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SC Events
16-07-2009, 06:03 PM
Hi All,

I am having a bad problem with humming and it's driving me nuts.

My Set up is as follows:

My top speakers (ProSound 300W) are going from the mixer's 'Main' out to a Kam KEQ152 Equaliser then in to a ProSound 1600W Amp.

My bottom speakers (R.C.L 600W) are going from the mixer's 'Booth' out to a Gemini EQ-300 equaliser then in to a Behringer EP1500 Amp.

My mixer is a Numark DM1635 (no longer in production)

I am running Virtual DJ through my Laptop and I thought it may have been caused by the laptop charger, but I completely disconnected it from the mixer and I still had the same amount of humming.

I did disconnect the EQ's and the humming reduced quite a bit, but it was still there.

Any ideas how to get rid?

Cheers everyone.

Steve the DJ
16-07-2009, 06:22 PM
You need a (or possibly a pair depending on your set up), Ground Loop Isolator such as this (http://www.maplin.co.uk/Module.aspx?ModuleNo=33172).

Put it between your soundcard and mixer.

SC Events
16-07-2009, 06:26 PM
I completely unplugged my sound card and the humming was still there.

Charlie Brown
16-07-2009, 06:26 PM
Hmm, I think you need to take the earth out of your laptop plug. I bet you £50 the hissing will stop. The magnets aren't that good.

SC Events
16-07-2009, 06:34 PM
It shouldn't be anything to do with my laptop as I completely disconnected it and the soundcard and the humming was still there as bad as ever.

CRAZY K
16-07-2009, 06:50 PM
Hi All,

I am having a bad problem with humming and it's driving me nuts.

My Set up is as follows:

My top speakers (ProSound 300W) are going from the mixer's 'Main' out to a Kam KEQ152 Equaliser then in to a ProSound 1600W Amp.

My bottom speakers (R.C.L 600W) are going from the mixer's 'Booth' out to a Gemini EQ-300 equaliser then in to a Behringer EP1500 Amp.

My mixer is a Numark DM1635 (no longer in production)

I am running Virtual DJ through my Laptop and I thought it may have been caused by the laptop charger, but I completely disconnected it from the mixer and I still had the same amount of humming.

I did disconnect the EQ's and the humming reduced quite a bit, but it was still there.

Any ideas how to get rid?

Cheers everyone.

Right, standard fault finding method works like this--

Set up your kit as you normally do adding each piece of sound equipment one at a time starting with the amp and one speaker and build it up from there one piece at a time until the hum starts---then you know which item is to blame.

Wont take long.:D

CRAZY K

Steve the DJ
16-07-2009, 06:51 PM
I completely unplugged my sound card and the humming was still there.


It shouldn't be anything to do with my laptop as I completely disconnected it and the soundcard and the humming was still there as bad as ever.

Apologies. I misread your initial post and the symptoms you described are usually associated with a Ground Loop "hum".

SC Events
16-07-2009, 07:15 PM
That's OK, I did suffer that problem when I used to use my Dell Laptop but now I use a much higher performing machine :D

ppentertainments
16-07-2009, 07:16 PM
I would follow Crazy K instructions but also try swapping cables about. It is suprising how much problem a dodgy cable can cause.

I had a problem not so long ago where the left side of my amp kept clipping. Changed the speakers over, speaker cables etc and all it truned out to be was the cable connecting the mixer to the amp.

SC Events
16-07-2009, 07:31 PM
I shall give it a go now, cheers chaps.

SC Events
16-07-2009, 08:05 PM
And the root cause of my problem is..........................................












My graphic EQ's. As soon as I turn them on, I get loads of humming.

If set all the frequencies to 0db then it's not too bad but as soon as I adjust the levels higher, I get humming.

Rowleys
16-07-2009, 08:07 PM
ioget it really bad it come from my laptop tho ..

i tryed cuttung earth but still happens so i conect my monitor up and it stop all the time

SC Events
16-07-2009, 08:33 PM
Thanks, but it's not coming from my laptop or soundcard. It's coming, somehow, from my graphic Equaliser's.

DJ Jules
16-07-2009, 08:52 PM
Thanks, but it's not coming from my laptop or soundcard. It's coming, somehow, from my graphic Equaliser's.

Is that still with nothing connected to the inputs (as in, no cables, no nothing?) If so, then you either have a faulty EQ or there is something near one of the EQ's which is interfering (look for power supplies, mains cables, etc).

If it stops when you disconnect your inputs, then you probably have a ground loop problem between your mixer output and one or more of your EQ's (or a dodgy cable). As has been said already, swap cables until something happens.

Do either of your EQ's have an Earth lift switch you could try switching in to see if that improves/eliminates the problem?

Julian

SC Events
16-07-2009, 09:01 PM
Yes, they both have an Earth Lift switch, but it didn't appear to do anything.

Thanks. :)

DJ Jules
16-07-2009, 09:11 PM
Yes, they both have an Earth Lift switch, but it didn't appear to do anything.

So is the humming still happening with the inputs disconnected?

Excalibur
16-07-2009, 09:42 PM
Yes, they both have an Earth Lift switch, but it didn't appear to do anything.

Thanks. :)

Important. Never flick an earth lift switch while kit is plugged in. Always switch all gear off before altering it. Change things one at a time, to eliminate things.

Alternatively, throw the EQ's away.

CRAZY K
16-07-2009, 10:04 PM
Change things one at a time, to eliminate things.



THERES AN ECHO IN HERE;)

CRAZY K

SC Events
16-07-2009, 10:11 PM
I have turned all the equipment off and tried the Earth Lift switch - No difference.

I have unplugged everything and plugged it back in one at a time and have only had the humming coming back when I plug in my 2 graphic EQ's and set the levels above the 0db setting.

Neither of them are that old and one of them was bought from a fellow DJ member.

Jiggles
16-07-2009, 10:17 PM
Take out the EQs then.

SC Events
16-07-2009, 10:19 PM
I need them though as my speakers bottom speakers lack 'punch' with the bass, otherwise I would.

Excalibur
16-07-2009, 10:31 PM
I need them though as my speakers bottom speakers lack 'punch' with the bass, otherwise I would.

With a big enough amp, these would remedy that particular defect.
http://www.classd.ltd.uk/2000w_pair-of-cd215-class-d_pa-speakers-for-djs-and-bands.html

SC Events
16-07-2009, 10:37 PM
They look lovely, but my money gets spent on flying a plane, which my DJ'ing pays for :D

When I have completed my PPL, I will definitely be upgrading my sound system.

A1DL
16-07-2009, 11:28 PM
Hmm, I think you need to take the earth out of your laptop plug. I bet you £50 the hissing will stop. The magnets aren't that good.


ioget it really bad it come from my laptop tho ..

i tryed cuttung earth but still happens so i conect my monitor up and it stop all the time


Talk of disconnecting the ground in the plugtop concerns me. Don't do it. Any appliance with an earth wire has it there for a reason and disconnecting it could lead to serious or fatal injury through electric shock.

Dynamic Entertainment
16-07-2009, 11:46 PM
I seem to remember a certain "qualified" electricion recommending doing the same thing Tony.....Wonder if Charlie is him in disguise. :D

Seriously though Charile, its not worth the risk, when you can buy suitable fixes :)

SC Events
16-07-2009, 11:46 PM
Talk of disconnecting the ground in the plugtop concerns me. Don't do it. Any appliance with an earth wire has it there for a reason and disconnecting it could lead to serious or fatal injury through electric shock.

I have no intention of disconnecting any wires. I have been studying Electrical and Mechanical Engineering for the last year and I don't think the strict H&S people would be too happy either.

It doesn't have anything to do with my laptop or soundcard it is coming from my EQ's which are mounted in a 6U ABS case along with 2 amps.

I may have confused some people as I put 'Hissing' in the title, but 'Humming' everywhere else. It is humming i'm getting through both sets of speakers.

DJ Jules
17-07-2009, 07:40 AM
I have no intention of disconnecting any wires. I have been studying Electrical and Mechanical Engineering for the last year and I don't think the strict H&S people would be too happy either.

It doesn't have anything to do with my laptop or soundcard it is coming from my EQ's which are mounted in a 6U ABS case along with 2 amps.

I may have confused some people as I put 'Hissing' in the title, but 'Humming' everywhere else. It is humming i'm getting through both sets of speakers.

Could be interference from a poorly shielded amp (though this is unlikely - if you've been doing electrical engineering you probably know more about this than me ;) ). If the EQ's are mounted in very close proximity to the amps in a 6U case it's possible though. It might be worth checking the earth connections on the amps, or taking the EQ's out of the Rack to see if anything changes?

Is this happening from both EQ's and through both Amps?

Julian

CRAZY K
17-07-2009, 08:56 AM
With a big enough amp, these would remedy that particular defect.
http://www.classd.ltd.uk/2000w_pair-of-cd215-class-d_pa-speakers-for-djs-and-bands.html

No need, these http://www.classd.ltd.uk/1400w-cd15sp_pair-of-classd_pa-speakers.html

are more than adequate as long as you attend the Excalibur Speaker pole mounting course regularly held at his house.

Well it was when I visited:D

CRAZY K

CRAZY K
17-07-2009, 09:00 AM
Talk of disconnecting the ground in the plugtop concerns me. Don't do it. Any appliance with an earth wire has it there for a reason and disconnecting it could lead to serious or fatal injury through electric shock.

I think the spelling was more shocking THAN 240 VOLTS:eek:

Ive had a few beltings off the mains ---but :eek:

CRAZY K

SC Events
17-07-2009, 10:38 AM
No need, these http://www.classd.ltd.uk/1400w-cd15sp_pair-of-classd_pa-speakers.html

are more than adequate as long as you attend the Excalibur Speaker pole mounting course regularly held at his house.

Well it was when I visited:D

CRAZY K

I already have fused vertebrae in my spine, so those speakers would break my back lol.

SC Events
17-07-2009, 10:40 AM
Could be interference from a poorly shielded amp (though this is unlikely - if you've been doing electrical engineering you probably know more about this than me ;) ). If the EQ's are mounted in very close proximity to the amps in a 6U case it's possible though. It might be worth checking the earth connections on the amps, or taking the EQ's out of the Rack to see if anything changes?

Is this happening from both EQ's and through both Amps?

Julian

I shall have another go.

Is there anything I can by to connect to the earth connections on the pieces of equipment, like an isolator or similar?

Danieleastwood.com
17-07-2009, 10:42 AM
I'm sorry to say this, but until you can get yourself a better (and that normally means more expensive) EQ, then you'll have to put up with this, or remove the eq completely. Unfortunately, the build quality of KAM stuff has diminished over the years as most of the components are very low cost and rushed together in a factory over in China or Taiwan.

I have a berhinger Ultra-curve for eq-ing, and thats horrendous for hissing. Until I have funds available for something like BSS or the ECLER card for my amp then it'll have to do.

I know the frustartion though, Not nice having that in the background before you play music through your system.

TonyB
17-07-2009, 02:30 PM
I shall have another go.

Is there anything I can by to connect to the earth connections on the pieces of equipment, like an isolator or similar?

You could be getting an earth loop caused by the cases of the EQ and amps touching - cure by using insulating tape where they touch. Also can be caused through the rack rails and there are things called humfrees you can use e.g. https://www.shop.liteopia.co.uk/products.php?p=27d38a

How much the equipment costs to buy is irrelevant as earth loops through the racking rails can happen to any gear.

SC Events
17-07-2009, 03:33 PM
How would I connect the Ground Loop Isolator in to my set up?

Cheers.

TonyB
17-07-2009, 03:46 PM
Ground loop isolator is an inline device and would go, as previously mentioned, between the output of a device such as a laptop and the input to, for example the mixer.

It wouldn't make any difference if the ground loop was being caused through the racking though.

SC Events
17-07-2009, 03:58 PM
Do you have any suggestions for isolation my rack?

I know the problem has nothing to do with my laptop or soundcard and is definitely something to do with my rack.

I'm trying to solve it ASAP as I am doing a Wedding tomorrow.

TonyB
17-07-2009, 04:01 PM
Firstly you need to remove the EQ from the rack and then see if it still causes a hum when its used. If it does stop the hum then you need to isolate it as described in my post above.

SC Events
17-07-2009, 04:46 PM
Could this also be the cause of the ProSound amp in to protection mode sometimes?

SC Events
19-07-2009, 11:21 AM
HA HA! Success! :D

I have found the cause of the humming. My Radio mic receiver is connected to my mixer via a Jack-to-Jack lead and I had left the volume knob turned up a bit. As soon as I turned it off - no humming :D

Next problem is to fix the link between the mixer and the radio mic receiver.

Thanks for your help and advice everyone.

Excalibur
19-07-2009, 11:54 AM
HA HA! Success! :D

I have found the cause of the humming. My Radio mic receiver is connected to my mixer via a Jack-to-Jack lead and I had left the volume knob turned up a bit. As soon as I turned it off - no humming :D

Next problem is to fix the link between the mixer and the radio mic receiver.

Thanks for your help and advice everyone.

Hmmmmmm. Can you use an XLR cable? Different jack cable? ( It is a screened one if it's jack, isn't it? ) GLI on the mic input? All worth a try.