RG -16 GND LOOP HUM outta nowhere.

T

ti_kg

New Member
I having been encountering a sudden ground loop hum.
I have an RG-16 in a shock mounted rack case and shelf full of pedals (some in loops 1-4 and others along with a 1qty line 6 m9 in the remaining loops.

I run through 2 half stacks taking the output from loops 1-4 into an ABY switch (with both outputs ON)

http://www.tonebone.com/bones-twincity.htm

My signal chain is as follows:

guitar > front of rg-16 > LOOP1-4 output > ABY > Amps

Amp 2 has LOOPS 5-8 running in it's EFX LOOP.

All was going well until last week. We had done some shows on the road and then got back to our rehersal space. I set up my rig as usual but now I was getting this very LOUD hum. I haven't changed anything about the rig and had just played a series of shows from dive bars to big theatres with no ground loop problems.

So I started trying to trace the problem.

If I go guitar > pedals (I run in loops 1-4 but now mounted on a pedalboard -both in bypass and activated) > ABY > Amps everything is fine. NO HUM.

If I run guitar > front of RG-16 > LOOP1-4 output > ABY > Amps, I get the LOUD HUM. And that's with ZERO loops being activated.

The only difference I can think of are all the custom patch cables I've routed into the RG-16. I didn't remove them to use in my:
guitar > pedals I run in loops 1-4 on pedalboard > ABY > Amps test.

But the minute I patch into the front of the RG-16 I get the HUM without any of the loops engaged.

I even took the RG-16 out of the rack to isolate it and the signal still contains a loud hum if I run through the RG-16. It's driving me crazy because it wasn't doing this 2 weeks ago.

POWER IN THE RACK
Using a power conditioner that feeds Power Pedal 2 which feeds the pedals in rack and also supplies power to M9. BOTH amps are taking power from the conditioner.

Could the RG-16 wall wart be the source of the problem?

I've been very happy with the unit and have come to rely on it very much but this new HUM is driving me crazy. Thankfully we are in the studio at the moment so I have some time to sort this out.

Many thanks in advance for your assistance.
 
i forgot to add i also tried this config:

gtr > front of rg-16 > loops 1-4 OUT into just ONE amp ( no ABY) and i still had the ground loop issue.

the other guitar player in the band lent me the HUM-X. i plugged the power conditioner into that but no luck.
 
If nothing at all changed in the rig, then I would have to suspect your cables. Not all hum comes from ground loops, and ground loops don't just appear (unless you have a situation where the paint on your rack rails gets worn off, but that doesn't appear to be the case here). I'd try swapping out each cable with a known good one and see if you get an improvement. Pay special attention to any cables you use with the RG-16 but didn't use when you tested the pedals by themselves. It also wouldn't hurt to tighten all of the screws in the RG-16, just in case.
 
rjmmusic said:
If nothing at all changed in the rig, then I would have to suspect your cables. Not all hum comes from ground loops, and ground loops don't just appear (unless you have a situation where the paint on your rack rails gets worn off, but that doesn't appear to be the case here). I'd try swapping out each cable with a known good one and see if you get an improvement. Pay special attention to any cables you use with the RG-16 but didn't use when you tested the pedals by themselves. It also wouldn't hurt to tighten all of the screws in the RG-16, just in case.
Click to expand...

OK I will check on those items. Thank you.
 
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