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  • Live band PA speakers

    Sorry for the long post. I'm a seasoned musician not a sound engineer. I'm building a PA speaker system for a live classic rock band playing 150 to 500 person venues. Equipment is torn down nightly by 50 year old high mileage type guys.

    Focus is on vocals and drums with a slight amount of bass and guitars fed in the mix for monitor feeds and minor adjustments. These instruments can carry themselves with stage amps.

    Crossovers are done with a DBX Drive Rack PA. I can drive subs with 2-Com Tech 800 amps 975w bridged. Mids with 1-Xti1000 275w and highs with 1-XLS202 145w. Probably need a better mid amp.

    I would like to see 41htz with 18 subs and cross in the 500-800 range, extend the mids to 3000-3500htz with 12s or 10s and let 1" horn drivers have the rest.
    I am looking at SigmaPro18A-2 with the recommended 7cu.ft. vented cab but I'm concerned about the 400 watt displacement limit (not sure what that means) or Peavey 1808-8cu in the recommended 6.5 cu. Ft. cab. Mids- Celestion TF1225 in a vented cab? and Selenium D220Ti-8 or Celestion CDX1-1746 CDs with Selenium HM25-25 horns.

    I have read about clustering subs etc. but with poor stage design everywhere I really need 2 single stacks.

    Any comments, suggestions, recommendations will be appreciated!

  • #2
    Re: Live band PA speakers

    I would shoot for trying to get the horns down to 1200Hz-1600Hz crossover, and subs-to-mids no higher than 160Hz.

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    • #3
      Re: Live band PA speakers

      Originally posted by Racertomtom View Post

      I would like to see 41htz with 18 subs and cross in the 500-800 range, extend the mids to 3000-3500htz with 12s or 10s
      Subs should go no higher than 125Hz, twelves should not be used above 1.6kHz, tens not above 2kHz.
      I'm concerned about the 400 watt displacement limit (not sure what that means)
      Displacement limited output is a critical factor in subwoofer design. Save yourself a lot of time, money and grief. Get some tested and tried designs, use the drivers recommended in them.

      I have read about clustering subs etc. but with poor stage design everywhere I really need 2 single stacks.
      If you do that you might as well not have subs at all. And since subs don't even need to be near the stage there's no excuse for not properly clustering and wall or corner loading them.
      www.billfitzmaurice.com
      www.billfitzmaurice.info/forum

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      • #4
        Re: Live band PA speakers

        Originally posted by billfitzmaurice View Post

        If you do that you might as well not have subs at all. .
        This may actually be a better solution than it sounds. The bass amp and cabinet is always on the back wall and can carry itself better than a mid quality sub. The band pass of the kick drum is 80-800htz. I am currently running JBL E140-8 15s with D220Ti drivers. Perhaps 10s on top of the 2 ways would be an acceptable band aid for the time being as the lack of low mid range is obviously the 15's inability to reach 2000htz. What cross over would you recommend for 15s?

        Originally posted by billfitzmaurice View Post
        And since subs don't even need to be near the stage there's no excuse for not properly clustering and wall or corner loading them.
        In these converted bars where bands were an afterthought, it's harder than you think to find 24 inches of unused wall space and cable to it. Can you elaborate on "don't even need to be near the stage"? Would a side or rear wall be effective and would a single wall sub be acceptable?

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        • #5
          Re: Live band PA speakers

          Originally posted by Racertomtom View Post
          Can you elaborate on "don't even need to be near the stage"?
          Since subwoofer frequencies are non-directional it doesn't matter where they are in terms of the listener, all directional cues will come from the mains. Having them even twenty feet away from the mains usually won't cause a problem.
          www.billfitzmaurice.com
          www.billfitzmaurice.info/forum

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          • #6
            Re: Live band PA speakers

            Originally posted by Racertomtom View Post
            In these converted bars where bands were an afterthought, it's harder than you think to find 24 inches of unused wall space and cable to it. Can you elaborate on "don't even need to be near the stage"? Would a side or rear wall be effective and would a single wall sub be acceptable?
            You are correct about "bars" where bands and live music is an afterthought ( been there ).
            With that in mind - it often calls for less than optimum placement.
            If you going to split the bass bottom from mains: take into consideration the separation distance with respect to bass wavelengths.
            From my experience: Even a separation of as little as 7' from the mains benefited from "alignment"
            "Not a Speaker Designer - Not even on the Internet"
            “Pride is your greatest enemy, humility is your greatest friend.”
            "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

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            • #7
              Re: Live band PA speakers

              Originally posted by Racertomtom View Post
              Perhaps 10s on top of the 2 ways would be an acceptable band aid for the time being as the lack of low mid range is obviously the 15's inability to reach 2000htz.
              You're experiencing the same old problems everybody that has ever done sound for a bar band experiences you're using the wrong tool for the job, but that's not your fault it's because speaker manufacturers have been a foisting a badly flawed design(the 15+1) on uneducated musicians and soundmen for decades. The primary duty of the PA in small bars is to get the vocals over the racket comming off the stage, and the vocal range is the weakness of this speaker design, so if you're gonna build something make it a design that does vocals much better... like a dual 10+1 for example. You could also do a three-way with a 15 but it's a lot harder to construct and build crossovers for and it'll be a lot bigger and heavier which will make it a bear to put on a stand. Now these things won't go that low but that's why you have subs, and if you're gonna build reflex boxes then pick a driver that won't be displacement limited below it's thermal power handling capacity, options there are the PV Lowrider and Eminince Definimax. Of course Bill has some good horn loaded designs on his web site that are worth checking out too, these will get you similar output levels with less input power and some of the recommended drivers are downright cheap, but build complexity is a little higher. Bottom line though is you should be able to construct a system that is a vast improvement over what you have now.
              Paul O

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              • #8
                Re: Live band PA speakers

                I've heard some very, very good 15+horn boxes that will project vocals just fine, but they're expensive and use external processing. The Nexo PS15 comes to mind.

                Generally the downfall of "affordable" bar band systems is the quality of the HF horn and compression driver.

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                • #9
                  Re: Live band PA speakers

                  Originally posted by clydethecat View Post

                  Generally the downfall of "affordable" bar band systems is the quality of the HF horn and compression driver.
                  The usual problem is that they cross over to them an octave higher than they should. The average 15/horn crosses around 2.5kHz, where 1.2kHz is called for. But a 15/horn is wasted size, weight and cost when a top loaded with a ten works better as a top, while no pole mounted 15 cab is going to compete with a real subwoofer, especially one wall loaded as they should be.
                  www.billfitzmaurice.com
                  www.billfitzmaurice.info/forum

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                  • #10
                    Re: Live band PA speakers

                    Originally posted by billfitzmaurice View Post
                    The usual problem is that they cross over to them an octave higher than they should. The average 15/horn crosses around 2.5kHz, where 1.2kHz is called for. But a 15/horn is wasted size, weight and cost when a top loaded with a ten works better as a top, while no pole mounted 15 cab is going to compete with a real subwoofer, especially one wall loaded as they should be.
                    Most that I've seen had crossovers around the 1.2K-1.6K mark. My objection is that "Peavey" sound that you just can't dial out.

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                    • #11

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                      • #12
                        Re: Live band PA speakers

                        The MT102 is a fine plan, I guess, but WAY MORE complex then needed. For your application, a simple reflex or Acoustic suspension box will do everything you should need. Pick your exact driver, then move on to the design, or pick your design, and choose the recommended driver, don't pick the two randomly. A simple design can be made for about any driver after you have selected.
                        Last edited by AMC; 05-29-2012, 01:21 PM.

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                        • #13
                          Re: Live band PA speakers

                          When using WinISD, does the port length include the cabinet thickness? In other words would a hole have a length of 0 or 3/4 inches.

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                          • #14
                            Re: Live band PA speakers

                            Originally posted by Racertomtom View Post
                            When using WinISD, does the port length include the cabinet thickness? In other words would a hole have a length of 0 or 3/4 inches.
                            Yes, include the thickness of the front baffle if you are building your vents, as opposed to inserting a vent tube that is trimmed to desired length.

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                            • #15
                              Re: Live band PA speakers

                              Originally posted by AMC View Post
                              The MT102 is a fine plan, I guess.
                              Perhaps, if you're an expert cabinet builder who can extrapolate the parts dimensions from a couple of simple diagrams, knows how to assemble them into a cab, and knows how to configure a crossover. But it's not something a newbie would be able to make use of.
                              www.billfitzmaurice.com
                              www.billfitzmaurice.info/forum

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