Full Range Line Array - NSB Driver - Here I go again. :)

[intelonetwo]

Hi Guys,
I'm at it again after a long hiatus. I am thinking about starting a Line Array project using the famous NSM Driver from Pioneer and Parts Express.

After listening to my Definitive Technology 2006TL, and C/L/R 2300 with 8" subwoofers inside each speaker for many months now, I am happy, but.......

The itch to build something is killing me. While at Barnes and Noble this evening, I saw the Audio-Express DIY Electronics magazine. It outlined a simple 89" full range sealed line array using a single 4" driver, no tweeters, no crossovers.

The speaker features a 4" driver, with a square frame, using 20 drivers per side, it is about 87" tall, or 89" with base, 6.2" wide, and i forget how deep, but its inconsequential at this time.

I want to build a simple design that does not include tweeters, or crossovers. I have always liked the prospect of a line array to be used as a full range speaker with some decibal manipulation supplied by the digital EQ like the Behringer DEQ 24/96.

I do not want to power taper, due to the loss of vertical spatial energy with any type of vertical movement. I just want to use simple series-parallel wiring, with 5 banks of 4 drivers in each column, totaling 20 per side.

Any comments about this project would be helpful. However, comments are C-T-C spacing, and Comb Filtering Effects are particuarly important to me. I will be sitting about 10-12 feet away from the speakers. They will be toed in about 15 degrees into my listening space. As the speakers are only seeing 1/20th the power, it is possible to use alot of gain from the EQ to give the array the necessary gain down low, and up high to fill the entire frequency range. Your comments are much appreciated. I figure the total cost of the project is less than $200, just like in the Audio-Express article. Thanks.

[KeithM]

The NSBs sound quite bad when there are only the drivers and no tweeters. The cone starts to break up around 4 khz and start really breaking up at 6 khz from the frequency response PE provides. I had a much shorter line array using NSBs and it sounded really bad without the tweeter. PE currently has a cheap BIC venturi tweeter for 3 dollars each.

[thylantyr]

Make a test box with five NSB's to see if you like it.
Get some scrap particle board. NSB's by themselves are
ok, it depends on how picky you are.

Here is one example where a full range NSB array worked
great for this person.

http://www.caraudioforum.com/vbb3/showthread.php?t=225275&highlight=bose

If you want to make an uber NSB array then I have
a killer recipe but you will need to invest money on
some tweeters and an active crossover setup.
You can beat store bought product costing tens of
thousands of dollars if you follow my lead

[intelonetwo]

Using the EQ, and some massive gain, can the breakup, lack of low end be compensated for.

Are the inherent disadvantages of using the NSB, enough to outweight the inherent advantaged of using the Line Array with EQ in a real world application

[KeithM]

the low power handling wouldn't be very good for EQ and cone break-up still doesn't sound very good when EQ'd (based off a friend's speaker, someone with a lot of knowledge correct me if I'm wrong).
And also after you get the EQ, it would actually be cheaper to get a crossover and cheap tweeters.

[thylantyr]

A great recipe for NSB line array is to;

* Use good tweeters like planars or ribbons, secondary
choice an array of low c-t-c dome tweeters.

* Lacquer treat the NSB cones, 4 - 6 coats.

* Port the NSB, tuned to 90-100hz.

* Add a subwoofer to compliment the system.

* Make the array low impedance and drive it with
a few kilowatts.

* Bandpass the NSB's with a steep active crossover
anywhere from [65hz - 100hz] to [1.5khz - 3khz]
depending on slope used. I use LR 8th order 65hz - 1.7khz. This shifts the focus from the midwoofers to
the tweeters, in my case an array of PT2's. The PT2's
really define the SQ now and the NSB's play a minor role.
Box tuning at 100hz helps relieve 'NSB work' because the
box is providing the upper midbass peak in response
that can offset some baffle step loss and if you play
your cards right, you can get 126dB(c) peak on upper
midbass in-room, 122dB(c) in midrange, and less SPL
on the tweeters. Overally, it's pretty brutal in SPL
and will amaze you with SQ.

After experimenting this array I'd rather use cheap
midwoofers and high quality tweeters vs. high quality
midwoofers and crappy tweeters. Ideally, if you can afford
high quality tweeters and midwoofers that is the best,
but if you can't use money saved by not buying esoteric
midranges to buy quality planars like PT2 and you can
do amazing SQ if you focus on details.