Hum when adding a wireless...advice please

[Garydean]

A customer of mine recently purchased a Shure ULX wireless system for his guitar. He uses a Cierra-tone head (tube), coming off a pedal board wired with George L's wires. His order on the board is correct with regard the tube screamer and an Echoplex. He runs the head at high gain. Prior to adding the wireless, minimal white noise would kick in once the tube screamer was engaged. Now with the wireless added to the mix, he's getting excessive "60 cycle hum" . He's been on the phone with Shure trying to figure it out to no avail. This happens with every guitar, Les Paul, Strat and other custom solid bodies. He plugs everything, amp, board and wireless into a Furman to eliminate a ground loop situation. All his heads are high end boutique type, happens with all of them.

Have we covered all our bases? Any suggestions would be greatly appreciated.

Gary

[Enzo]

Plugging everything into a power conditioner will NOT prevent ground loops. Ground loops occur when two pieces of gear are connected together and their chassis grounds are at differing potentials. That power conditioner is at the other end of their power cords from their chassis.

Where is the wireless in the system? You mention effects order on his board, but not how you are using the wireless. I would assume the guitar plugs into the wireless and the wireless receiver plugs into the first effect. But depending on your needs, the effects could all be out front feeding a wireless transmitter there, and the receiver back at the rear of the stage at the amp. SO I don't want to assume too much.

If you are plugging the wireless receiver into the first pedal, consider the following.

The receiver uses a power adaptor, so there should not be any ground loops anyway.


Let's isolate the problem. If the wireless is adding hum, then the pedal board is irrelevant, and so is the guitar. Plug the receiver directly into the amp input. Turn the amp up. Is there hum present more than if the guitar was plugged in direct? That would be the amount of hum the wireless added. Does that hum change when the transmitter is turned off? Does the volume on the guitar have any effect on this hum?

If the wireless is adding hum, then we want to isolate it to either the transmitter or the receiver. For example the receiver power adaptor could be under-filtering the DC. The transmitter could have a funny ground in the belt pack.

And how is all this set up? Where is the receiver with respect to the other gear? When I am wired, my guitar cord drops to my feet where it is plugged into my wah or whatever. When I am wireless, my guitar plugs into a belt pack. Is the receiver sitting down next to the wah or whatever or is it back near the amp somewhere with a long cord running back out to the wah? In other words, has an extra length of cord been added?

ANd for that matter, ever walk up next to your amp while wearing your guitar and notice your pickups senssing the field around the power transformer? If this receiver is sitting on or near the amp, it could be pickung up the power transformer field. Move the receiver several feet away from anything with a power transformer to see if it helps.

I had a customer once - a DJ - who kept bringing in his mixer complaining of bad hum. It worked fine for me every time. Finally I told him to bring in his entire rig, adn we set it up to wring out the problem. Sure enough it hummed. He had a small rack with the mixer horizontally in the top, and a couple large power amps in the rack below it. The bottom of the mixer was just about touching the upper power amp. As soon as I took the rack screws out of the mixer and lifted it six inches away from the power amp, the hum went completely away. The power amp power transformer field was coupling into the mixer circuits.

[Garydean]

Thank You Enzo for the fantastic reply. We're going to digest this a bit and post a reply is things are unchanged. Replacing the George L's cable with a heavy duty cable, from the receiver to the amp, made a big difference. We're gonna follow your suggestions the rest of the way.

Thanks again!!!!
Gary

[Garydean]

::::UPDATE::::

We use the wireless with no stomp boxes thru any amp and any guitar. NO hum.

as soon as we add a single pedal in the mix the hum is there. AC or DC powered doesn't matter...the hum is equally there when any pedal is introduced, doesn't matter what kind of pedal.


and stumped

[52 Bill]

as soon as we add a single pedal in the mix the hum is there. AC or DC powered doesn't matter...the hum is equally there when any pedal is introduced, doesn't matter what kind of pedal.

Do you mean any pedal by itself, or any pedal going through the pedal board setup?

[Garydean]

any pedal by itself, alone.

[BCRGreg]

Try the pedals on battery alone. If no noise is present, the power supply to the pedalboard is guilty.

I am assuming that all of the cables are of top quality, with no shorts.

[Garydean]

All the pedals were tried with DC alone. We even tried 4 different brands of high quality new cables.

thank you

Gary

[BCRGreg]

Is the output on the wireless set really high?