Has anyone built or is considering a dipole line array?

[Mazeroth]

I know a lot of guys have pieced together some NSB dipole line arrays, but I'm looking at something with better drivers. I have all the parts/drivers to construct my Dayton RS dipoles (RS28/RS180/RS315HF) that will be controlled by a DCX2496, but before I start that project I was really contemplating another pair of line arrays (already have some) but something a lot nicer. The only thing I can think of is to build a pair of dipoles with something like nine Dayton RS150s (54-56" line), eight Fountek ribbons, and more than likely a separate dipole sub with dual 12s or 15s (Dayton RS 15s would rock). Can you guys give me any pros/cons for a pair of speakers like I described above?

Also, I had a chat today with a buddy of mine and it's crazy that no one has published a set of plans for a pair of line arrays that don't use NSBs that either of us have ever seen. Do any exist?

Thanks!

[ThomasW]

I know a lot of guys have pieced together some NSB dipole line arrays, but I'm looking at something with better drivers

Thank you..... :T

For a line array to work best it needs to be tall. The ideal array is a tall as the room it's in....that being said I've built arrays as short as 6' and they worked fine.

If you want a reasonable amount of output it's better to use 6" or larger drivers. Doing that goes a long way toward eliminating compression issues at higher SPL and significantly helps the bottom end because....

Dipole subs take many, many, many drivers to obtain reasonable SPL at lower frequencies. When I was playing with the Arvo Ultra dipole, 8-12"s with EQ were about right for an average room. (12'X18')

It very hard to make a good 2-way array using ribbon tweeters. They just don't play low enough. They're wonderful if used in a 3-way

It's getting late I'll post more tomorrow....

[cjd]

Hey, NSB's sound better than they should and are a dirt way to experiment. :P

It's possibly a cost thing. Especially finding ribbons that'll cross low enough.

RS150 is probably too obscured, but the RS180 would be a fine candidate. Though even that is a bit obscured perhaps. Ribbons, might pull off a 3, but probably would want the 5i.

C

[dyazdani]

RS150 is probably too obscured, but the RS180 would be a fine candidate. Though even that is a bit obscured perhaps.

What do you mean by "obscured" That its usable frequency range is smaller than optimum?

Sorry for the dumb question ops:

[BobEllis]

The back of the cone is obscured by the frame and motor. Ideally dipole drivers would have nothing behind the cone so front and rear waves could be identical.

[dyazdani]

Man, I was thinking way too complicated

I understand completely now, makes a lot of sense...

[ThomasW]

I don't think anyone is running the NSB's in a dipole. They'd be quickly destroyed without the protection of a box.

Other than the problem with the large motor structure, the RS150 has low Xmax. In a dipole one needs lots of displacement, since the drivers are excursion limited, not thermal limited by VC heating.

The new 4 ohm RS-180 isn't shielded so it's an even better choice provided one doesn't need the shielding.

Chris is right, a line array made with the 5i would sound quite impressive. Of course so is the price. The 2.0 is much more reasonably priced but needs a 2K XO point and that start's limiting the choice of midwoofers.

The other more reasonably priced option is the Neo 8. Unfortunately they don't 'sing' like a ribbon. But they're very rugged and the price is right.

[cjd]

I have NSB's dipole - in fact, the trend may have been my fault as I think I was the first to try that and it was so well received at the 2004 DIY event here in Chicago. They're tough to destroy.

The Fountek 2 says 2.5k 2nd order... 3 is 2k.

Neo8 has its own issues on the top end. I would be more inclined to use it as a midrange in a 4-way dipole. Cross ~3-4k to your ribbons. That might even get you into 8" mid-woofers (Peerless Exclusive/Nomex, Dayton RS225, Hi-Vi perhaps)

C

[ThomasW]

I'm quite familar with the Neo8. I bought a pair for testing when they first came out.

Another option would be to use the Maggie MMGW as the mid/tweeter. Rated to 100Hz, they should sound sweet with a higher XO point and dipole woofer below. A pair per side at $300/pr is cheaper then all the other options.

[Victor]

...a separate dipole sub with dual 12s or 15s (Dayton RS 15s would rock). Can you guys give me any pros/cons for a pair of speakers like I described above?...

To share my experience with dipoles, - I use four 12-inch Peerless XLS woofers in two dipole subs as prescribed by Linkwitz, per side. That means a total of 8 drivers for my front channels. I am now building a version of tubezila (sealed sonotube) with two 15-inch Avalanche woofers.

This should tell you that I think that the dipole bass as wonderful as it is, - is not capable of delivering the bass that I like below 30 Hz. If you are into the organ recordings and high power movies as I am, then the dipole bass will not do for you unless you use many woofers, - more then what I used. In a dipole I would contemplate six 15-inch drivers per side, - may be…

Victor

[Jed]

Other than the problem with the large motor structure, the RS150 has low Xmax. In a dipole one needs lots of displacement, since the drivers are excursion limited, not thermal limited by VC heating.

Thomas,

An old design that I have been intriqued with in the past is the Danielle II MTMW dipole kit- introduced back in 1994. It used dual 4" kevlar focals, TC120, and a 10" woofer from Speaker Builder Magazine. Crossover points were 400HZ and around 3K. I never heard them, but an interesting design, if not flawed in your experience? My question is, is it inherently flawed to use a 4-5" dipole for midrange duty even if crossing over pretty high (400HZ)? There has to be some advantages to smaller diameter mids in a dipole- dispersion, low moving mass etc.

Jed

[Paul H]

Thomas,

An old design that I have been intriqued with in the past is the Danielle II MTMW dipole kit- introduced back in 1994. It used dual 4" kevlar focals, TC120, and a 10" woofer from Speaker Builder Magazine. Crossover points were 400HZ and around 3K. I never heard them, but an interesting design, if not flawed in your experience? My question is, is it inherently flawed to use a 4-5" dipole for midrange duty even if crossing over pretty high (400HZ)? There has to be some advantages to smaller diameter mids in a dipole- dispersion, low moving mass etc.

Jed

There's nothing inherently wrong with using 4" or 5" drivers as mids in a dipole, but I know I didn't for the following reasons:

Most 4-5" drivers as compared to 6 1/2-8" drivers have much less spl capability, especially as dipoles. In the 100 to 400 Hz area (which will likely be the crossover transition area) they have to work much harder tp push the same amount of air. Work harder = more distortion.

They typically have less efficiency, often 4-5 dB less than the 6.5-8" drivers. This is likely the reason for using a pair of 4" drivers in the design you noted above - they are probably paralleled to more closely match the efficiency of the tweeter and woofer.

Also, while they start becoming very directional ('beaming') at slightly higher frequencies than a 6.5", it's only slightly higher, not a significant difference.

Not a driver issue, but note that the 3000Hz crossover to the tweeter would ideally call for a centre-centre driver spacing of less than 4.5" - tough to do with an mtm.

Paul

[ThomasW]

...... :agree: