• Davejz
  • VC New Member
  • Offline
  • Registered: 2012-03-16
  • Posts: 3

Topic: Hum using pass thru

Hi,

I just got a new G-XT and I have an annoying hum through my amp
when using the pass thru. The ground lift isn't helping any.
I dug through the forums here hoping to find something. I have seen
others saying cheap power supply may be an issue? I really like the
product if I could just get the hum/noise issue sorted. Please if
someone could lend some help it would be greatly appreciated.
I have also read about someone using a Y-split cable?

equipment being used:

Les Paul custom
ENGL Thunder 50
Marshall slant half

I have no other pedals attached either inline with the G-XT or
in the effect loop.

Thanks,
Dave

  • From: Victoria, BC
  • Registered: 2011-07-25
  • Posts: 2,060

Re: Hum using pass thru

Hi Davejz,

I recall our lead engineer here telling me that it's really common for guitar amps to be sensitive to any type of ground loop. Are the amp and the G-XT using the same ground? i.e. both plugged into the same outlet, or even plugged into the same power-bar?

Anything you can do to make sure that the units share the same physical ground can help a lot with hum.

Cheers,
Craig

Craig @ TC-Helicon's Website

  • Davejz
  • VC New Member
  • Offline
  • Registered: 2012-03-16
  • Posts: 3

Re: Hum using pass thru

Hi,

Thank you for the response. I tried several troubleshooting techniques.
Yes, The amp and the G-XT are plugged in to the same power bar. 
I didn't try separating the power sources, but thats opposite
to what you suggested. The power is hooked up like this: G-XT into
an extension cord, to a power bar, to an outlet. The amp is plugged into
that power bar as well. Would an excessively long extension cord cause an issue?
I didn't have a shorter one to test. Its probably 50 feet long. Just thinking of things to eliminate.

Thanks again! smile

Dave

  • From: Victoria, BC
  • Registered: 2011-07-25
  • Posts: 2,060

Re: Hum using pass thru

Hi Dave,

Hmm, is the hum there regardless of the volume your guitar is set to, or if there's a guitar plugged into the G-XT at all?

How about if you disconnect the Mic out to the PA?

50ft for the extension cord is long, but I don't think that would cause an issue unless perhaps the ground portion of the cord itself is unreliable.

I know with some older amps people have had success using a DI in the run from the G-XT to the amp to isolate things. The trick is finding a DI with 1/4" on each end or using an XLR - 1/4" on one side.

Keep me posted and we'll try and get it sorted. If you're going through more troubleshooting, try to introduce one piece of gear at a time until the hum shows up. Start with just the guitar going through the G-XT to the amp, with no mic and with the G-XT unpowered, then progress through powering the G-XT, plugging a Mic In, plugging Mic out to the PA etc.

-Craig

Craig @ TC-Helicon's Website

  • Davejz
  • VC New Member
  • Offline
  • Registered: 2012-03-16
  • Posts: 3

Re: Hum using pass thru

The only time I didn't experience the humming was when the amp was
in standby. Guitar volume made no difference if amp was out of standby.

Excellent idea on TS the problem. I'll go through your suggestions
and get back to you asap.

Really appreciate the help!

Thanks,
Dave