Weird Crosstalk????

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This topic contains 4 replies, has 5 voices, and was last updated by Profile photo of DoctorG DoctorG 5 years, 5 months ago.

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    Profile photo of TWells

    I have a weird issue I can’t solve on my QU16. Here is my set up and problem:

    I plug my electric guitar into my amp.
    The amp speaker output plugs into a load box – bypassing the speaker – using a speaker cable as recommended by the manufacturer, not an audio cable or guitar cable. (Currently I only have a 50 ft speaker cable.)
    I then take an XLR out of the load box to a channel on the QU and it sounds great! So far.. so good.
    I then take two audio cables out of a stereo guitar delay pedal and plug those cables into the 1/4″ jacks on the two channels next to the guitar amp xlr. EVEN WITHOUT ANYTHING CONNECTED TO THE INPUT OF THE DELAY… I HAVE A SIGNAL READING ON THE TWO QU CHANNELS NEXT TO THE XLR LOAD BOX CHANNEL.
    In other words – I am getting a signal from a delay that shouldn’t even be sending a signal since there is nothing going into the delay input. It seems like the QU is somehow getting an electrical signal from somewhere when it shouldn’t be.

    I tried a different delay, powering the delay from a different power source, different channels on the QU. Same result.

    Any ideas what might be happening? You gotta be smarter than me! Thank you for your help.

    Profile photo of Andreas

    How does it sound? What Level? What Gain? Signal persists with Delay bypassed? What type of delay (i.e. analog using bucket brigade memory)?
    Maybe just the noise floor of that delay?

    Profile photo of Dick Rees
    Dick Rees

    Chances are that this is strictly a cabling issue. Your 50′ speaker cable is much longer than needed. Shorten it…as short as possible! Your other cables should be shielded cables between the peddle and the board.

    It’s likely an interactive combination of all this. The long, loaded unshielded speaker cable is providing a strong enough field to induce signals in the other cables. If you have another mixer you could test this by connecting the load box to one mixer and the cables from the pedal to the other, then use headphones and solo/pfl to hear if the pedal cables are picking up signal from the speaker cable.

    Profile photo of Giga

    Anther experiment on top of the recommendations above: try powering the pedal with a battery and or connect the pedal via a (good) DI.

    I’ve run into a similar problem when I was experimenting with reamping. This was with a Presonus Firestudio interface into a DAW but the same problems popped up.

    The shorter the cables you use the better and even rearranging the cables + pedal’s orientation can help.


    Profile photo of DoctorG

    I’m having some problems picturing what you’re doing and why. Seems overly complicated and ripe for a ground loop, the effect of which is noise of various sorts. Also avoid running low-level signal cables, even though shielded, parallel to output and power cables for any significant distance. (can’t be specific here, because the significance of the issue depends on several factors.)

    You mentioned a 50-ft speaker cable. If you used this because it was the only one you had and and it’s too long, you possibly coiled it up, this creating a magnetic field that could induce audio into signal cables near it.

    These are guesses, and a bit of a stretch, at that, but, as I said, I can’t quite picture your arrangement.

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