Home dbx User Forum dbx Archive Threads DriverRack PA & DriveRack PA+ PA General Discussion

DBX PA+ is getting the blame.

drankindrankin Posts: 2
edited August 2010 in PA General Discussion
I am a novice and am operating sound for a four-part male quartet (think Oak Ridge Boys) and have recently begun using a PA+ to eq the stage monitors. (We have also been using a separate PA+ for the house for sometime now.)

On a half-dozen occasions, the bass singer has hit a very low (and loud) vocal note, sufficient to "rattle the speakers". This seemingly has caused the stage monitors to shutdown for about five to maybe fifteen seconds. During this brief shutdown some crackling and low distorted input signal can be heard in the monitors, leading some of the group to believe it is a connection issue of some sort within the PA+. The consensus has been the PA+ is to blame as this never happened with the old graphic EQ used to set the monitors.

I am now thinking that what is really happening is that the QSC RMX1450 clip limiter is activating its "protective muting" mode. This never happened when using the old graphic EQ because of the higher amplifier output settings we used. When using the graphic EQ we used a much higher amp setting so the bass singer would have enough volume without a feedback problem. With the PA+ the amp output is being set much lower and yet the bass singer has much more volume available with no feedback problems.

I really don't think the PA+ is the culprit, yet it is getting the blame. Am I on the right track here? What should I be doing differently?

For the monitors we use a QSC RMX1450 in bridged mono mode with EV SRX200 full range speakers.

Comments

  • DraDra Posts: 3,777
    If you have another amp / speaker to chain out of the exiting amp that you could run at a much lower volume and set near you (for example), then if the monitors go out after the "low" note you'll have real world proof. If the add on goes dead also, then it could be the DRPA (or even the mixer I guess). If it does not then the monitor amp is the problem, like you said.

    Good luck,
    DRA
  • GadgetGadget Posts: 4,915
    I think you are correct.. I would try raising the HPF of the monitors first.. to say 60-75hz... that will eliminate some of the LF luffing that doesn't help anything...

    Next I would check and see what the limiter on the PA+ is set at...(if it's on at all..

    Remember this also, when you set the clip limiter on the amps that available power goes from 1450 @ 4 ohms to probably less than 1000 watts, and if you have 2 on the circuit that means that each speaker is getting less then 500 watts.

    I suggest you do a good gain structure and find the clip point of the amp (with the limiter off) then set that as the max level the monitors can go. You could also set a PEQ up on the LF and try and find a happy medium for the low end guy, where he isn't blowing you all away with low end but still can hear all the notes he needs...

    If you are using the limiters or comps on the DBX that can exacerbate the issues as well...if the limiters are breached they offer good protection for the speakers, but sound like ASS...
    G
Sign In or Register to comment.