my first HT project.... LINE ARRAY BABY

[Feandil]

well I've been getting help on CAF for my first line array

I'm doint 32 NSB towers... with a Eminence horn in the middle.... and likely a 12 or 15" sub (up to 120 hz) in the bass...

there's the thread...

http://www.caraudioforum.com/vbb3/showthread.php?t=212800&page=1&pp=15

Basically... where I'm at right now is this:

An externally hosted image should be here but it was not working when we last tested it.

the red is ports.... 2 inch for each 4 NSB chamber...

the 12" at the bottom ACTUALLY is a 15" now.... a Xtant 15... or a Orion Cobalt... haven't decided...

that's my question actually

I wanna bandpass the Orion cobalt/Xtant 15 in the bottom of the box...

Here's the response the Cobalt gives me... blue is ported... yellow if 4th order bandpass:

An externally hosted image should be here but it was not working when we last tested it.

Also the Xtant's Response is a little worse.... link to graph is in the manual here
http://www.xtant.com/html/techSupport/pdfs/A1544A.pdf

I would love to bandpass w/e sub choice I make... My budget is tops $160 for a pair of 15's (yea crappy budget)

The xtant's would work great with my impedence I need for my amps etc.... and they don't look too bad sealed... however I know if I do bandpass right it'll extend the range of the sub to were I need it to be around 120 hz...

thanks everyone

 

[Feandil]

sry pics didn't show up...

first one
http://feandil1.tripod.com/feandil/index.album?i=0&s=1

2nd one
http://feandil1.tripod.com/feandil/index.album?i=1

 

[Nappylady]

If you have two columns of speakers in your vertical array, you are going to have really, really nasty horizontal dispersion. You want to have just one column.

 

[Feandil]

This design was recommended to me by thy.... I don't exactly understand.... why wouldn't the columns reinforce each other?

and I basically just copied that mcintosh design.... hmmmm

No way that I could cut down on bad dispersion and keep the two columns?

thy actually recommended this first for me to choose either design

An externally hosted image should be here but it was not working when we last tested it.

 

[johninCR]

You put a low pass filter on one of the columns to make it only help with the bass which is where the NSB's need help anyway. That has to be what McIntosh does with theirs.

 

[Feandil]

but won't that still cause SOME overlap... xover's are just a filtering system right???

can you go into more detail about what exactly would occur in a side by side setup???

I've been reading JBL's line array guide and they said that as long as the center to center distance is less than a wavelength side by side mounting shouldn't effect anything

 

[Cal Weldon]

The easiest, non-scientific way to check what will happen is to take two of them on a open baffle, side by side playing some white or pink noise and move your head back and forth across the front of them. You will notice peaks and drop-outs and a shift from one driver to the other.

Next, turn the speaker 90 degrees so they are vertical and perform the same test. Notice the difference?

That's why you don't want more than one row in an array if all the drivers are carrying the same signal.

Cal

 

[Luke (Uof Iowa)]

http://www.audiodiycentral.com/resource/pdf/nflawp.pdf

 

[johninCR]

but won't that still cause SOME overlap... xover's are just a filtering system right???

can you go into more detail about what exactly would occur in a side by side setup???

I've been reading JBL's line array guide and they said that as long as the center to center distance is less than a wavelength side by side mounting shouldn't effect anything

That's why you do a low pass filter, so the overlap is only in the frequencies where the wavelength is longer. With the NSB's you need lots of them to generate bass. In fact, if you haven't already started construction, the 3 column array would probably be enough drivers to be able to make substantial bass even well below the 95hz fs. Operating below Fs like that does bring into play other considerations which must be addressed. As long as you don't factor in a cost for your labor, the price of the drivers makes it worthwhile.

 

[Feandil]

WOW.... thnx

I don't want to do a NSB bass array... if I must I'll step up the build to a column of 20 NSB's next to a column of 7 or 8" midbasses



well Only thing I can do is test like was recommended... just order the NSB's now and see what I like etc...

I can always order the array of mids if needed...

 

[RussianBlue]

I would second Cal.
Stick to one (Very long) column of NSBs, unless you plan on frequency tapering them. If you need more handling power, they can be piggybacked.
We did some tests with 8 drivers per enclosure, two stacked on top of each other with a horn in the middle. They are reinforced on the bottom by two 15" in a push-pull configuration. I can't really say that they sound fantastic - you get what you pay for, after all - just louder. Be prepared to make detailed adjustments with a good equalizer.
Good luck,