I have purchased a Focusrite 18i8 2nd gen, so far everything seems to work except the monitor output.

I have a set of powered speaker plus subwoofer from Sony, they are a set of old speakers that I am using as monitor speakers. The audio cable has a stereo 3.5 mm standard jack TRS

I have purchased a TRSF to TS splitter, since the monitor output is a 1/4 plug; but when I turn on the speakers, the audio goes only on the left speaker, and it sound like both left and right channel are playing on the left speaker only. I tried to connect the same speakers through the headphones output, and it works just fine; so I can say that the speakers are not broken.

At this point, either the monitor connectors on the interface are busted, or the splitter I am using is not working correctly. I used a different splitter, same exact type, and it still does the same as the other cable.

I don't understand where the problem is. The monitor output are 2 mono channels for L and R, so the cable I use is correct, because it is a TRS female to TS male L and R. Any suggestion?

3 Answers 3


The monitor outputs are balanced mono.

The connector looks like a headphone jack but has different signals. Tip is normal signal. Ring is inverted signal. Shield is ground. On most interfaces it works of you use a mono jack c


Output from the interface is either using line outs on the back or the headphone socket on the front. I suggest you use the line outputs on the back. Make up a cable to suit.

TRS Female should connect:

  • input Tip to output Tip (L)
  • input Ring to output Tip (R)
  • input Sleeve to output Sleeve (L & R)

  • output plugs are 1/4" male Tip Sleeve only.

  • input socket 3.5mm TRS Female
  • Thanks Mark; The problem seems to be present only with the rear line out (marked as Monitor) in the back of the unit; because it has 2 1/4 jack, while the front output for headphones is a stereo single 1/4 jack, so the front works fine, and my thought was that the rear connectors are damaged or something like that.
    – rataplan
    Commented Nov 25, 2019 at 19:18
  • 1
    The rear connectors are likely to be balanced outputs so Tip/Ring/Sleeve is actually +ve/-ve/Ground. They will work with a mono jack plug as this will ground the Ring/-ve connection and present an unbalanced signal.
    – Mark
    Commented Nov 26, 2019 at 12:38

I found the issue:

Not sure if this is a pure defect in those devices, but when using 1/4 jack, either on the front or the rear plugs; if you insert them too deep, the signal is affected. Tried to slide out the connectors in the back, so they do not sit perfectly flush with the case, but there is a very small gap, and now I get correctly the L and R channel merging in the stereo signal, so my speakers do play loud and in stereo.

Tried the same in the front, and the issue is less evident on the front plugs; but still, if you plug the connector all the way in, then there is a sound problem, like if something is shorten up.

I sent a mail to support to get an idea if this is an issue with my device, or if there is some sort of problem with the jack I use (regular 1/4 jack cables from Amazon).

  • No. See answer about mono balanced signals.
    – ghellquist
    Commented Dec 4, 2019 at 18:42

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