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Hum noise in PA after installation
by flevojax on 2011-05-10 07:50:13

Hello All

I just purchased the XD-V30 Wireless Mic Yesterday, i set up on the same line as my previous Sennheiser mic was on. My Sennheiser wireless mic was on channel 2 on the mixer board. i swapped the XLR cable from the sennheiser receiver and inserted in into the XD-V Receiver. At first the sound was spectacular, but about after a hour of testing the mic around the building, and on stage, i started hearing a loud hum noise in the system. The only way the noise goes away is if i mute channel 2 on the mixer board where the mic was installed. When i plug the Sennheiser wireles mic back up I dont get any hum.

The battery strength and signal strength is excellent. I tried different channels but the hum is still there. I also tried different channels on the mixer also. I took the mic home and tried it out on my home system but i didnt get a hum at at all

Do I need a brand new XLR Cable for this mic?

Could it be a grounding Issue?

Please let me know your thoughts or suggestions

Thanks

Flevojax



Re: Hum noise in PA after installation
by DanCornett on 2011-05-10 11:49:16

Since the 'hum' seems to be isolated to that particular channel, there are two places for 'hum' to make it's way into the system:  Before the transmitter, and at or after the output of the receiver.

I have found that the XLR connection to the V70 receivers can sometimes require a bit of 'convincing' to latch in tightly -- I don't know if that is also true for the V30 receiver.

I would try swapping cables.

Did the hum start "all at once"?

Another possible source of hum is the cables being moved to a different position than they were before.

You should also be aware that many "wall-warts" (i.e.: the little power adapter transformers which convert AC power to either lower voltage AC or to DC power) can be a strong source of hum if an audio cable ... or any mic-level "connection" ... is near to it.  I have one that is particularly nasty, and I have to be sure that no audio cables run within less than 4-5" of that power-block.



Re: Hum noise in PA after installation
by dboomer on 2011-05-10 13:16:10

It is possible that your XLR cable is bad.  Try switching it with another known good one.

Is the power supply for the XD-V and for the mixer plugged into the same place?



Re: Hum noise in PA after installation
by flevojax on 2011-05-10 13:53:10

the hum started a hour after installation

I will try to swap out the cables( when i took the XD-V30 to my home studio it worked perfectly with no hum when i used a known working XLR Cable

I believe the Wall Adapter was running alongside the XLR cable so i will try to separate the two to see if that  fixes the problem.

I will attempt this later on tonight i will let you the results



Re: Hum noise in PA after installation
by flevojax on 2011-05-10 13:54:36

The XD-V30 and the mixer are hooked up into the same power strip

I will also try a new XLR Cable



Re: Hum noise in PA after installation
by dboomer on 2011-05-10 14:45:14

Hooking your gear up in the same power strip is very important to keeping noise down, so you are doing the right thing there.

You might look at your mic cable.  If you have a cable with pin 1 connected to the shell it can cause problems like you describe (you can just clip it off to the sheel).  It should not be an issue ... but just for fun do you have phantom power running?  You could try switching it off and giving a listen (it shouldn't make any difference ... but you never know how it might be wired up in a mixer)



Re: Hum noise in PA after installation
by DanCornett on 2011-05-11 05:50:31

flevojax wrote:

...I believe the Wall Adapter was running alongside the XLR cable so i will try to separate the two to see if that  fixes the problem...

Just to be clear ... it is not usually a problem for the cable of the power adapter to run along side an audio cable; the problem (when it occurs) is with the "little black box" itself.  Those things are typically in an unshielded plastic box -- and that's the item to watch out for.  (I called it a "wall-wart", but it might also be in the middle of the cable, too.)



Re: Hum noise in PA after installation
by flevojax on 2011-05-11 14:28:14

I tried a brand new XLR cable and still got the same results.

I also tried putting an adapter on the Three prong power plug that will make it two plugs

The only thing that seems to work fine with no hum issues is when I run a unbalanced cable from the XD-V30 to the Direct Box and then to the snake.

when i do that i get no hums anywhere so far.

i will attempt again tonight to see if it still has no hum.

The Phantom Power is off but i will check it tonight to see if that will make a difference



Re: Hum noise in PA after installation
by flevojax on 2011-05-11 19:15:14

I tried a brand new XLR cable and still got the same results.

I also tried putting an adapter on the Three prong power plug that will make it two plugs

The only thing that seems to work fine with no hum issues is when I run a unbalanced cable from the XD-V30 to the Direct Box and then to the snake.

when i do that i get no hums anywhere so far.

i will attempt again tonight to see if it still has no hum.

The Phantom Power is off but i will check it tonight to see if that will make a difference

update""""

I checked the Phantom Power it was off

I didnt get any hum tonight

How do i boost the overall volume of the mic I have my fader past 0 to get a good sound?



RE: Hum noise in PA after installation
by Line6david on 2011-05-12 14:22:05

Hi,

Do you have the XD V30's output running to a line or mic level input?

What are the gain or trim settings on your channel strip set to?

If you could provide me with the make and model of the console that would be helpful as well.

Thanks,

David

Line 6 Customer Support



Re: RE: Hum noise in PA after installation
by flevojax on 2011-05-12 19:29:27

the output is coming from the unbalanced 1/4 output of the XD-V30 into a direct box, then to the snake on channel 1

The Gain is set to 1 o clock and the fader is set to 0

The mixer i have is an Peavey 2426 Console ( 24 channels, EQ, 2 Aux sends, 2 efx sends)

can you explain line level input and mic level input



Re: Hum noise in PA after installation
by flevojax on 2011-05-12 19:31:43

can you explain what you mean about the "pin 1 connected to the shell it can cause problems like you describe (you can just clip it off to the sheel)"

how would i clip it off



Re: Hum noise in PA after installation
by dboomer on 2011-05-13 08:10:55

The only thing that seems to work fine with no hum issues is when I run a unbalanced cable from the XD-V30 to the Direct Box and then to the snake.

when i do that i get no hums anywhere so far.

Your answer is right here.  When you connect a direct box between the two units the problem goes away because the transformer in the DI isolates the grounds.  You have a simple ground loop or pin 1 problem that you must solve.

In some cables there is a wire running from pin 1  to the shell of the connector.  IF you have one of these cables clipping the wire the runs between pin 1 and the shell MAY help.

If not you can either leave the transformer in place to solve the problem or you will need to do some research about troubleshooting ground loops and solve it that way.




The information above may not be current, and you should direct questions to the current forum or review the manual.