Ring Radiator Comparisons

[edgewound]

Go here: http://www.uspto.gov/patft/index.html

Hit "Quick Search" at the top left.

Put this number in Term 1: 5,878,148

Make Field 1 "Patent Number."

Hit "Search."

Hit "Images" to see the original, with drawings....

Interesting find, Zilch. Looks like maybe JBL is licensing the technology or having them OEM'd by BMS. We'll probably never know definitively....unless BMS is a takeover target of Harman ...wouldn't surprise me.

[JBL 4645]

Zilch

I can see on the RTA some nice HF extension there , are you using “wideband pink noise” to test the JBL HF horn?

[Zilch]

Yes. Behringer RTA sources the pink noise....

[JBL 4645]

Zilch

I knew it, as it can come in the form of many other sources like CD, sound generator, or the (Behringer), any I like your threads, very clear and detailed.

[Timothy Bailey]

can anyone advise me if it is practical to use a simple first order xover on these @ say 3.5 K

Above a 91db/w unfiltered mid bass Foster 8 incher from the late 1970's. Spherical enclosures!

The amp driving them would be a 'modified Leak Stereo 20' in triode mode IE about 6 watts maximum. It currently has a 1st order R/C input filter -3db @ 175 hz, and I would consider increasing this to ~ 420 hz OR 850, but I don't want to get closer than 2 octaves to 3.5K.

yes I WILL need to level match.

I would also probably be mounting them so the baffle's face neatly meets the lip of the horn ie _/\/\_ okay?

Roughly how much do a pr go for on Ebay?

THEN I'll think about ST's. I am 55 after all ;-)!

TIA from Timbo in Oz

[Timothy Bailey]

_|/\/\|_

IE the visble part of the bullet tweeter would be the curved in throat and no the straight sides of that throat.

I would hope that this might provide a little support for that part of bandpass immediately above 3.5 k.

As well as minimising early reflections of the mid-bass driver's output.

After all they'll be in spheres .

TIA again,

[Robh3606]

Hello Tim

You may want to drop a post in the Market Place Forum. I am sure you can get them, Mike cadwell has a lot of lenses and may be able to cobble a set together for you. If you can get a pair of 2405's you can change out the phase plug and horn to make 2402's. They are also readilly available on Ebay. I would think you would want the alnico version as they are relatively small and that would make enclosing them a bit easier. Just a thought but you could also continue the flare from the driver into the sphere however I don't know what the loading effects would be.

Rob

http://audioheritage.csdco.com/vbull...ad.php?t=11133

[Old Pink]

You are wrong, the 2407 is a 1" screw-on neodymium ring radiator with a 1.5" voice coil. In fact it is identical to the BMS 4540 but the BMS is rated 8 Ohms while the JBL is rated 16 Ohms. It would be interesting to measure the impedance curves of both types, to see if they really are different. The replacement diaphragm is much cheaper from BMS than from JBL (at least here in Europe).

I don't know anything about the 2407, but after doing a quick search on the JBL Pro site, it appears to be a 1.5" light weight compression driver with unique diaphragm. I would assume it is more closely related to the drivers we tested here:

http://audioheritage.org/vbulletin/s...ead.php?t=6050

It does not appear to be a ring radiator.

Widget

[Old Pink]

The 2407 is identical to the BMS 4540 but the BMS is rated 8 Ohms while the JBL is rated 16 Ohms. It would be interesting to measure the impedance curves of both types, to see if they really are different. The replacement diaphragm is much cheaper from BMS than from JBL (at least here in Europe).

A week ago, I asked BMS through this contact form
http://www.bmspro.com/contact/index.html
if the JBL 2407H is identical to the BMS 4540nd. I didn't get a reply.

Zilch: Is the limited low frequency extension of JBL 2407H and BMS 2540nd due to the horns? What frequency response do these drivers have on other (bigger) horns?

[Zilch]

2407 is (was) available in both "H" and "J" versions, 8 and 16 Ohms, respectively.

Similarly, BMS4540 is available in either impedance.

There are mechanical differences in BMS vs. JBL implementations of the driver....

[Old Pink]

Yes indeed, you are right. The german BMS distributor (where I got mine) is only stocking the 8 Ohms version. About the mechanical differences I don't know, I never had the opportunity to compare both brands directly. They might result by the fact that JBL is not buying the magnetical structure from the germans; they only buy the plastic part with the diaphragm and voice coil.

2407 is (was) available in both "H" and "J" versions, 8 and 16 Ohms, respectively.

Similarly, BMS4540 is available in either impedance.

There are mechanical differences in BMS vs. JBL implementations of the driver....

[Old Pink]

I dont know, I do know they look remarkably similar to each other, different mounting assemblies, and the JBL has a differently shaped front, but from the back they look really close. The 0.6" difference in diameter is not to be dismissed either.

BMS rates the 4552ND at 113db1w@1M! What does JBL rate theirs as?

What about the picture of the diaphragm Edgewound put online? It says 2407, is it the diaphragm for the 2407?

You cannot compare the 2407 to a 4552ND because the 2407 has a 38mm voice coil and the 4552 has a 44.4mm voice coil. The plastic body is fastened with 4 screws to the magnet assembly with all 38mm types, while all 44.4mm types are fastened with 6 screws.

[Old Pink]

You cannot compare the 2406 to a 4552ND because the 2406 has a 38mm voice coil and the 4552ND has a 44.4mm voice coil. The plastic body is fastened with 4 screws to the magnet assembly with all 38mm types, while all 44.4mm types are fastened with 6 screws.

I have measurements of the BMS 4540 on the DDS ENG 1-90 horn. It has real extension beyond 20kHz but I wouldn't try to cross it over at 1000Hz. The JBL 2406 is actually closest to the BMS 4552ND ($145) and the 2407 is closest to the BMS 4540ND ($96). BMS will build custom diaphragms for their drivers so the resonance frequency and sensitivity of the BMS and JBL drivers may not be equivalent. I have been using BMS drivers for years and think they sound great. I have used the 4552, 4540 and 4590.

I measured some of these drivers for tomp787 and the DDS ENG 1-90 horn with the BMS 4540 would be my top choice for the top end of a 3 way system with a crossover above 1600Hz. If you want to crossover at 900Hz the 4552 would be the more appropriate driver although it does not have the same high frequency extension as the 4540.

I will post some screen captures of measurements tomorrow.

[Old Pink]

They really do sound great, and at $320 they are a bargain compared to the price of a 2446.

A good friend of mine (who unfortunately lives on the other side of the U.S.) has just finished his own design for a cornerhorn, and is using a BMS 4590 (coaxial) for the mid and tweeter. After listening a while and getting over the idea that it's better just because it's different idea, he says the BMS units are really, really good. He doesn't even have it on an optimal horn yet. He is using a P-Audio PH-4525. He would like to try some kind of wood horn or tractrix.

Of course, two drivers at $320 each ought to sound good.

Bruce

[Doctor_Electron]

Using the proper crossover/eq the response of the 2404 can be made flat,
with great off axis performance.

Can someone on this forum help me as to how this is done? I have a pair that I used to replace the 035ti's on my 4410s. They seem better, but I know they are performing far from optimum. Also, any help with properly padding them down to make up for their greater efficiency compared with the 035ti's.
BTW, these monitors are used in a near-to-midfield enviornment.
Thanks.