Ring Radiator Comparisons

[Oldmics]

2407 Info

Coil O.D 1.530 (fudge factor)

DCR 5.6

Phase Plug is plastic

Diaphragm material appears to be polymer as it is clear and you can see thru it

[Zilch]

Polyester or titanium diaphragm?

Phase plug is metal or plastic?

[Guido]

Definitely a BMS Driver.

Made in USA? Interesting

[Guido]

Yup, that's the plan. This weekend, probably.

Preliminary report: 2407 sounds VERY good on 2342 biradial horn, the only combination I've really listened to thus far. Using NL200t3 crossover, I have it padded down about 6 dB more....

Hi Zilch!

Do you have any news here? I'm toooo curious

[Zilch]

Sorry, diverted by the arrival of 275nd diaphragms, a different puzzle.

More listening results for 2407: Clear, bright, perhaps overly so, independently verified by forum visitors. I may have to use AutoEQ or build up the requisite crossover (link above) to hear how they really should sound.

I'll get back on it, I promise. Also have DDS horns to try with them. Gonna take a little effort, is all....

[bbrown]

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

[Zilch]

Do you have any news here? I'm toooo curious

Hang on, Guido.

I'm building AM4212/00 crossovers to run 'em....

[Next week, maybe....]

Gotta be steeper slope (24 dB/octave) to play them down at 1.3 kHz successfully....

[TimG]

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.

[TimG]

The first image is the BMS 4540ND on the DDS ENG 1-90 horn and the second is the JBL OASR horn. My sound card and measurement system with a 96kHz sampling rate allow measurement up to 48,000Hz, but my microphone only has a calibration file up to 20,000Hz, so I can't be sure of the response above 20kHz.

[Zilch]

Just completed 24 dB/octave 1.3 kHz AM4212 crossover to run these (right), here shown on PT-F1010HF waveguide. Comparing LP performance to N3134 (left).

1) The crossover
2) BMS 4540nd on DDS ENG-1-90
3) BMS 4540nd on JBL OASR
4) JBL 2407H on DDS ENG-1-90
5) JBL 2407H on JBL OASR

Zilch deems them, ummm ..., "similar."

[Gotta order up some 2406H's now.... ]

[Jan Daugaard]

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]

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?

In the latest RTA curves above, the crossover is shutting them down. It's essential to do that in order to play them that low.

The "shelf" from 1 kHz to 3 kHz is also apparent in both drivers.

The specs say the useful range begins about 1200 Hz. TimG's measurements confirm response limitations below that. See also:

http://audioheritage.org/vbulletin/s...mesh#post75158

The diaphragm is only 1.5" diameter. It's not the horns; it's a tweeter....

[Zilch]

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....

[scott fitlin]

WHAT do the JBL 2407,s sound like? Compared to traditional JBL slots and bullets?

[Zilch]

They are "Mellower," though all of the HF response is there. The diaphragms are Mylar, generically speaking, not metal.

2406 sounds the same.

You'll have to wait for others to hear them to confirm this. I don't have slots, only bullets and 2404 mini-butts to compare.