pocket amp grounding

disaster

Active member
Messages
45
I just picked up a new Waves iGTR pocket amp.  Very cool.  I use it all the time but it produces a somewhat annoying side effect.....I get "hum".  I have a strat HSS knock-off.  I get hum in the humbucker as well as the single coils.  Its not terrible, but I'd like to get rid of it.  The pocket amp uses batteries or a DC power supply (thing you plug into the wall that converts AC to DC).  I use the DC power supply exclusively.  However...... the DC power supply is a 2-prong device.  No connection to ground.  So the guitar ground is "floating" or isolated from ground.  Obviously when I contact the strings the noise is reduces quite a bit (not entirely, but better).  The bridge is tied to the guitar ground in the control cavity (tied to the Vol Pot case).  Any ideas on how to reduce/eliminate the "hum"?

thanks.
 

jimh

Senior member
Messages
1,344
Have you tried it on batts only?  Does it still hum? If not, then you need a better quality AC/DC adapter with better regulation and smoothing, preferably not switched mode. 
 

disaster

Active member
Messages
45
Thanks.  I tried batteries & also get "hum", but less (i think).

I tried an experiment.  I added a ground wire from the bridge directly to the house ground.  All "hum" canceled (whether holding the guitar or not).  Operated noise free for ~ an hour.  So I think I now know that the guitar needs to be grounded, I just have to figure out how to do it simply & safely.  I'll probably try and create a short patch cable for the cord that will allow a ground wire to tie into the house ground.  I'll probably have to figure out if I need some type of current limiting circuit since the player will now be directly grounded whenever playing the guitar.  But the hum will be gone.
 

dbw

Senior member
Messages
4,531
Disaster, why not install a grounded banana jack in the amp?  Assuming you know how to open the amp and find a grounded point...
 

disaster

Active member
Messages
45
banana jack suggestion......

Thanks,  I'm thinking I'll add a "Y" jack at the guitar input.  I can connect one input to the amp (any amp).  I can connect the 2nd input to a ground cable to connect to the house ground.  Whenever I get noise (pocket amp or any other amp) I'll use the ground cable.  If no noise present no ground requried.

Thanks.
 

mayfly

Senior member
Messages
8,161
If you are getting hum with batteries, then it's the guitar pickups pickingup RF and 60Hz Hash in the room - likely from your body.

Do you have your bridge grounded?  Oh - and are you using a heavy rock setting, or a clean setting?
 
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