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GCI Brutalist Jr. Build Manual

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GCI BRUTALIST JR. BUILD GUIDE
The Brutalist Jr. is the DIY little brother to the GCI Brutalist, a high powered distortion pedal loosely based on the Providence
Stampede SDT-1. It runs on 9v DC power or 9v battery and has controls for volume, loudness (a high and low boost chained into
one control), and gain (distortion.) Components have been carefully chosen to provide a powerful distorted sound when placed in
front of a semi-clean tube amp, but please feel free to experiment with component choices. Alternate resistors, capacitors, and
diodes can change the tonal and gain characteristics of the circuit. External switches can be added to make these choices
switchable.
If you are inexperienced with soldering, please watch YouTube tutoritals and get comfortable with "tinning" wire ends and making
solder connections to PCBs and pots before beginning this build.
This kit is designed was designed and prototyped in the USA. Consequently, these instructions are in English units. Apologies to
any non-US builders who need to convert to metric from this antiquated system.
If you enjoy building this kit and find it useful, please show us your work by tagging
www.facebook.com/KurtBallou/
or
www.instagram.com/godcitymusic/
and use the hashtags #godcityinstruments and #brutalistjr.

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Summary of Contents for GCI Brutalist Jr.

  • Page 1 GCI BRUTALIST JR. BUILD GUIDE The Brutalist Jr. is the DIY little brother to the GCI Brutalist, a high powered distortion pedal loosely based on the Providence Stampede SDT-1. It runs on 9v DC power or 9v battery and has controls for volume, loudness (a high and low boost chained into one control), and gain (distortion.) Components have been carefully chosen to provide a powerful distorted sound when placed in...
  • Page 2 Feel free to buy parts a la carte from any electronics supplier, but Small Bear Electronics http://www.smallbear- electronics.mybigcommerce.com/ have been kind enough to create a parts kit for this project. Full kit (includes everything except PCB) and mini kit (includes everything except PCB, enclosure, and knobs) available here: http://smallbear- electronics.mybigcommerce.com/kit-the-gc-brutalist-jr/ MODS...

  • Page 3: Components Checklist

    COMPONENTS CHECKLIST Film & Ceramic Electrolytic Resistors Capacitors Capacitors Op Amps Part Value Color Code Part Value Code Part Value Part Value 2.2M Red Red Black Yellow Brown TL072P 2.2M Red Red Black Yellow Brown 2.2n 3.3u TL072P Brown Black Black Brown Brown 330p 100u Brown Black Black Brown Brown...

  • Page 4: Hardware And Tools

    HARDWARE AND TOOLS Hardware Tools Part Value Soldering Iron Input jack 1/4" stereo Rosin core solder Output jack 1/4" mono Solder sucker or wick Footswitch 3pdt Flat and phillips head screw drivers Enclosure 125BB Needle nose pliers Battery snap 6" #24 leads Side cutters DC jack 2.1mm...

  • Page 5: Getting Started

    GETTING STARTED Sort and clearly identify all components and hardware. Be sure not to lose anything because the kit does not include any extras.
  • Page 6 Resistors can be identified with a multi-meter or by using this online calculator (http://www.digikey.com/en/resources/conversion- calculators/conversion-calculator-resistor-color-code-5-band)
  • Page 7 Capacitors can be identified by using this online calculator (http://www.electronics2000.co.uk/calc/capacitor-code-calculator.php) and this online conversion table (http://www.justradios.com/uFnFpF.html)
  • Page 8 NOTE: These instructions refer to the “Kurt Ballou” side of the PCB as the “front side.” All IC’s, diodes, capacitors, and resistors are connected to the front side. When the pedal is completed, this side will still be visible when the back of the enclosure is removed. These instructions refer to the face of the pedal enclosure, where the knobs and switches are as the “front side”...
  • Page 9 POPULATE THE PCB Step 1: Add the diodes. First find the 1N5818 diode. This provides protection against incorrect power supply polarity. Next find a pair of 1N914 diodes. These are the clipping diodes. Bend each diode’s legs at 90 degrees and install them through the front side of the PCB.
  • Page 14 Step 2: Add the resistors. These are non-polarized and orientation is not critical. Sort the resistors, then, one by one, bend the legs at the resistor bodies to 90 degrees and insert them into the PCB from the front side. Then, from, the back side, bend their legs out to hold them in place until it’s time to solder.
  • Page 17 Step 3: Add the 8 pin IC sockets. ONLY SOLDER THE SOCKET! The IC’s get inserted into the sockets after the sockets had been soldered. Insert the sockets into the PCB from the front side. Then, from the back side, bend their legs out to hold them in place until they are soldered.
  • Page 19 Step 4: Add the film and the ceramic disc capacitors. These are non-polarized and orientation is not critical. Sort the capacitors and, one by one, insert them to the PCB from the front side. Then, from the back side, bend their legs out to hold them in place until it’s time to solder.
  • Page 21 Step 5: Add the electrolytic capacitors. These are polarized, which means the orientation is critical. The positive side will have a longer lead and goes into the square solder pad. The negative side will have a shorter lead and a stripe running along the side of the cap, and goes into the round solder pad.
  • Page 23 Step 6: Potentiometers: The potentiometers will have a small metal tab sticking out of the top of their bodies. Snap these tabs off with a pair of needle nose pliers. The potentiometers will not fit in the enclosure properly with these tabs still attached. Identify each pot at label each with a V, L, and D for Volume, Loudness, and Distortion to ensure they don’t get put into the enclosure or board in the wrong order.
  • Page 25 PREPARE THE ENCLOSURE Step 1: Print the paper drill template PDF at 1:1 and attach it to the enclosure as described on the drill template. You may find it helpful to tape the template in place before center punching the holes.
  • Page 27 Step 2: Put on work gloves. Step 3: Use a center punch (or sharp nail) and hammer to create divots at the center points of the holes. Remove, but do not discard paper template.
  • Page 28 Step 4: Drill using the divots as starting points to ensure that the drill doesn’t walk off center. Brace the enclosure while drilling to prevent the enclosure from spinning around if the drill catches.
  • Page 30 Step 5: Use a countersink, if necessary, to de-burr the holes. Step 6: Add paint, labeling, and/or artwork.
  • Page 31 ASSEMBLY Gather all of the remaining hardware, the populated PCB, and the finished and drilled enclosure. It is time to assemble. As hardware is added to the enclosure, tighten each with a pair of pliers or appropriate size socket. Step 1: Install the potentiometers into the enclosure from the back (inside.) Pin 3 (see diagram below) of the potentiometer should be toward the left with all 3 pins facing the bottom of the enclosure where the footswitch will be mounted.
  • Page 33 Step 2: Locate and install the LED bezel from the front of the enclosure. Note that it has a small, round, plastic base with two holes marked (+) and (-) for the positive and negative leads of the LED. Locate the LED and notice that one leg is longer than the other. The longer leg is the (+) positive lead.
  • Page 37 Step 3: Install the power jack through the enclosure and tighten the nut from the inside. Be careful to not over tighten as the plastic threads could strip. Step 4: Install the 3pdt footswitch. Orientation is important. There will be a notch in the threads of the switch. This notch should point at the potentiometers.
  • Page 38 Step 5: Install the audio jacks. The stereo jack will be the input jack and will go to the left when looking at the back of the enclosure. This jack has 3 solder tabs. The mono jack will be the output jack and will go to right when looking at the back of the enclosure.
  • Page 39 Step 6: Time for wiring. Ground wires (G, G1, G2) will be black, power wires (V) will be red and signal wires (I,O) can be any color that is not red or black to avoid confusion. Cut the following lengths of wire: | G1 –...
  • Page 42 Step 7: First, install the LED into the bezel. Next, install the PCB on to the potentiometers and solder them in place. PCB should be oriented such that the “Kurt Ballou” side with all the components faces out. When properly installed all 3 pins of each potentiometer should pass through the PCB.
  • Page 44 Step 8: Complete all wiring connections by following the attached wiring diagram. Wires will be trimmed to length as needed, making sure to allow length for the loose end of the wire to be stripped. Do not pull the wires tight during this process as this will put tension on the solder joints and lead to potential failure of the connection.
  • Page 47 Step 9: Install battery, enclosure back and knobs. Knobs will have a small set screw that will need to be tightened with a small flathead screw driver in order to properly operate the potentiometer. Step 10: TEST! If all the instructions were followed and soldering was done carefully, the pedal should be ready for use. Enjoy the Brutalist Jr.!

  • Page 48: Tech Support

    TECH SUPPORT Due to the nature of this project, there is no specialized technical support. Look in the mirror, say to yourself “I can do this” three times, then try again. If you’re still having trouble, ask a friend with building experience. DIY! SUGGESTED MODS If you like tweaking, here’s a few places to start.
  • Page 49 TL082 • Generally any op-amp that is pin compatible with a TL072 could be swapped into the circuit. However, be mindful that very high performance op-amps may not be the best choice. They generally require more careful PCB design than is afforded in this kit. Global Treble Adjustment: C13 is used to control the final treble response of the circuit.

  • Page 50: Wiring Diagram

    WIRING DIAGRAM...