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Double Bass AI Clarus DI Hum

  • Thread starter Thread starter appler
  • Start date Start date
A

appler

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#1
Hey, guys. I have a small problem with my Acoustic Image Clarus series I amp. When I have an XLR cable plugged into the direct out of the amp there is a very apparent hum. Has anyone else ever experienced this situation? Should I send the amp to Acoustic Image for repair? Thanks for your time.
 
#3
appler said:
Hey, guys. I have a small problem with my Acoustic Image Clarus series I amp. When I have an XLR cable plugged into the direct out of the amp there is a very apparent hum. Has anyone else ever experienced this situation? Should I send the amp to Acoustic Image for repair? Thanks for your time.
Click to expand...

+1 on mje's question. Does the ground lift button have any effect on it?
 
#4
I once had an experience with my GK MB combo, where plugging in the DI caused hum coming out of the combo speaker. I concluded it was the PA system improperly grounded, a suspicion bolstered by the fact that it was an outdoor gig. Never had the problem before or since.
 
#6
The humming comes from the amp so I hear it through my speaker. Changing the volume has no effect. To be honest, I didn't think of the ground lift so I'd be really surprised if that wasn't the issue.

On a related note, what exactly does a ground lift do?

I'll update this as soon as I try it again. I'll be recording bass guitar through it on Sunday.

Thanks for the help, guys!
 
#7
appler said:
The humming comes from the amp so I hear it through my speaker. Changing the volume has no effect. To be honest, I didn't think of the ground lift so I'd be really surprised if that wasn't the issue.

On a related note, what exactly does a ground lift do?

I'll update this as soon as I try it again. I'll be recording bass guitar through it on Sunday.

Thanks for the help, guys!
Click to expand...

The XLR jack is a connector for a balanced line, essentially the + and - of the audio signal is carried within the two inner conductors. The outside (ground) conductor helps to shield those two from outside interference.

A 60 cycle hum (frequency of AC current) is often caused by a ground loop-- where two devices' grounds meet, and the ground potential is different (like when the devices are connected to different AC supplies/circuits), causing noise/hum. A ground lift disconnects the ground at that device's end of the circuit, to remove that potential for hum-- the cable is still shielded as the ground shielding is still being supplied from the other device where the ground remains connected.
 

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