Audio Out for Eumig 824 Sonomatic

[Steve Klare]

Ethan,

I'd say you need to look into the instructions for your mixer and find out what it takes to produce a balanced connection. On my mixer you need a TRS (Tip-Ring-Sleeve) plug with Eumig's pin 2 connected to the ring. The plugs you show are 1/4" TS (Tip, Sleeve), which would only be able to provide an unbalanced connection on my mixer (Eumig Pin 2 connected to the sleeve).

Does this have to apply to your mixer too? -not in the least! That's why you need to do research here. (You may even find these inputs are always balanced and the choice of TRS or TS is unimportant!)

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!

(The DIN cable looks fine! At least that part was simple!)

[Ethan Knightchilde]

Do you think these will work ok?

https://a.co/d/3TLrqcu

https://a.co/d/cD3BFuq

[Ethan Knightchilde]

Ethan,

What you have there is a DIN 2 pin loudspeaker connection. It's what Janice was talking about in post #20, and what I referred back to in post #51. It is a usable signal for this with the caution it is meant to drive a speaker and depending on the volume setting, the voltage could be high enough to damage a line level input. There are commercially available devices to reduce the voltage and prevent this, but I built my own (-because I like to build things!).

There is a standard polarity here. I'll do a little ohmmeter work later and be sure what it is before I say so.

The cover that comes with the 1/4" phono plug covers all that needs covering.

(I'm kind of curious what that Eumig spec. sheet says underneath your connector!)

Gotcha. OK then I’ll look for a DIN to DIN cable and a phono plug as planned. Here are the spec pages.

[Steve Klare]

Ethan,

What you have there is a DIN 2 pin loudspeaker connection. It's what Janice was talking about in post #20, and what I referred back to in post #51. It is a usable signal for this with the caution it is meant to drive a speaker and depending on the volume setting, the voltage could be high enough to damage a line level input. There are commercially available devices to reduce the voltage and prevent this, but I built my own (-because I like to build things!).

There is a standard polarity here. I'll do a little ohmmeter work later and be sure what it is before I say so.

The cover that comes with the 1/4" phono plug covers all that needs covering.

(I'm kind of curious what that Eumig spec. sheet says underneath your connector!)

[Ethan Knightchilde]

Not to muddy the waters but…

I was looking through my box of legacy cables and connections to see if I could find anything usable before buying more and I found this.

For my intended purpose of connecting to a mixer and then the receiver, would splicing this to a cable with a 1/4” mojo jack for output through the speaker jack work equally well? (Janice had shown this in an earlier post.)

Another question—regardless of which option I should got with, what should I look for that will “wrap” the area of the cable where the soldering is done?

(Sorry for all this. Thought I DID preface this entire thread by saying I am unfamiliar with such topics.)

[Steve Klare]

OK, you've got your balanced input, which is good. On my mixer (Behringer Xenyx 802), the lines are configurable unbalanced or balanced (all depending on the use of a TS or TRS phono plug). Beyond the balanced inputs' benefit of canceling out ground loops, it also doubles the input impedance from 10 kOhms to 20 kOhms, this also eases the reduction of input voltage level I was talking about a few pages ago because of the Eumig's 50,000 Ohm output impedance.

I hope yours does the same.

One of the nice things about using a mixer, is it deals with all this kind of connection nonsense in isolation from the input to the amplifier. Once you have that part in good order it's always the same.

Janice's idea of using the speaker output to drive a line level input has the merit of very low impedance, but scares me a little because the voltage available can be too high for line level. When I wanted to plug in my Kodak Pageant, I had no choice but to go this way, so I put a voltage divider in between:

Getting Line Level Audio from a Kodak Pageant

[Ethan Knightchilde]

I guess if it's shielded cable that in of itself should be good enough. Our kind of audio isn't that demanding.

What kind of mixer do you have?

Samson MDR 624. I’ll use the mono line in channel 2 for this. (Channel 1 will be from
the Elmo 16CL and channels 3/4 will be from the Elmo ST1200 HD.)

The mixer plugs into a Yamaha Receiver RX-V677.

[Steve Klare]

I guess if it's shielded cable that in of itself should be good enough. Our kind of audio isn't that demanding.

What kind of mixer do you have?

[Ethan Knightchilde]

Good times. For the cable, are DMX and MIDI anything special or doesn’t it matter as long as it’s 5 pin male to male?

[Steve Klare]

I'm with Ken here: soldering into a 5 pin DIN can get difficult. I think the easy way would be to buy a 5 pin DIN to 5 pin DIN cable twice as long as you want and cut in in half (-lengthwise!). This cable will have every pin wired, so you should use your new Ohmmeter Skills to find the bare wires to pins 3 and 2.

Soldering onto a 1/4" phono plug is much easier. (-just don't forget to slide the cover over the cable first!)

The question then is what is your mixer expecting (-and YOU thought you were done with all this!😉)

If the mixer is expecting a balanced signal, solder the wire for pin 3 to the tip terminal and the wire for pin 2 to the ring terminal.

If the mixer is expecting an unbalanced signal, solder the wire for pin 3 to the tip terminal and the wire for pin 2 to the sleeve terminal.

(Given the grounding situation with the average Eumig projector, "balanced" is the way to go.)

Oh! -and when you are done, coil up the unused cable-half and throw it in the drawer (You never know...)

[Ethan Knightchilde]

Next stage! For someone who has never done this before, what you would recommend in terms of materials? Should I find a cable of suitable length with a mono 1/4” jack, cut the cord at one end, and solder onto a 5 pin DIN?

[Steve Klare]

"Anyway, is the suspicion that the DIN output is a mix down of whatever the heads pickup based on the switch for track 1, 1+2, or 2?"

Yes.

[Ken Finch]

The user manuals for the Eumig 810d and the Baur 610 both show which pins should be used for the line out. I run the output from both to my Yamaha audio video amp via a Realistic mixer with no problems. I use standard screened leads for all the interconnects. Soldering DI N plugs can be a bit tricky. Use a small vice to hold the plug which also will act like a heat sink. Ken Finch😉

[Ethan Knightchilde]

Interesting. The 824 is dual 8 but doesn't have separate sound heads for each gauge.

Anyway, is the suspicion that the DIN output is a mix down of whatever the heads pickup based on the switch for track 1, 1+2, or 2?

[Steve Klare]

Hi Paul,

I think Ethan's ohmmeter measurements show that there are only two active pins in that connector. Since one of them has to be a signal return, then there is only one left to be "signal" therefore this machine can't be outputting two channels of audio.

The fact that his schematic has only one opamp amplifying the signal from the head kind of reinforces this theory.

It gets interesting when you look over in the West where the heads are:
.

Now, in my imagination, this is a workable arrangement to get a twin track soundhead. That switch imediately to their East is three positions. Slid upwards it shorts the upper head and allows the lower head only to be amplified. In the middle, it shorts nothing and puts the two heads in series for blended monaural from the two channels. Slid low, it shorts the lower head and allows the upper head only to be amplified. So this should be the right diagram for this machine.

Those two coils in series with each head I believe are a sighting of those famous hum-buck coils out in the wild! (Get your binoculars!)

(Of course these symbols aren't the same ones I'm used to, so I'm interpreting them the way I want to!)

The recording heads are also in the schematic, way down south.

That other schematic for 810D also has two heads, but that's different: they are marked "Super 8" and "Regular 8" because that one is built for both.