Originally Posted by Erich H
How many woofers would you consider are needed to consider it an array?
On the 893, the absolute minimum order on the 8" woofers is 100pcs but the price is kind of high when that few are ordered. I can contact Eminence and get a current price and see what they can do.
A few misc. ramblings from the peanut gallery when it comes to line arrays.
Back in Feb 2012 to July 2013, I built a pair of line arrays of my very own--and they do work--eventually. They ended up being 3-way vertical line arrays with 12 five inch woofers, 20 three inch mids and 48 tiny dome tweeters in straight boxes standing 6 feet, 2 inches tall. To compress the world history of vertical line arrays from the 1950's to present day, and to account for straight line, curved line (CBT) and hanging boxes to include "J array" etc--I'll make it short for once. The main rule that must be applied and you can't get out of it is the center-to-center distance must be adhered to because they will boost/cut each other, comb filter and do fun with phases when running a long line. The biggest problems start at the highs but improve as you go lower in frequency. Even with 48 tweeters stacked up with around 1.4" center-to-center distance between them, they will decouple from each other at 10KHz and fall off as the frequency increases--it don't matter if they go to 100 KHz, the output will decline because of the distance between them. I "fixed" it with a broad EQ boost at 16KHz of +6dB, if your spacing is wider than 1.4", you need even more boost.
That being said, I do like line sources--part of that is they sound very "big", have narrow vertical dispersion, high SPL capabilities and low distortion. The other reason I like them is because if I didn't, I just blew 18 months of my life and more money than I want to admit building them--denial works well for me! Those monsters were banished to the garage but I did listen to them in my house for a weekend, very interesting sound but for home use, probably not a good idea for HT.
Now Erich sneaks up behind me with a gun, puts me out in a building Breaking Bad style and I'm forced to come up with an array "kit" for DIYSG. This is how I would do it! First thing, the longer (taller) the array is the better it sounds and your typical room is 8 to 10 feet ceilings--it will be tall. This is what I would use and why. I would use the Faital Pro 3FE22 which are neodymium 3" full range drivers made specifically for line arrays and they would be my mid/tweeter section. They are 3.19 inches or slightly less from edge-to-edge of the frame when mounted. I'd make "segments" with 9 of those per "segment" wired 3 series/3 parallel and use the 16 ohm versions so each "segment" is 16 ohms. When stacked, 9 of them will be 3.25 x 9 or 29.25" tall. The box WILL be made out of 1/2" birch to a max height of 30" to limit the "seams" between segments. Two segments would be five feet tall and 8 ohms, three segments would be 7.5 feet tall to fit most rooms and ~ 6 ohms while the big daddy four segments will be a solid 4 ohms for those that have 10 feet (or taller) ceilings.
In real world testing, they will go down to 160 Hz easily and with a bit of EQ, easily go past 16KHz and are very efficient. You could use say three 8" woofers in each segment and cross them at around 350Hz so cramming them tight won't be an issue. To cut weight, I'd be looking at the neo woofers used in the HTM 8 in 4 ohms wired in series for 12 ohms each segment. This will create a 6 ohm load for two segments and a four ohm load for 3 segments in normal rooms. 9 of those Faital Pros give around 97dB of output 1w/1m so whatever 8's can do it--go with those. I bring up the Celestions because of their light weight mainly--arrays get heavy! Be aware if using 4 "segments" the bass might be down around 3 ohms so plan your amps accordingly.
In theory (where I live!) the "rule" for perfection is no more than a 1/4 spacing of the distance of the highest wavelength. For example, 10 KHz wavelength is around 1.35 inches long so if you want perfection with dome tweeters, just get ones that are 1/4th their size or around .34 inches in diameter. If you want "perfection" at 20 KHz, just get tweeters the size of 0.17 inches and stack 'em up! In reality, that is not going to happen but my stack of tweeters spaced at slightly under 1.4" apart started to roll off at 10KHz--or basically one complete wavelenght in the real world. I would assume using 3 inch full ranges as tweeters considering they would be spaced 3.25" apart would start rolling off at around 4 KHz? Faital Pro avoids this by having a mild "rising response" in SPL as it increases in frequency until around 18KHz (I think) Faital Pro specifically designed them to be used as line array drivers so it makes sense. Yes, they will start beaming, yes they will start to "decouple" with each other and yes the polars will look like a comb filter--yes it will! The "reason" they actually work without hurting the children is when they start doing their nastiness, your ears are not very sensitive to it and at over 10 KHz, your ears are very insensitive to all the sin the line array is doing. Just be aware of that going in.
The lunatics of the world that build line arrays generally hang out at the DIY Audio forum--they build straight line arrays with Vifa TG9 (I think) 3.5" full ranges, use other 2 to 4 inch full ranges, build 2 way versions or try out the hanging box PA style line arrays for fun.
Now if Erich really wanted to use those 893 woofers, I'd use six per 30" tall segment and wire three on either side of the full ranges for a 12 ohm load. They would be heavy, very wide (which is actually a good thing) and look very, very cool. Cost? $33 each at PE for the 3FE22 full ranges so purchase 18 of them to make 2 segments for the smallest line I would use but you can do two "mini arrays" for stereo for testing purposes. For each "segment" it would be 9 FRs at $300 and three Celestion Neos at $180, then the crossover at ~$50 and the bezel, flatpack, connectors and shipping for "only" $600 per "segment" For the smallest array of 2 segements each side, figure around $2,400 for the kits. Parametric EQ is a good idea so if going two channel, the PEQs from the pro side or MiniDSP gets thrown in the calculations.
This is how I scare away people from trying to duplicate my arrays, my parts are not available anymore and costs really jump when ordering crates of them. Personally, I think it would be tough to sell array kits because they are very expensive to do correctly, most people don't have experience with them in a home environment and once kits hit the thousands of dollars, most people might notice that as "real money" so pause at taking the chance.
The other downer is Erich can track me down and send me a special surprise in the mail (the ticking kind) if he gets stuck with hundreds of drivers in his already clogged up warehouse. Now if Erich wanted me to front the money to get 10 line array kits made--I would not hold my breath! It would be a fun project but as far as stocking all that stuff, I would do something like segment bezels or maybe crossovers and you buy the drivers yourself from PE. Still, just the cost to design one is pretty high so--in the long run it would not be a horse I would bet on.
The TG9 array would be the cheapest option, I think those drivers are around $12 each and if you used 16 of them, not too extreme in cost and around 6 feet tall or so. Wired 4 series/2 parallel for 16 ohms each segment and with PEQ, they can make it to 80Hz. With 3.3 inches, 8 of them wired for 16 ohms would be around 27.5 inch segments but at $12 each driver, you can play the array game with only around $200 for two "segments"--just don't forget PEQ!
If you want more exotica, Vifa also has a fiberglass cone version for $16 each.
I don't really see line arrays discussed much in these parts, they are an odd duck but if Erich just made the "segment bezels" those would be HUGE sellers IF people want line arrays. The bezel is the hardest part. The other problem is arrays and HT really don't get along--I don't have an array theater but only a pair and pondering it gives me a headache. I do wonder how those CBT arrays that Parts Express sells would sound hung upside down as surrounds--until my wife brought me back to earth. No idea what kind of volume PE does with their kits, Erich could ask them nicely about it and go from there.
In summation--I think I got lost myself! Tread lightly!