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MOTM, MU, I'm confused
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author MOTM, MU, I'm confused
l3v3l6
I'm new to this stuff, so pardon my noobishness. What's the more popular format in the large module styles, MOTM or MU (5U?). The reason I'm asking is that I'm working on a PCB where I want to follow the same form factor that Synthensizer.com and MOTM uses but I'm stuck on which power connector style to use. The dotcom connector uses a 6 pin MTA with +5 and they claim to be an industry standard. But, looking at the MOTM boards I'm seeing here, 4 pin connectors are the choice, with no +5. To further add to the confusion MFOS is 5U and appears to have 3 pin connectors.

Is there a standard for the location of module power connectors, top, bottom, left, right?
paterursus
Dotcom/MU is by far the more common format right now. MOTM is a DIY-heavy format, and it's almost entirely in that guise that it survives. As you've probably figured out, they're the same height, but MOTM has a different minimum width unit than Dotcom. I can't speak to MOTM - my 5U modules are all Dotcom - but I have power connectors at the bottom of the boards, in the middle, and at the top. There doesn't really seem to be a standard there.
If you check out this sticky thread in the 5U forum there's a lot of good information on the power connectors. As you'll see in that thread, you can build adapters for the differing formats, and there are people who have both in their systems. A number of modules actually have headers for both. If you're picking one and want to go with the more common format, go with DotCom.

EDIT:
Here's the thread on making the format adapters.
cornutt
To add to that, they both have their advantages. But the 5U market is probably not large enough at this point to support two formats, and alas, MOTM seems to be on the way out. Fortunately, power and signal levels are the same between the two, so a Frankensynth incorporating both is possible. That's what I have.
abelovesfun
I also have MU and MOTM and euro. They all play together very nicely, I just put extra 1/8" jacks in between my sets of MOTM mult jacks. It is sad that MOTM has been... slow to have any new stuff, it's a great format that is much easier to design for since the panels are easier and cheaper to make. I want to make 5U offerings of my modules, but the idea of hand-braking every single MU panel puts me off it.
l3v3l6
paterursus, cornutt, abelovesfun, thanks for the excellent information.

abelovesfun, what do you mean by hand-braking?
JohnLRice
Welcome to Muff's, l3v3l6! w00t

paterursus has already provided the links I would have! thumbs up I'll repost here the handy chart that sonicwarrior created and I've updated a bit a few times.


And I agree with what others have said, the MTA-100 connector and Synthesizers.com wiring standard is used/supported by a strong majority of all 5U makers.

You might consider setting up your modules so that they can also run on +-12v, not only to make it easier for people with 5U systems that have +-12v supplies but also so you can more easily port over to eurorack if desired. Especially if you make your PCB eurorack size compatible . . . I think it's brilliant the way STG Soundlabs and Modcan etc stated making their modules to have eurorack sized main PCBs and then make separate PCBs for the panel controls that the main PCBs plug into. thumbs up we're not worthy

Regarding the difficulty/expense of "proper" MU panels: Take a look at Rob Hordijk's panels, they are MU sized with MU mounting holes but constructed like flat thick MOTM panels. Might lose some sales but . . .something to consider if it means the difference between not making modules at all or actually getting production rolling? cool
JohnLRice
l3v3l6 wrote:
abelovesfun, what do you mean by hand-braking?
It's a machine used to fold over the edges of sheet metal, like the thin MU panels to give them rigidity.
LED-man
On my website are informations about the Panel sizes, power/power connectors too:

https://www.dsl-man.de/display/SKM/5U+Format+knowledge
JohnLRice
LED-man wrote:
On my website are informations about the Panel sizes, power/power connectors too:

https://www.dsl-man.de/display/SKM/5U+Format+knowledge
Good collection of data. thumbs up You might want to add information about the differences in mounting holes, something like the following? (this is off the top of my head so please verify and/or enhance)

MU has mounting holes centered on the middle of the "unit". A 1 MU panel has a single hole top and bottom and a 2 MU panel has two holes top and bottom, etc. For panel sizes 3 MU and up some manufacturers might not put mounting holes centered over every MU.

MOTM has mounting holes in the corners of the panel that conform to standard rack rail spacing. Almost all panel widths have 4 mounting holes with very few exceptions. So a 1 U MOTM panel will have two holes top and bottom and so will a 4 U MOTM panel and even a 7 U panel might only have two holes top and bottom.
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