God City Instruments – Decker V1.0 Build Guide
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GOD CITY INSTRUMENTS – Decker V1.0 Build guide
The God City Instruments (GCI) Decker is a simple FMV (Fender Marshall Vox) EQ circuit similar to the tone
stack found in many classic amps. A volume trim control is also available on the front panel to compensate for
any loss or boost in volume caused by equalization. The op amp stages of this circuit can easily be tuned to
provide a healthy amount of boost and/or overdrive if so desired. It can be built as a stand-‐alone pedal or as
an add-‐on to a gain circuit in need of amp-‐like EQ. By adjusting values, a wide range of tonal options are
available. Duncan Amps has a Windows application that can be used to quickly tune this circuit to the desired
frequency response.
http://www.duncanamps.com/tsc/
This pedal is an easy build, but this guide is intended for people who have some experience building pedals.
Component sourcing, component identification, assembly techniques, wiring stomp switches, etc. is not
covered. The GCI Brutalist Jr. assembly guide has helpful information for less experienced builders. That guide
can be found here:
http://www.kurtballou.com/brutalistjr/
For your convenience, complete parts kits including everything you need except the PCB can be purchased
through Small Bear Electronics. Be wary that they may need to make substitutions for work-‐alike components
which may or may not influence the tone of the pedal. Be aware that transistors may have been substituted
for work-‐alikes with different pinouts.
http://smallbear-‐electronics.mybigcommerce.com/kit-‐decker-‐pcb-‐not-‐included/
Available separately is the GCI 3PDT utility PCB for PCB pin 3PDT footswitches. This PCB makes footswitch
wiring quick and easy. Not compatible with solder lug style switches.
Don’t forget to connect the ground pad of the PCB to the ground lug of the input, output, and DC power jacks!
Due to the scope of this project, technical support is not available. However, consider joining the GCI DIY PCB
Builders group on Facebook to get advice from and share your work with other builders. We require that all
group members agree to the rules before being accepted into the group.
https://www.facebook.com/groups/2454786551255317/
Component values for the PCB as well as some alternate values are listed below. This is a BOM for the PCB
only. Resistors and diodes are 6.3mm leg spacing, film and ceramic capacitors are 5.08mm leg spacing, and
electrolytic capacitors are 2.54mm leg spacing. I/O jacks, DC jack, switch, enclosure, and knobs are not listed.
The schematic and a drill template for a 125B (1590N1) sized enclosure are also attached.
