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Subwoofer build

esenjayesenjay Posts: 5
edited October 2011 in dbx Archive General Discussion
Hello all,
I am building some sub woofers for a college project, engineering students. They will be for a local nonprofit event called the Father/Daughter Ball. The event takes place in a hockey rink, after thaw, so it is BIG - about 1,000 attendees. The dance floor is approximately 50 feet X 120 Feet. Building is over 120 X 300. Walls are concrete so tons of echo.

The current sound system uses two Mackie SRM450 V2 speakers, 300 watts to 12" drivers and 100 watts to the tweeters. The low end, with a 125 hertz crossover is an 18" 1,000 watt Mackie. The base feels weak in the venue, so we are going to build them some.

Questions:
How do you determine the amount of bass needed compared to the mains? Is there a mathematical model?

We bought two Yamaha P5000S amps, http://www.yamahaproaudio.com/products/power_amps/p7000s/specifications.html, that can provide 2 X 500 or 1 X 1400 watts. Would you go with four 18" drivers or two higher output 18" drivers. Our initial thoughts are that four drivers will equal higher SPL and reduce potential muddiness. What are your thoughts.

Recommendations for speaker designs with suggested drivers - we are in the US. Please advise why you suggest what you are putting forth.

Is there any alternative ideas to our approach?

Thanks,

Esenjay

Comments

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    GadgetGadget Posts: 4,915
    Actually.. I prefer 12" subs...I have some that KICK MAJOR ASS, and I built them...They have FAR less distortion, are FAR more efficient, have go FAR lower.. frequency wise. They are however, larger, heaver, and WAY more difficult to build. They are the LABsubs and were designed by Tom Danley, and a group of pro audio types, and are horn loaded...dimension wise they are 46X46X22.5" and weigh just under 200 LBS...

    The others are located here in the FAQ section:
    viewtopic.php?f=60&t=1334

    And are easy to build...cheap and sound pretty darn good for a small inexpensive sub...we have built lots of them and everyone that has them has been very impressed...they are NOT LABsubs... will not sound as good, or go anywhere near as low... will have significantly more distortion, BUT are pretty good for what they are...

    2 subs per top should do the trick here... larger more potent speakers might require more subs.. but those tops with 4 subs should be fine..

    So, if you want a challenge.. have VERY GOOD woodworking skills, have room to store them... 2 LABsubs is worth 4-6 of any single 18" sub...

    Gadget
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    esenjayesenjay Posts: 5
    Hi G,

    I remember listening and talking to you about your Lab Subs when you ran the event sound for Atlantis at Tall T Days awhile back. I loved them. I sent you an email from this site, FYI. I tried to call you but the number Andy gave me got no answer.

    How many drivers are in those Lab Subs? Would I run both amps to four 12" drivers in the box? I am dangerously familiar with a Lab based design, aka internet research, and what I have read does not scare me too much. I am a pretty skilled carpenter and know a bit about some of the compound joints involved in the horn. All in all, I am interested in the design for our project. I would need the numbers and driver suggestions though. Let me know if you have that email.

    Esenjay
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    GadgetGadget Posts: 4,915
    So your local then? Wow that would be a switch.. I never got anything from you...email or phone.. (I do get thousands of emails a month... and it is possible you ended up in the spam filter... but geez...we also did the Street dance in Keewatin the year before for around 2500-3000 water bags and it was AMAZING! We also did the street dance in Hibbing the year before..

    So where are you out of then? Andy, John, Joe and even Chucky have my phone #... hell it's all over this place.. I get calls form people all over the world...

    Anyway we have put 6 LABsubs on a single 5000 watt Digam amp..outdoors against 8 JBL SR4719's with a of Crown MAC 5000's on each pair...(that's 20,000watts) and you couldn't even tell the JBL's were on...

    You are slightly under powered for a lab a side ... the 7000 will give you just what you need.. I use a MAC 3600 one channel per side...and it works well...1400 watts is just under the optimum for the labs.

    So, let me know if your in the area.. PM me and I'll send you my phone #
    G
  • Options
    DraDra Posts: 3,777
    Unless you want to make this an investment, why not rent subs for the dance?

    DRA
  • Options
    DennisDennis Posts: 801
    Dra wrote:
    Unless you want to make this an investment, why not rent subs for the dance?

    DRA

    The original post indicates it's more about the journey than the destination.
  • Options
    DraDra Posts: 3,777
    I suppose it could be read that way. But not definatively. :wink:

    DRA
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    esenjayesenjay Posts: 5
    This is definitely more about the journey, although well designed subs based on good mathematical models will play into our grade as well as a quality end result for the event.

    We are all interested in this project, so we are enjoying it. It is sometimes hard to filter out some of the tech speak as well as opinion.

    If we are underpowered for the LabSubs, then the Colossus project may be better. We are stuck with the Yamaha P5000S amps, although we think these are pretty good from the research we have done. So, we are also looking at the G Subs design on speakerplans.com - http://speakerplans.com/index.php?id=gsub

    Thoughts on the two designs? G Subs combine the two drivers into one cabinet, may make handling easier if we build in a tilt caster system.

    With 8 ohm stereo 500 watt amplification possibilities, so 4 drivers in either 2 or 4 cabinets, any recommendations on drivers? Please no Ford/Chevy talk - why you would recommend a driver will help us in our project. Also, recommend based on these two designs, unless you have another design to put forward for consideration.

    Lastly, we intend to use a PA+ or a 260 to set up sound and establish crossover freq's. FYI in case this influences your recommendations.

    Thanks again,

    Esenjay
  • Options
    esenjayesenjay Posts: 5
    How about these?

    http://www.parts-express.com/pe/showdetl.cfm?Partnumber=294-676

    If I am throwing 500 watts at them, how high should the RMS capability be? I have seen 1/3 higher and 25% higher, either is good? Can you get to much speaker for amp?

    Thanks,

    Esenjay
  • Options
    GadgetGadget Posts: 4,915
    Rog isn't a bad bet speaker wise.. but what driver is he using on those? Believe me... those LABsubs underpowered will put out MORE and lower bass than any front loaded box...In think we decided they work best with 1500-1600 watts.

    You didn't answer the question about your location?And what church? I gather Atlantis is opening for Hairball this weekend at the civic center (echo drome) I of course will be @ Walker as I am every weekend.. had an AWESOME band last weekend...Sam Kuusisto.. (and too many guitars.. LOL) Also did 'Island Breeze'.. a very good youth outreach group .. for the Solid Rock Church of GOD.

    I'm still exhausted.. 2 shows a day is a LOT for this old soundman...

    If your TRULY on a quest and it's about the journey, and you have the space the LABsubs are like nothing you have ever heard before.. they ARE meant to be run in groups to get full potential.. but I have been running only 2 for years in small club apps and they still ROCK LIKE CRAZY!

    As I said they ALSO are much more efficient than other designs.. so with the same power WILL be louder than any other box by a considerable amount!
    G
  • Options
    GadgetGadget Posts: 4,915
    How about these?

    Great drivers.. but you need a cabinet design for them...and you don't have the power for them either...
    G
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