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Tube amp harsh buzz/humm


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I have a carven valve master 100 tube head with a small daisy chain of pedals (in line from guitar to the amp). I'm getting a humming/buzzing noise. It is very slight/non existent on the clean channel but very loud on the gain channel. If I hit a kill switch or a volume pedal to off I still get the noise (it does change the tone of the noise slightly though). When I walk around with the guitar the tone and the volume of the noise changes. Same situation for all different guitars and cables. New preamp tubes. Noise is there with or without the daisy chain. It fades away when I play (or at least it's not noticeable to my ear.

 

I just want the sound to go away when I'm not playing on the gain channel our when I hit a kill switch.

 

Could this be a grounding issue? Maybe it is an issue with my cables and I only have bad cables to work with.

 

Any thoughts? Similar situations?

 

Thanks on advance :)

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He said hes tried different guitars and without the pedals. I would try it in a different building. maybe flouresant lighting or a dimmer switch is the cause. have had this problem in certain venues.

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I've been struggling with a similar problem with my 1961 Ampeg Reverberocket. I switched cords, guitars, then amps and had the same hum in my other amps! The I discovered if I shut the Ampeg off the hum in my 1964 Fender Concert reduced, and if I unplugged the Ampeg the hum disappeared from the Concert. I also have a Fender Pro Junior which has a bit of hum regardless of whether it has a guitar plugged in or anything else. The Ampeg hums a bit on its own, but more so when I plug my Gibson SG into it. My single coil guitar doesn't really seem to aggravate it.

 

I replicated the experiment last night, and the SG causes hum in the Concert when the Ampeg is plugged in to the wall, more when the Ampeg is turned on.

 

Weird.

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Could be the main cap, could be the power supply section, esp the power supply transformer

 

I tried putting a kill switch in my effects loop and that seems to have killed the noise (When stomped) but that's not fixing the problem. I'm really leaning towards the problem being the power supply (Or at least the grounding). I did some research on ground loops and www.ebtechaudio.com makes a couple Hum Eliminators that I'm going to try. Apparently having multiple units (Amps and effects, but that wouldn't account for the humm while not having any effects plugged in) all plugged in will cause a fight for witch unit is going to be the ground causing a humming noise.

 

Also I am going the replace my main tubes, It's been on my list of things to do for a while now.

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Could be the main cap, could be the power supply section, esp the power supply transformer

 

 

Almost certainly not any of the "main caps" and absolutely not the power transformer. How did you arrive at this???

 

Read the symptoms and apply real troubleshooting skills.

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I tried putting a kill switch in my effects loop and that seems to have killed the noise (When stomped) but that's not fixing the problem. I'm really leaning towards the problem being the power supply (Or at least the grounding). I did some research on ground loops and
www.ebtechaudio.com
makes a couple Hum Eliminators that I'm going to try. Apparently having multiple units (Amps and effects, but that wouldn't account for the humm while not having any effects plugged in) all plugged in will cause a fight for witch unit is going to be the ground causing a humming noise.


Also I am going the replace my main tubes, It's been on my list of things to do for a while now.

 

Remove everything from the effects loop. If the hum and noise are gone in the high gain channel, you know that the noise is being generated and/or amplified by devices in the loop.

 

It's not your power tubes either. Sort out the noise problem before changing your tubes.

 

Things that will increase your noise... compressors and overdrive pedals, because both increase gain by factors of 10 or 100, so any small amount of noise that is present will become very large.

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Another thing to look at (in addition to Aged's comments) is the routing of your guitar cable. Make sure you are not routing your guitar cable by the amp's transformer (do you route the cable through the amp handle? Or under the head on the transformer side?).

 

Also remember, tube amps are inherently noisy, especially high gain ones. If you have your gain cranked up to max, I don't care what you do... you will most certainly have noise and lots of it.

 

Your killswitch experiment showed is that the noise is introduced before your effects loop. So you know it's not due to the output tubes. You said that there is also some noise when on the clean channel, so it isn't your distortion tubes. When tubes go bad, they typically get muddy. Sometime they will become more microphonic. But they do not just buzz.

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