High efficiency woofer to match with DDS waveguide?

[Ben P]

Hey all,

I'm looking to build a high efficiency two way. I'm planning on using the DDS ENG 1-90 Pro waveguide. The compression driver is probably going to be the Radian 465pb, but that could change. The Radian 475pb, the BMS 4550, the Beyma CP-380M, and the Peavey RX22 are also considerable. I can't find a woofer to match that looks right to me. I'd like these things:

1) Efficiency >94db
2) Driver w/ 3"-4" voice coil for low power compression
3) Relatively cheap, like <$400US, which I think would leave out TAD and PHL
4) 12"-15" driver, to try and match polar response pretty close to the wave guide
5) Smooth, flat frequency response from 100-1.5kHz
6) Fs and Qts that allow a ported -3db point preferably between 40-45Hz

I'm most willing to compromise on the bass extension. I know I can get a -3 at 60Hz, maybe even 50Hz. The bass extension I want and the frequency smoothness I'd like seem to not match up in any of the drivers I've found. I can find a driver that's smooth to 1kHz, but I don't think the DDS will go that low based on what I've read.

If I have to compromise, cheaper is better, as this is only my "first try" and if it turns out good I'll probably try to figure out a way to make my own waveguides. In which case, I'll make some more and use a larger waveguide and a more expensive woofer. My current favorite woofer is the Selenium 12ws600, but it will only get to the high 50's. It's flat and cheap. The Selenium 15ws600 goes low enough, but it isn't flat - it has a strange dip at 300-400Hz. The BMS 15n630 might work, but the BMS frequency graphs are hard for me to read. The Radian 2216 looks okay, but they don't show the response above 1kHz which make it seem questionable. That's the way it seems to go, always something. So, I'd love to get some recommendations from people that have more experience.

[Tommythecat]

I have a friend who uses a B&C 12 for midrange, I believe one of the PL series. Very good driver, might have to look at the "midbass" specific PL driver for maximum extension.

But what I'd really like to see is how one of the B&C Neo's works. Like: http://www.partsexpress.com/pe/showd...number=294-680 . Ever since I noticed an Eminence Kappalite 15's weighs a ton less than that B&C 12 my buddy has - I'm going Neo all the way. Okay, maybe not the subs, but it doesn't seem to cost too much more to cut down on weight these days.

[joecarrow]

Is that $400 per driver? The JBL 2206H/J seems to do alright. It doesn't go so low, but it has some flat on-axis extension- the spec sheet claims it will go up to 2khz. I didn't model this in a ported box- did you look at it yet?

[timber_mg]

If you figure in BSC 94 isn't all that simple, but there are essentially a whole couple of options at your disposal from a variety of manufacturers.

I would recommend tuning to where you want to go (providing you don't have a woofer with silly high fs) and EQ the rest. There are so many options, but many of the more linear drivers above 1kHz are of the lighter coned variety and hence won't give you as much LF.

There are however one or two interesting heavy diaphragm 12" drivers. Perhaps have a look at

B&C 12NW76
EMINENCE DEFINIMAX 4012HO

Or if you can EQ a lighter driver perhaps something nice from B&C

B&C 12HPL76
B&C 12PL32

Or even a 2.5" coiled Delta-Lite-II 2512.

the 4550/2 are known to have good mechanical parameters for low X-o. Otherwise the DE-250 (B&C) isn't thaat expensive and has notably clean power response and a modern phase plug.

[Ben P]

Thanks for the response so far. I didn't expect this much love for B&C.

joecarrow: Yeah, that's $400 per woofer. I chose that kind of arbitrarily, but most of the woofers I've been looking at are less than that. I have looked at the JBLs. They do look good, both the 2206 and the 2226, but neither go low enough. With the 2206, I get a -3 of about 70Hz. They do have great distortion numbers - <1% 2nd and 3rd harmonic from 100Hz-1kHz at 110db.

timber_mg: BSC = baffle step compensation? I just want sensitivity and I can't think of any woofers that I've looked at that have a spec'ed sensitivity in between 91db to 95db. 94db seemed like a safe cutoff point.

By eqing, do you mean active eq? I'd rather not do active eq, and passive seems like it might be difficult to accomplish. Would going for a low -6db be okay and then just leave a 3db droop below 100Hz?

I forgot to mention that I want to do a 3rd or 4th order passive crossover for this. I'm going to need quite a bit of compensation on the horn, so I was hoping to keep the woofer crossover as simple as possible - just a basic low-pass plus the baffle step.

I was hoping there might be something "better" than the Selenium 12ws600. It can do a -3db at 50Hz and is very flat up close to 2kHz. I think the RCF L15 p200ak looks good but it has a 5db resonance in between about 1kHz and 1.5kHz that would have to be dealt with.

Ah, the Eminence Definimax 4012ho does look pretty good. Actually, the TS parameters are really close to those of the Selenium 12ws600.

The B&C DE-250 has the better phase plug? That's why the Peavey is on my list, because I believe the phase plug will work well with the DDS. I have no other ideas about which driver has the better phase plug. I know that is important, though. The metal dome and separate surround on the Radians make me think they'll behave better than any of the one piece diaphragms. What little bit I've read about them seems favorable.

[Paul W]

Here is a list of characteristics to consider in the selection process, not necessarily complete, and in no particular order...

High 1st breakup frequency.
Low Le/inductance.
Smooth impedance curve
Low impedance at HF
Low mass
High Bl
Shorting rings
Open frame to minimize midrange reflections.

The widest selection of drivers I've seen with these characteristics is Eighteensound.com. Earl Geddes uses, I understand, the B&C TBX in Summa.

You're right about the DDS 90 not working for a 1k crossover...the near-conical section is just too small to provide pattern control that low. Here is the DDS w/BMS4552ND at 0.5 meters, 0-15-30-45-60 degrees.


If you're going to build your own WG with pattern control below 1k, you can probably match a 15". If DDS with a higher XO, the largest I'd go would be 12", like the 12NDA520.

"Dave" at Loudspeakersplus.com can drop ship Eighteensound drivers not on the LSP+ website.

[noah katz]

I got some Eighteensound 12ND710's for use with BMS 4552ND on Eioghteensound XT1086 waveguides.

http://www.eighteensound.com/index.aspx?mainMenu=view_product&pid=238

They were $235 ea from Loudspeakers Plus

But maybe not low enough, 60 Hz F3 tuned to 54 Hz in 2.2 cf

[Ben P]

Thanks. Noah, how do you find the bass extension at only 60Hz? Adequate? How do you think your speakers sound? I'm tempted by the Eighteensound 12NDA520. The Active Impedance Control seems cool. It should get slightly lower than the 12ND710.

If there's anyone else reading that interested in something like this, the Ciare 12.00NDW1 ( http://www.ciare.com/oem/pdf/1200NDW1.pdf ) should go lower than any other 12" drivers I've found. The FR above 1kHz is much rougher than I'd like though.

[Paul W]

Noah,
When you have a chance, would you post horizontal and vertical response for the 1086?

[Ludvig]

Excuse me for jumping in, but you can find horisontal and vertical measurements of the XT1086 in the thread "Xt1086+bms 4540nd" post #23. The curves are very smooth and well controlled off axis. Note that the SPL scale resolution is only 2 dB.

This is with the 4540ND though, so maybe there are some differences in the response off axis. compared to the 4552ND. On axis they seem to measure very identical according to the BMS datasheets.

[Paul W]

ops:

So much for my memory!

[noah katz]

"Noah, how do you find the bass extension at only 60Hz? Adequate? How do you think your speakers sound?"

Can't say, they're still in their boxes. But I'll be using with four Avalanche 18's, so no worries