Missing audio connectors

[evanshultz]

https://github.com/KiCad/kicad-footprints/blob/master/TODO.md doesn't include (or doesn't include many) various professional audio connectors:

• 1/4" / phono
• XLR
• speakON

Some of these footprints exist in the old library but are outdated. I'll update and expand this collection of audio-specific connectors.

[poeschlr]

Nice catch

[terjeio]

@evanshultz I want to make 3D-models for Pro-Signal PSG01550 and PSG01551 RCA/phono sockets, I have footprints for them already but most likely not KLC compliant so needs to be updated. Are these in the list of those you want to add or should I keep them on my todo list?

[evanshultz]

Go ahead. I'm going to be adding only Neutrik and Amphenol pro audio connectors (XLR, speakON, etc.) to start because they're generated considered "standard" or "reference" and most other brands of connectors are compatible. Thanks for the proposed contribution!

[evanshultz]

@poeschlr @jkriege2
Question on pin numbers for these audio connectors that don't have pin numbers that are sequential integers starting at 1. Here are some examples (see the PDF drawing):

• http://www.neutrik.com/en/speakon/speakon-chassis-connectors/nl8md-v
• http://www.neutrik.com/en/audio/plugs-and-jacks/1/4-vertical-jacks/nj6fd-v
• http://www.neutrik.com/en/audio/plugs-and-jacks/jacks/combo-a-series/ncj6fa-v

Shall we give them normal audio conventions (and have a corresponding symbol) which I'm used to? That would mean the following pin numbers (in order from the list above):

• 1+, 1-, 2+, 2-, etc.
• T, T+N, R, R+N, etc.
• 1, 2, 3, T, R, S

If we use this pin numbering, where should the symbol be centered? Most of them will not have a pin numbered simply 1. Do we use the closest pin number to 1? Or center the body geometry?

[jkriege2]

For the (switching) audio-jacks, there exist generic symbols, e.g.

So if possible I would make the footprints compatible to that symbol.

For the XLR- there are also generic symbols XLR3-XLR5, so I would make the compatible to thise, e.g.

For the combines XLR+audio-jack, I would define a new symbol that is specialized.

One could think about adding a second variety of the symbols with some kind of postfix like _StandardStereo or something and then mention in there as text the names of the standard audio-signals, maybe as pin-labels opposite to the pin-number (is there a global standard for those or is it just everybody does it that way to be compatible? In the first case, we should also name the standard).

For the footprint centering: I think here we should for now stick to the THT:pin1=(0,0), SMD:pkg_cntr=(0,0) rules, but maybe discuss whether we modify them for switches and connectors, e.g. like this:

1. vertical switch/connector: (0,0) marks the connector/switch main axis/fronpanel dril-hole-center ...
2. hor. switch/connector: (0,0) is on the switch/connector-axis and maybe on the proposed PCB-edge

I think that would also work for pots ... or generally for everything that can be operated by hand. We would get problems with the check scripts though and I'm not sure about my rule 2 above!

What do you think?

JAN

[evanshultz]

XLR uses just pin numbers, and that's fine with me.

But switching jacks have pin numbers that aren't standardized, in my experience, so using intelligent pin numbers seems best to me. It's far easier to check a schematic and PCB if the pin numbers are helpful rather than just numbers. For example, the symbol you showed above uses 1, 2, and 3 for S, R, T (normal audio convention would be T, R, and then S). And the 4-6 for the switched outputs. Using T, T+N, R, etc. is much more obvious and I believe would help KiCad users make sure their design is built right.

Since Neutrik is so well-known (and copied!) for audio connectors I put significant weight on using their naming conventions.

But, it would mean non-number pin numbers. We've talked about this a few times (I recall a discussion regarding switches but can't find it now). I'll rework the audio connector symbols (and footprints, if needed), and add new ones, if this is OK with y'all.

[jkriege2]

What do T,R,S,T+N,... stand for?
Then why not use 1,2,3,.... for the different rings on an audio jack, starting from the tip, numbering towards the mantling and then using S1, S2, S3, ... for the switches where the number indicates the ring they are connected to ... wouldn't that make sense + it allows for extendability of the system to any such connector.

[jkriege2]

Also I noticed Neutric using RM and RN contacts .... but I'm not so clear what these names stand for ...

[evanshultz]

@jkriege2
It sounds like you're looking at a combo XLR + 1/4" connector like NCJ10FI-V? The poles of an XLR are numbered 1, 2, and 3, with well-defined connections (1 = ground, 2 = +, 3 = -). Having switched terminals is commonly called "normalling", and thus the nomenclature of "N" terminals. The poles of a 1/4" stereo are also well-defined but use a different terminology (T = tip, R = ring, S = sleeve).

And XLR connector may use 1-3. A stereo 1/4" may use T, R, and S. But a combo connector, as described above, would naturally use both since the terminals are distinct and the signals to/from the connector are implementation-dependent so they cannot be known. (For example, the XLR and 1/4" may go to different circuits. Or they could be wired together. This is only known by the designer.)

Where did you see RM contacts?

speakON connectors (like NL4MD-V) have two poles for each terminal, which could be grounded or not, and adopt 1+, 1-, 2+, etc. markings. Regardless of the electrical connection, one signal (1-) will be the reference for the other (1+) so they go together. Also, this marking indicates polarity/phase through the device (audio input to audio output) which is also extremely important in an audio system.

If we don't adhere to this well-understood terminology in the audio industry for KiCad's audio connectors, then I believe (with relevant experience) our symbols and footprints will be unintuitive.

[jkriege2]

I found that there: http://www.neutrik.com/zoolu-website/media/download/2804/Jack+Circuits (lower row)

[evanshultz]

If the jack is normalling (typically passes through, but is broken when a terminal is plugged in), the nomenclature is *N.

I'm honestly not sure about the "sleeve make" and "ring make" versions, but I suspect they're the opposite of a normalling jack in that plugging in a terminal makes a connection instead of breaking it. This might be used for an effects send/return connector. The nomenclature for those signals is *M while the other terminals are normalling with the common nomenclature.

Does that answer it?