how to eliminate ground hum?

Can I use a DI box with an earth lift switch?
Yes, that will work and it's not dangerous...

Try removing the hum with iZotope RX, it's a great app and they have a demo:
http://www.izotope.com/products/audio/rx/

Or apply an Eq with a sharp notch filter - look for the humming frequency (50-60Hz) and apply the Eq with the Q factor set very steep to 80-100 - then reduce the gain of that frequency band by -24 dB, that should also do the job.

I can sympathize. Ground hum can be very frustrating to diagnose and eliminate. The ideas that you have suggested are all worth trying. You can lift the ground from the keyboard with one of those little adapters. You can get them at any hardware store. That can be the quickest, easiest and cheapest fix. Don't alter your keyboard by removing the ground prong from the plug or anything like that. The 3-2 ground lift adapter will do the same thing and it's reversible. If that's what the repair shop was suggesting, I'd find a new repair shop. If that's their idea of a solution, chances are they might have missed something while diagnosing the problem. A power supply problem in the kbd. would be one of the first things to check out.

But, assuming the kbd. is OK, here are some other ideas.

Have you tried a different audio cable to connect the keyboard?

Have you checked the outlet(s)? Maybe you have a problem with your AC wiring that you didn't know about? You can buy a cheap outlet checker at the hardware store. Mine is a little plastic thing, about the size of a ground lift adapter, w/ 3 LEDs that light in different combinations to show wiring irregularities. Is the keyboard plugged into the same AC circuit as the rest of your gear? If not, try that.

You could try the DI ground lift, too.

It could be any piece of connected gear that is interacting w/ the kbd. to cause the buzz. My friend recently spent a few long days chasing down a similar problem only to discover - by accident - that it was his display monitor that was causing the problem. Ideally, you have to isolate the problem. The best way to do that is to completely disconnect (AC & audio cables) everything except the kbd, computer and interface and see of the problem is still there.

Recording the noise separately and inverting the phase of that track should work in theory but I think you would have to record the noise-by-itself track in perfect phase w/ the noise-plus-keys track in order to cancel is completely. In any case, it would be an interesting experiment to try. If you can afford it, Izotope RX is very effective for this type of problem http://www.izotope.com/products/audio/rx/

-John

Do NOT use the hardware store 3 prong to 2 prong adapter to remove the ground plug. That WILL expose you to the possibility of a dangerous shock. Ground plugs are there for a reason - to protect you - and you remove them at your peril.

Standard grounding fixes - try and make sure all your gear is connected to the same circuit. If everything's on the same power bar, or connected to the same outlet it can help.

Any dimmer switches in the room? Those can cause interference and hum. Turn'em off.

Try different cables, different outlets, different locations in the room. Does it make a difference?

A few companies make cable adapters (not ground lifts) with names like Hum-X and Hum-Eliminator (I think) which will attempt to cure the problem.

And the DI box solution might work as well.

I had some major ground hum problems with tube mics in my studio which defied all logic, and 2 different electricians couldn't figure it out. Putting everything on the same circuit helped a little... Eventually my problem was traced to a bunch of those new mini-flourescents in the next room. When they were switched off, the hum went down 20db...

Keep experimenting, and troubleshooting, but keep it SAFE.

Removing ground earth plug is a very good idea
especially if you have experience that the Juno synth don't have HUM noies when plug outside your studio...

Be sure that ground cables are connected by using an indipendent Ground earth point

if there are Industry, Resturant, air condictioner, electric motor near your home location on the same ground earth you can get the HUM and other high frequencies noise...
you need to have a good Individual connection Ground point

check here for details and correct info

http://en.wikipedia.org/wiki/Ground_(electricity)

Also...
I cannot use Ground Heart on my studio because the HUM is audible a lot...
I have disconnected the Ground Heart...
My Recording Studio is NOISELESS since 1980!!!

Also... Hum noise can be audible if you use BAD cables...

I have bougth a Lot of XLR cables with wrong anti-phase connections...
I've been force to open XRL plugs to weld properly the connectors...

Check... is not dangerous...
just try to unplug the ground connector only in the Juno. (you will be able to reconnect it... if not works.

Check also with different audio Cable

I have my personal life-safe-electrical shock and i use a 4000 watt UPS system

G

Message was edited by: fermusic

Sampleconstruct wrote:
Can I use a DI box with an earth lift switch?

Direct Box can change the inpedance on audio output ... if that happens the Juno sounds could be not the same as is without DI box ... could be dangerous for sound quality

Juno is not a new CE device...
I suggest to don't use Direct BOX....

I suggest to follow the qualified technical support advice.

G

<http://www.sweetwater.com/store/detail/PRO1000/>

I rent an old house with old electrical that is as noisy as can be.

Got this....hum and noise problems...gone.

Due to electrical issues in my previous studio I had ground loop issues. I removed the third prong or lifted the ground with an 3-2 adapter on every piece of gear I had. It solves the hum issue completely. This condition continued in my studio for 21 years with no shocks, mild, severe or otherwise. Unless you are recording in the shower or are using your gear outside the danger or ground lifting is pretty much non existent. They would not be allowed to sell ground lifting adapters if they were dangerous. I also had to remove all cfl light bulbs to eliminate a buzz (not a hum) from my guitar

I have a couple Monster Power filters in my studio and I can definitely hear a noticeable improvement since I began using them. I don't think they will cure a bad ground but they do help.

-John

All your suggestions are fine.. After having done all your suggestions, occassionally I still have a hum. When I can't get rid of the hum, I remove the ground plug. Been doing that for 40 years. Not shocked yet.. I probably would not resort to that if I was playing live on a stage and it was raining. But in the confines of my studio, it's ok..

Another way of looking at it, depends on your set-up. If you're a profession studio, fix it. - if it's a home studio you can spend $2 on a ground lifter adapter or up to hundreds on different solutions.

Here's a good article I found recently about grounding, and other electrical safety issues for musicians:

http://www.guitarnuts.com/technical/electrical/safety/index.php


It's true, in a properly wired environment most of us can consider ourselves safe from a potentially lethal grounding shock. But, it doesn't take a rainstorm to make a ground-lift dangerous. If your wiring is faulty anywhere in your system, the ground plug can be a lifesaver. I don't think you'll find many electricians who'd recommend using ground lift adaptors. The original 3-2 prong adapters were designed for plugging modern 3-prong equipment into older 2 hole outlets. Not for isolating your gear from the path to ground.

Just sayin.

Fortunately, most of the gear we use... keyboards and what not, is plastic of one kind or another. The insulation would protect us from the kind of shock that an internal direct short could cause.

Except for that metal screw on the side of the case...Yeeoch!

pancenter-

That was what I did - got a good UPS, and plugged everything into that..