Issues with Driverack PA - Volume deteriates slowly
bobfors
Posts: 11
Am running JBL JRX 115's through a QSC 2450 and JBL 118S's through a QSC 850 via an Allen and Heath MixWizard WZ3 16:2. Everything has been working GREAT until the other day...we noticed the output volume was slowly detiriating over the course of a set. Had to stop and reset (turn off and on) the PA. Then the volume was fine again for another almost full set (30 minutes).
I have troubleshooted the heck out of everything (mixer, subs, mains, etc)even with another small Yamaha PA...no issues
Any ideas why this would happen? It's definitely the PA doing it. Fix? Please help.
Bob
I have troubleshooted the heck out of everything (mixer, subs, mains, etc)even with another small Yamaha PA...no issues
Any ideas why this would happen? It's definitely the PA doing it. Fix? Please help.
Bob
0
Comments
Just curious: Did you notice if the DriveRack was getting warm?... Have you tried a hard reset as described in the manual (not by just cycling the power)?... Did you setup the gain structure?... Was the DriveRack clipping?... Were your amps clipping?... What do your speakers sound like when it starts to deteriate?... Are you using compression?...
How long has has everything been working great?... What has changed?... What have you just tried or changed recently?...compression?...
Also,...are you running the subs in stereo/parallel mode or bridge-mono mode on the RMX850?... IMHO if in stereo/parallel mode you may be way underpowered but it's probably not related to the problem in hand...
Kevin
Has been working well for close to 1 year. Nothing was clipping, and am not using compression.
Speakers dont sound like anything as the volume decreases. Gigs start out very normal and sounding good, and the volume just deteriates...no unusual sounds or anything.
It's like someone is slowly turning down the volume over a 20-30 minute period of time.
Running subs in the bridged mono mode.
Gain structure? Didnt see that in the manual anywhere.
Thanks for the reply!!!!
Bob
I would do the hard reset as described in the manual... Be advised that you will need to re-enter your program afterwards... I would also set the gain structure as described in \"Appendix A\" in the back of the DRPA manual but it's probably not related...
Do you know if you were getting adequate power (120VAC) to the DriveRack when this happened?... Did it happen to the 115s to the subs or both?... Are you using battery type UPS in front of the DriveRack?... If so...is it a cheap one or a decent one?...
Kevin
Never had these issues before though and have not changed anything over time. Very strange that the colume slowly deteriates over time......
These might be some key questions to consider... If you were out giging and nothing was changed with your equipment then was your power source the only thing that did change?...
Do you know if you were getting adequate power (120VAC) to the DriveRack when this happened?... Are you using battery type UPS in front of the DriveRack?... If so...is it a cheap one or a decent one?...
Kevin
I do have a Power Conditioner in the chain, but do not have a UPS at all. Is this recommended?
The strange thing is that everything else was fine and didnt notice any spikes, or other equipment doing anything strange...just a steady decrease in volume on the main's....
Bob
A UPS is recommended prior to the DRPA so it won't shut down before your amps in the event of a power interruption... Based on information posted here and on other sites the DRPA has the potential to spike amps if it's turned off before the amps... Since a lot of folks are using a battery type UPS to prevent this... I thought a cheap one could be causing a problem... Hey,...it's just a process of elimination...
Are you saying that the subs are NOT decreasing in volume when this occurs?... If that's the case I would switch the amps to see if the problem follows the amp or not...
Kevin
I thought I troubleshooted the amps out of it, but I used a smaller PA and bypassed the amps. I didnt repower the amps though when it happened...just turned them down for a second, re-powered the Driverack (turned it off and back on) and then turned the amps back up...fixed it....normal volume. If it were amps, thinking I would have had to turn them off and reset, etc..... crazy.....
Will check the subs also. Could not tell if they were decreasing also...just didnt have any siound. Assuming so.
Bob
I would try leaving the DriveRack on and only cycling power to the amps... The result of that step may either isolate or help us in figuring out what's going on...
Has any wiring or cabling been changed prior to the problem?...
Kevin
Will try the amp reset to see if that isolates it any further.
Kevin
Just remember, when troubleshooting, only change one thing at a time.
Dra
PS- the DRPA doesn't have mutes to punch in and out. But you can turn the x-over gains down to inf (off)
Bob,...It's best to follow Dra's procedure... What he's suggesting makes a lot of sense... He knows a lot more about this stuff than I...:)
Kevin
It could also be a thermal problem, but the reset that you did would not likely have allowed enough time for anything to cool.
Have you tried just plugging a signal directly into the power amp and the amp to the speakers? How did you isolate the problem to the DRPA?
As others have said, the hard reset is always a good place to start.
Please post back.
Mikey
A bit of trivia... Edgar Winter refuses to have any green stage lighting. Ever seen an albino under a green light.
Dra
I hard reset the Driverack and did some other troubleshooting. Found a bad XLR cable that was going from the left channel - high to the left channel on my amp. Thinking an overload on one channel may be the culprit, or have something to do with it.
Still strange even with a bad cable that after powering off and then on again, it fixed it. I thought once cables went bad, they went.
One thing I noticed is that I dont have a lot of picks for Amps and Speakers in the wizard. I may have one of the first models that didnt list the equipment I have now. The recent owner's manual has an appendix that lists available choices, and they are listed there, but are not on the Driverack itself.
Band practice tonight...will see if that took care of it.
tops amp - 37%
Subs amp - 41%
Tops Hi-pass 125hz BW24 (0 db)
lows Hi-pass 45hz BW12 Lo-pass 125hz (-.2db)
Lo PEQ 45hz Q 1.215 (+6.5db)
162hz Q.939 (-3db)
Limiters - both +18db over easy 4 (260 has a brick wall, the PA does not so bare that in mind)
You are luckier than most, getting the PEQ settings.
Dra
I have JBL JRX 115's through a QSC 1450 for mains and JBL 118S's through a QSC 850 for subs.
Assuming the first list of specs are for the compresor settings?
Yes, select custom for amps and speakers.
The other settings are for the crossover, PEQ speaker tunings.
What are you referring to with compressor settings?
Don't use the compressor useless you what everything to be compressed if your signal peeks. Limiteras are what you will need to use protect your speakers.
Dra
Cables.
I can say without reservation that bad cables can be intermittent. In other words they can work fine and then if you twist them just right, and viola, you have your problem right back.
I've gotten to the point with cables that if they fail once, I toss them. I know people who spend hours trying to fix cables where they think the problem is only to find they haven't fixed the problem after hours of work. Cables are the backbone of any system if you have one intermittent cable in your configuration, it can ruin many venues.
Volume decrease.
The problem of the volume change sounds like an amp is going into thermal protection for some reason. It sounds like it happens gradually.
One thing that may cause a similar gradual thermal condition is a build up of low frequency which over time is over loading the amp.
Have you set the 'selectable low frequency filters' on your amps. You can set them for 30Hz or 50Hz according to you amps spec sheet. This may help.
W
Thanks to EVERYONE for the replies!!!!!
Rock on!!!
Bob