Reverse Landfill Pentamix - DIY Build

Reverse Landfill’s unique approach to modular synthesis is something that they are becoming known for. Their cryptic silkscreens on their panels also makes for some interesting patching if one is unfamiliar with the modules. The Pentamix is one of Martijn’s newer modules that helps bring all of the other Reverse Landfill modules together.

A 5-channel audio mixer, the Pentamix’s real magic happens when you patch the inverted output and use the another output to send out to an effect and then back again into the Pentamix.

With its 555 pentagram, this mixer brings a new dimension to ones rack… but enough about the module, let’s get onto the build… 

Resistors and Diodes...

Start with the resistors on this build. There are not very many of them (12 to be exact) and their polarity doesn’t matter. Each resistor set is marked so its easy to figure out what goes where if you can read a BOM.  You can find all of the Pentamix’s documentation on the Reverse Landfill website for quick reference. 

Diodes are next and one thing we love about Martijn’s modules is the extra power protection. The diodes (x2) will protect your module if the power is reversed for any reason. The 2x resistors next to the diodes are there for extra protection. One thing to know about diodes is that their polarity does matter. You want to be sure that the black line on the diode lines up with the silkscreen on the PCB. A quick tack down of these and its time to move onto the IC sockets and caps. 

The IC Socket and those lovely capacitors…

The IC socket consists of 8 pins that mounts in the U2 spot on the PCB. Once you place this component, do not set the IC chip just yet. Hold off until it is the last thing left to do. With the capacitors, start with the ceramic ones (the small orange disc capacitors). Place these on the PCB (in c8, c9, c11 and c12) but be careful not to have them touching the board.

You want to make sure there is enough room between the ceramic coating and the PCB so that there is a good solid connection with the solder. After these caps are tacked down (polarity doesn’t matter), it is time to head on over to the electrolytic where polarity DOES matter.

These caps are the black cylinder shaped components with one leg longer than the other. They also have a white stripe down the side which represents the negative side of the cap. If you look at the PCB you will see a small “ + “ sign. This is where you will place the LONG leg of the cap. Upon placing the electrolytic capacitors, clip the ends and head on over to the power header. 

Pentamix - Time Lapse Build

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Do you have the power?

The power header is shrouded, meaning it has sides around the pins. Orientation is very important here, because without the correct orientation, you could fry your module. Start by soldering one pin and make sure the header is flat on the PCB.

Once you see that everything is flat and lined up with the silkscreen, tack down the other pins ensuring that your solder connections are ace. 

Jacks, pots and all the other goodness…

Flip the PCB over and insert the pots and jacks into their relevant positions, but do not solder anything yet. At this point, you will want to place the panel and use a couple of the nuts to secure it into place. The panel should sit comfortably on the jacks and panels. If everything is lined up correctly, flip the module over and solder the pins on the pots/jacks. Flip the module back over after tacking everything down and tighten down the rest of the nuts to secure everything into place. We used our Synth DIY Toolset to lock everything in place. 

Pentamix Build Gallery

Fancy Knobs?

Last but not least are the knobs and IC. Start by turning the pots all the way counter clock wise so that they do not turn anymore. You want to make sure that all of the tops of the pots line up with each other. This way you can ensure they are in the right position to accept the knobs. The Pentamix came with all black Davies 1900H clones, which we set aside and did not use.

We wanted to stay with the look of Reverse Landfills previous modules and use the clear knobs with the grey top. These were kinda tricky to find and required a special order at (part # GTP6M-12×16-S). These knobs are mounted on top of the pots by simply pushing down on them. Careful not to put too much pressure on the shaft of the pot. We used a microfiber cloth to help push things into place. 

Part #GTP6M-12x16-S -

IC Placement

The IC chip is the last thing on the menu. You will want to make sure that the legs of the IC chip are sitting at a 90 degrees angle so that the chip will fit correctly into the header. The important thing here is making sure to line it up correctly; orientation matters.

Once this has been set, you are done building the module. Head on over to your rack and attach it to a tester or get to patching. We attached ours to our Synthrotek TST module and found that everything was ready to go. 

Reverse Landfill Pentamix - The Final Thoughts...

Reverse Landfill Logo

The Pentamix by Reverse Landfill was a relatively easy build with special attention needed when mounting the IC and the electrolytic caps. Outside from this, the build itself was pretty quick. The aesthetics of the module are clean and the 555 pentagram really stands out on the panel. When we placed the knobs on, it really gave the module a look like its brethren kin (NOISE, Monotropa, CREEP CLUSTER, etc) which we really liked. 

One thing is for sure, whenever Reverse Landfill releases a module, we have to pick it up due to its uniqueness and its ability to bring add something to our rack that has never been heard before.

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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