Karaoke Forums

how do I get rid of the loud hum when the music isnt playing its driving me crazy and it only happens at one of the bars I do shows for and not others.

That sounds like some sort of ground loop interferance. Could be the plug you plug into isn't properly ground, or also sometimes happens with unbalanced cables picking up magnetic or radio wave interference or even the field that emminates from neon lights.

I'd first try a ground loop isolator:

http://www.google.com/#hl=en&biw=1003&b ... a97aebfa72

If that doesn't work, you may want to invest in balanced cables throughout your system, assuming that the major components have balanced inputs/outputs, which they should if they are pro-level stuff.

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C Mc
KJ, FL

I agree sounds like ground. But in this case since it is only at this club I would think it was a bad ground line on the main power plug your plugging into. Try another receptacle. If that doesn't help ground to a waterpipe. This usually occurs on pa or mics.

The fact that it only happens at this club means nothing. When he plays in other places it could be that he plugs his equipment in differently or there is a lesser potential difference between grounds, etc.

Fixit, I believe Topher is on the right track however before you go out and spend money on cool little devices there are easier ways to address ground loops (or at least confirm that this is the issue). The #1 best way to eliminate a ground loop is to ensure that all equipment that is interconnected in your system is all connected to the same ground path. In other words, use a heavy duty power strip and make sure all your amps, mixers, computers, TV's, etc are plugged into the same strip.

If you can't do that, try to determine what is causing the ground loop. Mute each channel on your mixer or remove the input to each channel until the sound goes away. Once you've identified where it's coming from, now you can work on isolating it's ground from the rest of your system. Remember that everything in your system has a ground connection, even if the electrical plug isn't grounded. The sheild of every cable in your system is the ground, I've gotten ground loops through RCA and VGA video cables to TV's before.

Ground loops are discussed quite a bit in other threads on the forum so you can search to find more info if you'd like. What you want to know that will help you is what causes them. Basically when more than one path to ground exists in your system (i.e. if you have equipment plugged into two different outlets and then interconnected via audio or video cables) and the electrical potential of those two grounds is different. The difference in potential causes a voltage to flow from one ground point to the other (over-simplifying for ease of understanding) across all those share ground connections (audio or video cables) in your system, which causes the hum.

Good luck, common issue that causes a lot of confusion and frustration.

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DJ Tony
Let It Rip Karaoke

thanks for all the help,I will be there again this Saturday night and will try plugging into the same power strip for everything and go from there.

No disrespect to everyone who posted above. I truly value their advice given to me through the years. But before you do everything that was suggested, try first to disconnect the coax cable behind the tv where you hook-up your RCA connection. That coax cable can be an outside house antenna feed or coming from satellite cable box.

I had the same problem on this one club. A dj told me to disconnect that cable behind the tv because he played there before and that's the only way to eliminate the hum. Good enough, it disappeared. Hard to imagine how one tiny coax cable connection can be the culprit of all my frustration but it solved the problem.

If that doesn't work, well........ start the elimination/isolation trial & error. Good luck!

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To be fortunate enough to derive an income from a source as fulfilling as karaoke music has got to be as close to heaven as we can get here on earth!

I agree with Brian. Took the same advice from another thread and it eliminated the hum. My hum was only coming from my CAVS player channel - disconnected the coax and it was gone.

(I had plugged an RCA cable into a TV that had coax also hooked into it)

Well once again, remember that coax is a shielded cable (and the shield acts as a ground) and it does usually run to a ground block before going to the antenna so it's actually not all that surprising. I would agree this is another thing to check, but I wouldn't say it's a more likely cause than electrical connections, that is by far the most common way to end up with ground voltage.

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DJ Tony
Let It Rip Karaoke

Sure the fact that it only happens at this club means something! Only an amateur would overlook it! The purpose of ground is to make sure there is no difference between any base potential (ground).

It means nothing in terms of determining whether or not there is a ground loop causing a hum. Only an amateur would overlook the fact that this poster never told us how his equipment is connected to mains power. Only an amateur would overlook the fact that the ground is common across all the interconnected equipment. Only an amateur would fail to understand that the ground is used as a reference in all things audio and that any instability of the potential (for instance a 60Hz sine wave) will induce a hum.

The fact is with the small amount of information the OP provided, the fact that it only happens in one club is completely insignificant in terms of determining if it's a ground loop or other issue. I play in clubs where having the bar's TV plugged into a different circuit than the rest of my rig is no problem because the grounds have equal or close enough to equal potential. In other clubs, that same situation causes a ground loop because the potentials between the two ground connections are different. Simply plugging those TV's into my power strip (no humX or such silly device connected) eliminates the loop and shocking, the 60Hz hum goes away.

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DJ Tony
Let It Rip Karaoke

Anytime I get a hum with my DJ equipment it is always a grounding pin. I either snap off the grounding pin on the plug, or use a 3 prong to two prong adapter.

Hmmm.
So far one person has shown to me he fully understands this.
He used the term "lesser potential difference".
Anyone care to guess why?

I love my humX, and I don't EVER have these problems, so far in over 50 clubs/houses/bowling alleys whatever. I like my silly little device! It works. I've taken it away before just to see if it works, and quite a few times a loud hum appears when it is gone. A friend of mine has helped me set up my equipment a few times. One time he did the power part and I knew right away when the system came on he didn't use it. I'm sure there are other things I could do, but my humX works, and it is obvious in the sound quality on occasion. So if you get down to your last nerve and can't figure it out, give the humX a try. Hasn't done me wrong yet. It's a nice addition for us dummies who don't know who PIV is. I got an A in an electrical engineering class during my Navy training and I still don't know how the crap really works. A HumX for the DumX navy guy.

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[glow=red]Yo sucka, we need this hea CHOPTER, and we need it now![/glow]

Thanks, Hamsamich. I will give that HumX a try. I have a Dell laptop 3 pronged power adapter I can’t use because it emanates a nasty hum to my system.

Someone in another thread recommended cut off the ground prong. He said that’s what he did it and that eliminated the hum. I really don’t want to disable the ground when I know that’s for my own safety. The thought of getting an electrical shock is scary.

HumX is a little pricey but I think its well worth the money if it can eliminate the buzz. http://www.sweetwater.com/store/detail/HumX/

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To be fortunate enough to derive an income from a source as fulfilling as karaoke music has got to be as close to heaven as we can get here on earth!

Better, and more likely to work in my opinion, is the Hum Destroyer:

http://www.zzounds.com/item--BEHHD400

That actually removes the source, no matter the reason.

I agree that the most likely source is the bar TV, and sometimes you can't plug those into the same AC outlet. The easiest fix usually is to remove the satellite or cable connection from that TV. But if you can't do that, the Hum Destroyer works.

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[color=#ffff55]Mickey J.[/color]
Alas for those who never sing, but die with all their music in them.
-- Oliver Wendell Holmes, Sr.

OK, rather than respond to a few things individually, I'll cover it all here. First and foremost, DO NOT EVER remove the grounding pin from a plug. That is a horrible idea and one that could lead to death. This isn't over-reacting panic, it is the truth. The equipment we deal with, in particular power amplifiers, deal with very voltages and currents. If a component failure should occur, it's that path to ground that's going to save you. If you take that grounding pin out now you've removed that simple path to ground. So stray voltage is now going to find a different path. It could be through your audio cables into your mixer and into your body, it could be through that mic cable and to the current singers' mouth, the options are very tough to predict and believe me none are particularly pretty. So don't do it. If you're going to ignore all the warnings and do it anyway, please don't recommend to others that they do it. Oh and just FYI to all, using a one of those 3 prong to 2 prong adapters is no better unless you are taking that tab or wire on the top of the adapter and appropriately grounding that (that's what it's there for if you didn't know).

OK, now the HumX. My less than glowing opinion of the HumX and similar "silly" devices has nothing to do with whether they work or not. They do work, they are an isolating transformer that provides a way to maintain a safe ground while ensuring there is no ground loop issue. However, I don't like them because they are not necessary. They're quite pricey (far more so than the components they contain would ever warrant) and they're made to take advantage of people who don't have a clear understanding of electrical power. So as Hamsamich says, if you're at the end of your rope and can't or don't want to figure it out, then get one of those. Just be aware that you're spending that much money to fix a problem that could be fixed for no cost.

Finally, I've noticed both Laptops and TV's have been a common source of this issue lately. Unfortunately no one makes a ground isolating RCA or VGA adapter. And to remove some confusion, it makes no difference if the adapter is a grounded adapter or not. It makes no difference that the power supply is a AC to DC transformer, there are still ground connections. For these reasons I'd actually recommend if you're going to buy one of those devices, get the HumX or similar rather than the Hum Eliminator. The latter is focused solely on isolating audio devices which as we've seen here, aren't always the issue. The HumX actually addresses the issue where it truly exists, in the electrical connection itself. We deal with a lot of strange equipment most audio engineers don't typically have to contend with. This makes the job of a KJ eliminating a ground loop far tougher than it is in a normal live audio environment.

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DJ Tony
Let It Rip Karaoke

I use Dell Laptops for my Karaoke setups, D800s. If you unplug the power supply from the laptop you will notice the hum goes away while running on battery alone. I use the item at below link to cure this:

http://www.amazon.com/Behringer-U-CONTR ... Promotions

I use the exact same device that Topher suggested. The Ebtech HumX is a spendy little device but has worked every time I have a loud hum which is only present in maybe 20% of my setups. I thought $60 was outrageous for this little plug but ended up being worth it in the performance arena. I never worry about potential hum issues anymore cause I always keep it in my gear bag.

Seems like some bars or restaurants have issues. I'm thinking that wiring on the circuit that I'm connecting to was not properly grounded in the first place. Bars are notorious for adding electrical circuits without using a licensed electrician, rather they usually have a customer that does handy work that is working off a bar bill.. Saves them lots of money and gets it done without getting the local government involved.



I purchased mine at Guitar Center.

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FlipSide Karaoke
Scott

I used the usb sound card because on Dell laptops even plugged into a ups I got hum. You get hum from other devices it would probably take other action.

Another satisfied user/owner of the Ebtech HumX.

Spendy?--Yes

Works?--Yes

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Music speaks to the heart in ways words cannot express.