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Aux fed subs and mono mains

trshottrshot Posts: 54
edited March 2013 in PA Connectivity
Hello people of the forum!

I've read a bit about running Aux fed subs in some threads here. I'd like some feedback on the pros and cons of this method. More importantly can I achieve this with my DRPA+ ( I believe Gadget wrote that you can) running mono mains and the two sub setups I alternate between. One setup is two JBL SRX 4718's with a Crown CE4000 in stereo. The second is two JBL MR528S each with a bridged CE4000. My desk is the new Mackie Dl1608 iPad controlled mixer with JBL MR515 mains. If this is possible with the DPRA+ my question then becomes.....how do I interconnect everything and configure? Thanks for any input you can offer..

Comments

  • GadgetGadget Posts: 4,915
    The FAQ section is our friend...
    viewtopic.php?f=60&t=2228
  • trshottrshot Posts: 54
    Hello Gadget,

    Thanks for your quick response, am I wrong interpreting the link you provided? It appears that the mains and subs are sharing one output and the other for a monitor.

    I came across this thread last night, viewtopic.php?t=1469

    In summary, I'm looking to send two separate signals thru the DR having separate volume controls for each. Main out for mains and an Aux send for subs.
  • GadgetGadget Posts: 4,915
    :mrgreen::mrgreen: :roll: :mrgreen::mrgreen:

    I guess I should engage my brain before posting :oops:

    Ya that's a better thread for what you want to do... I assume you still have questions?

    Make sure you choose a POST fader send aux...that way when you change volume on the faders you will change BOTH mains and subs..

    The benefits are MANY and drawbacks are few.
    1. Reduced low end wash on stage because you are sending only Low frequency heavy sources to the subs
    2. Every mic on the stage isn't being subjected to the shear amount of LF + the vibrations from the stand..
    3. Less room buildup , especially if you remove the boomyness with the PEQ's
    4. If you HPF the monitors in the 150-180hz area you will usually be able to lower stage volume and have far greater monitor clarity
    5. You will be able to control the FOH volume better.. less monitor and stage volume to climb over...

    It's the BOMB...

    The one drawback comes if you don't have enough auxes to do what you need... :?
  • trshottrshot Posts: 54
    Ahhhhh Gadget, I like where this is heading and the good news is, I have six Aux sends!

    And of course there are more questions, lol :D

    In the link I posted you mentioned it can be done.. What I don't see is how to achieve this with the DR. Keep in mind as noted, I run two different sub systems dependent on venue size. What is the signal path for input and output and setting up the DR?

    Do I start with a main out into DR R/mono IN and an Aux out to Left IN for subs?

    What's the DR's set up to (magic) make tops and bottoms work together for my listed speakers, x-over settings, gains, recommended filters for both of my subs.....and anything else I missed!

    If I'm right about inputs, do I still use R high OUT for mains? What do I do for sub output connections for both set ups?

    Again, thank you!
  • GadgetGadget Posts: 4,915
    Do I start with a main out into DR R/mono IN and an Aux out to Left IN for subs?

    Yes, and for this you'll need to set up a custom setup for each.. not just one...in the wizard set up a stereo (input) , dual mono (output) (answer the prompts) setup..

    Use all custom or presets where available.. it matters not.

    Here's where "you got some spalinin to do!"

    Why would you run one CE4000 amp on the SRX 4718's and dual CE4000 on the MR528?

    The MRX528 is a 4 ohm 1000/2000/4000 watt speaker
    The SRX 728 is a 4 ohm 1600/3200/6400 watt speaker

    The CE 4000 is Bridged mono 2800 watts that has a 4 ohm minimum impedance in bridged operation...your running 2, 4 ohm speakers in stereo for a total of 600 watts per driver...in bridged operation your amps can provide 1400 watts per driver...

    Your answer will determine your crossover points...
  • trshottrshot Posts: 54
    Hi Gadget,

    You mentioned wrong sub, SR4718X, not 728...the 4718 is 600 continuos (http://www.jblproservice.com/pdf/SR-X%2 ... R4718X.pdf)

    Hope this helps!!
  • GadgetGadget Posts: 4,915
    Ah.. not the X subs.. and ya, they can't handle the power...that the MRX can and is a totally different animal..

    Ya, different presets, but then the driverack can give you plenty of presets...

    my next question would have been about the purpose of the system... because the LIVE and Memorex :mrgreen: are two different animals

    So I still have to ask, what applications are the 2 systems going to be used for? Please be specific...
  • trshottrshot Posts: 54
    Haha, I loved that memorex poster! 8)

    The system is for my top 40 band...I use the single bottoms for smaller shows, corporate events mostly with poles and mains. But, I'm thinking about trying the coupling method for the +3db and to take the drink holders away from the crowds! ....and the duals for club/ outside venues
  • GadgetGadget Posts: 4,915
    Ok, in that case the only real difference will be the HPF of the subs...wish I knew what tops amp your using but chances are it too is underpowered...

    MR system:
    Subs:
    HPF 40hz BW18
    LPF 100hz LR24

    Tops:
    HPF 100hz LR24

    Raise the HPF to 45 hz BW18 for the older single JBL's and if you have way too small an amp for the tops raise the HPF to 118hz LR24...

    The rest you will need to do yourself, as in the "start here" threads and the "Faq's
  • trshottrshot Posts: 54
    Thanks Gadget,

    I run my mains on a bridged Crown XTI 2000
  • GadgetGadget Posts: 4,915
    so... 1000 watts each, should be fine @ 100hz LR24...
    :mrgreen:
  • trshottrshot Posts: 54
    Why did you suggest two different HPF's 40 & 45hz instead of 40 for both? The older boxes have a 30 hz spec.. What I'm I missing here?

    So, in summary both the master (mains) and aux (subs) sends are now independent and each are used to balance the system getting the benefits you mentioned above! :mrgreen:

    I'm looking forward to hearing the benefits!

    Thanks G!!
  • GadgetGadget Posts: 4,915
    The HPF is largely a function of the box... and the power available, if you lower the HPF you start to sap REAL power... if you consider the fact you haven't got "program" power available even... means that the higher you lopass the more system volume you will have, the less you'll excite the room, and the better you'll sound.

    In a room the bass tends to couple and form super nodes, which tend to skew the bass a lot...

    The older subs are "less forgiving" and really not capable of reproducing the really low end without massive power and the increased potential for woofer damage....

    The 500 series isn't equipped with the best drivers JBL has, but still needs a LOT of power to reproduce the lower notes...I think you'll find that using these numbers you will be happier with the sound till your equipped to push the envelope...
  • trshottrshot Posts: 54
    Ahhhhh, I knew I was missing something here. Thanks for your help and educating me on aux subs and settings!
  • GadgetGadget Posts: 4,915
    These are the variables that no one seems to address when talking about power amps, rooms, and crossover points...I also recommend you use the PEQ's to tame the low end... I usually set up a bell @ 60hz and set a Q of about 4.0-5.0 and lower the threshold till the BOOM goes away, then I raise and lower the center frequency to zero in on the problem frequency..I further mess with Q and gain to get JUST the right treatment... the subs are now punchier, and tighter as well...
  • trshottrshot Posts: 54
    G-
    As Ive mentioned in past posts, your an asset to this forum, I've learnt a lot from your postings here.....and also learned that I need to learn a lot more too! I especially like the FAQ's and refreshing my knowledge when I reread :mrgreen:

    What are your thoughts on this? Would I be better off using one MR and a bridged amp than the two SR's running an amp in stereo?
  • trshottrshot Posts: 54
    trshot wrote:
    G-
    As Ive mentioned in past posts, your an asset to this forum, I've learnt a lot from your postings here.....and also learned that I need to learn a lot more too! I especially like the FAQ's and refreshing my knowledge when I reread :mrgreen:

    What are your thoughts on this? Would I be better off using one MR and a bridged amp rather than the two SR's running an amp in stereo?
  • GadgetGadget Posts: 4,915
    Well I can't find anything about the 2044H woofer, I have to assume it is a 3" voice coil 18"? The older SR's us a woofer with a 4" voice coil, but the total excrusion is only a little over1/4"...NOT making for a very good sub woofer... for instance, the 12" in my Subs travel almost 2" :shock:

    The older subs never were all that great.. but only you can compare because you have both...The MRX were a lower line sub (midgrade "portable" sound...). My guess is they are likely 6 of one 1/2 dozen of the other...when using 1 MRX and 2 SR..
  • Hello there, I been reading this forum and I am on the same boat, I use a AUX send for the subs,and I would like to keep it tht way, no vocals coming from the subs.
    My question to Gadget is, if I may, how do I accomplish tht using a mono sub. I am a volunteer at my church, and I hv done a lot to improve the sound, and I just got a Driverack PA plus, followed all the directions, used the auto balance and auto EQ at 25 feet, and it sounds horrible, I was embarrassed because I said it would improve the sound.
    Our set up is: We have 2 JBL MS112 on the ceiling, and 2 Peavey 115TLS Subs under the stage, all powered by 2 Mackie FR M1400. The sub amps are on subwoofer setting, on mono mode, and we have an aux so we don’t have voices and other sounds going to the subs, the the full range JBL are on stereo mode, out the main output of our mixer.
    I would appreciate your input.
  • GadgetGadget Posts: 4,915
    You'll need to be a bit more specific as to how to how you set this up...things to check for...do...
    make sure the Aux is post fader,
    turn the sub amps to fullrange
    send the mixer signal to the DRPA left input
    use the wizard and set the system up stereo, then dual mono (if want aux fed subs)
    set up a 2X4 stereo tops and stereo subs (NOT a 2X3 stereo tops and mono subs) you'll be feeding both tops with the left hi out and the sub with the right low out..
    set the xover to 118hz LR24
    run the post fader aux into the right channel

    store the config in one of the unused memory locations and re-name

    skip the auto balance sequence for now, with aux fed subs you will be varying the output to suit anyway..

    turn the subs off and if you can turn on only one of the top speakers if not the results are going to be difficult to understand (bad usually) unless you know how to deal with the results

    place the measurement mic on the floor on a soft towel or carpet will do in a pinch, aimed at the speaker that is still on and in axis..20-25 feet out

    use -0- or flat response for the pass...

    If you can take a picture of the graphic product and post it here I can see if I can tell what's going on...
  • Thanks,I will post the pics tomorrow night
  • Thanks, I returned the unit, it didnt improved the sound enough to justify the cost.
  • LoGruvzLoGruvz Posts: 6
    Hey Gadg!

    Wondered of you can help me out. I have same scenario but unlike the Church Guy I haven't done anything yet just want to try and get it right the first time. I am running mains EV SX300 x4 (2 on each side daisy chained to one each) with a Crown Xti4002 stereo HPF at 83Hz as spec sheet tells, Yorkville Subs LS808 x2 coupled/daisy chained in bridged mono sub mode from another Crown Xti4002 (Yorkie told me 90hz LP but no info on slope or HP). Don't worry about the monitors right now I don't ever seem to have any problem with them BUT if you want to chime in I can give those a shot too. I have 2 EV ZX190 daisy chained running off one channel of a QSC GX7 (Aux1) and the drum monitor off the other channel (Aux2) it is a Behringer VP250. Board is an AH Mixwiz WZ3 16:2. I have been running mains stereo L/R and the subs mono aux fed off of Aux 6 post fader. From your posts looks like I will be setting the mains up on the High Left and the single aux6 fed feed on right channel LOW.
  • GadgetGadget Posts: 4,915
    Yes, that's what I would do, and bump the crossover point up to 100hz LR24...
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