question for the djs.

matéo · #1 (**permalink**) Jun 21, 06

Ok so I have a djm909 that has gone in for repair. In the meantime I am using a Allen and heath xone32. The mixer is plugged into my rca inputs from the stereo receiver which is connected to two speakers. Kind of a home theatre ona budget set up. neways. The same day I borrowed the new mixer I also bought new styli for my carts. Since I hooked the mixer up and installed the carts I am getting a humming noise. This humming noise does not go away when i unplug the turntables nor does it go away if I plug the mixer into the wall as oppose to a power bar. I have tryed placing it everywhere and I still get the hum. The hum goes away sometimes when I touch the mixer or put pressure on it but obviously I can't do this constantly. I am wondering if this is the mixer or the receiver or is there any other possible reasons.

PS I havent tryed listening to the mixer yet in headphones without the reciver plugged in will do so tonite.

help please. I have two demos that I really need to get recorded right away.

G3N3R4L · #2 (**permalink**) Jun 21, 06

sorry.. but to start at the start... are the tables grounded?

btw i have a 909 as well... <love it>

Akeel · #3 (**permalink**) Jun 21, 06

matt, sounds like there's something wrong with the connections inside the mixer, probably cuz your loaner model is a hunk of ass.

G3N3R4L · #4 (**permalink**) Jun 21, 06

i vote hunk of ass.

i always vote hunk of ass.

mux · #5 (**permalink**) Jun 21, 06

sounds like a ground loop.

make sure the stereo and the turntables/mixer are plugged into the same circuit. if they're already setup like that, check the plug with a circuit tester, and if your ground is fucked, report it to your landlord and get it fixed. if the ground is fucked, a power surge could kill your gear.

C_squared · #6 (**permalink**) Jun 21, 06

Quote:

Originally Posted by Akeel

matt, sounds like there's something wrong with the connections inside the mixer, probably cuz your loaner model is a hunk of ass.

Akeel has spoken.

matéo · #7 (**permalink**) Jun 21, 06

Quote:

Originally Posted by mux

sounds like a ground loop.

make sure the stereo and the turntables/mixer are plugged into the same circuit. if they're already setup like that, check the plug with a circuit tester, and if your ground is fucked, report it to your landlord and get it fixed. if the ground is fucked, a power surge could kill your gear.

well i doubt it has anything to do with my home since the djm 909 worked fine in the same setup. I have tryed plugging all the gear into the same powerbar and seperate plugs. Both get a hum. If the turntables are turned off and the mixer is on I will still get the hum which I would imagine rules out any possibility of a problem with the turntable grounding. Which leads me to another question. The ground wire on one turntable has a metal clip on the end which has come off making it difficult to ground so i stripped the wire and connected it bear to the mixer ground. Could this be a problem. (excuse my ignorance)

GENERAL I loved the 909 until the control started fucking up on me. Now its in repairs for warranty service. :(

mux · #8 (**permalink**) Jun 21, 06

Quote:

Originally Posted by matéo

well i doubt it has anything to do with my home since the djm 909 worked fine in the same setup. I have tryed plugging all the gear into the same powerbar and seperate plugs. Both get a hum.

First off, I'm assuming this is a low, bassy, 60hz hum, and not a buzzing, or a whining or hissing sound.

FWIW, the ground is the round prong in a three-prong plug. If the mixer doesn't have a three-prong plug, then it's definitely not grounded. If it *does* have a three-prong plug, there's a good chance the outlet isn't wired properly; that's *very* common.

Standard AC electricity oscillates between high and low 60 times per second (60hz), which, when audible, sounds like a deep bassy hum. Why do I bet that the DJM900 has a "wall-wart" style adapter? If the mixer isn't grounded properly, the current that *should* be going out to the ground is very possibly travelling over the RCA cables from the mixer to your stereo, where it's being interpreted as an audio signal, a la 60hz hum. This is what happens a lot in rock shows, which is why guitar "DI" boxes often have a "ground lift" switch.

The two things that need to be plugged into the same outlet are your decks/mixer *and* your stereo system... if they're all plugged into the same outlet (better yet, a power bar plugged into only one of the two plugs in a single outlet), and there's *still* a hum, then yes, it's probably the mixer that is fucked.

Quote:

If the turntables are turned off and the mixer is on I will still get the hum which I would imagine rules out any possibility of a problem with the turntable grounding.

This is correct.

Quote:

Which leads me to another question. The ground wire on one turntable has a metal clip on the end which has come off making it difficult to ground so i stripped the wire and connected it bear to the mixer ground. Could this be a problem. (excuse my ignorance)

Almost definitely not, assuming the wire itself is making good contact with the grounding post on the mixer. The fact that the hum is present with the turntables turned off is pretty much evidence that it's not the turntable grounding.

matéo · #9 (**permalink**) Jun 26, 06

thnx alot mux for all the info. As it stands the problem is still there.

I did notice that the sound is evident even when the mixer is turned off. I guess this rules otu the mixer. must be the receiver inputs.

mux · #10 (**permalink**) Jun 26, 06

How far away is the stereo, or more to the point, how long are the RCA cables?

Are they running near anything that they might pick up noise from? A television or computer monitor, maybe a bunch of power cables, a radiator, etc?

matéo · #11 (**permalink**) Jun 26, 06

no they're prety long and are setup just the same as my previous set up. the only thing that i could imagine bringing in interference is my serato box which I disconnected and moved anyway. theres a power bar beside the receiver i gues i could move. me dunno.

Edoe · #12 (**permalink**) Jun 28, 06

xzone32's are pretty crazy mixers <3
but my friend jimmy had his crapout on him once..lets just say it wasn't pretty and when he got it looked at by the repair ppl they were beyond confused on what happend to it. i'm no technical genious, but i'm with akeel on this one. sounds like u got a worn out replacement.

ebbomega · #13 (**permalink**) Jun 28, 06

Quote:

Originally Posted by matéo

well i doubt it has anything to do with my home since the djm 909 worked fine in the same setup. I have tryed plugging all the gear into the same powerbar and seperate plugs. Both get a hum. If the turntables are turned off and the mixer is on I will still get the hum which I would imagine rules out any possibility of a problem with the turntable grounding. Which leads me to another question. The ground wire on one turntable has a metal clip on the end which has come off making it difficult to ground so i stripped the wire and connected it bear to the mixer ground. Could this be a problem. (excuse my ignorance)

GENERAL I loved the 909 until the control started fucking up on me. Now its in repairs for warranty service. :(

I find typically that you get the hum with grounding problems even when the turntables aren't turned on.

This may seem like a silly question, but do you have a wire connecting your tables to the ground on your mixer? It doesn't look like that's been asked/answered.

If the sound is going away when you personally touch the mixer I've giving you a billion to one odds that your mixer is not properly grounded.

matéo · #14 (**permalink**) Jun 28, 06

Quote:

Originally Posted by matéo

The ground wire on one turntable has a metal clip on the end which has come off making it difficult to ground so i stripped the wire and connected it bear to the mixer ground. Could this be a problem. (excuse my ignorance)

I'm going to try a different rreceiver and if that fails visit long and mcquade to get another one.