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Hum and output problems. Any help appreciated.
Chrisrattler
Posts: 3
hello. I'm Chris from Sunderland, north east England.
I've been reading the forum for several months now and have learned so much from it.
I bought a driverack pa (from a friend) several month ago and it has now developed a few problems.
Firstly my equipment.
All powered speakers.
Tops: pair of rcf art 522a.
Bins: pair of ev elx 118p
Mixer: soundcraft mfx 12
Use one rcf art 310a for monitor.
All connected with neutrik leads.
Full band setup of drums, two electric guitars, bass and three voxs. All drums and amps miced up. Bass di'ed.
Several different setups through the driverack pa depending on room and past gig experiences of that venue. (all pubs, bars and clubs). 80 to 300 audience.
Out of mixer on left output into left input of dbx pa for main with two way split into bins and tops (from left low output and left high output) and then right input used for monitor from aux and out of right mid for monitor.
Other setup is aux fed subs and not use the monitor through the dbx pa.
Rack driverack pa with Behringer four gate and behringer dual comp/gate.
I'm the singer/guitarist/pa guy and mix from stage.
First problem was a large hum in my top speakers. Spent ages trying to solve it and in the end the problem was solved by moving the driverack pa away from the mixer. Simple. Apparently a transformer problem between the mixer and the dbx pa.
Next problem was as well as the hum, there was a hissing/crackling/general crappy interference type noise still happening.
The left high output got the blame as when I wiggled the xlr at the left high out end it cracked like mad.
Moving the xlr to the left mid output and changing the crossover solved the problem and the sound was crystal clear.
My questions are:
1)Do I have to accept and live with keeping my mixer and dbx pa apart? I'd like to put my (unracked) mixer on top of the 4u rack case at gigs but this causes the hum
2)any idea what is causing the high left output problem and how to fix it?
I hope I've provided all the info needed and thank you for your help.
Thanks
Chris
I've been reading the forum for several months now and have learned so much from it.
I bought a driverack pa (from a friend) several month ago and it has now developed a few problems.
Firstly my equipment.
All powered speakers.
Tops: pair of rcf art 522a.
Bins: pair of ev elx 118p
Mixer: soundcraft mfx 12
Use one rcf art 310a for monitor.
All connected with neutrik leads.
Full band setup of drums, two electric guitars, bass and three voxs. All drums and amps miced up. Bass di'ed.
Several different setups through the driverack pa depending on room and past gig experiences of that venue. (all pubs, bars and clubs). 80 to 300 audience.
Out of mixer on left output into left input of dbx pa for main with two way split into bins and tops (from left low output and left high output) and then right input used for monitor from aux and out of right mid for monitor.
Other setup is aux fed subs and not use the monitor through the dbx pa.
Rack driverack pa with Behringer four gate and behringer dual comp/gate.
I'm the singer/guitarist/pa guy and mix from stage.
First problem was a large hum in my top speakers. Spent ages trying to solve it and in the end the problem was solved by moving the driverack pa away from the mixer. Simple. Apparently a transformer problem between the mixer and the dbx pa.
Next problem was as well as the hum, there was a hissing/crackling/general crappy interference type noise still happening.
The left high output got the blame as when I wiggled the xlr at the left high out end it cracked like mad.
Moving the xlr to the left mid output and changing the crossover solved the problem and the sound was crystal clear.
My questions are:
1)Do I have to accept and live with keeping my mixer and dbx pa apart? I'd like to put my (unracked) mixer on top of the 4u rack case at gigs but this causes the hum
2)any idea what is causing the high left output problem and how to fix it?
I hope I've provided all the info needed and thank you for your help.
Thanks
Chris
0
Comments
DRA
I also wire up my own cables and they're all fine.
I must say that I haven't yet tried the high right out yet which could rule in or out a routing thing.
Whenever I swapped cables, whatever my problem was, remained. Ruling out the cables.
I've opened up the unit and can't see anything obvious with the board (although I know very little about boards etc).
The mixer is on top of the rack which includes the dbx pa and they do touch with metal. In happy to live with keeping them apart but was hoping (against the odds) that there would be a magic answer!!
I'm also confident that the humming is definately an electrical transformery type thing as when I move the mixer off the rack it lowers massively and then when I move it away by only inches it disappears.
I also tested it with the dbx pa not plugged in via xlr at all. Straight from the mixer to the pa but with the dbx pa powered up with nothing plugged in at all. Massive hum until I moved the mixer and driverack away from each other!
The high left output is more of a concern though as its restricted my use of the unit!
Again, thanks for your help
Chris
Have you tried connecting the cable directly to the speaker...
Make sure to verify that it doesn't follow any cable shift, or that a cable shift eliminates it...
If the units are separated (no hum), run a wire to ground them together to see if the hum returns. Not sure what that will tell you, but will tell you something.
DRA