Balanced Input & Output

so my Zynthian is running. But I have an important question for me: the audio outputs are balanced outputs, but my self-built mixer does not have a balanced input. How do I connect and what do I use to connect the Zynthian to my mixer?
Thanks for the answer.
Greetings Klaus

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Hi @Tangram

Welcome to this wonderous world / universe.of Zynthian. I hope you enjoy all it has to offer, not just the device but the friendly community too.

There have been a few posts in this forum about balanced inputs and outputs, e.g. this one announced their arrival and discussed their configuration.

The inputs are configurable which is quite cool but outputs are fixed TRS balanced. This is not an issue though. Connecting a standard TS mono 1/4" jack to the Zynthian will carry the output signal just fine as if it were single ended (unbalanced). You can use mono TS cables to connect your Zynthian to your mixer without issue. That is probably the most common configuration of Zynthian users.

thanks for the quick answer. But that can’t be quite right.
I used normal mono TS cables and no sound comes out of my speakers. Only when I pull the plugs about 1cm out of the socket do I get contact and I hear the Zynthian ->see picture.
Is that right?
Am I using the wrong cables?
Or do I have to use a stereo plug and solder the mono plug accordingly?

Otherwise, the Zynthian is a really cool synth.

Best regards


Which Zynthian version do you have?


this is my system


Do you have photos of how the inputs and outputs are wired from within the case?



Apologies, it’s rather difficult to actually see the wiring on the TRS connectors.

How is the self built mixer input wired? Does it work with other balanced output stuff?

Yes, it works with Jeanny, MicroMonster and so on. No problem. Only with the Zynthian there is no output.

I have the newest Kit with the ZynADAC v1.0 . For the photos, I must repuild my zynthian, but not this evening.

Hello, sorry it took me so long to reply.
This is my output card.
If I don’t put a plug in Out, no matter L or R, there is no signal on the signal outputs. See picture red points.

If I insert the plug all the way into the socket, no signal comes through. If I insert the plug to just under 1 cm, there is a signal at the red dots, see picture.

I use plugs like this:

What should I do?
Maybe someone knows an answer.

Greetings Tangram

Will you pay a picture of the connector that connects this board to the sound card? Born ends what plugged in.

Do you mean this connector?
P.S: I have to remove it first and then take a picture. This picture here is from the assembly instructions.

We need to see it in place to see try to diagnose your problem.

I will make a Photo this evening.

This is right. Signal is sent to headphones when no jack is plugged in the line out connector.
You can check the ZynAuCon module scheme in the zynthian-hw github repo:

(zynthian-hw/ZynAuCon/ZynAudioCon.svg at master · zynthian/zynthian-hw · GitHub)
(* this is from the latest version that adds a volume pot)

As you can see, when no jack is plugged in the line out connector:

  • OUT+ is “normalled” to NOUT+, that feeds the headphones
  • OUT- is normalled to ground.

When a mono jack plug is inserted

  • OUT+ is grounded because the ring is bridged to the sleeve (ground).
  • OUT- is disconnected from ground and it’s drived to the tip.

Your problem seems related to the jack plug or the cable. It seems that the tip is not well-wired. Have you tried with a different cable?

On the zynthian side, it could be a faulty jack connector (female), but it would be bizarre that both were broken in the same way, and you seem to have checked both of them.

But i suspect you already tested with several cables ;-DD

So, in this case the only possibility would be that the OUT- signal is not arriving to the ZynAuCon, neither of them.

You could try to swap the ribbon that connects the ZynADAC to the ZynAuCon. If the OUT- pins are faulty, it should work when swapped.

If this is not the case, we should think that the ZynADAC is faulty. Perhaps a bad PCM5242 ;-(
I hope no!!

In such a case, you still have an easy solution, given that you don’t need the balanced output, of course. Simply build a “custom” TRS cable with tip-ring crossed, so you can use the OUT+ in your mixer mono input.


Sorry, in my post from 3.2.2022 in the 2nd picture you can see that I have a headphone jack and a volume poti in my output card. The picture from 6.2.2022, as written, I have taken from the construction manual. That was probably my mistake.
I will try again tomorrow morning with different plugs.
Then I will remove the ribbon cable from the Zynaucon 1.4 and measure directly on the ribbon cable whether the signals arrive. I may then have to remove the circuit board of the Zynaucon 1.4 and send it to you for checking.
I’ll get back to you tomorrow. Now I have to sleep.
Greetings tangram

I’ve checked everything again. Ribbon cable is ok. No pin bent. The ZynADAC is OK, otherwise no sound would go into the mixing console at all.
Just build me a “custom” TRS cable with crossed tips so I can use the OUT+ in my mixer as a mono input.
I don’t know any other way.
Greetings tangram

So, I have now soldered 2 cables and it works now :+1:.
Thanks again and until the next problem :grinning:.
Greeting tangram