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Some Eurorack technical questions
MUFF WIGGLER Forum Index -> Eurorack Modules  
Author Some Eurorack technical questions
synthmaker
I was wondering if any experienced Euro format DIYers or makers
could point me to some info about the various dimensions associated with
the format especially regarding panels and clearances.

Specific questions that I have so far not found much info on include:

What is the standard thickness of the panels?
How much clearance should be allowed between panel mounted board edge and panel edge so as not to interfere with the top/bottom mounting rails?
Is standard panel height 128.5mm?

Also I'm sure this will stir up a quagmire of pain and suffering but
what would be the best choice of power connector to use
in order to be compatible with the majority of other Euro modules?
I notice that there seems to be a few different ones in use.
Would the 16pin slotted and keyed connector be the most
universal or ?. I really only need connections for +/-12V and GND.

Also are people using anodized blanks and silk screening graphics
or are they using a metalphoto or engraving process?

And lastly what are the favored choice of jacks? Cliff or ?
and are they 3.5mm or 1/8"

Any info would be much appreciated
Thanks
Bruce
phono1337
http://www.doepfer.de/a100_man/a100m_e.htm

all the mechanical details you should need
jarvis
i usually give myself 7mm of clearance on the top & bottom, but that's cutting it a little close in terms of tolerance (works fine for the vector rails I use though).

I tend to use .1" thick aluminum for panels, and they seem to be comparatively the same as the manufactured modules I have.

Kobiconn makes decent 1/8" jacks, but make sure you check the length of the jack collar - some of their shorter ones don't work so well with the .1" thick panels. There seem to be a lot of people that grumble about the Cliff jacks, so maybe avoid those, but they are handy for perpendicular mounting of PCBs to the panels. The kobiconn jacks seem to have a tighter footprint, so you can squeeze more in on the front panel with those.

I haven't honestly paid much attention to 1/8" vs 3.5mm. I doubt there is any kind of consistency between manufacturers on that, let alone with users' patch cables. Maybe I'm wrong?
negativspace
I'm very interested that you're very interested in these things. eek!
Monobass
I'm a big fan of the kobiconn too (make noise, malekko, Cwejman etc)
synthmaker
Thanks for all the info.

Any comments on the best power connector to use.
The Doepfer one looks like a standard 100mil x 100mil dual row header.
Is this the case? And then a ribbon IDC connector.
No polarity so good for reverse connections.
I like the enclosed keyed box style but can it be used with the Doepfer?

.1 thick panels are surprisingly beefy for 3U height.
I guess without the structural rigidity of side bending it needs the additional heft
to keep from flexing especially in the narrower widths.
It does challenge certain hardware choices though.

Bruce
Monobass
I measured a malekko panel thickness today actually - 1.5mm or 0.06 inches

Not sure I have anything thicker than that.
amphonic
I leave 10mm clearance top and bottom for the rails. Metalphoto for the graphics.
Hi5
keyed IDC connectors are nice to avoid plugging things in backwards. The typical Euro buss board doesn't use shrouded connectors so going keyed or not at doesn't make a difference functionally.
Hi5
so does this mean we will see a Euro line of Modcan modules?
I really hope so. screaming goo yo
daverj
Actually, there is no such thing as an 1/8" jack. They are 3.5mm. The other format that is similar is the Switchcraft Tini Jax, which are slightly larger and not compatible. Those are .141" while 3.5mm is .138" That's enough of a difference for 3.5mm cables to be loose in Tini Jax, and Tini cables to damage 3.5mm jacks.

The term 1/8" jack came from them being roughly 1/2 the size of 1/4" jacks, but they're not actually 1/8".

I personally find the Cliff jacks to be too fragile. Kobicon (from Mouser) are considered good. Some of us have been using jacks from a Chinese manufacturer mentioned in this thread:

https://www.muffwiggler.com/forum/viewtopic.php?t=6457


I use Metalphoto panels that are .090" thick. Some manufacturers use .063" thick panels. I believe Doepfer uses 2mm, which is .079"

I make my boards a maximum of 4.25" tall, centered on the panel, to give enough clearance. Some rails are slightly thicker than others and if you cut it too close, the modules might be a tight fit in some cases. I measure Doepfer rails as having 4.4" between them, so 4.25" gives .075" clearance between the board and rails.

The panel sizes are shown in that link posted a couple of messages above, on Doepfer's site. The panels are typically about .012" - .015" narrower than the calculated HP width. This gives a little wiggle room between modules. I usually make my boards .100" narrower than the calculated HP width to give them .050" clearance on each side, and to account for slight misalignment to the panels. Theoretically that extra clearance isn't needed, as long as the boards are no larger than the panel width.

I use keyed, shrouded headers for the power connectors, and make sure my ribbon cables have both connectors crimped on correctly so pin one of both connectors matches the stripe on the ribbon. That way if the user has a power distro board with keyed headers, the ribbon will work correctly. Some manufacturers are sloppy about this and just crimp the connectors on any which way, since Doepfer power distro boards aren't keyed. I think that is bad form. I made a ribbon tester that has keyed headers, so it not only tests the ribbon cables for opens and shorts, it also checks that the keys are facing the same way.

It's common to put the power connector on the back of the module in a vertical orientation with pin 1 (-12v) facing down. It's not required, but it's one of those things that is a good practice to minimize user confusion (power distro boards all have vertical headers with pin 1 down). But it's very important to clearly mark the back of the module with a "-12" marking at the correct end of the connector.

You can get away with using a 10 pin header on the module if you aren't going to use the 5 volt rail. But of course the supplied ribbon cable must then be 10 pin to 16 pin since power distro boards are always 16 pin. It doesn't hurt to use a 16 pin header

If you have a lot of logic on the module, it wouldn't hurt to consider designing it in such a way that a jumper on the back of the module could select between using the 5v bus vs the 12v bus to supply your logic (or a low voltage regulator). 5v power supplies are not all that common in Euro cases, so it's probably not a good idea to expect them, but if enough new modules give that option it will encourage case makers to start including powerful 5 volt supplies, taking the heavy load off of the 12 volt rails. Certainly not a requirement, but something to consider.
Jason Brock
synthmaker wrote:

Would the 16pin slotted and keyed connector be the most
universal or ?. I really only need connections for +/-12V and GND.


Keyed connectors are fine but I've run into one or two situations where they are on the wrong side and I had to file them off. I don't think they are necessary, especially if you don't need the +5v or gate/cv busses.

The majority of manufacturers who only use +/- 12v and ground will still use a 16-pin header, but then only use a ribbon cable that is the width of 5 pins.
I think this is by far the best solution because you can instantly look at this cable and know which way to plug it in.

lizlarsen
Dave explained it all really well. Just chiming in to say I also use 0.09" panels and metalphoto. My board heights are all 4.375", centered on the panel, which is tight but no one has had any clearance problems with that yet. The extra height really helps with some layout concerns for parallel-mount boards.
appliancide
daverj wrote:
Actually, there is no such thing as an 1/8" jack. They are 3.5mm. The other format that is similar is the Switchcraft Tini Jax, which are slightly larger and not compatible. Those are .141" while 3.5mm is .138" That's enough of a difference for 3.5mm cables to be loose in Tini Jax, and Tini cables to damage 3.5mm jacks.

The term 1/8" jack came from them being roughly 1/2 the size of 1/4" jacks, but they're not actually 1/8".

I personally find the Cliff jacks to be too fragile. Kobicon (from Mouser) are considered good. Some of us have been using jacks from a Chinese manufacturer mentioned in this thread:

https://www.muffwiggler.com/forum/viewtopic.php?t=6457


Just to expand on this a bit, I checked some datasheets to get the specs from the more common "3.5mm" jacks....

Kobicon - 3.6mm ±.04mm
CUI - 3.6mm ±0.05mm
PJ-301B from the link above - 3.6mm ± 0.15mm
Cliff doesn't have their datasheets online as of this posting
Switchcraft 41 aka Tini-Jax - 3.68mm or .145" ± 0.005" (which is .127mm, not much tighter than the no-names above)

Switchcraft does seem to be making 3.5mm jacks that do conform to the accepted standard being used by the Asian manufacturers:
http://www.switchcraft.com/Category.aspx?Parent=651

dizzy

Then there's the plugs...
synthmaker
Wow tons of info thanks.
This should get a sticky.

I am not sure at this point if I will be going Euro on a regular basis
but I have a sequencer that I mentioned in a previous post
https://www.muffwiggler.com/forum/viewtopic.php?t=33713
that I think will receive a good reception in the Euro format.
5U guys like their knobs and jacks to be big and have only one function
per knob and are somewhat less receptive to unconventional modular interfaces.
Also I have spent close to 700 hours developing this design and would like it to reach a larger audience than 5U can provide.

Bruce
synthmaker
Question about screw mount slotting.
I see some makers are providing a slotted mounting screw hole.
How do you get this done. Any Metalphoto users
know if this is a standard punch size and if so what size is it?

Thanks
Bruce
akos.turi
I designed some basic, eurorack sized modules. Pots are mounted on the PCB. If I put the modules in the rack, circuit boards are on the right side (pic attached). Every other company use the left side to put the PCB. Would it be a problem? Should I follow any company standard?

My panels (original):


My panels should be? hmmm..... (mirrored):
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