MIX 01 balanced inputs and outputs

Modules
#1

Hello all! I love the Mix 01 and I want to expand the input and outputs to case-mounted TRS jacks.
I am not very skilled at reading schematics and I am having a hard time deciphering what the pinout of the 3 pin and 5 pin bus headers are. Once I know the pinout I want to connect as many inputs and outputs as reasonably possible to my case.

My questions are:

  1. What is the pinout of the 3 pin and 5 pin headers?
  2. What are those keyed connectors specifically called? I am lost in the apparently vast world of 3 pin and 5 pin keyed headers as I search online for the male counterpart. I am happy to buy your bus cables and hack them to bits making what I want, but I would prefer to built my own harness.
  3. How many new connections does this method allow?
  4. Is adding new inputs/outputs as simple as soldering TRS jacks to the input bus/output bus, or is there additional components needed to accomplish this?

I appreciate your time and your work!

-T

#2

Glad to hear you like it, so do we! We had the same idea and made balanced input/output pairs with Neutrik jacks.

  1. they have ground in the middle, so the 3-pin is [1, gnd, 3] and 5-pin [1, 2, gnd, 3, 4], if that makes sense. So the 3-pin has two channels, 5-pin has four channels.
  2. JST PH
  3. So on the Mix 01 you have the inputs, normalled inputs, outputs and normalled outputs on 4 connectors. The ‘normalled’ ins/outs can be thought of as the default connections, if nothing is in the jack. So if you want to add balanced stereo outs, you’d use the regular output 3-pin connector. If you want the balanced outs to disconnect if you put something in the output jack on the mixer, then you’d use the normalled output connector. Makes sense?
    Same for the inputs, of which obviously there are four.
    In terms of ‘new connections’, the short answer so far might be zero, since you’re not accessing any channels beyond those available on the front panel.
    But there’s an additional stereo bus input connector, which lets you add two inputs, or the summed outputs from another mixer, directly to the mixer bus. This gives you in a sense unlimited expansion possibility.
  4. If you want balanced ins/outs then you need balanced line drivers / receivers such as the THAT 1606 / 1646.

Sorry if this is a bit long and confusing, in reality it’s really quite straightfoward! Perhaps the schematics will explain it better.

The easiest thing to do is to add balanced stereo outputs, for this you just connect a line driver to the output connector. Then you could add two or four balanced inputs, normalled to the mixer channels, meaning that if you plug something into e.g. channel 1 on the front panel then it disconnects the balanced input. If you want to go more advanced and add inputs straight to the bus, then you need to work out how you control the level of each input and how it is mixed on the stereo bus.

I should finish up the balanced input/output boards we made and make them available to DIYers. Happy to post the details if you prefer to build it yourself.

#3

Thank you so much for the thoughtful response!
This answers all my questions!

Thank you!

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#4

So here is my idea: I have been adding these VHM-314 bluetooth receiver boards to everything I own that handles audio like my Mackie mixer and my car stereo. I want to add two of them to the input bus but I dont want the 4 inputs to normal to the jacks, I want to be able to use the 4 inputs as well as the bluetooth channels if that makes sense. Each bluetooth receiver has a L/R/G output. I think this is definitely possible, I have ordered all the JST connectors. I think this could be a pretty cool addition. Thank you so much for the input!!! I was having trouble understanding what you wrote but then I looked at the schematic for a while, read what you wrote again and it makes sense. Just to make sure… connector U2 is the “normalled” connector that will cut off when a jack is used, and U3 is the input bus? I am still wrapping my head around how dc currents interact on the same circuit. Thank you!!!