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awesomedjz
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Oct 23, 2009

Hum noise

Okay I will try to be as precise as can be on my problem.

I am using L1M1 2 bb. I've been noticing a hum. Here's what I have noticed about the hum.

Using mixer, main out XLR to 1/4 inch trs into channel 1. With the volume at around 4 to 6 on the powerstand and the R1 turned up at about 6 I get a hum. No volume on the mixer at this time. I can also turn the power completely off on the mixer and get this hum. The hum does not get louder as I turn up mixer either.

The hum sounds alot like the hum you would get as if you unplugged your speaker and grabbed the end with your fingers,, that BZZZZ hum.

The further I turn up R1 the louder it gets.

Any ideas ?
11 REPLIES 11
ST - Pro
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May 11, 2020

Re: Hum noise

Hi AwesomeDJz,

Sounds like a ground-loop.

Does the hum go away if you unplug the mixer from the AC power supply?

Does the hum go away if you remove all inputs from the mixer? If so, then add things back one at a time until the hum returns. Then you will have narrowed down the problem and you can tell us about that.



Are the mixer and the L1® plugged into the same AC power supply (power bar)?

Have you tried a different cable? (e.g. XLR to XLR)? You would have to turn down the trim on the L1® to make this work.


Here are some more ideas about Hum
Cap
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Jan 29, 2004

Re: Hum noise

Laptop? If yes, which make & model? Controller?

(#1 cause of hum in a DJ system is the laptop power supply, especially Dell.)

(#2 is DC powered controllers.)

If neither of these, ST's advice is the absolute best way to find the culprit.
Lou_D
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Aug 29, 2007

Re: Hum noise

Awesome,
We were participants in a similar discussion, a while back, and I advised trying a “Hum-X”.
That's my story and I'm sticking to it!
proflowery
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May 11, 2011

Re: Hum noise

More things to:

1. Remove Laptop Cable and try with battery only
2. Make sure no open audio leads (Ipod/ipad line out, etc.)
3. Mixer cable maybe defective (Try USB mixer)
4. Maybe ground loop noise coming from a PC Back-up battery on the same circuit (This one drove me nuts at home for months)
5. Turn off Wireless adapter and see if this is the culprit (A DJ friend of mine says that some Dells have had this issue)
mikep_2
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Apr 14, 2010

Re: Hum noise

I have had this a few times and for different reasons. Once I realized I had the phantom power turned on on one of the channels and turning it off fixed it.
One time it was the laptop power adapter and switching the adapter fixed it (cable end had gotten bent).
The other times it appears to be the cables since switching out the 1/4" cables fixed it so now I know which cables not to use.
Unplug/disconnect everything and reconnect one at a time from the 1/4" plug into the L1 backwards to the mixer connections, laptop etc.
awesomedjz
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Oct 23, 2009

Re: Hum noise

I used my old mixer this last night, hooked up the new mixer I bought and same problem. I get the hum and it gets louder when I turn up the trim on the L1 and the T1. Something else I hadn't noticed before as I was turning the mixer off on the back it shocked me. I also noticed when I touch the 1/4 jack on the L1 it shocked me.
Now I know it's not my cables or my equipment, it doesn't shock me using my other mixer.
awesomedjz
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Oct 23, 2009

Re: Hum noise

Also on another note, it still humms with nothing connected to it,,,, just xlr to 1/4 ts to the bose. Mixer is Behringer Eurorack RX1202FX Pro Stereo Line Mixer
ST - Pro
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May 11, 2020

Re: Hum noise

Hi AwesomeDJz,


quote:
Originally posted by AwesomeDJz:
I used my old mixer this last night, hooked up the new mixer I bought and same problem. I get the hum and it gets louder when I turn up the trim on the L1 and the T1.

Sorry, I didn't understand this what you wrote above.

Do you get the hum with
- just the new mixer
- old mixer and new mixer connected together
- old mixer by itself

quote:

Something else I hadn't noticed before as I was turning the mixer off on the back it shocked me. I also noticed when I touch the 1/4 jack on the L1 it shocked me.

Which mixer (new or old) or both?

If you are getting shocks, you don't want to be using whichever piece of gear is causing it. You also don't want to be connecting that piece of gear to other devices because you might damage them.
quote:


Now I know it's not my cables or my equipment, it doesn't shock me using my other mixer.


Are you using a power bar? Have you tried a different one?
awesomedjz
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Oct 23, 2009

Re: Hum noise

Sorry

I used my old mixer last night with no problems at all no hum.

Hooked up my newer mixer thismorning and was troubleshooting the problem thats when I got the shock from the mixer and then I was about to turn down the bose and turn it off and my hand touched the plug at the Powerstand and it shocked me too.

Yes using a powerbar. Going to try using a different powerbar.