how low will OB NSB line array play?

[exipnos]

Hi there,

I have a bunch of NSB's that I'm planning on using as OB line arrays. I will include 16 NSB per array. I'm not sure on the size of the baffle but I'm open to going as wide as around 14" for the front.

The question is how low will the NSB array play?

I'm trying to decide what kind of speaker design to. The issue is if I need to include woofers for the low (3way )end or if I will be okay just combining it with a subwoofer (2way). I'm concerned about crossing to a subwoofer to high since the bass migh then be localized.

Thanks for you help.

Exipnos

[Scottmoose]

Good question. Not very is the short answer. I don't know exactly, it will depend on the room and the speakers' placement within it etc. I don't think you're going to be able to get away with a 2 way using just the NSBs and one or two subs though -I can't see the NSBs motoring down to anywhere near the 70Hz they'd have to to prevent bass from being locallised with a single sub, and even if you used two subs in stereo, wound up to their limits, I doubt there would really be many that could go high enough to make the integration seamless. I could be wrong in that though, but I suspect you'll need some woofers, or mid-bass units before you can bring in the sub[s]


Cheers
Scott

[exipnos]

Thanks for the reply.

If I incorporate woofers then could I make them double duty for high and really low subwoofer bass?

I guess I need my woofers to match the sensitivity of the rest of the line array. I was therefore thinking of using 4 12" woofers in the base of each line array. The woofers are cheap at about 15$ each and the spec says they play 20-5000hz. I was going to place the woofers 2 high in a v configuration. The woofers will also play dipole like the rest of the line array.

Could I therefore make a 3 way speaker that also double as a subwoofer? I would have 7 of these line arrays in a dedicated HT room. I would therefore have 28 12" woofers to provide bass from about 140 downwards. Could this setup provide very low bass say in the 15-20 region at decent SPL?

If my room (15' wide 23' long) will not work for really low dipole bass then I might incorporate a sealed sub for the really low end stuff.

I read that optimal subwoofer placement is usually not the same place where the surrounds go. But I assume that since its dipole bass, room modes issues are mitigated.

Could this work?

Ps. I know that such line arrays are way overkill for surround duty but since its low cost I'd rather go with one design all around.

[chipco3434]

The NSB' s are pretty much finished after 150Hz. I have built several OB's with NSB's. One with Onkyo and the other with PT-2 tweeters. Both had 13" baffles.

Since you will be putting these up against the wall, why not a folded horn for the bass. I am currently running Tuba 18's for the bass and I am quite satisfied with their bass response. They have the capability of removing plaster and making the CD skip. In any event, they are very efficient and match up perfectly with the OBLA. They are pretty light for effects ~ although I'm not an HT type, I think their done at 40Hz.

You can check them out here...

http://www.billfitzmaurice.com/plans...products_id/11

[thylantyr]

Make a test box, OB, sealed and ported. Pick the one you like.

[exipnos]

thylantyr - I will make a test box to see what I like. But I don't have measuring equipment and I would therefore like to know peoples experiences with OB NSBs.

Cheers,

Exipnos

[thylantyr]

If you port the NSB and use alot of those drivers you can probably
get away with just adding a subwoofer low pass ~80hz. I run my
NSB array with no subwoofers at the moment and I enjoy the music
in spite of knowing that there is no deep bass. When I crank it,
I usually knock 'stuff' off the TV because there is alot of upper
midbass, thanks to the ported design, low impedance wiring,
and 2kw of ampliifer.

All that is needed is just a subwoofer. If I plug my ports to make
the box sealed, there is less midbass. It works but it's not
as exciting as the ported design. If I did an OB design then it
will be worse than sealed and lack even more midbass. Let the tuned
chamber do the work, but ported boxes are bigger - catch 22.

If you use NSB for mains, do a ported box... If you do NSB arrays
for surrounds then you can cheat and use a non ported design
to keep the box size lean.

[chipco3434]

thylantyr

Just a quicky... What was your box volume for 16 NSB's? Did you port in groups of 4?

[exipnos]

chipco3434 - If I'm not misstaken, thylantyr used 1.5 cu. ft. chamber for a group of 4 NSBs. Ported to 100hz.

[thylantyr]

yep

And a big 6" diameter port in the rear of the box, per each
chamber. Good boom boom sound. Aim the tower rear in the corner of the room close to the wall and it gives you perception
of more bass.