Quick & Dirty 4430-Inspired Two-Ways Part II

[Zilch]

It's confusing, perhaps, but consider the following:

1) The HF curve location is a function of the HF driver impedance. Note in the second curve posted by Giskard cited above, it shifted rightward ~2 kHz as he changed the impedance from 8 Ohms nominal to 3.5 Ohms actual for 2425H. We have to measure or otherwise know the impedance of the HF driver for the curve to be accurate.

2) Where the voltage drive curves cross is not the crossover frequency. The HF curve must be raised by the difference betwen the sensitivities of the HF driver and the woofer, and their response characteristics at the frequencies of interest, to approximate the system crossover performance.

John W wanted to know if using the LF section from 4425 would yield a better result than the "standard" NL200t3 when using a 2214H woofer in his project:

http://audioheritage.org/vbulletin/s...ead.php?t=7110

Here's the two LF curves shown with a 4-Ohm HF impedance. It'll be interesting to see how his speakers actually measure:

[John W]

Thanks, thats clear illustration of the affect the extra inductance has. I am working on a measurement setup and will post any meaningful data that I can.

[Zilch]

For more options, I added 4430's 2.6 mH, 12 uF.

Orchid = 4430 2.6 mH, 12 uF
Yellow = 4425 3.8 mH, 14 uF
Green = NL200t3 3.0 mH, 20 uF

Choose LF as required for optimum system performance upon testing....

[Ian Mackenzie]

Zilch,

This is becoming a very long thread!

There is some very good reference stuff in places but it takes a lot of time to find specifics.

Would it be possible to edit the reference stuff like the schematics and the measurements and partition them in a project thread or what ever?

I am just wondering what is your agenda at this stage?

[Zilch]

Hi, Ian!

Actually, I'm working on a summary which includes direct links to the references. While there's lots of material here, it condenses nicely into just a few major related themes. I'll likely submit that summary as a separate "project" thread.

I'm almost done adding new material, I promise. We've got 2342's coming in, 2352's to look at, and the 2346's, of course. Also, E140's reconed to 2235H's are going in the 4507 boxes as another alternative LF component, as several members apparently have these.

The study of 1-3/4" diaphragm variants on alnico versus ferrite 1" motors will likely end up in a separate thread, like we did with ring radiators and compression drivers earlier. That's a subject of more general interest.

Several members are building systems according to the guidelines developed in this thread. I'm encouraging them to post their results here so they are contiguous with the source material rather than scattered in the archives. I may be reconfiguring an Olympus pair myself, as well.

Yes, the thread is long, but the summary will facilitate accessing the information and, I hope, bring new clarity to the endeavors documented here. In the meantime, readers might avail themselves of the utility of "Search" within the thread, available just above on each page.

I've read it through a couple of times recently. It takes me about half a day each time to do it, but it DOES make sense when viewed comprehensively. I'll make that a simpler task here shortly. No mystery, it's all about building two-ways based upon the 4430 formula.

Let me try this approach first. If it's still too unwieldy, I'll be willing to put some effort into reconfiguring it entirely in a project forum, assuming it deserves such standing....

[Zilch]

No mystery, it's all about building two-ways based upon the 4430 formula.

Hotrod "Bookshelf" 100° x 100° waveguide implementation here:

http://audioheritage.org/vbulletin/s...ead.php?t=7671

O.K., O.K., itza 2.1-way, then....

[Zilch]

1) Alleged "Mid-format" 2352 Optimized Aperture Biradial horn (right) is nearly as large as Everest/2346. Both dwarf 2344A (front).

http://www.jblpro.com/pages/pub/components/23525354.pdf

2) Looking like a bug on a tricycle, 2435HPL neodymium driver (3" diaphragm, 1.5" exit) will play lower on these horns, which are good down to 500 Hz. Maybe I try 800 Hz for starters.

Can 243x drivers operate well with OA horns? They seem to meet the design criteria:

http://www.jblpro.com/pub/technote/tn_v1n21.pdf

3) Both horns and and 2509A brackets (not easy) had to be drilled for smaller-diameter mounting circle of 243x drivers. A rubber grommet reduces the bracket's 2" center hole down to the requisite 1.5". Rapid horn flare precludes reversing the bracket for more compact footprint.

4) RTA on 1 kHz AM crossover. Clearly, the HF compensation is wrong, but the response is there.

How do they sound? Well, kinda like everything else around here, ummm, "crispy." Tightly controlled 90° x 50° directivity. I'm goin' out on a limb and sayin' the midrange is cleaner than on the smaller waveguides, initial impression. We'll see after I get the compensation worked out better....

Edit:

5) Better.

[Zilch]

2509A brackets in the E-Tent sale for $104, free shipping:

http://www.jblpro.com/Tent_Sale/index.htm

2510 at $65 will work with 243x drivers, too, but it's notches instead of holes for mounting....

[jbljfan]

But when you need them, you need them. Thanks for the pointer. Is "better" (compensated?) still crispy?
Regards,
Mike

2509A brackets in the E-Tent sale for $104, free shipping:

http://www.jblpro.com/Tent_Sale/index.htm

2510 at $65 will work with 243x drivers, too, but it's notches instead of holes for mounting....

[Zilch]

Is "better" (compensated?) still crispy?

Hiya, Mike,

Yup, "Better" was still crispy, but not overly so. Johnaec heard them yesterday (along with the amazing little Hotrods,) and deemed them "Fine."

I did a little more today, and got them within +/- 1.25 dB. Don't know what's going on down there at 2 kHz; gonna have to take impedance measurements for a clue.

This is all passive, so I can't "boost" anything to fix that. Gotta figure it out, is all. Put the slope I want in 'em, too.

I think I'm about done compensating until the 2235H recones get back here to install in the 4507 boxes. That's what these are gonna mate with, to become MEGA 4430's!

[No, NO, I ain't doin' 2360's. Nope....]

[Rudy Kleimann]

2509A brackets in the E-Tent sale for $104, free shipping:

http://www.jblpro.com/Tent_Sale/index.htm

2510 at $65 will work with 243x drivers, too, but it's notches instead of holes for mounting....

The 2510 does not include a yoke to mount to the top of the cabinet like the 2509A, nor does it provide any means to swivel the driver and horn up down, or side-to-side. It is really meant to be used as a "flypoint" mount to hang the horn and driver in the air on cables or chains.

The 2509A mount is pricey, but it does the job right.

[Zilch]

Dutchman found some 4430 clones: http://audioheritage.org/vbulletin/s...ead.php?t=7795

[DRG]

1) Take B380 w/2235H set vertically on "foot"
2) Mount 2344A w/2426H/J on top
3) Cross @ 1 kHz w/CD compensation (M552)
4) Biamp

Something I'm missing here?

I really wish Keele, Eargle, and Smith would respond...

[Robh3606]

"I really wish Keele, Eargle, and Smith would respond..."

Well they already have in a way. Look here.

http://audioheritage.csdco.com/vbull...6021#post76021


Rob

[DRG]

Thank you very much David and Don.

http://www.audioheritage.org/html/pr...bl/4430-35.htm