Neutral Labs Scrat - DIY Build

Hot off the release of the MEG module, Neutral Labs is at it again with their new Scrat module. The Scrat is an aggressive sounding multimode Steiner-Parker filter with a twist: You can change the resonance flavor by plugging in components like diodes, capacitors or resistors (even LEDs and/or light-dependent resistors) directly to the front panel.

When we heard that there was a new module released, we couldn’t wait to get it on our build table. Upon its arrival, we fired up the trusty iron and got to building the new Neutral Labs Scrat!

  • Note: Do not open all of the component bags right away. They are grouped in bags to help identify parts and keep the build organized. (A big thanks goes to Neutral Labs for taking the time to do this for DIYers).
Completed SCRAT

Diodes and Resistors

Start off by placing the D1-D6 diodes (not D7) with the black line matching the white line on the PCB. Orientation is important because of polarity of the component and the module will not function or work correctly if this is messed up. In the case of the resistors, you do not have to worry about polarity so you can place these on the board facing either way. 

Just make sure you get the right component in the right place according to the BOM that is provided in the build guide. Once you have placed all of the diodes and resistors, tack everything down and move onto the IC sockets. 

The IC Sockets...

Next up are the IC sockets. We will refrain from setting the IC’s at this point in the build because we do not want to overheat them, or short them while completing the build. There are 2 small IC sockets and 1 larger one. Line up the notch in the socket to the PCB outline of the socket and set the parts. 

You can flip the PCB over easily by placing a small piece of cardboard over the parts as you turn it over. Upon turning it upside down and on its back, you can now solder the legs into place, thus completing this portion of the build.

Neutral Labs Scrat - Time Lapse Build

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Capacitors and Transistors

The caps are up next and they are relatively quick to place and tack down as long as you pay attention to the polarity of the electrolytic capacitors. Their longer leg goes on the plus side as outlined on the PCB.

Watch out for solder bridges here too as some of the small caps have pads that are quite close to one another. It does help to bend the legs after placing the caps to keep them in place prior to tacking them down.

When you are done with the electrolytic caps, it’s time to move on the small caps whose polarity doesn’t matter (there are 2 of these). 

When you have completed the capacitors and they have been soldered into place, line up the JFET transistor with the PCB silkscreen. Solder it into place paying special attention to how long you keep your iron on the component. Why you are here, tack down the power header too just to get it out of the way.

Note: You do not want to leave your iron on these parts too long due to the possibility of frying/shorting it.

5-pin Precision Headers

Flip the PCB over and you will want to locate the the panel port headers (J5 and J6). These pins will be flush with the PCB and will be where you place the various components to use with the module. Once these have been placed, quickly check their alignment by soldering 1 pin down and then flipping the module over to line up the panel. If things line up, flip the PCB back over and complete the soldering. If they do not line up, simply reheat up the soldered leg on the PCB and adjust accordingly. 

SCRAT Audio Demo

We have put together a short demo of the Neutral Labs SCRAT module to demonstrate how to utilize the module. In this video, we use the supplied “nut” cards and a few other modules so that you can hear the basis of what the module sounds like. 

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Scrat - Build Gallery

Finishing up the PCB

We are almost done with the build as we move onto the front side of the PCB. Start off by placing the orange LED in D7 (remember we left this one blank earlier). Polarity matters on LEDs so make sure that the short leg goes on the negative (minus) side. Do not solder the LED yet as we need to place the pots and jacks onto the PCB. 

Remove the nuts from the jacks (J1- J4) and pots (P1 – P4) and set them aside. Keep one nut on the switches (SW1 – SW3) as it will help to line up the switches when placing the top nut. You will also want to clip off the anti-rotation tabs on the pots with a wire cutter prior to placing the panel. You can discard the anti-rotation washers. Fit the parts without soldering yet and then set the front panel into place. Hand tighten the jack nuts and the pot nuts so that the panel will stay in place when you flip the board over to solder everything into place. Make sure the LED sticks out from the PCB to touch the panel prior to soldering it down. 

The Completed Module

At this ping in the build, you are done except for placing the ICs and powering up the module. When placing the ICs, take note that they have little notches or dots on the top of them. This should line up with the notched out section of the IC socket. If you place these in the wrong direction, you could risk frying either the module or the IC. (Note: You might have to bend the IC socket lets in to help them sit correctly).

The very last step in the build is placing the knobs and powering up the module. We always test our modules with the Synthrotek TST module prior to directly connecting the module to our modular system. When it all tests positive and nothing catches fire, we can consider it safe to continue. After completing this step, you are done building the Neutral Labs Scrat module and you are ready to jam.

Neutral Labs SCRAT - Final Thoughts...

Let us start off by stating the obvious. We love Neutral Labs modules and their Elmyra synth. The newest addition to their lineup, the Scrat falls right in line with its brethren kin. It can be brutal as well as beautiful. It can be dirty and yet very clean. One thing that stands out about this module is how the user interacts with it. You can place various parts in the socket on the front panel and change the module completely.

Each time you use it with different part, you have a new sounding module. This is unique and there isn’t a lot of modules out there that behave like this. The quality of the kit is superb and the build guide is easy to follow as long as you take your time. As for the module itself, it matches the MEG and the Nermal in style and looks great sitting next to each. 

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 …

~ f i N

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