Diy Dj

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A friend of mine who is a DJ has constant problems with his off the shelf B-52s, such as blown drivers, blown x-over, etc, and he is well withen the linear range of his amp (a rather nice Crown), and the supposed power handeling of his speakers.

However, I wanted to ask, what should you look for when producing a highly efficent, high power handeling, bass machine where SQ is not the first concern, but it is a concern (he hates that many DJs in our area are very loud but you can't understand a thing).

Would a line array with pro driver woofers, and horn mids and tweeters be good, or is it better to go with a standard box design, etc? Just wondering, and since he is a mobile DJ portability is a concern.
Okay, here's the answer: you *can* have everything.

I don't know anything about the speakers you mentioned, or if they have a reputation, but if you're blowing crossovers, that sounds like shoddy construction.

You also might check to see if there's clipping someplace in the signal chain before the amplifier; if the amp is within its linear range, but the signal coming from the mixer is clipped, your speakers could still be getting a clipped signal and taking damage.

There are lots of good, high-efficiency, good-quality speakers around. Look at PHL, B&C, Eminence, etc. The 6"-8" midranges from B&C look really good (to my eyes at least) and aren't outrageously expensive.

Line arrays are good, but read this paper first:

Especially important are the parts that talk about the transition from near-field to far-field. I didn't pay enough attention to this when I designed my speakers, (line arrays for 200hz and up; monopoles for the bass) and while they sound great up close, the bass drops off with distance a lot faster than the treble. Don't let that happen to you!

One more suggestion: go active! An active 3-way is scary to design and build, but hearing music actually sound good at a high SPL is worth it.
B-52 is a brand right? So what is he using precisely?

The problems you describe make it sound like he's overpowering his system. A problem that can happen to about any system. Buying or making a new system is useless unless you he knows the cause, otherwise it could just happen again.

What your friend can use, really depends on what he needs. What sort of music does he play, how many people, what kind of events (only weddings or houseparties, etc.), indoors or outdoors.

I can't think of any mobile DJ that would benefit from a line array (it's kinda big for the intended use). Most mobile DJ's over here just use a 12/1" top with 15" or 18" sub or something similair (depends again on the specific needs).

Mvg Johan
He does no house parties, usually larger venues (Relay For Lifes, Fairs, High School/College dances, Frats, Sororities, block parties, etc).

Well I think that he needs new speakers, because his amp isn't running into clipping, and neither is his source.

Right, I was thinking a line array would be too large.

I think that he needs to go fully active with some speakers.

I have been looking at B+C 15" woofer, 8" midrange, and a eminance horn or something....
Line arrays too big? I disagree!

My PA system is based around two line arrays that are just shy of 4 feet tall (~1.2 meters), 4" deep (~10cm) and, uh, about a foot wide. They play from 200hz up, and I have not yet found the upper limit on their volume. 50 watts doesn't get them even close to distortion, though they do require a little eq; cut in the upper midrange and boost in the high treble. And the best part? They're made of 5" OEM car speakers (not even the deluxe dual-cone model!) that cost $0.30 apiece! (about $1 each shipped.)

Pictures? Some other time. KTHXBYE.
A line array is more than just a lot of speakers combined. A true line array is difficult to achieve, even for people that have the money for it, since it's asking for some engineering skills as well, every time you fly the sytem. Even some of the bigger brands out there claim to have line-arrays while in fact they have not, they do however have a lot of speakers combined :smash:

Line arrays become effective when you're doing (real) big parties where you don't want the people up front to be blown away and the people in the back lacking danceable sound.

At big parties you need the array stack pretty high, about 15 ft. or higher. Any idea how a DJ can still be mobile and reach those heigths safely? I for one don't.

@Nappylady: You mention the use of 5" units. Do you use those for the entire frequency-spectrum? The centre to centre should be less than a wavelength apart, meaning that 5" can't form a line array above 2.8 kHz.

I don't doubt the facts about your system as you present them, I just wouldn't call it a line-array.

@BJackson: Up to how many people are we talking here? And what is he using now? If he's doing big parties it doesn't sound like changing his soundsystem is something you do overnight or so.

Mvg Johan
Is my system a line array? Hmm.

It definitely breaks the 1 wavelength rule. They are 5" units, and I do use them for everything above 200hz. I've thought about augmenting them with tweeters, but they sound okay. If you're more than 10 feet away from them, you can jump up and down and not notice a variation in tone color.

One thing I definitely notice is that the bass response drops off with distance a lot faster than treble response. I attribute this to the use of 2 vented subwoofers per side to cover everything from 200hz down. In the whitepaper I referenced earlier, it talks about the difference in dropoff rate between near-field and far-field; it then mentions that line arrays change from near- to far-field much farther away than monopoles. I assume that this is the reason for my sound system to sound really bassy up close but, uh, thin far away.

Eventually, I want to have a very wide horizontal line array of woofers, and the two vertical "satellite" arrays. I suspect that this will cure my problem... but it will be probably years, and thousands of dollars, before I know for sure.

So are they line arrays? They smell like line arrays to me... but they might not fit every condition.
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