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mattmcss
03-17-2006, 04:00 PM
Alrite, so I want to start a new project here soon and thought line arrays would be an easy one to try.

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=264-813

Planning on using 8 drivers per side, runnign them in series/parallel to get a 4 ohm final load, and approx 96 RMS power rating.

I'd run these 2, and a subwoofer of some sort, probably a 15" DVC or 2 12" daytons on a plate amp of around 400 rms.

Would I be missing some mid bass? I know these are extended range drivers but do they lack in the lower range?

Any help would be greatly appreciated

thylantyr
03-17-2006, 11:57 PM
Line array with full range drivers isn't ideal, but it doesn't stop people
from building them...... http://www.seventh-veil.com/products.htm

You should model those drivers in WinISD {or whatever} to get an
ideal of how much bass it might offer. An array of small speakers can be
pretty amazing for bass. See if it models well in a ported box, perhaps design
the speaker with a midbass peak to compensate if it lacks {see below}.

My NSB array {4" cheap midwoofers} are in a ported design tuned to 100hz
with a big peak in bass, works nice even though the modeling looks fugly.
Any issues can be dialed in with an EQ.

Built a 4 driver prototype using cheap wood, ported box and then cover the port to
see what it's sealed box sound is like. If you like the 4 driver sound, then proceed
with the 8 driver design. If you don't like the sound, sell the four drivers.

mattmcss
03-19-2006, 05:34 PM
Have any thoughs on what 4" drivers would work well in this setup? I'm just trying to avoid using crossovers =) , a little confused on em still.

thylantyr
03-19-2006, 08:21 PM
This helps you design a proper line array.
http://www.audiodiycentral.com/resource/pdf/nflawp.pdf

Any drivers can be used in line arrays as long as you
understand on what is happening.

I used 49 cent Pioneer buyout midwoofers in my budget line array;
http://home.pacbell.net/lordpk/robarray/

If I can get audiophile sound from 49 cent speakers, then I'd imagine
anything can be done if you plan well.

But I also used tweeters to make a better sounding array in spite
that those 4" drivers I used were full range rated.

a. even if they are full range, they have response issues
b. in a line array, you can calculate where a good crossover point would be
to minimize comb filtering gremlins, the calculation is based on the driver
center to center spacing, so the center to center spacing for those 4" would
yield audible gremlins so it's best to cross them over and choose a line array
of tweeters to match.
c. even if you get sonic gremlins, maybe you like it.

mattmcss
03-20-2006, 07:14 PM
Yeah , I know they'll have issues with reproducing the high frequencies, maybe I should look into a tweeter as well ? I don't know how i feel about porting the enclosure, if anyone could help me with the port size and everything that'd be awesome, I'm still a little sketchy on that right now, I'm looking for some drivers on PE.com right now, so hopefully I'll post some up !

thylantyr
03-21-2006, 01:04 PM
Define your project goals and budget, maybe something can be figured out.

mattmcss
03-21-2006, 01:59 PM
I choose line arrays because of the effeciency and small footprint, i'm just looking for good sounding set of speakers as cheaply as possible. I'm not against making a crossover for them but for simplicities sake i decided to try and go full range.

Sub bass duty will be provided by a subwoofer, of course.

budget, probably 300 for the pair for drivers, i'll figure out the materials cost later.

thylantyr
03-21-2006, 09:53 PM
goals:

*$300 for drivers
*no crossover
*mate to subwoofer
*provide ample midbass
*high sensitivity

Use the driver you posted and model eight of them in a ported box,
somewhere in the 1.5 cu. ft. range, somewhere in the 80hz tuning.

But, because the driver excursion is low you won't move much air
so I would design an artificial boost in midbass and let the port tuning
do some work to place less strain on the driver.

Tune for a midbass peak of +3dB to +6dB, you get extra 'umph' on midbass.

Change the tuning from 80hz to 90hz and you'll see what I mean. Use WinISD.

Next, for better sound I would make a dual chamber design. Four drivers
per chamber. That means each chamber is 0.75 cu. ft. tuned to 90hz.

Get a 4" x 2.5" port and place one in the back of the speaker box, centered
in each chamber, two rear ports total.

Place the speaker box near a wall or a corner of the room and you get some
loading effects for more midbass.

Whatever you do, make a 4 driver test box first and test the sound.

These are rough numbers, fine tune it as needed.

For ultimate SQ, you can polyfill the walls leaving the port open to breath.
http://home.pacbell.net/lordpk/robarray/Rear_chamber-2.JPG

Those drivers are rated for 87dB sensitivity.

An eight line would calculate to;

10log8 .... a 9dB boost in sensivity for having 8 of them in a line.

electrical is.

I see these wiring options;

1 ohm
4 ohm
16 ohm

1 ohm = +9dB sensitivity
4 ohm = +3dB sensitivity
16 ohm = -3db sensitivity

Add the mutal coupling sensitivity [+9dB] + the electrical sensitivity [either 9, 3 or negative 3]
to get an idea on what final sensitivity is.

1 ohm;
87dB + 9dB +9dB = 105dB

4 ohm;
87dB + 9dB +3dB = 99dB

16 ohm;
87dB + 9dB -3dB = 93dB

Now you know why I did 1 ohm tweeters and 2 ohm mids on my array, to get a calculated
104dB.. :)

geolemon
03-22-2006, 02:27 AM
Alrite, so I want to start a new project here soon and thought line arrays would be an easy one to try.

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=264-813

Planning on using 8 drivers per side, runnign them in series/parallel to get a 4 ohm final load, and approx 96 RMS power rating.

I'd run these 2, and a subwoofer of some sort, probably a 15" DVC or 2 12" daytons on a plate amp of around 400 rms.

Would I be missing some mid bass? I know these are extended range drivers but do they lack in the lower range?

Any help would be greatly appreciated
Those are very similar to the 3" fullrange TB drivers that I bought for my line array project, actually.

I had started by trying to find 2" fullrange drivers, and I auditioned a bunch (Aura, HiVi, TangBand, and a couple more), but none of them really sounded accurate enough.

I auditioned some 3" guys as well, and the TangBand ones that I bought were really quite decent:
http://www.madisound.com/cgi-bin/index.cgi?cart_id=7561169.21&pid=1757

I needed things small, because my line array is an in-car line array (OK, it's more accurate in my application to say a "phase aligned array" ;)).

I'm currently running mine without tweeters, and the response is liveable. They are good up to 18K, and I'd say it sounds comparable to your average decent "soft dome tweeter" component set in that respect.

I'm planning to augment mine with a 6dB/octave slope crossover way up in the 10Khz or 12Khz territory, with my Focal TN52's in my factory A-pillar locations eventually, but it's quite livable without. Just would add a hair more detail and sharpness that I prefer (I'm admittedly a "hard dome" guy).

As far as the low end goes - the answer is sort of a function of physics:
The lower you ask a speaker to play, the more displacement it must produce to yield the same dB output.

Naturally, a speaker normally accomplishes this by increasing it's excursion level as frequencies decrease (and it's easy to understand how - same amount of power from your amp at all frequencies, but the cycles are slower at lower frequencies- so roughly speaking, the duration of the "push" in one direction lasts longer, so the speaker is driven out farther in each direction before the signal reverses it's direction for the other half of the waveform).

These are little speakers - you are going to reach your limits.

I've got mine running down to 250hz (naturally the response chart shows them able to extend down to 200hz), and they show no signs of strain... and I've got them on a lot of power... three of them on over 100w on each side.

I'm running a separate midbass driver to go from 75hz to 250hz.

brandontw
03-22-2006, 11:37 PM
in my only slightly educated opinion, i think you would be better off running a tweeter or two on a generic crossover than trying to run full range speakers.


i have been scoping these for line array use... using 16 per side of those would yeild quite the power handling:up2somet: even 8 would be good...
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=290-010

im not quite sure about these though...thats why im still in the scoping phase:cool:

i would still say use tweeters and a crossover....


thats my .02$

mattmcss
04-02-2006, 01:25 PM
Alrite so i got WinISD pro this morning and modeled 4 of these drivers in a sealed enclosure.

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=264-815

With a 1.5db gain at 145 hz it seems to show pretty flat down to around 200 hz and drops a little after that.

I doubt I know what i'm talking about , does anyone know any good sites i can read up on speaker building?