Division 6 CEM3340 VCO - DIY Build
This voltage control oscillator is based off the famous Curtis 3340 IC which has been around for quite some time and have been utilized in many legacy synths. Our build of the Division 6 CEM3340 was a quick and easy build and is recommended for anyone just getting into modular DIY.
What is the Curtis 3340 IC?
Many synths today utilize chips that mimic the famous Curtis 3340. While this chip is no longer manufactured in mass volume, there is a few places that still sell the chip. What makes this chip so special is it is a self contained, precision voltage controlled oscillator.
Note: The chip used in this kit is not an original Curtis 3340 IC, but it’s damn close!
It features both exponential and linear control scales and up to four buffered output waveforms. ( triangle, sawtooth, square and pulse). They do not require a temperature compensation resistor because they provide their own compensation. Multiple control voltages can be mixed within itself.
CEM3340 Time Lapse Build
The Build ...
There are two boards and one panel that are included in the kit that we received. (Synthrotek offers multiple kits and fully assembled modules as well).
First up was the resistors and diodes. After placing the diodes, and checking the resistor values with our component tool, the soldering began.
For the most part, a top down soldering method was used since there was ample amounts of space between components. This also helps with not having to flip the board over and over again in order to keep the parts in place.
Options, Options, Options...
Once the resistors were completed, we headed onto the caps. There are multiple values of caps on the main board so pay special attention to what goes where. Synthrotek has also provided a really clear BOM and build instructions for reference (ie. use them).
Upon knocking out the resistors, we tacked down the power header and the IC chip bracket. Start by placing a little solder on one of the pads and then line up your header or bracket. Flip the board over and head up the underside of the pad.
By applying a little pressure to the component, it will pop right through and stay in place while you tack down the other pins. This is a real quick and easy way to solder these in; and it also keeps things in place!
When you finish up the power header and the IC bracket, it’s time to move to the trimmer pots. These are 6 little soldering points and you are done with the main logic board. Set this board aside and head onto the jacks. In our kit, the nuts on the jacks were packaged separately, which made jumping into soldering very quick.
We like to tack down one pin on the jacks just to hold them in place while we test fit the panels on our builds. With this build, we just used some Frog Tape and held everything in place prior to tacking it all down.
Upon putting the panel on, we had to break out the drill and round out the mounting holes in the panel. They were about 1mm to 2mm too small and the panel would not sit flush. After drilling them out a tad more, the panel slipped right on.
Time to tighten down the nuts, flip the board over and solder the remaining pins from the pots and jacks. Now, reverse it. Remove the panel and set it aside. It is time to join the two boards together with the 90 degree header pins. Pay special attention to the orientation (refer to the assembly instructions provided by Synthrotek that we mentioned earlier). Once these two boards are joined, place your panel back on the jacks and pots. Time for knobs.
Division 6 provided two matte black knobs with blue accents to place on your now nude potentiometers. When it is all put together, locate your ribbon cable. (Included in your kit is a 10/16 Eurorack power cable that you will use to power the module). You are done.
After completing the build, we always test our modules in our smaller cases to ensure that there are no shorts or smoke present. We test all of our DIY modules on our Synthrotek TST module due to its ease of use and hookup. Everything checked out fine. Time to power it up in the rack!
Module Control and Specifications
- Square, triangle, and sawtooth waves
- Coarse and fine-tuning controls
- Adjustable 1V/O CV input
- Mod, PW and hard-sync inputs
- Reverse-polarity protected
- Eurorack-style power input
- I/O connections on one edge of board; can be connected to wires or separate control board
- 1V/O CV
- Mod CV (AC-coupled)
- PW (Adjusts duty-cycle of square wave up or down)
- Square / pulse wave
- Triangle wave
- Sawtooth wave
- Power supply: +/- 12V to 15 VDC
- Power connection: Eurorack 10-pin shrouded header (Can hook wires to pin holes instead if not building for Eurorack)
- Current draw: 9mA (+12V) / 6mA (-12V) / 0mA (+5)
- Coarse tune
- Fine tune
- main board: 50mm x 60mm
- Eurorack HP: 4
- Eurorack depth: 64mm
Division 6 CEM3340 Purchasing Links
Synthrotek has many different options when it comes to purchasing the Division 6 CEM3340 VCO. We wanted to keep it simple by just placing images of the options and linking out to the direct purchase. The prices are excellent and the quality of this build is way worth it! Head on over to SR and tell them we sent ya!
Our Final Thoughts . . .
The Division 6 CEM3340’s output is beefy and sounds close to the original chip, which totally blew us away. The cool thing about it that there are two, yes two VCO’s at once. Couple this with 1 V/O and you can really change up the tones. Being that there is a hard sync also allows the VCO to lock in and stay constant.
With all this being said, we need much more time to play with the module, and it’s easy to see why people love this chip and all that it is capable of. Used in many stand out tracks over time, we can simply state that Division 6 has done it again with their modular version of the infamous CEM3340 VCO.
If you have questions about the build process or suggestions/feedback about this article, feel free to let us know by contacting us We look forward to hearing from you!
Until the next build …