• Ernie Ball
  • MusicMan
  • Sterling by MusicMan
Joined
Jan 24, 2011
Messages
15
Location
Augusta, GA
Hey everybody! Yay for first post, but I hate that it's for a bad thing. :(

So I drove to Nashville (a 6 hour drive for me) to pick up my brand new Island Burst Petrucci BFR...sounds amazing, plays amazing, looks amazing...and I'm super happy with it....until I get home today.

Here's the issue: If I just run mono out of either jack (1 at a time, not both connected at the same time), then it's great. No hum, buzz, nothing but sheer sonic beauty. However, the moment I plug in both at the same time, I get a very audible hum (we're talking overdrive pedal level hum or worse) from whatever amp is plugged into the magnetic. The selector switch has no effect on the hum whatsoever, nor does the guitar volume from either set of pickups. I just plug a cable from an amp into the Piezo jack, and HUUUUUUMMMMMM. It also doesn't matter if the amp to which the piezo jack is connected is on or not. If it's grounded to an amp, it's humming.

I spoke to MM Customer Service (really nice guy btw, very patient and helpful), and the guy was kind of flabbergasted. He said that he'd never heard of this issue before, but to test different cables and different amps to make sure it was the guitar. He said (regretfully) that I may need to send it to MM. Being a new guitar, it's under warranty, but I REALLY don't want to have to send back the guitar I just bought yesterday.

Has anyone experienced any issue like this before, or have any idea just what the heck might be the issue? Any help would be GREATLY appreciated.

For the record, I'm using Monster Rock cables. My 2 amps are a Peavey JSX and a Fender Acoustasonic Jr. To double check the issue, I also ran tests on my PA here and a friend's Line6 Spider2. The effect is not nearly as drastic on my friend's Line6 as it is the JSX, but it's still there.
 

nobozos

Well-known member
Joined
Nov 10, 2002
Messages
675
Location
Pekin, Illinois
I know it's a drag, but the best answer is to send the guitar in. It's under warranty, (as long as nobody has tried to "fix" it) and the Customer Service is excellent.

You know, on one of those jacks, you can use a stereo cable, and if I remember right, tip is acoustic, and ring is magnetic. So, it is possible to get both sounds with one cable instead of two. If you wanted to go to two different amps, you would just need to go from the stereo plug on one end to two mono plugs on the other.
 

beej

Moderator
Joined
Aug 16, 2004
Messages
12,370
Location
Toronto, Canada
Hey there- Welcome to the forum.

It sounds like you have a ground loop. This often happens when you connect to two different amps and have a shared ground. The signal has multiple paths to ground, and so you get a persistent hum. If that's the case, it's not guitar related at all, this happens all the time to people with more complicated rigs.

You have a couple of options to eliminate things, but essentially you need to isolate the ground of one of your outputs. Popular way is to use a DI box on the piezo signal that has a "ground lift" (transformer isolated ground).
 

PeteDuBaldo

Well-known member
Joined
Jul 16, 2004
Messages
10,202
Location
Central Connecticut (Manchester) USA
Beej is right, whenever you use both outputs on the JP it is a good idea to run a ground lift for one of the outputs to minimize the hum (I lift the piezo ground). It doesn't sound like a problem with the guitar, it sounds like you just need to use a ground lift and then enjoy sonic perfection!
 
Joined
Jan 24, 2011
Messages
15
Location
Augusta, GA
Thanks for the quick reply guys!

beej I think you may be on to something with the ground loop...I'm headed to borrow a direct box right now to try it, and I'll post results asap. Thanks!
 
Joined
Jan 24, 2011
Messages
15
Location
Augusta, GA
Beej for the win!! Plugged in the DI box, and immediately the angels began to sing and light shone down upon my rig from heaven. Oh, and the hum went away too. ;)

Seriously, thanks a lot!!
 

bazxkr

Well-known member
Joined
Mar 15, 2010
Messages
428
Location
London, UK
Wow, that was baptism of fire if ever there was one.... glad it got sorted quick well done guys.

Welcome to the forum skydiver if you can find the time to put the JP down and come on the forum LOL

Cheers
Baz
 
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