Effects loop problem: any experts out there?

When I plug anything into the effects loop, I get a very loud electric hum. I want to put a volume boost pedal (MXR EQ) into the effects loop but the very loud hum immediately kicks in, whether or not the pedal is switched on or not, and whether or not I have any master volume dialed in. I have the leads lined up to send -in / out-return.

Is there anyone out there who can help me please?

Check the cables first. Put one end into Send, and the other into Return. Listen for hum or volume drop or distortion or anything else. Next, I would suspect ground loop. Run the pedal on battery. If it doesn't run that way, plug it into the same outlet as the amp.

Keep the signal cables away from the power cord, and away from any computer equipment. FAR away.

Try a different pedal, preferably one that can run on battery.

If it's a ground loop, then an isolation transformer like the HE-2 should help.

The problem was a ground loop. I installed batteries in the pedal and no problem. But the pedal has 6 LEDs and eats batteries, so I want to use 9v power. I tried plugging the amp and pedal into the same plug board, but still had a problem. By the way, I have the same problem with my Maverick, just not as severe.

What are my other options please?

How are you powering the EQ pedal when not using batteries?

When not using batteries I power the pedal using a 9v adaptor.

Ebtech HE-2. Or an isolated DC power supply (not a cheap wall-wart).

werdna said:

When not using batteries I power the pedal using a 9v adaptor.

Click to expand...

If you want, I've got an Ebtech HE-2 that I've never used I'd be willing to sell you. I bought it because I thought I might need it, threw away the packaging, and have literally NEVER used it.

Let me know.

Thanks Mark IV, but before I read your post I got myself an isolated DC power supply, and the problem has gone. Otherwise I am always interested in picking up stuff off forum members. Thanks very much for the advice.

The electra dyne would be improved with a solo boost switch. All mesas should come with one.

No prob, Bottle Rocket. Which power supply did you get?

The owner's manual says it's better to run your FX throught the front of the amp......just saying!