Bill and Will's Synth
MOTM 420 Two Dot Oh Construction
"MOTM-420 Voltage-Controlled Filter"


October 2009 -

Why a second MOTM420 page?  Well, we're building another 420, and it's a little different when you're working from a Synth Tech 2.0 thing rather than a full-blown "kit."  So if you feel the need, cross reference this with the KitPage here.

We're going go right into building the thing.

Table of Contents

This page has become really long, so here's a table of contents that we hope will make it easier to traverse:

Parts - presents a Bill of Materials for "two-dot-oh" builders and notes about it

Panel - presents the MOTM format panel

Construction Phase 1 - Resistors, Capacitors, IC Sockets, Power Plugs, MTA headers

Construction Phase 2 - Trimmers, Panel connections

Set up / Testing

Use notes


OK - so - In 2008 (or about that time), Synthesis Technology stopped producing full-blown kits, and moved toward what Paul calls "2.0" (two-dot-oh) DIY. This assumes the builder will buy certain parts from Synthesis Technology - PCB, Panel, and in some cases a Special Parts Kit of the particularly hard to find parts - and will get the rest of the parts from Mouser or Digikey or - well - wherever.

For those who are building this as a "two-dot-oh" project, Will and I, with feedback and review from others, have developed a parts-list / bill-of-materials in the form of an XL spreadsheet (as usual).

Please don't take it as gospel. We've been over and over it and are relatively confident in our specifications - and we hear that several people have used it successfully so you should be good.  The BOM assumes that you get the "extra parts kit" from Synthesis Tech.  Synthesis Technology offers some parts like pots and knobs at particularly good prices... these options are offered in the BOM.

Click here to download our XL spreadsheet Parts List


If you're building this as a "two-dot-oh" project, we also assume you get the panel from Synthesis Technology:

Construction Phase 1

All the stuff in Phase 1 gets soldered using "Organic" Solder.  At every break in the action, we wash the board off to get rid of the flux.

Resistors, Caps, Power

As usual, whereas we are vigilant about orienting all the resistors, caps, etc. consistently so their values can be read easily (in case we need to trouble-shoot them later), we oriented the resistors with the "tolerance" stripe on the left (relative to the text on the pcb).  We got started doing it this way when we started building our synth and now we do it so all our modules are consistent with each other.  You might want to do it the opposite way - with the "tolerance" stripe on the right.

One of the caps we got is a little fatter than its corresponding spot on the PCB, but we didn't have any trouble fitting it in.

Semiconductors - Misc - Via Holes

We used an IC jack for the 1013 op amp 'cause we weren't totally sure the one we got is correct.  Here it is installed in the jack:

Construction Phase 2

All the stuff in Phase 2 gets soldered using "No Clean" Solder.

Pots, Wires

the PCB mounted pots and wires

We cut the wires like this:

VR1 - 7" twisted triple Red, White, Black
VR2 - 7" twisted triple Red, White, Black
VR3 - 7" twisted triple Red, White, Black
SW1 - 5" twisted triple Blue, White, Green
J1 - 7" coax
J2 - 7" twisted pair Red, White
J3 - 7" twisted pair Red, White
J4 - 5" coax
J5 - 5" coax
J6 - 5" coax
J7 - 5" coax

Tempco Resistor

just like that

Construction Done

Set up / Testing

Use Notes


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The fine Print:
Use this site at your own risk.
We are self-proclaimed idiots and any use of this site and any materials presented herein should be taken with a grain of Kosher salt. If the info is useful - more's the better.  Bill and Will

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