Excessive (Katana) amp noise

OK, I’m new to electric guitars. I have a Yamaha Pacifica 612, which I have had for a few months, using a Fender Mustang Micro, either with headphones direct, or plugging into my Mac and MainStage. No problems. Now I have a Katana 100 MkII, and there is a lot of noise. Some clean sounds are fine, but in many patches (note, patches available for download in the Tone Studio) the noise is horrific.

So I’m trying to track down the cause, and whether I need to return the amp. Since I haven’t used one before, I don’t know what is normal and what is not. For example, if I turn on the amp with no guitar connected, ‘clean’, no mods, gain, or effects (everything switched right down apart from master and volume), I get a lot of hum, even at low volumes. Is this normal?

If I plug in the guitar, the hum disappears, then as I turn the volume knob up it gets louder, before reducing again at full volume. Is that supposed to happen? With some patches, I can remove the noise and get a really nice sound with the guitar tone control turned all the way down, being able to increase (ie ‘brighten’) it more if there is no gain and on ‘clean’, but anything like a Lead or Brown has a lot of noise.

Any ideas? Is the amp faulty? Is it my wiring, or the presence of a computer in the room?

Hi Alun,

Initially you mentioned ‘noise’, but later only mentioned hum. Is it both, or just hum?

The hum should be about half the frequency of standard tuned A string - A is 110Hz, hum is likely either 50Hz or 60Hz, but may be double that depending on how it is generated. This is a common problem with single coil guitars. I use a fairly short and higher quality cable between guitar and amp to reduce this. You can also have faulty GND in your wiring, but it doesn’t sound like this is your case with your description. You can pick up an outlet tester in hardware stores or online. Should look something like this from Amazon.

I have a lot of computing devices near my guitars, and I have a modeler. These generate noise that can sound like buzzing and often has a rhythm to it. Frequency range varies. I get this a lot with a single-coil guitar, and excessively when it is sitting on it’s stand and I start a game on the computer. Turning down the volume on the guitar or modeler will quiet it as does moving the guitar away from the computer.

I also have a wireless guitar transmit/receive system. When the receiver is too close to the transmitter, I get a great deal of buzzing. Being a radio engineer, I can think of several reasons for this. I move away with the guitar and the noise quiets.

There are some folks here with the Katana, so they may add their personal experience for you.

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It may also be worth plugging the amp into another power outlet somewhere else in your home to see if you get the same hum.

It’s possible that something on the same circuit is generating a lot of mains noise which is getting picked up by the amplifier.



I appreciate you taking time to reply, Keith. My problem is that I can’t seem to pin down whether it is the amp, the guitar, the cable, or mains circuit. The guitar is absolutely fine, zero noise, when using the Mustang Micro, either directly with headphones, or usb to MainStage or GarageBand. That suggests it is not the guitar. Yet I get a crackling when I adjust the tone knob, and noise is highest when the guitar volume control is partway up, which suggests it is.

On the Katana, guitar volume fully up, all FX, mods, etc off. Hum is very noticeable on Clean setting with gain at 9 o’clock, but can be removed by turning the guitar tone knob all the way down. It is downright objectionable on Crunch with no gain at all, and the note knob can’t clean it up. Yet curiously, there are patches which have significant gain dialled in which are clean.

I’ll see if I can set it up at my neighbour’s house to check the circuit. Right now, there are some usable settings, but much of the amp’s settings are not usable, and I’m no wiser as to the cause.

Update: I think the Katana is faulty. I have connected it to my Mac and used the Tone Studio without problems. I just tried to connect it to use with MainStage/Garageband and I get nothing. The driver looks fine. I have no problems using those programs with the Fender Mustang Micro, and the docs suggest the USB connection should work for DAWs too, but it doesn’t. Unfortunately, I don’t think there is anything I can do about it. I bought it from Andertons, and the return policy is 14 days. As luck would have it, my daughter arrived back the day after I received the amp for a 16-day visit, and stayed in the room where I keep the keyboard and amps. So I haven’t been able to give it a good try out until today, which is just beyond the 14 days. It is half-usable, anyway, but I would hesitate to buy Boss gear again, or to buy online. I would like to try things in a music store before paying hundreds of pounds.

Try another guitar / instrument cable.

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Unfortunately, I don’t have another electric guitar. I have two cables (originally bought for mics, I assume the same thing is fine for guitars?), and they are both the same.

I wouldn’t. If it is faulty then I would suggest it’s a rare anomaly. Boss gear is normally highly reliable and built to withstand the apocalypse.

If it is faulty then, if you are based in the UK, you have at least 1 year warranty on it.




Hmm, they may not be…

Mic cables are often balanced, which have 3 conductors (TRS or “stereo” jacks).

Guitar instrument cables are unbalanced (TS or “mono” jacks).

If I were you, I would try to pick up a guitar instrument cable to check with. You should be able to get a cheap one on fast delivery with Amazon.



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I got a fender 10’ guitar cable. The problems were indeed all about the original cable. Now the noise is little to nonexistent. So now it all sounds great! Thanks for your time looking into this.


With all due respect, it’s none of the above.

The “problem” is normal and readily fixed. You need to download and use Boss Tone Studio. It’s not hard to use. The amp settings in the software offer far more options. One of the settings is identified as NS which stands for Noise Suppression. Click on it and set it to approximately 50 (goes from 0 to 100). Then make sure you click the activate button. It’s all right there to see. The hum and noise will disappear and you will have clean tones regardless of volume. I set it on every patch I use. If you download patches, most will have this option activated, if not, you can always add it.

If I have to crank up noise reduction to the max in order to use some of the patches (many were still far too noisy to use even after this), then this is not solving the problem, it is trying to work around the problem. The problem is to isolate the source of the noise in the first place. In this case, the problem was the cable. With that replaced, I don’t need any noise reduction outside high gain/boost settings on Lead or Brown.

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