Noise when using midi out

edited June 7 in General

Tried plugging the LXR midi in and out to my audiobox presonus 22vsl and I have this constant high pitched hissing noise. If I disconnect the **midi out cable ** from the LXR the noise disperses. I also tried switching the cables around and the same thing happens so it does not seem to be the cables.

Currently I have the LXR (7.5v 1000ma PSU) inserted in its own wall socket. The audio interface is powered via usb from a surface book dock and I have TRS cables going from OUT1L and OUT1R to the audiointerface.

Comments

  • normally the midi input of the soundcard should be isolated by an opto isolator. so in theory there should be no way for GND loops. do you have a midi thru box or another midi thru device to test this? If it does not happen with other MIDI devices I would suspect an error in the presonus interface.

    I don't know the presonus interface, but the midi cable should only connect to the LED inside the opto isolator.

    Is the noise coming from the LXR outs or from the soundcard outs?

  • edited June 12

    Hi Julian, unfortunately I dont have a midi thru device to test with.

    I'm getting the noise from the soundcard where I have my headphones plugged in. Will try to hook the LXR up straight to my monitors as well to check if the noise is there and to the audiobox interface outputs.

  • why are you using TRS cables? LXR outputs are not balanced so you have have a floating input on the ring

  • edited June 14

    @Altitude said:
    why are you using TRS cables? LXR outputs are not balanced so you have have a floating input on the ring

    Due to lazyness, only had 1 TS and 2 TRS cables at, do you think the TRS cables are interfering and causing the noise? Since Im connecting the LXR to unbalanced inputs on the audio interface the ring contact should not connect to anything on either the LXR or the audio interface?

  • @julian said:
    normally the midi input of the soundcard should be isolated by an opto isolator. so in theory there should be no way for GND loops. do you have a midi thru box or another midi thru device to test this? If it does not happen with other MIDI devices I would suspect an error in the presonus interface.

    I don't know the presonus interface, but the midi cable should only connect to the LED inside the opto isolator.

    Is the noise coming from the LXR outs or from the soundcard outs?

    Tried running one cable straight from the lxr to the monitor (No noise) and one from the LXR->Audio interface->speakers and the noise is present when running through the audio interface in both monitoh the monitor and headphones so it seems to be an issue with the audio interface when connecting midi out to it.

    What to do?

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