Hi all,

Heres a fault for you that has mystified two disco suppliers so far with no answer in sight.


Numark CD player, connected to powered Behringer mixing desk/amp.

Everything is fine for most of the time, but suddenly and this hasppens totally without warning, the leds on the CD mixer all go up to red and stay there, we get a continueous buzz through the speakers.

To cure it we switch to the karaoke machines so that we can keep the music going and switch of the CD player for a few mins, this seems to cure it.

The only common denominator we can see is that on the three times its happened the room was very hot, sweltering in fact.

On one of the occaisions, I was dipping the mix to switch to a karaoke singer, but this could be coincidence as it didnt happen like that the other times.

We took the CD mixer back to the supplier who had it on test for a week and they couldnt find anything, and we took it to another shop and they couldnt find anything either.

We have changed the cables, checked any connections etc and switched the channel to the mixing desk.

Can anyone offer any suggestions please.

Plug everything into the same socket, speakers, mixer and CD players and it should stop.

Hi i agree with adds,but hums n buzzes normaly come from an earth fault!
In the old days when we used turntables an earth would go down on a headshell touch the arm and you would get a buzz go near and you got a hum.
Seems to me your newmarks are breakin down under pressure and a shop cant make em do that and a reboot turn of n on will give it a jolt to wake it up again.
I always plug amp mixer cd player to 1 power source and lights on another so as adds says try that and if that fails borrow someones cd players and see what happens then.
It does seem like its the cd players (flog em and get d****s )
Oh have you just changed to the newmarks and did you have this fault before?

Just a quick question...(or 2).

You mentioned that the CD players were a "CD Mixer" in a couple of places - do you mean that they're one of Numarks CD-Mix 1 or CD-mix2's with the 2 cd-decks built-in to a mixer (all-in-one)?

Also, is the loud buzzing that you get sounding over the top of the music, or replacing the music - could the buzzing be described as astounding loud music, so loud that its distorting terribly, therefore sounding like buzzing?

If so, I'd start suspecting the faders and gains on the CD-mix1/2.

Sounds like a PSU fault on the CD player, if it's putting all the red lights on (ie going into the red). If its a Numark CD mix then these run rather warm at the best of times and they do develop voltage regulator faults. The KAM KCD950 mk1 had a similar fault (made by the same people) which was caused by the 7805 regulator ic going wonky when warm.

Hi all,

Thanks for the advice, its a cd mix 1, the sound replaces the music and is very loud, its a buzz rather than a hum.

We do plug all our sound into one socket, we put cd, mixer, amp and radio mic into one cabel and lighting into another, and smoke machien and bits onto a third.

The only commoin thing was the hot conditions, might get a small fan on it, would that help do you think?

We do have another CD mix but this is a cd mix 2, we dont like it very much, its a bit fiddly, they have replaced flick switches with buttons.

Both shops thathave looked at it say that they sell hundreds of these and have never had any back before and look at you as if you are an idiot.

They did change the crossfader for us FOC, but I cant imagine that we would have worn 2 out in 3 years, unless anyine can tell me thats the norm.


Thanks again guys

This is now with an engineer as its got worse happened 4 times in one gig.

Will let you know how it comes out.

Hi all,

We have had this with an electrical engineer, he has been unable to recreate the fault, but did notice something strange withe power transformer and he has given us a new one, do you think that this could be it. To be honest we are still a little reluctant to use it not knowing for definate that its identified and fixed.

We may have to just use it a kids party or 2 and see how we get on.

Just a little bit of a vague statement then. As has been said, it could be external to the Numark unit, so you need to put all your stuff together to isolate the problem.

I suggest you 'borrow' or hire a cheap venue to set up your gear one afternoon, and methodically test it. If you were near me in Sussex, I would happily help. I usually 'borrow' the local primary school hall for a small donation.

Surely, there is someone on DJU near you who can help? C'MON, techie required in West Midlands to help DJU member in need

Thanks all, good idea, the neighbours do get a bit uptight if we set up in the front room.......

We have a church hall that we can use, they charge £8 for 2 hours, so thats cheap....will do that. Ia m convinced that its the Numark cd player, as its never happened with either of the karaoke machines or the other numark cd player.

maybe its time to retire it altogether, but its only been used for 3 years and thats only a couple of gigs a week max. so I would be dissapointed if thats the life expectancy of kit.

Check that you dont have the phantom power on the Behringer mixer on, this can cause problems if you have the disco unit going in on a balanced chanel.

The next step is to put the unit through a different mixer, see if the problem re-occurs. If its an intermittent fault, they are pigs to find.

Earth problems are usually a hum, not a Buzz. If you haver eliminated the crossfader (a common failure) my next step would be to look at the op amps, without having it in front of me this is really difficult.

Hope it helps....worth a try.

Which retailers have had a look, you could post them on here.

I have never found the fault on my active speakers.

HZ could find it in the week and a half they had them back...............

Next time I am up 'yer way' I will bring them up and drop hem off to you, if fixed I'll gladly buy you THREE pints of liquid








Not water type, alcholic type

Just out of interest, are there any dimmers in the room where you hear the fault?

A bright question!