I have a humming sound coming from my speakers which has always been there. My compresser/limiter takes care of this but I know its there and its annoying me. My set up is Mixer to Equalizer to Compresser to Amp. Would there be something needing earthed? and if so how do I do this. Thanks

Could be one of a number of things. First make sure that you are using good quality screened cable, invest in some good quality interconnects - Signal cable is more critical than Loudspeaker leads

Secondly, make sure that you are running your signal cables around those carrying mains voltage, and not over or under them. I know that this is difficult on Disco set ups, but it can make a difference.

If any part of your system has an "earth lift" switch, try switching it to the "out" position

If you have the option, make sure that all mixer - compressor - amplifier interconnections are made using balanced line options and good quality cable. If you have the option, then run the system in "balanced" configuration throughout. Ensure that you are using the 775mv (0db) outputs and inputs on your mixer / amp.

If your amp & cd player are mounted in the same rack, try seperating them by 1U, if you have the space in the rack case.

NEVER be tempted to disconnect the Earth lead on the mains conenction of your audio equipment. This used to be an old engineer trick to get rid of "earth loops", however, it could cause death or injury should a fault occur.

If it still occurs after this, then you are highly likely to be stuck with it, since it equally be a capacitor or component problem in our amp or elsewhere in the audio chain failing. I suspect that you are using the noise gate option on your limiter to supress the hum during idle?, when no music was present?. This would suggest that the problem is not with the amp, and elsewhere in the audio chain - maybe your mixer or the leads inbetween.

Don't forget to try and not lay wires on top of each other, especially mains and speaker

Thanks for the prompt reply , I will take a look at all your suggestions and let you know how I got on. Thanks again

Ow ow ooh! am I too late?

Try all the above...but also try to narrow down which item or lead is creating the hum.

Try PHYSICALLY taking each box out of the "chain" one at a time:

EG:

Mixer > Equaliser > Compressor > Amps = Hum

(take out the Equaliser, and try it like this...)

Mixer > Compressor > Amps = Hum (so it cant have been the equaliser)

Mixer > = No Hum (so it cant be the mixer)


Try the leads too, using the same process of elimination


Also...whether the above helps or not...hum can sometimes be passed from one unit to another in a rack mount case, through the metal rack "ears" and the metal rack strip on the rack case. So, (just once) you should try running all your rack mount items out of the rack, to eliminate "conducted hum" from the mystery. If THIS is the problem..then there are some plastic isolators that you can buy called "Hum-busters". They are stupidly cheap, although I've not seen any around for a few months.

Also, do you notice the hum ALL the time or only if certain items are faded up (you know Im thinking record decks here)