NSB mods - Do You know any I have not seen?

[Jared]

I have seen the cone coating mod, and the replacing of the dustcap with a wooden dowel, and the adhering of heavy material to basket.

What are the reccomended mods to the NSB's I am doing arrays of 20 drivers per speaker with a central tweeter.

The tower shape is a teardrop with a flat front baffle from a top down view. The shape is created by routed out ribs to adhere cloth to and then the fiberglass. I am at teh stage right now of glueing in the 100+ ribs.

This initially was a plan to experiment with a different type of speaker to me ( line array) but then changed to an effort of asthetics.. and now that I am putting so much work into them, I want the end result to not sound like a "first effort with a line array"... ie I keep gettign tempted to look into some nice drivers but cant afford to right now..
Any pointers to help the NSB's at this time will be most welcome.

[thylantyr]

Your project budget is?

I've tried these mods.

1. Cone treatment: I used 'thinned' lacquer, 4 to 6 thin coats,
let dry between coats.

2. Coolant mod: This mod is neat and I don't know what the long term effects will be on the materials in the driver but power
handling gets a tremendous boost. After building the array
of 16 per tower I didn't need this mod after all.

3. Phase plug mods: At higher frequencies we were able to
hear a difference doing blind testing but it's subtle. If
you crossover the NSB at 3 - 4khz don't bother.

4. Cut spider mod: It didn't work, bad news.

5. Basket dampening mod: I couldn't hear a difference.

and now that I am putting so much work into them, I want the end result to not sound like a "first effort with a line array

The sound system sound quality is really determined by the
'sum of all parts'. The PT2/NSB array I built for a friend
would cost me $750 per tower if I were to build another, but
the sound quality is pretty high in reference to store bought
product I auditioned recently. I haven't found any loudspeaker under $12k that gives me the same performace as the this line
array. To be honest, it's not a fair comparison to compare
a line array design to a standard floorstander. It's like saying
the Ferrari is a bad car as it can't tow my trailer like my old truck
can. I was never impressed with store bought loudspeakers
anyways. DIY all the way! // rofl //

If your budget is higher and you can afford good tweeters,
fully active setup, high powered amps that can handle low impedance, digital crossovers, you can make the NSB array
awesome.

If you have specific questions on my babble, fire off an email to
my username @ hotmail.com

[Jared]

I stopped doing things with a budget because that never worked out very well. Now I just keep the fun stuff to under 1k a month, including car stuff, entertainment, etc.

Right now I have 40 NSB's And planned on a simple monoblock per channel.. will try the "T" amps I think with lead acid battery power supply. Maybe use the lead acid battery's to stabalize bottom of array somewhat.

what is the coolant mod ?

how much did your 4-6 coats help/hurt on the cone?

on your phase plug mods, what did you use? Are you the guy who tried just a wooden dowl or did you use actual shaped plugs? I was not planning on doing the phase plug mod as I think it might be a littel bit too tedious for me to do reliably 40+ times.

btw - I will cc you an email of this if you dont get back on.. I just figure it is a good idea to keep this on the board for future searches...

[thylantyr]

If you want to make a good NSB array then get some PT2's,
and port your NSB's and use good cabinet construction methods,
dampening/bracing and make sound conditioning pillows for
the walls using polyfill and batting.

Give those NSB's a big power amp and wire then for a lower
impedance load. You will be amazed. I drive a QSC 2450
at 1200w/ch @ 2 ohms on the NSB array wired for 2 ohms.
The PT2's are 0.8 ohm driven by Adcom. Works well and I've
clipped both amps with no issues other than blowng fuses
in the main circuit breaker in the house. // hehehe //

I've done a crude test where the QSC was bridged to offer
2400w into 4 ohms but the amp was tweaking a bit
at full power into that 2 ohm load. I was able to drive it
at about 75%, very interesting. Makes me wanna go out
and get another QSC but this line array is not for me, it's
for my friend, I'm still in possession for various reasons.

what is the coolant mod ?

Ferrofluid. The problem is. The stuff I bought orginally is
educational grade available online for $30/bottle, water based
and it dries out after a month {not good}. The oil based stuff
can be purchased from the source but they have a $100
minimum order. If you can't afford the real stuff you can mix
the cheap fluid with 'thick' motor oil. Try 5 to 10
eye dropper 'drops' inside the dust cap. Cut a small hole in the
dust cap. Ideally a tiny syringe would be sweet so the hole is
smaller. {see above, the 2400w amp clipped isn't giving
the NSB's grief so I don't need the coolant ... YET! }

how much did your 4-6 coats help/hurt on the cone?
The cone is untreated paper. Adding lacquer will make it last
along time but nobody plans to keep their NSB loudspeaker
for 10 or 20 years ? /heh ... You lose some sensitivity when
you treat cones. You sacrifice some sensitivity for sound quality.
The 16 NSB array I have wired for 2 ohm can get very loud,
enough to cause pain so I'd rather improve SQ.

on your phase plug mods, what did you use?
I found a rocket nose cone {balsa wood} online and had to
use a lathe to trim it down a bit to get the right diameter.
Then you cut the cone to length. Then, you treat the balsa wood
with Minwax wood hardener, let it soak and absorb the liquid.
If you don't do this, you will squeeze the cone and cause dimples,
it's soft wood. Then paint the wood. Last, screw a flat head
metal screw on the base of the phase plug. Remove the dust
cap with a razor blade and insert the phase plug, the magnetic
field will hold the metal screw.

Are you the guy who tried just a wooden dowl or did you use actual shaped plugs?

Not me.

I was not planning on doing the phase plug mod as I think it might be a littel bit too tedious for me to do reliably 40+ times.

/agree


My NSB evil diary here;

49 cent line array
http://www.caraudioforum.com/vbb3/sh...highlight=cent

Rob Array - {49 cent line array} Sneak Peak
After the array was done, I started this thread here;
http://www.caraudioforum.com/vbb3/sh...highlight=cent

Rob Array {49 cent line array} - tweaks & optimizations
http://www.caraudioforum.com/vbb3/sh...d.php?t=219376

If you search that forum on line array you may get some
hits.

I didn't get your email so post yours and I can give you
some strange ideas.