Control Voltage (CV) with Red Panda Pedals

This article is from 2016.  Refer to this knowledge base article for updated information.

Control voltages (CV) work with the expression pedal inputs on our pedals, but there are a few things to keep in mind. The correct CV range for our pedals is 0-3.3V. The Particle and Bitmap scale the CV input by the knob setting, so you can send +5V or +10V and use the pedal's knob to bring it down to 3.3V. The Raster expression input overrides the knob, so you will need to scale the CV output.

The expression input is a 1/4" TRS phone jack with +3.3V on the ring, sleeve grounded, and input voltage on the tip.  The expression input has current limiting in case you use a TS (mono) cable, but it is best to use a 1/4” TRS (stereo) cable with the ring unconnected. We sell a CV to expression cable at our web site, and the Expert Sleepers 'floating ring' cable is another option. You can also use a 1/4" TRS insert (Y) cable and connect the sleeve side of the dual ends to your CV output.

Building Your Own Cable

The rest of this article describes how to make your own cable.  For 3.5 mm (Eurorack-style) cables, you need a 1/4" TRS plug for the expression jack and a 3.5 mm TS plug for the CV output. Connect them tip to tip and sleeve to leeve using a mono instrument cable (one conductor plus shield).  The ring tab on the 1/4" plug will be left unconnected, but make sure it does not touch the plug body or either of the wires.

Here are the parts we use to build our CV cables. Choose one TRS plug, depending on whether you want a straight or right angle connection.

1. Cut cable to desired length

2. Strip and tin wires

For 3.5 mm plug (Rean NYS226L):

• Use a knife to gently cut the outer insulation 20 mm from the end of the cable. Be careful not to damage the copper shield inside.
• Remove the outer insulation.
• Pull the copper shield together and twist, forming a single twisted wire at at right angle to the cable.
• Use a knife to gently cut the thin black layer 5 mm from the previous cut (see picture at right).
• Remove the black covering, exposing a clear insulator over the inner conductor.
• Use a knife to cut the clear insulation 2 mm from the previous cut (see picture at right). Be careful not to damage the inner conductor.
• Pull the clear insulation off, exposing the inner conductor. There should be about 13 mm of exposed copper wire.
• Twist the inner conductor.
• Tin both wires

For 1/4" straight plug (Rean NYS202):

• Use a knife to gently cut the outer insulation 20 mm from the end of the cable. Be careful not to damage the copper shield inside.
• Remove the outer insulation.
• Pull the copper shield together and twist, forming a single twisted wire at at right angle to the cable.
• Use a knife to gently cut the thin black layer 5 mm from the previous cut (see picture at right).
• Remove the black covering, exposing a clear insulator over the inner conductor.
• Use a knife to cut the clear insulation 2 mm from the previous cut (see picture at right). Be careful not to damage the inner conductor.
• Pull the clear insulation off, exposing the inner conductor. There should be about 13 mm of exposed copper wire.
• Twist the inner conductor.
• Tin both wires

For 1/4" right angle plug (Rean NYS208):

• Use a knife to gently cut the outer insulation 20mm from the end of the cable. Be careful not to damage the copper shield inside.
• Remove the outer insulation.
• Pull the copper wire shield together and twist, forming a single twisted wire at at right angle to the cable.
• Use a knife to gently cut the thin black layer 5mm from the previous cut (see picture at right).
• Remove the black covering, exposing a clear insulator over the inner conductor.
• Use a knife to cut the clear insulation 10 mm from the previous cut (see picture at right). Be careful not to damage the inner conductor.
• Pull the clear insulation off, exposing the inner conductor. There should be about 5 mm of exposed copper wire.
• Twist the inner conductor.
• Tin both wires.

3. Solder 3.5 mm Plug

• Feed the inner conductor through the tip lug, from inside to outside.
• Feed the outer wire through the bottom hole. The cable clamp tabs should be lined up with the outer insulation.
• Solder both wires. It helps to use no-clean solder flux.
• Trim the leads.
• Use pliers to squeeze the cable clamps snug around the cable.

4. Solder 1/4" Plug

Before attaching the 1/4" plug, slide the following pieces on in order:

• 1/4" plug body (threads towards the unfinished end)
• clear plastic sheath for 1/4" plug
• 2" heat shrink tubing

For 1/4" straight plug (Rean NYS202):

• Lay outer wire flat on against the long sleeve connection. Trim length as needed.
• Feed the inner conductor through the tip lug, from inside to outside. Use pliers to squeeze it tight around the lug.
• Leave the ring lug unconnected.
• Solder both wires. Using no-clean flux helps, especially with the outer wire.
• Trim the inner connector.
• Use pliers to squeeze the cable clamps snug around the cable.

For 1/4" right angle plug (Rean NYS208):

• Feed the cable through the large hole.
• Lay outer wire flat on against the long sleeve connection. Trim length as needed.
• Feed the inner conductor through the tip lug, from inside to outside. Use pliers to squeeze it tight around the lug.
• Leave the ring lug unconnected.
• Solder both wires. Using no-clean flux helps, especially with the outer wire.
• Trim the inner connector.
• Use pliers to squeeze the cable clamps snug around the cable.

5. Heat Shrink

• Slide a 2" piece of heat-shrink tubing over each of the cable clamps, leaving the solder joints exposed.
• Use a heat gun to shrink tubing.

6. Finish

• Slide clear plastic sheath up over solder joints on both ends.
• Screw on both plug bodies.

7. Test

Using a multimeter:

• Verify that the resistace is 0 Ω from sleeve to sleeve.
• Verify that the resistace is 0 Ω from tip to tip.
• Verify that there is no continuity between tip and sleeve.