Hoping for some help with switch wiring

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New member
Feb 4, 2022
Hello! I'm hoping for a little help. Probably easy for someone more experienced than I.

The TL;DR is that I'm wondering if I can wire an Elma Type 04 switch (4:3) as seen in the Stereo / Mono / Mono Rev diagram below.


I'm following this guide for a monitor controller build. It's all very straightforward except that I noticed that his switch diagrams don't seem to apply to my switches.

I'm not worried about the input and output switches, as I was able to figure out how to convert the connections to work on my switches. BUT... The STEREO / MONO/ MONO REV switch seems to need to be wired very specifically, and I'm not sure if my switch should be wired exactly like his diagram, considering I had to create my own switch diagrams for the input and output.

For example, here is his input switch:


And based on tracing signal flow on the connectors and switch action, I had to modify to this (you can reverse the L/R labels if that makes more sense):


Now here is his diagram for the STEREO / MONO/ MONO REV switch:


I can certainly wire it as shown, but again, I'm worried that since I discovered that his connectors differ from mine, that it won't work as expected.

Switch Information

Both of us are using 4 pole, 3 position switches (4:3)

He's using Altronics and I'm using Elma Type 04. Here's the data sheet for my Elma switch.

My switch:

At this point, things start getting fuzzy for me. I don't really understand what they're showing me in that data sheet and image above.

I don't even understand if all these diagrams are from the view of the BACK of the switch. You know – the way you'd look at it if you were soldering it.

My Question

Sorry for the long post. I suppose my question is if the wiring in the diagram of the STEREO / MONO/ MONO REV switch can be used for my Elma Type 04 switch.

If not, then I'll probably need some hand holding on how to convert the connections.

Thanks so much!!!


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Well-known member
Jul 2, 2007
Both switches are identical so your Elma switch is perfectly fine for the job.

I am also trying to put together a monitor controller at the moment and I like the very nice Rob Squire/Ambertech article.
But I’m wondering why there are no resistors for the mono sum on this switch ?
I know that the resistor values depends on source and load impedance for switching to mono, so the resistors values would have to be chosen on a case to case situation and vary depending on each system setup.
I’m pretty sure the mono switch works ok as is, but isn’t it better to add resistors for summing to mono ?
Wondering why these resistors are not even mentioned in the article.
Thanks for any explanation