Rat King Modular GATES - Eurorack Modular Build
As summer draws near and the hot weather rolls into California, it’s an optimal time to stay inside and catch up on some DIY modular kits.
When we heard that Rat King Modular was releasing a new module named GATES, we immediately hit up our friends at Synthrotek and ordered one up as soon as the kits were available. (The module had been released as a fully assembled version about a month prior and we were anxious to finally get our hands on the kit version).
Within a few days, the kit arrived and it was time to get busy building the Rat King Modular GATES!
What is the world is GATES?
To keep it plain and simple, GATES is a vactrol-based VCA and VCF module with high-pass and low-pass audio inputs on one side and a voltage controlled amplifier on the other. You can use each function separately or together, as the filter audio output jack normals to the audio input of the VCA. GATES is also a variable frequency response and resonant Low Pass Gate, meaning you can dial in smooth cutoffs or unique rhythmic sounds. It’s pretty badass to say the least!
What's in the kit?
The kit comes with everything you need to assemble the GATES Module. Vactrols, pots, jacks, diodes, resistors, etc. The panel is a beautiful matte black that the Rat King is famous for and as for the PCB, well you don’t have to ask us how we feel about those.
As previously stated in our build/reviews of the EVENT, TONE and Random SEQ the Rat King mustard yellow PCBs soak up solder the way a sponge soaks up water. They are nice and one of our favorite PCBs to solder on.
The Build ....
The build itself was pretty painless. We utilized top down soldering for all of our resistors and diodes to start. Upon completing the top down method, we quickly flipped the board over, cut legs and touched up. The process was quick and easy.
Next up was the IC Sockets and Caps, followed by the vactrols. Make sure you pay attention to the orientation of the vactrols. You need to make sure and match the white dot on the vactrols (shorter leads) with the cathode on the silk screen PCB graphic (on the side toward the jacks). This is very important.
Flip the board over and populate the electrolytic caps and the power connector ensuring that their orientation is correct as well. After soldering these components up, it’s time to move onto the jacks and potentiometers.
At this point, you want to insert the ICs and line them up accordingly. Jacks and pots are then placed on the PCB but not soldered. Upon lining everything up, carefully place the panel over the jacks and pots and hand tighten the nuts to each. This ensures that the components are in place prior to tacking them down.
GATES Build Gallery
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- Gates – Resistors and Diodes
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- Gates – Resistors and Diodes Rear PCB
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- Gates – IC Sockets and Caps
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- Gates – IC Sockets and Caps Rear PCB
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- Gates – Jacks and Vactrols
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- Gates – Jacks and Vactrols Rear
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- Completed Gates – Left
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- Completed Gates – Rear
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- Completed Gates – Right
Once everything is lined up and it looks good, tack everything down and call it done. At this point, you can tighten down the nuts (we used our new Synth DIY Tool Set) and add the knobs to finalize the look of the module.
Pat yourself on the back at this point … you have just built the GATES by Rat King Modular!
GATES Calibration:
VCF Trimmer
- Mult your input signal (sine wave recommended) and connect one signal to channel 1 of your oscilloscope.
- Take one of the other multed signals and patch it into the LP INPUT. Turn the CUTOFF knob fully CW.
- Patch the left-hand OUTPUT jack to channel 2 of your scope.
- Turn the VCF trim pot so that channel 1’s amplitude is as close as possible to matching the GATES OUTPUT amplitude (it may be slightly different).
VCA Trimmer
- Mult your input signal (sine wave recommended) and connect one signal to channel 1 of your oscilloscope.
- Take one of the other multed signals and patch it into the VCA INPUT.
- Patch 5V into the VCA CV jack (the CV jack below the INPUT jack).
- Patch the VCA OUTPUT jack to channel 2 of your scope.
- Turn the VCA trim pot so that channel 1’s amplitude is as close as possible to matching the GATES OUTPUT amplitude (it may be slightly different).
Features and Specifications
GATES Features:
- High pass and Low pass inputs on left side
- VCA featured on the right side
- Dual output jacks (one for each side)
- Both sides can be used together or separate
- Excellent for unique rhythmic and percussive sounds.
Power and Specs:
- Width: 8HP
- Depth: 22mm
- Power draw:
- +12V: 50mA
- -12V: 50mA
Purchasing Information
If you don’t want to purchase the kit version of the GATES module like we have detailed/built here, Synthrotek also offers the fully assembled module and the Panel/PCB combos. (Just click the links below to be redirected to their store to pick one up).
Panel and PCB Combo
- Black Matte Panel
- Mustard/Gold Dual Sided PCB
- List Price: $24.99 USD
- Click on the image to be redirected to the Synthrotek Store Page
GATES DIY Kit
- Includes all components, PCB and Panel for assembly
- List Price: $65.00 USD
- Click on image to be redirected to the Synthrotek Store Page
Assembled GATES Module
- Fully assembled and calibrated
- List Price: $115.00 USD
- Click on image to be redirected to the Synthrotek Store Page
Rat King Modular GATES - The Final Word
In the end, we are big fans of the Rat King GATES module. It was an easy build and all in all easy calibration. As you can see in the build video, soldering was quick and efficient as our total build time was less than an hour. There is no reason that this module could not be completed by a novice builder or someone new to the DIY world.
With the easy to read documents provided by Synthrotek and Rat King Modular and the low cost factor… there is no reason not to own this module (in whatever form you choose to purchase). With all this being said, we cannot wait for another Rat King module and look forward to patching some crazy sounds with the new GATES.
Don't forget....
If you have questions or comments about the Rat King Modular GATES build, please feel free to reach out via our Contact page.
Interested in picking up the Rat King Modular GATES? Click on the links above to head on over to Synthrotek (it’s exclusive) and let them know that we sent ya!
Until the next build …
