What does this mean?

truecam123

Member
Messages
307
Recently took my amp head to church and ran it through the mesa boogie cab clone using a balanced line out direct to the board. The hum coming out of the mains is crazy loud though. I run a small pedal board. If I turn my guitar volume all the down the hum goes away. This is the same whether I'm using a les paul or Strat. So does this mean the cause of the hum is the guitar since it disappears when the guitar volume is turned off?

I've tried all the trouble shooting techniques with no real relief. The one thing that I do notice is that I can touch a pedal jack or some other part of of the chain with my hand, and a lot of the humming will go away. Almost like my hand is acting like a ground. But I can't figure out how to translate using my hand as a ground into fixing my humming problems.

I've flipped the grounding switch on the cab clone and used a grounding adapter etc with no luck. The amp was recently checked out so I believe all the components are good.

I should mention that it does the loud humming thing while plugged into my home PA as well so I don't think it's unique to just playing it at the church (ie, dirty power, lights etc)

If I run directly into the amp, guitar to amp with no pedals, same issue.

Any thoughts?
 
Last edited:

pdf64

Member
Messages
7,932
So does the same rig / setting work ok somewhere else?
If so, maybe enquire about the church's electrical installation / suggest having it checked, as it may not be properly grounded.

I can touch a pedal jack or some other part of of the chain with my hand, and a lot of the humming will go away. Almost like my hand is acting like a ground
Keeping your hand touching the strings or bridge etc should have the same effect?
If so, to some degree that's normal.
 

truecam123

Member
Messages
307
So does the same rig / setting work ok somewhere else?
If so, maybe enquire about the church's electrical installation / suggest having it checked, as it may not be properly grounded.

The same rig does not work somewhere else. I have the same issues when I plug the rig into the PA at home. Loud Buzz. So I don't think it's the electrical outlets/system but rather something in my set up.

Keeping your hand touching the strings or bridge etc should have the same effect?
If so, to some degree that's normal.
And yes touching the strings does quiet it down.

There is some amp noise when I just plug the head into a cabinet, it's just much louder when I am plugging into the PA.
 

truecam123

Member
Messages
307
So does the same rig / setting work ok somewhere else?
If so, maybe enquire about the church's electrical installation / suggest having it checked, as it may not be properly grounded.

Keeping your hand touching the strings or bridge etc should have the same effect?
If so, to some degree that's normal.
The same rig does not work somewhere else. I have the same issues when I plug the rig into the PA at home. Loud him/Buzz. So I don't think it's the electrical outlets/system but rather something in my set up.

There is some amp noise when I just plug the head into a cabinet, it's just much louder when I am plugging into the PA.

And yes touching the strings does quiet it down.
 

DaveKS

Member
Messages
16,704
Have you tried a different guitar cable?
Let me rephrase this question.
Have you tried a better, higher quality guitar cable that has good shielding?

Does hum sound change as you turn onstage? Can you find a direction to face where hum seems to wane a lot? If so then interference is coming from stage lighting or some other environmental source.

Are pa, your amp etc all on same circuit? Stage lighting? Lighting if you answered yes to above ??? needs to be on its own isolated circuit. As a test if you can do it, kill stage lighting and see if hum goes away.
 
Messages
1,814
Take 15 minutes to diagnose the problem. Start at the amp and work your way back. Try direct into the amp. If the buzz is present in that setup it's NOT the pedalboard. Swap out the guitar. Swap out each pedal.

Just listening to the way your talking it sounds like the guitar or a cable. Maybe a bad switch or cap causing a ground issue in the guitar itself.

Just be methodical in troubleshooting and you'll have the source of your problem in short order.
 
Messages
826
Try moving the cab clone away from the head - it could be picking up the magnetic field of the power transformer in the head.
 

truecam123

Member
Messages
307
Take 15 minutes to diagnose the problem. Start at the amp and work your way back. Try direct into the amp. If the buzz is present in that setup it's NOT the pedalboard. Swap out the guitar. Swap out each pedal.

Just listening to the way your talking it sounds like the guitar or a cable. Maybe a bad switch or cap causing a ground issue in the guitar itself.

Just be methodical in troubleshooting and you'll have the source of your problem in short order.
I feel like I have been methodical but still can't figure it out. It is still there when the guitar is plugged straight into the amp.

I am using monster guitar cable which I thought were good but maybe I need to spend a little more money on a better one. Any suggestions on the best guitar cable?

And it occurs with both guitars start and les paul.
 

truecam123

Member
Messages
307
Let me rephrase this question.
Have you tried a better, higher quality guitar cable that has good shielding?

Does hum sound change as you turn onstage? Can you find a direction to face where hum seems to wane a lot? If so then interference is coming from stage lighting or some other environmental source.

Are pa, your amp etc all on same circuit? Stage lighting? Lighting if you answered yes to above ??? needs to be on its own isolated circuit. As a test if you can do it, kill stage lighting and see if hum goes away.
No it does not change with different positioning. The circuits are not together and stage lighting does not affect it.

I will try a new guitar cable. I asked the other guy for suggestions on a really well shielded one but I will ask you as well since you seem to have some knowledge in this area.
 
Messages
1,814
Doesn't sound like the guitar. It's either the cable or the amp. Could be dirty power at both locations but it sounds like a bad ground. By you touching the guitar you are essentially acting as a ground for the circuit. If you switch out cables and it doesn't get solved take the amp to your tech.
 

truecam123

Member
Messages
307
You think it's possible that it's just not a quiet amp and there will always be a certain amount of hum coming from it? It's a semi custom amp at 80 watts and a variac for half power.
 
Messages
1,814
Here's my thing. If you plugged 2 different guitars direct to the amp and they do the same exact thing it's one of 3 things.

1. Both guitars have a bad ground (not likely).

2. Bad cable. Replace the cable with a known good cable that works as expected in a different amp. Evaluate with the new cable.

3. If neither of those steps above work take the amp to a qualified tech and have them go through it. It's usually a $65 bench charge to diagnose.

My point is this man. When trouble shooting anything you need to control for each section in the signal chain by isolating each section to determine the cause. It's great to evaluate the noise and theorize what it may or may not be but the only way to really know what piece it is is to test each piece on the chain. Otherwise you're just taking guesses at it and won't make any progress.
 

truecam123

Member
Messages
307
Here's my thing. If you plugged 2 different guitars direct to the amp and they do the same exact thing it's one of 3 things.

1. Both guitars have a bad ground (not likely).

2. Bad cable. Replace the cable with a known good cable that works as expected in a different amp. Evaluate with the new cable.

3. If neither of those steps above work take the amp to a qualified tech and have them go through it. It's usually a $65 bench charge to diagnose.

My point is this man. When trouble shooting anything you need to control for each section in the signal chain by isolating each section to determine the cause. It's great to evaluate the noise and theorize what it may or may not be but the only way to really know what piece it is is to test each piece on the chain. Otherwise you're just taking guesses at it and won't make any progress.

Ok, thanks for the advice.
 






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