First Attempt at Pro Audio Speaker Construction: Advice Needed

[phish_sticks]

Hello all, i have been tasked with DJ'ing my school's prom. I have built many, many speakers and subwoofers, but never for the purpose of sound reinforcement or live performance. I plan to build 2 towers, in MTM configuration (unless someone has a better suggestion, i'm all ears), with the goal of the best possible sound quality while still being loud enough to fill a gym sized room from about 80-20,000 hz (I will be using 3 12" subwoofers from 20 - ~100hz).

I was looking at the Dayton 295-025 8" woofers and the selenium 264-362 supertweeter. What would be a good crossover frequency to shoot for, and will the drivers i selected perform well in a Mid-Tweeter-Mid configuration? Are there better drivers that would do the same thing for the same or less money? Also, should i make the cabinets sealed, or ported?


Thank you all for the help. Any information is greatly appreciated.

Daniel Josey

[dcgold2000]

Re: First Attempt at Pro Audio Speaker Construction: Advice Needed

Before you buy, take a look at the high output offerings from DIY Sound Group.
http://www.diysoundgroup.com/

[Melby Audio]

Re: First Attempt at Pro Audio Speaker Construction: Advice Needed

Also, what kind of 12" subs do you have? I could see you running into their limit pretty quick depending on what they are.

[Sydney]

Re: First Attempt at Pro Audio Speaker Construction: Advice Needed

...I plan to build 2 towers, in MTM configuration (unless someone has a better suggestion, i'm all ears), with the goal of the best possible sound quality while still being loud enough to fill a gym sized room ...

Is it a gym?
Not towers but modules light enough to be elevated on poles/etc ( people make better walls than windows ).

[Paul O]

Re: First Attempt at Pro Audio Speaker Construction: Advice Needed

Daniel.. have you been to a prom or a high school dance in gymnasium or large ballroom? My first thought is that your plan is a couple orders of magnitude too small for an event this big.. you're still thinking in home audio terms. First thing is forget about 20hz extension, just achieving 40hz with enough SPL is going to be a big challenge, and same goes for the rest of the spectrum you want a system with as high a sensitivity as possible to keep power amp requirements as low as possible. To achieve that with 8" drivers I think you'll need to use three 8's per side so it may make more sense to step up to a pair of 10 or 12" drivers and then mat them with a proper compression with a crossover no higher than 2khz. For suns there is simply no way you could go too big, if you stay with a reflex design you will need big power as in multiple kilowatts of amplifier but if you were to build a set of tapped horns or one of Bill Fitzmaurice's horns then amp demands drop considerably.

[phish_sticks]

Re: First Attempt at Pro Audio Speaker Construction: Advice Needed

Is it a gym?
Not towers but modules light enough to be elevated on poles/etc ( people make better walls than windows ).

I plan on making them towers so i can use them without stands. I am more concerned with the drivers i chose and if they will sound good, the actual design of the box and physical dimensions of the speakers will be worked out when i find out where the prom will be held; as of yet, i dont know if its in a gym, auditorium, etc. And the 12" subwoofers i am using are the Polk DXI 12's, i have pushed the 3 of them with close to 1500w without issues.

[Sydney]

Re: First Attempt at Pro Audio Speaker Construction: Advice Needed

As part of a non-profit school for the arts; I've done many school outreach gigs/dances etc. These have varied from horrible combination rooms ( lunchroom/gyms ) to auditoriums that had some attempt at acoustics.
Didn't know if you were on an elevated stage, as a rule I get the 80-20,000 hz stuff up the the air and pointing down, to remove acoustic shadows from the audience.
And I give up on filling the entire area and focus on a mapped area - if dancing is involved.

[Dewmiester]

Re: First Attempt at Pro Audio Speaker Construction: Advice Needed

A line array may do the trick.

http://www.billfitzmaurice.com/TLAH.html

[Ron_E]

Re: First Attempt at Pro Audio Speaker Construction: Advice Needed

I found this link in the Econowave thread. http://www.diysoundgroup.com/home-th...ema-8-kit.html

Ron

[billfitzmaurice]

Re: First Attempt at Pro Audio Speaker Construction: Advice Needed

I plan on making them towers so i can use them without stands.

Bad idea. The high frequency section has to be at least 6 feet off the floor, preferably more, to reach the audience further out while not rendering those close in deaf. The low frequency section needs to be close to the floor, preferably wall loaded. The only way to accomplish that is with pole mounted mains and separately placed subs.

And the 12" subwoofers i am using are the Polk DXI 12's, i have pushed the 3 of them with close to 1500w without issues.

Those are auto sound subs, with response and sensitivity attuned to the needs of a 200 cubic foot car. They won't work very well in a 2500 cubic foot living room, let alone a 100,000 cubic foot gym.
What you're proposing is similar to trying to drive ten inch spikes with a four ounce tack hammer, when what you need is a four pound sledge. :eek:

[Paul O]

Re: First Attempt at Pro Audio Speaker Construction: Advice Needed

And the 12" subwoofers i am using are the Polk DXI 12's, i have pushed the 3 of them with close to 1500w without issues.

Is that in your car or the house? You need to do a little experiment.. setup the subs outside on the ground somewhere, walk 50-75ft away and tell me how much bass you get. That is a good simulation of using the system in a very large room, I know what the results of this will be but you need to see/hear for yourself to understand that the advice given is not nonsense it's just the physics of sound in action.

[mattsk8]

Re: First Attempt at Pro Audio Speaker Construction: Advice Needed

How big is the hall and how much time do you have to build? Guessing prom is around April right?

I see Bill Fitzmaurice lurking down there, you should look into his designs and his forum. Pro Audio is an entirely different animal than home audio, you need LOUD and something that plays wide. For starters don't think about what you've learned about SQ because that takes a back seat to playing to the whole crowd, figure SQ out after you learn about dispersion. If you don't have PA equipment already, this will be expensive. You'll need an EQ, amplifier(s), preamp, etc.

[djkest]

Re: First Attempt at Pro Audio Speaker Construction: Advice Needed

I think you should seriously look at BFM's designs as these are exactly what you need.

Maybe you could horn-load your subs that you have now.

[Melby Audio]

Re: First Attempt at Pro Audio Speaker Construction: Advice Needed

If you really have a clean 1500w pro power amp, you might be able to achieve barely enough SPL to get by with those subs. But keep in mind running non pro subs at high wattage for a long period of time is a recipe for cooking your voice coils. Also keep in mind that many car amps have inflated specs, so they may not do as well as you think with real power.

[Sydney]

Re: First Attempt at Pro Audio Speaker Construction: Advice Needed

RE: Woofer capacity:
As an example - I use (2) 18" woofers in an area approx 25,000 cu ft.