this will be helpful later, such as soldering wires from one side of the jack to one pot and the other side to the other pot, and the bottom most pin on the jack to the left tab on pot and so on.
Here's a photo of the completed control box's insides:

Now it's time to wire the cable to the vibrato circuit board. Strip and tin six wires (or conductors in your cable) and solder one into each empty hole. Having six colors of wire is much more helpful now. Next, taking great care to match the correct wires to the correct pins of the DIN plug that will lead the the lugs of your speed and depth pots, solder each of the six wires to six pins of the plug and reassemble the plug. Note that if your plug has a strain relief boot that you must slide that onto the cable BEFORE you solder the wires to the plug. The holes left by the removed trimpots will be triangular in shape. The top of the triangle corresponds to the middle lug of the pot in the control box. The other two corners are the outside lugs. It doesn't really matter which goes to which, the only difference is in whether your speed or depth increases or decreses as you turn the control clockwise. If when after you've finished you find you'd like it the opposite of the way it turned out then just reverse the wires to the outside tabs on the pots in the box. It's much easier than rewiring the plug or the wires in the ciruit board. Below is a photo of the cable wired to the circuit board.

Once your cable and box are wired up it's time to test the box. Plug the cable into the box and turn on the organ. Switch on the vibrato. Hopefully the vibrato works. If it does anything than you're probably in good shape, if not you'll need to go back and check your wiring. If you've got vibrato turn your knobs and see if the speed and depth change. If they do then you're done, if not then you need to check your wiring, and check for shorts.

Here's a photo of the completed box which I mounted to the top of the organ with velcro.:

And here's a little MP3, first you'll hear the depth and speed at minimum, then the depth will increase to maximum, followed by the speed, then the depth back to minimum, followed by the speed, then finally, some fast changes of the speed and depth.

Finally, a very crude illustration of the wiring to help possibly make things a little clearer.