Combining 5U MOTM and Synthesizers.com modules in the same cabinet

This article only discusses wooden cabinets, not racks. To fit 5U MOTM-format modules, (including Modcan B-series), into a wooden Synthesizers.com type of cabinet, there are three main things to consider: How to physically mount the MOTM-format modules, what number of each module format can be fitted and the power considerations.

Dimensions
The width of 5U modules varies. Some manufacturers use the width of the original Moog modules (1U = 2.125"), and as such, these fall into a sub-format called MU (for Moog Unit). MU module manufacturers include Synthesizers.com, Club Of The Knobs, Krisp1, Mos-lab, Moon Modular, STG Sound Lab, and ModuSonics. Other 5U manufacturers, like Synthesis Technology MOTM, Oakley Sound Systems and Modcan B-series, use the slightly narrower width of 1.75". Thus, MU and 5U modules cannot be mounted in the same row in racks that use metal pre-tapped holes.

Height Issues
Synthesizers.com and MOTM-format modules are technically the same height. The real difference is the fact that Synthesizers.com-format modules are formed on the sides for adding strength.

The mounting holes of MOTM-format modules are also placed at a slightly different vertical height to those on Synthesizer Dot Com modules. This means that if placing a MOTM-format module on the floor of a Synthesizer Dot Com cabinet its mounting holes will not reach the top rail completely. To counter this, make sure that any MOTM-format modules are centered in the rails before drilling mounting holes for them. Mark the holes making sure the module is centered and drill the hole with a 1mm or 2mm bit. Then screw in one of the mounting screws to tap the hole before mounting the module. The MOTM mounting holes will be closer to the edge of the rails than the Synthesizers.com ones.

Width issues
To consider how many of each module fit in the case, the widths of single space (1U) modules are 2.125 inches for Synthesizers.com modules and 1.75 inches for MOTM. 22-space Synthesizers.com cabinets have rails that are 46.75 inches wide. The table below shows all the combinations of Synthesizers.com format modules and MOTM-format modules you can have in a 22-space Synthesizers.com row. Specifically, it shows, (all dimensions in inches):
 * The number of single space Synthesizers.com format modules.
 * The resulting space remaining in the cabinet.
 * The number of (whole) MOTM format units available.
 * The gap that will remain when the case is full.

Some combinations work better than others. With eight Synthesizers.com format and seventeen MOTM-format spaces there is no gap at all. Note that this table will only work if all the MOTM-format modules are mounted in a block together and the Synthesizers.com modules together. Putting them in-between each other would, if you used a Synthesizers.com case with pre-drilled mounting holes, mean more gaps. Different Synthesizers.com mounting holes can be drilled in the relevant place(s) to leave the smallest possible gap.

Power considerations
All modules from the 5U manufacturers need a +/- 15v power supply. Eurorack, Frac Rack and 6U Wiard 300 series modules also use +/- 15v. Some 5U manufacturers also need a +5v source, specifically Synthesizers.com and some of the newer MOTM modules from Synthesis Technology, e.g. the MOTM-650. Most 5U manufacturers sell suitable power supplies:
 * Synthesizers.com sells +/-15v and 5v supplies
 * MOTM Synthesis Technology sells 2 supplies, one with only +/-15v (MOTM 900) and one which also has 5v (MOTM 950)
 * Cyndustries sells +/- 15v supplies
 * Modcan sells +/- 15v supplies

Synthesizers.com use a 6 way AMP MTA-100 connector to get power from the power supply to modules. Power is distributed from the power supply via a power harness which contains a number of these connectors. They sell 2 models: the small power harness has 20, the large has 40.

MOTM Synthesis Technology use a 4 way Molex KK 0.156" connector – those that only need +/- 15v. These are the same power connectors that Frac and Wiard 300 series module use. Some of the newer modules, that also require 5v, use the same type of connector but with 6 pins (not the same one as Synthesizers.com use). Power is distributed from the power supply via power distribution boards. There are two main versions – one with only 4 pin connections (i.e. +/- 15v only) and one with a mix of 4 and 6 pin connectors (providing +/-15v and 5v).

Modcan and Cyndustries have the same type of connector as MOTM to distribute power to modules except they only use a 3 pin version which provides +/-15v only. Power is distributed from the power supply via a distribution board. The Modcan one is completely compatible with Cyndustries modules.

Synthesizers.com with MOTM format
To only add one or two Synthesizers.com or MOTM format modules to a system mainly of the other format then use the Synthesizers.com QMPSA adaptor which convert between the two formats. This adaptor also provides a 5v source so Synthesizers.com modules can be run off a MOTM +/-15v power supply. For more than a couple of modules this probably isn’t the most cost effective solution though. For more modules it’s easier to use one of MOTM 995 convertor boards. This gives a combination of 6 pin Synthesizers.com with 4 pin and 6 pin MOTM connectors and can be connected to either a Synthesizers.com or MOTM +/- 15v and 5v power source.

The other option is to use a Synthesizers.com power supply with a power harness to connect to the Synthesizers.com modules. Strip one of the 6 pin connectors off the power harness and, using the colour-coded wiring guide on the Synthesizers.com site, wire the harness directly to one of the two main MOTM power distribution boards. They have binding posts that make this easy to do. If the 5v is not required for MOTM modules simply snip this wire short on the Synthesizers.com harness and tape it up.

Modcan with Cyndustries
Adding Modcan and/or Cyndustries is a relatively straightforward task and in many ways similar to connecting Synthesizers.com and MOTM together. The only difference is that Modcan/Cyndustries use 3 pin, rather than MOTM’s 4 pin connectors. With Modcan probably the easiest option is to ask for the power cables to be terminated with MOTM style 4 pin connectors. Then use exactly the same type of distribution system used with a MOTM or MOTM/Synthesizers.com mix system. Modcan are +/-15v only, 5v can be disregarded. This would also work for Cyndustries modules. The other option would be to use a Cyndustries power distribution board, which provides connectors for 4 pin MOTM and 3 pin Modcan/Cyndustries. This could be wired to a suitable power supply using binding posts as with the MOTM distribution boards.

STG Soundlabs Distro Board
A further option is the distribution board made by STG Soundlabs. These can be ordered with a combination of Synthesizers.com, MOTM and Modcan/Cyndustries connectors. They have a set of screw terminals for attaching the power supply. STG can also provide suitable cables for powering Synthesizers.com modules from this distribution board.