Entry level line array I made for my friend.
http://home.pacbell.net/lordpk/robarray/
Drivers Per Tower
16 - 4" Pioneer midwoofers {Partsexpress buyout driver, 49 cents each}.
10 - Dayton PT2B planar tweeter, ~ $25 each in bulk.
Driver Power Handling
Midwoofers are rated for 5 watts rms.
Tweeters are rated for 80w rms.
Calculated Line Array Sensitivity
Low impedance mode: 104dB {3.2 ohm midwoofers, 0.8 ohm tweeters}
High impedance mode: 98dB {8 ohm midwoofers, 3.2 ohm tweeters}
Line Array Power Handling
Very high, it's running four QSC PLX3402 in bridge mode, 3400w per amplifier,
13,400 watts total using pro audio amplifier ratings.
Maximum SPL, 8 - 12 feet distance in room
Upper midbass: > 126dB[c] {meter hit it's limit}
Midrange: ~ 122dB[c]
Tweeters: ~ 115db[c]
Cabinet Construction;
Two piece design with rotating top section.
3/4" oak plywood, stained and polyurethane.
3/4" MDF front baffle, primered and painted gloss black.
3/4" solid oak base trim.
Bottom Section {base}
This is the central hub for all wiring using terminal blocks and it's the control center for
driver impedance selection and each tweeter has it's own dedicated fuse. It's wired for
either 8 ohms or 2 ohms on the midwoofers, 3.2 ohms or 0.8 ohms on the tweeters, a
switch controls selection.
Driver Chamber;
It's a ported design where four midwoofers share a common chamber and
each chamber is tuned to a calculated 100hz, F3 - 75hz. One 6" rear ported per chamber,
four chambers per line array tower.
Cabinet Dampening
5/8" MDF, 12"x12" panels installed on every chamber wall except the front baffle.
Acousta-Stuf inside poly-batting to make sound conditioning pillows on each chamber wall except the front baffle.
1.25" dowel per chamber for cross bracing to lower cabinet resonant frequency.
Driver Modifications
The midwoofers received lacquer cone treatments for sound improvement.
Crossover
It's an active setup. A Behringer DCX2496 {digital crossover} is used for the
tweeters and midranges. Crossover frequencies can be adjusted on the fly as per
listener needs. You can program the DCX with tons of settings for different applications.
Typically, I use a Linkwitz Riley 8th order stope, 1.71khz on the tweeters/mids,
and high pass 65hz on the midwoofers.
Amplification
Select high impedance mode and use weak amplifiers, the high sensitivity nature
of the line array will generate more than enough SPL for the normal listening session.
If you feel in the mood for a concert in home, switch to low impedanc mode and
run big power amplifiers like those proamps that's driving it.