Home dbx User Forum dbx Archive Threads DriverRack PA & DriveRack PA+ PA Configuration Wizard
Options

JBL STX 825

MichaelMMichaelM Posts: 2
edited November 2012 in PA Configuration Wizard
Hi guys...I'm new here and have spent some time reading much of the "read this first" info, but I'm not sure I have a lock on what I need to do with this..any suggestions are appreciated!

Our band (3 piece, Classic rock, playing in local clubs) is buying a set of JBL STX 825's to replace an older set of JBL's. Since JBL (or DBX) hasn't listed a preset for them yet, I'm not sure how to set them up in the PA+. Here's our setup:

Each side has:
1) JBL SRX718 sub, powered by a Crest CA9 in bridge mode (1800 RMS into each sub).
1) JBL STX825 in biamp mode, powered by a Crest CA12 (ch. A, 1200 RMS to woofers, ch. B, 700 RMS to horn)
Using a Crest X20 R Mixing console through the DBX Driverack PA+. It'll be a triamp, stereo setup, with both amps for each side sitting at the speaker location so there are short speaker cables in use.

Since the STX825's don't have a preset yet, how do I set them up in the Driverack? Should I run them full range on the low end and just use the subs as additional reinforcement to the lows? (That would require the 2 speakers to overlap some frequencies...).
Thanks for any help or suggestions!
Michael

Comments

  • Options
    DraDra Posts: 3,777
    There are presets in Crown amps, but there is no details on the settings. You may need to call JBL and get the info there.

    Generally a bad idea to let the lows of the top speakers go to the bottom trying to reinforce the subs, although Marty McCann at Peavey has promoted that school of thought, at least he did many years ago. You can always try it and see if you like it.

    DRA
  • Options
    Dra wrote:
    There are presets in Crown amps, but there is no details on the settings. You may need to call JBL and get the info there.

    Generally a bad idea to let the lows of the top speakers go to the bottom trying to reinforce the subs, although Marty McCann at Peavey has promoted that school of thought, at least he did many years ago. You can always try it and see if you like it.

    DRA
    Actually I think that's Marty McCann FORMERLY of Peavey. He retired a couple of weeks ago, lucky guy.

    As to the OP, why would you bi-amp the 825's? I believe I'd tweak it full range first and check the results. The SRX have a stellar reputation for sounding good that way and I'll bet the STX will as well. Try running the subs summed mono crossed over wherever Gadget says to (cue Gadget) with stereo tops. You ought to have a smokin' setup.
  • Options
    GadgetGadget Posts: 4,915
    Who Me :mrgreen:

    I noted that they provide a 1.3K crossover point for Bi-amping.. I never found a speaker (Except Tom Danley designs) that didn't sound better properly actively crossed over...

    I'll have to digest this a bit first...but if you can get a response form JBL that would be best...
  • Options
    DraDra Posts: 3,777
    Marty was a pretty sharp guy. He once described a way to use one amp to provide a main center, plus have left and right shaded zones.

    Set the amp to bridge mode.
    Connect the left and right speakers normally to their +1 & -1, +2 & -2 outputs. Even in bridge mode the amp still operates as normal. These speakers will be used for side fill, front fill etc.
    Connect the center speaker to the normal bridged outputs (+1 & +2). This output yield approximately +5db output for the main room zone.
    You obviously would not have any further zone balancing control, but the concept proves that in a pinch there are ways to do things that are outside the box. This was written up in Peavey's Monitor magazine back in the late 90's, I believe.

    DRA
  • Options
    DennisDennis Posts: 801
    Dra wrote:
    Marty was a pretty sharp guy. He once described a way to use one amp to provide a main center, plus have left and right shaded zones.

    Set the amp to bridge mode.
    Connect the left and right speakers normally to their +1 & -1, +2 & -2 outputs. Even in bridge mode the amp still operates as normal. These speakers will be used for side fill, front fill etc.
    Connect the center speaker to the normal bridged outputs (+1 & +2). This output yield approximately +5db output for the main room zone.
    You obviously would not have any further zone balancing control, but the concept proves that in a pinch there are ways to do things that are outside the box. This was written up in Peavey's Monitor magazine back in the late 90's, I believe.

    DRA

    You may have left a step or two out....bridge configuration reverses the polarity on one input so speaker polarity on that side has to be reversed to compensate.
  • Options
    DraDra Posts: 3,777
    Now that you mention that, that does ring a bell. Seems like everything was banana plug, "A" - normal, "B" - reversed, then the 3rd piggy-backed between the 2 hots. Nice catch Dennis.

    DRA
  • Options
    DraDra Posts: 3,777
    http://www.peavey.com/support/technotes ... gemode.cfm

    Peavey support found it on Peavey.com. It doesn't have all the pretty pictures of the mag article, but it will do.

    DRA
Sign In or Register to comment.