humm on system.

[bluishbob]

Hey all,
Playing with the school system today ready for a concert tomorow, there is a real bad hum when you raise the output signal.

I have traced it to be somewhere between the mixer, amp and speakers.

It sounds similar to a ground earth hum. But the desk and mixer is plugged into the same set of plugs.

The output to the amp is through a set if mono (i think) jack-xlr converters.

Before i rip out half of the cable ties that some pilock has put everywhere tying all the wires together (probabily causes some of the other cases of humming), does this sound to you like it needs balanced connections? If so i will pull it all out and try to re do it with xlrs and if that works, get the school to buy some sterio jack-xlr converters.

[Corabar Steve]

Converters have been known to cause hums. Can you try it with some leads that don't require them?

[bluishbob]

yes, thats what i was suggesting, replacin with xlrs (it just means pulling a box of sound stuff apart).

We have a stage box betweeen mixer and stage with sterio jack connections, which is fine, but the converter cables from the stage box to the amp on stage are mono jack to xlr. So i could move the mixer on stage and see if using xlr output with xlrs to the amp would stop it.