Passive Line Splitter question


2016-03-22 2:54 am
Hi all,

I have a Presonus Firestudio Project and a Mackie Profx16.

I'd like to split the incoming signal XLR (Mic or Line) and feed the two devices simultaneously.

The Presonus has the following input impedances: Mic 1.6 kOhm and Line 10 kOhm.

The Mackie has Mic 3.3 kOhm and Line 20 kOhm.

I want to introduce a resistive load to the Presonus feed to balance the split signal.

1.7 kOhm resistors to pins 2 & 3 (Mic) and 10 kOhm resistors to Pins 2 & 3 (Line)

I have drawn a diagram, however not sure about the correct placement of the resistors or whether I have to halve the load seeing there are two pins (2 & 3). Can anyone point me in the right direction or offer some newby advice?

See attached.

I have a 24 point patch panel that I have to wire up (6 Mic and 18 Line), and I want to get it right.

Thanks in advance!
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I am guessing that should be kOhms rather than ohms for the mic inputs.

You should be able to use/make simple splitter cables there just fine. Audio signal transmission works on the premise of output impedance being much smaller than input impedance, so no power matching there (if anything, this is voltage matching).

Of course the source will see both cable lengths and inputs in parallel, but assuming your cable isn't super long this shouldn't be much of a problem, and 1k6 || 3k3 still is a good kOhm, high enough.

All of this assumes that inputs and outputs are properly balanced and wired up in accordance with AES48-2005. You may have to insert some series resistance into one leg's shield otherwise.