I can hear hum from my combo

Y

yy46

Member
My FM3 when I play at home is plugged into the return jack on a small combo amp (bypassing the cab block and plugging in OUT2) and I hear a faint hum.

  • When the amplifier is on and FM3 is on - I hear noise, whether the potentiometer is at min or max, (I know I should be at max) either way, the point is that the level of the signal does not affect the volume of the noise. It doesn't matter if the selected preset is clean or hi-gain, the guitar is muted and the noise is still there.
  • When the amplifier is turned on and the cable is removed from the FM3 side - there is no noise (the amplifier itself does not generate noise, even with the cable)
When I start to play, I can't hear the difference anymore, even when I play quietly, the noise can't be picked up. It's more that it's annoying when in an empty room the guitar is turned down and all you hear from the speaker is hum... And also I know that my guitar is not clean anymore...Its hum added to my entire guitar sound.
Maybe it's a simple thing and I don't know about it.
I was thinking about cable but with bad cable It should be worst when potentiometer is max, volume actually doesn't matter
It looks like FM3 generates some extra something that translates into hum/noise.
Is that normal? Do you have any idea how I can fix it?
 
yy46 said:
My FM3 when I play at home is plugged into the return jack on a small combo amp (bypassing the cab block and plugging in OUT2) and I hear a faint hum.

  • When the amplifier is on and FM3 is on - I hear noise, whether the potentiometer is at min or max, (I know I should be at max) either way, the point is that the level of the signal does not affect the volume of the noise. It doesn't matter if the selected preset is clean or hi-gain, the guitar is muted and the noise is still there.
  • When the amplifier is turned on and the cable is removed from the FM3 side - there is no noise (the amplifier itself does not generate noise, even with the cable)
When I start to play, I can't hear the difference anymore, even when I play quietly, the noise can't be picked up. It's more that it's annoying when in an empty room the guitar is turned down and all you hear from the speaker is hum... And also I know that my guitar is not clean anymore...Its hum added to my entire guitar sound.
Maybe it's a simple thing and I don't know about it.
I was thinking about cable but with bad cable It should be worst when potentiometer is max, volume actually doesn't matter
It looks like FM3 generates some extra something that translates into hum/noise.
Is that normal? Do you have any idea how I can fix it?
Click to expand...
I had the same problem with the FM3. I had the hum on both Outputs (XLR's and TS).
The Problem was solved with a complete Reset of the FM3 after a complete Backup.
If there is Hum after a Reset - a Behringer HD400 - solves this problem.

Sorry for my English.
 
And what will it give me?
My houes is not big, Propably all bottom circuits are in the same loop.
I know it's good to eliminate some interference but... do you want me to connect the FM3 3 rooms away from the amplifier? It's completely impractical...
 
allan13 said:
I had the same problem with the FM3. I had the hum on both Outputs (XLR's and TS).
The Problem was solved with a complete Reset of the FM3 after a complete Backup.
If there is Hum after a Reset - a Behringer HD400 - solves this problem.

Sorry for my English.
Click to expand...
I will check this tomorrow...
Do you have to use Behringer HD400 after complete reset right now?
 
yy46 said:
I will check this tomorrow...
Do you have to use Behringer HD400 after complete reset right now?
Click to expand...
Not for the XLR Out. With the TS Out - sometimes - but I do not use Humbuster Cables.
But in general it is good to have a Hd400 always in the bag. And for ca. 30 €, it's a nobrainer.
 
yy46 said:
My FM3 when I play at home is plugged into the return jack on a small combo amp (bypassing the cab block and plugging in OUT2) and I hear a faint hum.

  • When the amplifier is on and FM3 is on - I hear noise, whether the potentiometer is at min or max, (I know I should be at max) either way, the point is that the level of the signal does not affect the volume of the noise. It doesn't matter if the selected preset is clean or hi-gain, the guitar is muted and the noise is still there.
  • When the amplifier is turned on and the cable is removed from the FM3 side - there is no noise (the amplifier itself does not generate noise, even with the cable)
When I start to play, I can't hear the difference anymore, even when I play quietly, the noise can't be picked up. It's more that it's annoying when in an empty room the guitar is turned down and all you hear from the speaker is hum... And also I know that my guitar is not clean anymore...Its hum added to my entire guitar sound.
Maybe it's a simple thing and I don't know about it.
I was thinking about cable but with bad cable It should be worst when potentiometer is max, volume actually doesn't matter
Click to expand...

yy46 said:
will I
It looks like FM3 generates some extra something that translates into hum/noise.
Is that normal?
Click to expand...
It’s premature for us to point at the FM3 given the informations you provided.

Disconnect the FM3 from the amp, and the guitar cord from the FM3, then plug in headphones to the headphone out on the FM3, turn up the OUT 1 and listen carefully. Do you hear hum? If not then the FM3 is not the problem.

Connect the guitar to the FM3 with the guitar’s volume off. Hum? Turn up the guitar’s volume. Hum? If so, either the cable or the guitar is the problem.

Does the combo amp have a three-prong grounded plug and is that plugged directly into the same outlet as the FM3? Two-prong plugs are not good and can cause ground loops. A tech should replace it.

If the guitar cord was ok above, then swap the guitar cable with the cable between the FM3 and the amp. Do you get hum? If so you should make or purchase a humbuster cable. See the manual for more information as they are not a regular TRS to TS cable.

yy46 said:
Do you have any idea how I can fix it?
Click to expand...
Let’s find the problem first, K?
 
yy46 said:
And what will it give me?
My houes is not big, Propably all bottom circuits are in the same loop.
I know it's good to eliminate some interference but... do you want me to connect the FM3 3 rooms away from the amplifier? It's completely impractical...
Click to expand...

I wanted to find the problem, not giving you a solution. Sorry for my mistake. Follow Greg‘s advice, it is the best so far.
 
The cable that is connected to the amp's fx return comes from the FM3 fx send jack, not the headphone jack.
I still hear noise when plugged into the headphone jack. Disconnecting the cable from FM3 at all causes the noise to disappear.
Combo amp have a three-prong grounded plug and its plugged directly into the same outlet as the FM.
I plugged the combo into a different power outlet, it's the same, still hum. Noise only occurs when FM3 is on. When FM3 is off there is no noise.
 
yy46 said:
The cable that is connected to the amp's fx return comes from the FM3 fx send jack, not the headphone jack.
Click to expand...
Read again what @Greg Ferguson wrote. The point was to isolate the FM3 from other sources of grounding or induced noise. Listening through the headphone will tell you whether the FM3 itself is the problem area. Do some reading on ground loops and then probably the easiest thing is to read the the section of the manual about the Humbuster cable and build one to connect from the FM3 to the amp.
 
Listening through the headphones only is ok. No hum.
When plug to fx send on fm3 to fx return on amp- I’ve got hum. If I connect from headphones output to fx return on amp - the same hum .
I will have to check humbuster cable …
 
yy46 said:
Listening through the headphones only is ok. No hum.
When plug to fx send on fm3 to fx return on amp- I’ve got hum. If I connect from headphones output to fx return on amp - the same hum .
I will have to check humbuster cable …
Click to expand...
Yeah, you don’t want to connect the headphone jack to the amp. For the most part you’re accomplishing the same thing as out 2 (send) in regards to ground issues.
 
yy46 said:
Listening through the headphones only is ok. No hum.
Click to expand...

Then the FM3 is not the problem.

yy46 said:
When plug to fx send on fm3 to fx return on amp- I’ve got hum. If I connect from headphones output to fx return on amp - the same hum .
Click to expand...

That still points to your system having a ground-loop, which is a situation where electronic devices are connected together, and one has a better path to the electrical ground than the other, resulting in electricity flowing through the cable to the other device. That is audible as a 50-60 Hz hum. The humbuster cable is used by special circuitry to sense that noise and cancel, or at least reduce it.

You can often fix the problem by putting both units on the same power-strip, or outlet if they’re on the same circuit. If there’s a wiring flaw in the amp, which happens way too often and can cause the problem even when both are grounded, then a technician should look at the amp’s wiring and fix it. You don’t want to mess around with systems with ground-loop problems, people have died getting stuck in the middle.
 
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Some great diagnostic tips here. I also had a hum, exactly like what you describe. Went through a lot of diagnostics too, then I bought the humbuster cable, no more hum.
 
I’m going to make/buy humbuster cable to try get fix this problem , thanks for letting me know about this.
I’m going to check on Thursday (rehearsal day) when connected to other amp if I can see the same problem …
 
I play through two Marshall JCM900 amps in stereo. One of them had a slight hum, the other didn't. They were both plugged into the same A/C circuit. Humbuster cable fixed the problem. Never had a hum in any amp, anywhere since doing that.
 
yy46 said:
When connected to xlr out - still hum
Click to expand...
I would do the FM3 System Reset.
I had the same thing and the Humbuster Cable does not solve the problem with the hum on the XLR out.
In my case i think it was a software thing. System Reset repairs this.
 
allan13 said:
I would do the FM3 System Reset.
I had the same thing and the Humbuster Cable does not solve the problem with the hum on the XLR out.
In my case i think it was a software thing. System Reset repairs this.
Click to expand...
The Humbuster cable is meant to be used on the OUT2 (send) output.

Depending on certain ground problems the Humbuster cable will not solve every problem, but based on the OP’s original description of the hum not being extremely severe it seems like the Humbuster cable will be the easiest, quickest and inexpensive first step. On a certain level understanding electron flow and the potential between negative and positive charge is not hard, but it is very necessary to understand it thoroughly and precisely to not make mistakes in assessing problems.
 
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