M13 Input Level And Swelling Noise

[elliptic]

I'm having a problem with my M13 where there is a hissing, sort of swelling white noise surf-ish sound whenever the input level is at 10 on the guitar and the notes are roughly between low E and an octave above.

 

It happens with all my guitars - a '72 Telecaster, a '75 Les Paul Deluxe, a '69 Mustang etc - so it's not that the guitar has a particularly hot output.  It's a surf kind of swell of noise that starts just after the note is struck and swells and fades over about a second or two, with the duration being directly related to the volume i.e. it gets shorter as you turn the volume down or pick softly or mute the note.

 

I don't think it's clipping as it doesn't start right with the note attack, and the intensity doesn't change with the volume changing (it actually swells at the start), just the duration. The underlying note isn't distorted, there's just a background noise.

 

I've reset to factory settings, and then I re-installed the firmware (2.04) entirely, made no difference.  If I set to true bypass and switch off all effects it disappears entirely and everything is clean.

 

It does remind me of the surf kind of noise you used to get with early chorus pedals except that it doesn't matter what type of effect it is, even just a single eq or reverb has exactly the same problem, and it happens when there is no effect switched on when set to dsp bypass.

 

I've never come across a problem like this.

[elliptic]

Here's an audio file so you can hear it as I don't think I described it very well. If I have the only M13 on Earth that has this problem I will be very surprised.

 

The first bit starts off with no effects and just switches between true bypass and dsp bypass.  The next bit is straight (true bypass) and then with a chorus. The problem is the same regardless of what effects are in the chain.

[phil_m]

I had to listen to your clip with headphones to hear what you're talking about, but I do hear it. Do you have the noise gate on at all? Other than that, how do you have the M13 connected? Are you plugging your guitar into the M13 and then going into the amp, or do you have the M13 in an effects loop? If you have it in an effects loop, it is possible to clip the input of the M13.

[elliptic]

Guitar->M13->amp, although I tried going in to the fx loop return and the noise is there too. If you record using the looper the noise gets recorded, regardless of the pre/post setting, so it really does seem to be in the input stage.

 

Noise gate is off, but turning it on doesn't make any difference.