Unbalanced Output To Balanced Input Cable
The unbalanced gear will get it s ground via the mains so you want to separate the ground loop.
Unbalanced output to balanced input cable. At the unbalanced output connect the screen wire to the input ground pin together with the cold wire. A high quality isolator using an input transformer with an internal faraday shield increases rejection to almost 100 db at 60 hz and about 65 db at 3 khz. However with this method there are cases in which the user could experience high levels of unwanted distortion and in the extreme cases the output device could be damaged by plugging in a standard unbalanced cable. The structure of a balanced audio cable is similar to an unbalanced cable with one addition.
The diagram above shows how the cable works. At the balanced input do not connect the screen wire to anything. In many cases you can reverse the process when feeding a balanced output signal to an unbalanced input. You can with some caveats.
I ve read online that the best way to convert balanced xlr to unbalanced 1 4 mono is to buy a cheap passive di box and run it backwards xlr as input 1 4 ts as output. Apparently this will convert whilst also maintaining the balancing of the xlr cable which i don t believe the other answers would and so help to reduce noise. This produces an unbalanced output that can be used to feed an unbalanced input via either a ts or trs plug. Connecting mains powered unbalanced outputs to balanced inputs.
Quarter inch ts tip sleeve cables are generally used for unbalanced signals. In both cases one jack is normally used for each audio channel left and right. The advantage of using balanced cables to connect between balanced outputs and balanced inputs is that balanced connections have better noise rejection thanks to a second inverted signal that has equal resistance to ground as the initial signal this inverted or reverse polarity signal is used to cancel noise and to make the signal more robust. For the best possible noise rejection use a 3 conductor cable wired as in figure 2 from the unbalanced output to the isolator input.
Not only that it s possible that connecting a balanced output to an unbalanced input might be detrimental to the signal depending on the design of the balanced output stage. The impedance balancing means that the balanced interference rejection on that circuit is retained. In many cases interconnecting a balanced output to an unbalanced input will work just fine your signal will be unbalanced. In most cases the negative output of a balanced output can be connected to ground but in some cases it should be left disconnected.
These are most commonly used with electric guitars which often output to an amplifier.