[solved] Hum from one power amp whenever I plug axe into it

mistermikev

mistermikev

Experienced
so... racking my brain over here. sometimes formally writing your thoughts will flush something out so here goes...

I have several power amps that I run to from the axefx3. no issues. just bought this ampeg ap-3550. If I plug my guitar straight into it - no problem. if I plug my guitar into a preamp and straight into it - no problem. if I use the sm cable, and plug it into the out 3 from the axe... problem. big hum and very little signal.

I use the sm out 3 to go to a peavey classic 60(left peavey right ampeg) and no problem on that power amp. even if I switch the cables - no problem on the peavey, ampeg hums.

even switched the speakers (idk how this could ever cause it but at a certain point you try a rain dance) - ampeg hums pv does not. switching the ground polarity on the ampeg doesn't do anything.

consistently... I plug anything else into the ampeg and it's clean... axefx3 out and it hums. both peavey and ampeg are in the sm power conditioner... which is chained from the power conditioner the axefx is powered from. I have moved cables around just to see if it's a proximity thing... nope.
if while it's on - I unplug the axefx from the input... no hum.

even tried plugging the ampeg in for power into the sm rack conditioner the axefx is on... still hums.

if you have the answer... you will win a limited edition fur lined bathtub. (jk, you win my thanks and respect).
 
i could go on... turn axe fx to empty preset... no ins/outs... hums. have tried dif inputs on the ampeg too... speaker and input... does not solve the problem. on the off chance the axe fx output 3 was really loud, went to global and adjusted the output level from 0 to 18 - no dif. change the phase and I hear a different type of hum... so that's progress!
 
FractalAudio said:
No idea what a "sm cable" is but did you try a humbuster cable?
Click to expand...
thank you for the speedy response. I have tried a stereo cable... and I was wondering if this was a possible solution. I can take a stereo cable and clip the secondary ground and try it. will do asap.
sm cable is just my shorthand for same.

TG3K said:
I think "sm" is "same". Or at least that's the way I read it.
Click to expand...
thank you sir. yes, short for same.
 
mistermikev said:
thank you for the speedy response. I have tried a stereo cable... and I was wondering if this was a possible solution. I can take a stereo cable and clip the secondary ground and try it. will do asap.
Click to expand...
Clipping the ring (what you meant by secondary ground?) on one end of a TRS cable doesn't make for a Humbuster cable. Rather, short the ring and sleeve pins at one end of a TRS cable, and plug the shorted end into the amp.

Have you tried outputs other than Out3?
 
yeky83 said:
Clipping the ring (what you meant by secondary ground?) on one end of a TRS cable doesn't make for a Humbuster cable. Rather, short the ring and sleeve pins at one end of a TRS cable, and plug the shorted end into the amp.

Have you tried outputs other than Out3?
Click to expand...
I thought we wanted to clip sleeve on one end? guess I haven't looked at that in a bit... short them... ok, will try that. need to move some stuff to get at my box of cables.
yes, I did try other outputs... and accidentally tried the expression out... and it still hums. literally any connection to the axefx3 and it hums.
 
mistermikev said:
I thought we wanted to clip sleeve on one end? guess I haven't looked at that in a bit... short them... ok, will try that. need to move some stuff to get at my box of cables.
yes, I did try other outputs... and accidentally tried the expression out... and it still hums. literally any connection to the axefx3 and it hums.
Click to expand...
Instructions on how to build a Humbuster cable are in the manual.
 
FractalAudio said:
Instructions on how to build a Humbuster cable are in the manual.
Click to expand...
right. the problem is I was thinking about it... I had seen that when I first bought the axe but figured I'd try reg cables and see what I thought... very quiet on everything else. but in thinking about it... I thought the idea was a secondary shield... as you see sometimes in fx and such. ground connected on one side only. sorry, diverging. working on making a cable now. will go look at the manual before I apply solder.
rushfan said:
Yes, make a hum buster cable, and it will very likely solve your problem.
Click to expand...
I'm encouraged by that... but then I'll still be wondering why all other devices work great - 2 preamps and 3 poweramps... but i'll stop thinking there... it gets me into trouble! haha!~
 
well... looked at the pic...
500px-Humbuster2.png

ring and sleeve are joined on the amp end. no love.
this isn't ordinary hum. it literally sounds like what you hear when you touch the tip on a live cable. the hum is louder than signal.
FOR THE RECORD - I THINK IMPORTANT TO POINT OUT TO ANY POTENTIAL LISTENERS... I DO NOT BELIEVE THIS IS ANY SORT OF PROBLEM WITH THE AXE. AS I MENTIONED I USE IT WITH SEVERAL OTHER PREAMPS/POWERAMPS AND NONE OF THEM HAVE THIS ISSUE. THIS IS LIKELY SOME SORT OF WEIRD GROUNDING ISSUE ON THE AMPEG END.
 
ok, have completely ruled out fault on the axe... and have ruled in ground issue for sure. with the axe literally off... still hum if plugged into the axe. unplug and hum goes away.

might try a dif power cable... and perhaps spin in a circle 3x and bow to the sun cause in all my years have not experienced such an odd issue.


doh stop... found it.
 
IT'S THE FLIPPING POWER SUPPLY CABLE TO THE AMPEG! REPLACED IT WITH THE SHITTIEST LITTLE CRAP POWER SUPPLY - HUM GONE. ONE OF THE GROUNDS ON THE POWER SUPPLY MUST BE BAD (THAT IS KIND OF SCARY).

thank you all for hanging in there with me. I very much appreciate the help. without your help I don't think I would have figured it out.
 
mistermikev said:
IT'S THE FLIPPING POWER SUPPLY CABLE TO THE AMPEG! REPLACED IT WITH THE SHITTIEST LITTLE CRAP POWER SUPPLY - HUM GONE. ONE OF THE GROUNDS ON THE POWER SUPPLY MUST BE BAD (THAT IS KIND OF SCARY).

thank you all for hanging in there with me. I very much appreciate the help. without your help I don't think I would have figured it out.
Click to expand...
Where's my sign?
 
I was going to say to check the power cable. if stereo cable is to close to a power cable it would do the same. I have fixed many computer monitors that reacted that way and it was because the monitor cable was sitting on or twirled around a power cable.
 
correction... looks like it's the actual power supply jack.
FractalAudio said:
Where's my sign?
Click to expand...
you mean like bill engvall? I'm not sure you've earned a sign... I might have... i earn those daily.


rickster71 said:
I was going to say to check the power cable. if stereo cable is to close to a power cable it would do the same. I have fixed many computer monitors that reacted that way and it was because the monitor cable was sitting on or twirled around a power cable.
Click to expand...
i had done some moving around of cable to see... several times, but it didn't change anything. I generally thread my power cables to one side and audio to the other. never cross streams - haha.
 
You must log in or register to reply here.
Back
Top Bottom