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Ampeg PF-500 humming

JRL174

JRL174

Guest
Mar 11, 2015
23
2
64
#1
Is anyone have issues with their PF-500 humming when run into the PA using the XLR line out jack? The hum is in the Pa and not coming from the amp cabinet. The amp seems fine on its own. I have tried to correct the him using the ground lift but this doesn't eliminate the hum.

I have unplugged my pedal board from the amp and my bass. I have also tried a few different cable between the amp and the PA. It still hums. Is this an issue with the XLR line out jack?

Any ideas, suggestions, recommendations would be greatly appreciated.
 
#3
254 stringer said:
Don't know much about pa gear but is it with one board or every board you plug into. The only thing I can think of right off is there phantom power from the board I know it caused an issue with my sans amp before.
Click to expand...
Just the one board. A Mackie DL1608. It doesn't seem to happen with my Soundcraft Gig-Rac 1000 (different band). We don't use phantom power for anything on either board but, I will check with the guy who runs the Mackie.

Thanks for the input.
 
#10
Well I have a PF800, which is the same preamp, and mine has never hummed. But it does sound like you were getting a ground loop somewhere. I can't guarantee it'll solve the problem, but sometimes I get hum in my rig from some sort of weird ground problem with certain PA's, certain tube amps, and my REDDI DI, and the Whirlwind Lifter always fixes them. It's an outboard pin 1 lifter for your XLR jack, and for me it's worked when ground lift switches hadn't. Costs like $12, a very handy thing to have with you just in case.

But have you tried the XLR out into other PA's or mixers to see if it was just a weird miscommunication with that particular PA?
 
#11
JRL174 said:
Just the one board. A Mackie DL1608. It doesn't seem to happen with my Soundcraft Gig-Rac 1000 (different band). We don't use phantom power for anything on either board but, I will check with the guy who runs the Mackie.

Thanks for the input.
Click to expand...

JimmyM said:
Well I have a PF800, which is the same preamp, and mine has never hummed. But it does sound like you were getting a ground loop somewhere. I can't guarantee it'll solve the problem, but sometimes I get hum in my rig from some sort of weird ground problem with certain PA's, certain tube amps, and my REDDI DI, and the Whirlwind Lifter always fixes them. It's an outboard pin 1 lifter for your XLR jack, and for me it's worked when ground lift switches hadn't. Costs like $12, a very handy thing to have with you just in case.

But have you tried the XLR out into other PA's or mixers to see if it was just a weird miscommunication with that particular PA?
Click to expand...

Looks like only the fellow LOUD product is doing it ;)
 
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#13
JimmyM said:
Well I have a PF800, which is the same preamp, and mine has never hummed. But it does sound like you were getting a ground loop somewhere. I can't guarantee it'll solve the problem, but sometimes I get hum in my rig from some sort of weird ground problem with certain PA's, certain tube amps, and my REDDI DI, and the Whirlwind Lifter always fixes them. It's an outboard pin 1 lifter for your XLR jack, and for me it's worked when ground lift switches hadn't. Costs like $12, a very handy thing to have with you just in case.

But have you tried the XLR out into other PA's or mixers to see if it was just a weird miscommunication with that particular PA?
Click to expand...
Thanks! I will check out that device.
 
#16
bassrich said:
Does it do it through another PA?
Click to expand...
It doesn't seem to happen with my Soundcraft Gig-Rac powered mixer, just the Mackie. I also played it through a couple of large venue PAs last year and had no problem. However, there may have been a hum and the soundmen (who are much wiser than I) corrected it and didn't bother me with that detail.
 
#17
morgansterne said:
Are they plugged into the same outlet? Slight voltage differences between the two outlets will cause hum. An outlet wired backwards will blow @#$/ up.
Not that I know this from personal experience or anything . . .
Click to expand...
No. Different outlets. Have tried power conditioner, rearranging where it's plugged in, keeping it away from other electronic devices, etc.
 

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