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My M13 Is Making A Swirling/warbling Noise


xXBansheeXx
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So I had some amp issues and I sent my amp out to be repaired while I left my M13 being unused for about a month. When I got my amp back, I put it back into the rig and now I have this relatively higher pitched warbling noise. It almost sounds like a squeaky ceiling fan, it's about that speed and pitch if you can imagine it. All the effects and everything still work, when I turn them on, the warbling noise takes on the effect, so it's somewhere in the beginning of the signal path in the M13.

 

Before you ask, yes I have trouble shot everything in my rig, every pedal, every cable, whatever this is, it's inside the M13. If I go into the setup menu and switch the M13 to true bypass, the warbling goes away. Then as soon as I kick an effect in, the effect comes in with the warble in it. So something happened to my M13 over the past month to cause this swirling/warbling sound. Has anyone else experienced this or have any idea of where to start looking?

 

Thanks

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please give the following info:

 

amp type

 

original issue with amp

 

cable connection from m13 to amp 

 

can you perform a reset on the m13?

 

i could be wrong, usually am ^_^ but i've found when something is repaired and then a problem develops in a different area, sometimes it's the repair that causes the second fault. 

 

have you tried different effects in place of the m13?

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The amp is a Mesa Dual Rectifier, some tubes blew and burned some resistors. I have the M13 in the effects loop on, so the amps send goes into the M13 input and the M13 output goes into the amps return. I wouldn't know how to reset the M13 and I don't have any midi cables or anything to re-install the firmware. I haven't tried any other effects in the loop of the amp, but the fact that I switched the M13 to true bypass and the problem went away tells me that it has nothing to do with my amp.

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The problem has to do with the Mesa's effects loop. It's a parallel loop, so what you're hearing is comb filtering. It happens when you try to use any digital effect in a parallel loop unless the effect has a "dry kill" feature. The M13 doesn't have this. With a parallel loop, you have to parallel signal paths. When you introduce A/D and D/A converters in that loop, a small amount of latency is introduced, so the signals are no longer aligned with each other. The signal going through the loop is lagging slightly behind the amp's dry signal. This causes phasing - the swirling and warbling.

 

It goes away when you bypass the M13 in true bypass mode because the signal going the M13 at that point is a purely analog signal. Once you turn an effect on, though, it will happen again. There's not really an easy solution. This is why a lot of people have parallel loops modified to serial loops.

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Factory Reset

There may be times when you’d like to reset your M13 to its Factory settings. You may 

want to recall a particular Factory Scene, for example. To do a Factory Reset, first back 

up any Scenes you’d like to keep (see MIDI Backup on page 2•5), then follow these steps: 

• Turn the Model Select Knob under LCD 4 until “Rst Fact?†is displayed.

• Press down on the Model Select Knob - “Reset To Factory?†will be displayed.

• To initiate the Factory Reset, press down on the Model Select Knob again.

• All Factory defaults will be reset, including Scene Presets and Global settings.

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Factory Reset
There may be times when you’d like to reset your M13 to its Factory settings. You may 
want to recall a particular Factory Scene, for example. To do a Factory Reset, first back 
up any Scenes you’d like to keep (see MIDI Backup on page 2•5), then follow these steps: 
• Turn the Model Select Knob under LCD 4 until “Rst Fact?†is displayed.
• Press down on the Model Select Knob - “Reset To Factory?†will be displayed.
• To initiate the Factory Reset, press down on the Model Select Knob again.
• All Factory defaults will be reset, including Scene Presets and Global settings.

 

 
See my response above. The M13 isn't the problem here... Well, it is, kind of, I suppose. But there's nothing that can be done about it. The M13, and most other digital effects, doesn't play well with parallel effects loops.
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The problem has to do with the Mesa's effects loop. It's a parallel loop, so what you're hearing is comb filtering. It happens when you try to use any digital effect in a parallel loop unless the effect has a "dry kill" feature. The M13 doesn't have this. With a parallel loop, you have to parallel signal paths. When you introduce A/D and D/A converters in that loop, a small amount of latency is introduced, so the signals are no longer aligned with each other. The signal going through the loop is lagging slightly behind the amp's dry signal. This causes phasing - the swirling and warbling.

 

It goes away when you bypass the M13 in true bypass mode because the signal going the M13 at that point is a purely analog signal. Once you turn an effect on, though, it will happen again. There's not really an easy solution. This is why a lot of people have parallel loops modified to serial loops.

I'm aware of the phasing issues with the effects loop, but I've been using this pedal for years without the described issue. This issue is new and has nothing to do with the effects loop. It seems to be some kind of feedback issue. I'll try the reset when I get off work.

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Well, were you using it in the loop before? It is a parallel loop, and, honestly, I've seen dozens of guys complain here over the years about not being able to use the M13 in the effects loops of Mesas.

 

I suppose there are some effects on the M13 that might work OK in the loop. Particularly those that allow the mix to be 100% wet. Most of the mods, delays, and reverbs. Although with that, I'd think only the mods would be useful.

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Well, were you using it in the loop before? It is a parallel loop, and, honestly, I've seen dozens of guys complain here over the years about not being able to use the M13 in the effects loops of Mesas.

 

I suppose there are some effects on the M13 that might work OK in the loop. Particularly those that allow the mix to be 100% wet. Most of the mods, delays, and reverbs. Although with that, I'd think only the mods would be useful.

Yeah, it's always been in the loop. I have it assigned to only be in the clean channel and I don't notice the phasing as much in the clean channel. But this is not phasing at all, it's a constant like 1000khz squeal that sounds like it has a circular motion to it.

 

EDIT: Another thing to add, if I turn the amp on and don't play anything yet, the sound isn't there, but if I make any noise at all with the guitar, the warbling sound slowly starts to fade in until it's full blast much like feedback from a PA system would. You know how it starts faint and then quickly builds on itself exponentially until it's a full blown squeal? It's just like that except it sounds like it's going through a rotary speaker. And this is with no effects on whatsoever. So it's very reminiscent of a feedback issue. I have yet to try the M13 on another amp because I have it rack mounted on a drawer in my flight case and it's not easy to get to. But I'm almost positive it's the M13 with the issue.

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  • 3 weeks later...

Hi,

I don't know if this will help, but I have a similar issues with my Fender Twin Amp.

 

I wanted to place the M13 into the amp's effect loop, but the had too much earth hum to make it viable.

I tried various methods to isolate the earth but still no good.

 

I then replaced the tubes in the effects loop with the best quality ones I could get and these had higher gain than the Fender Groove Tubes.

 

The result was that apart from the earth hum being increased I also had the squealing and warbling sounds that you describe.

Replacing the original tubes fixed the squealing and warbling.

 

So if the tubes in the effects loop were replaced when your amp was repaired, this could be a possible source of you problem.

 

Hope this helps.

 

Cheers,

Luke

P.S. I still haven't found a way to use the M13 in my amps effect loop. :(

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