Audio Out for Eumig 824 Sonomatic

[Steve Klare]

Best of Luck!

I can testify that making something like this work well feels really good!

[Ethan Knightchilde]

I’m sure I’ll be posting questions once I start.

[Steve Klare]

Make it quick! (It hurts less that way!)

-but seriously: make sure you end up with at least one cable that is as long as you need it to be, even in the case it means sacrificing the other connector.

You'll need to strip the wires and use your ohmmeter to trace out Pins 2 and 3.

I'm surprised your Elmo is Hummy: usually these are pretty good along these lines.

[Ethan Knightchilde]

The DIN cable and 1/4” jacks have arrived. Anything I should keep in mind before I cut the cable?

[Ethan Knightchilde]

I ordered the DIN cable, 1/4" plugs, and a female 1/4 TRS to L/R male 1/4 TS breakout cable. I'll let you know how it all goes.
Incidentally, I believe my ST-1200HD generates a bit of amplifier hum. Output from the yellow monitor jack creates an unbearable noise but the green monitor jacks aren't nearly as bad.

[Steve Klare]

This is where the mixer itself decides. Mine is designed to accept either TRS or TS plugs and have the inputs be balanced/unbalanced based on that choice.

Is this mixer new to you? If not, what's worked there before?

My gut is telling me if your mixer inputs are dedicated as balanced only, a TS will work. (My gut is good...not infallible!)

It would be interesting to build a kludge from parts drawer stuff and see what happens.

[Ethan Knightchilde]

Is this what you mean?

1/4” TRS to a left and right 1/4” TS

-or what you want to avoid?

Basically yes. It would be a female TRS breaking out to two male for mixer input. But if the mixer is expecting a balanced input, what’s the solution if it wants left and right 1/4”?

[Steve Klare]

Is this what you mean?

1/4” TRS to a left and right 1/4” TS

-or what you want to avoid?

[Ethan Knightchilde]

So there really is no way around going from a 1/4” TRS to a left and right 1/4” TS breakout and it is what it is?

[Steve Klare]

My experience with these has been chains of adapters are a real headache! For example, my mixer output to my amp (30 cable feet away) looks like this:

Two 1/4" TS to 1/8" TS adapters plug into the mixer right, left outputs, then a double 1/8" TS to single TRS 1/8" stereo female adapter (a "Y") for my 1/8" TRS male cable to plug in and run 30 feet to the back of the house. (Let's not even talk about what it's plugging into back there right now!)

Now: this is 3 sets of contacts in succession and the 1/8" inline ones are a little...tentative!

So help me, if I even think about this connection too much I lose a channel or sometimes both! Sometime soon I want to simplify this to two 1/4" TS plugs hardwired to a robust 1/8" TRS jack mounted in a plastic box.

Sometimes you need to just give up and build exactly what's needed, as simple as possible.

[Ethan Knightchilde]

Related question. The stereo inputs on the mixer are left and right. Balanced per the spec sheet. All the 1/4” stereo breakouts (female to male) I’ve seen are TRS female to TS male. Is the solution for that to get a breakout that is 1/4” TRS female to two male RCA style plugs (though the female RCA to make 1/4” adapter that would go between those and the mixer are TS as well)?

[Steve Klare]

Hi Brian,

Actually it's pretty easy to tell. If it's just amplifier hum, when you run the volume up and down the hum comes up and down with it. A ground loop is always there, even with the amplifier turned down to minimum. At the same time, fixing the ground loop does absolutely nothing for amplifier hum: that's a battle for another day.

I started seriously messing around with this maybe 2008-2009 and I found the internal grounding on my own Eumig 800 was pretty bad compared to an Elmo ST. I was measuring several hundred millivolts between that DIN Pin 2 and the third prong on an outlet strip it was plugged into. I found that the third prong on the machine's power inlet wasn't connected to the main chassis, but to the frame of the power transformer. I took out one of the mounting bolts and put a star washer under it and the several hundred millivolts dropped way down. I've read stories of this connection becoming so poor someone actually got shocked by one of these. (maybe someone didn't re-tighten those bolts all the way...)

This is mostly preventative anyway. Right now I'm running two Elmo ST-800s, a video projector with disk player and a Kodak Pageant through my mixer. One of the STs is running unbalanced because I want to ground that whole end of the audio system. Everything else is operating balanced. To me it's just good form, kind of like stopping at a stop sign at 4AM: it's probably not completely necessary but it takes care of trouble even before it's arrived.

In Ethan's case balanced/unbalanced might not even be a choice if his inputs are always balanced. The question then becomes which plug does he need to use to correctly hook up?

[Brian Fretwell]

Ethan,

I don't think an imbalanced connection is the way to go if it is a choice. Eumig 800s often have grounding issues and connecting imbalanced can give you a ground loop.

How this manifests itself is something like this: Have you ever stood next to a speaker, for example a public address system, and heard a low, buzzy tone always coming out? That's what we are trying to avoid here.

The first time I hooked a projector into an Amp, I had this and it sent me back to the internal speaker for a couple of years it was so nasty!

Unfortuantely with some Eumig projectors that it more the hum bucking coils being out of adjustment, not an earth loop. I'd compare the output an extension speaker with that through the external system before deciding what it was.

[Steve Klare]

OK, does your manual describe the 1/4" plug you need to use as something like "TRS" or "TS"?

This is where it can start to get just a little bit weird! With my mixer, a balanced monaural input requires what you (and most everyone) call a "stereo" plug. As a matter of fact, a balanced stereo input requires TWO of them! (-one per channel). On the other hand, an imbalanced stereo connection would require two "monaural" plugs! (ouch!)

In this scheme of things, it's not Stereo Left (tip), Stereo Right (ring) and Return (sleeve) but instead Signal (tip), Balanced Return(ring of a TRS Plug) and Imbalanced Return (sleeve of a TS Plug)

When I first encountered this, it made my head hurt!

I'm hoping this doesn't apply to you. If your inputs are always balanced, either TRS or TS might work, but I'd like to let the manual speak for itself.

If it doesn't apply to you, please try to forget it: you may sleep better!
.

TS Plug(Left) vs. TRS Plug (Right)

[Ethan Knightchilde]

The mixer says that the mono input channel is electronically balanced. That aside, I haven’t found a single balanced mono 1/4” plug. They’re all stereo!

If I get a stereo plug like the one below, is it going to affect my ability to pan or will there be any annoying jiggling with the plug in the mixer's jack, etc? (It seems I've run into those both before at some point.)

https://a.co/d/24O3mQt