A new Ring Radiator?

[Joe Alesi]

I'll donate an old beat up 2402 horn and phase plug to who ever wants to cut it down in the name of science. I still have a small pile of them left!

Mike Caldwell

Hello Mike,

That is very kind of you, but I already have some spare parts to butcher...errr... modify and I am in Australia. Perhaps one of our US boys is also interested in a try?

Thanks again for the kind offer

[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).

Hey Joe

JBL buy some of the newer models from BMS anyway. See DJK's posts on this at AA HiEff. The 2407 is apparently a 4540ND

I'm not a brand 'fanboy', I'd use whatever I find best for the job.

[Old Pink]

It seems that the 2408 replaces the 2407 on the VRX923. While the 2407 is a 16 Ohms version of the BMS 4540nd, the 2408 is a different (more simple) design, and I suspect the reason behind this is to avoid paying royalties to BMS. The diaphragm of the 2407/BMS is rear mounted on the magnet while the diaphragm of the 2408 is front-mounted, similar to classical 075. The ring-shaped diaphragms of the 2407 and 2408 are both 1.5" (38mm) Mylar types.

I was trying to find any info I could on the 2408H and came accross these pictures of the diaghragm and phase plug.
This is different from the 2407 and looks a lot like an updated ring radiator.

[hjames]

Repeatedly reposting to yourself starts to look an awful lot like webspam

[johnaec]

Repeatedly reposting to yourself starts to look an awful lot like webspam

I don't think so. It seems to me he was just conveying new info as he got it.

John

[Zilch]

2407H is 8 Ohms nominal. I just measured the DCR on one at 4.3 Ohms.

Though I couldn't swear to it, I've likely posted the impedance curves here previously....

[Old Pink]

I just measured DCR on a BMS 4538 (Ferrite Magnet version of 4540nd) and I got 4.9 Ohms. I checked the BMS website and indeed they offer the 4540nd in 8 and 16 Ohm versions.
There is also a ferrite magnet version of the 2407 called 2406, but the magnet is much bigger than the magnet of the BMS 4538. Also the 4538 is flange mount while the 2406 is screw-on. As the 4538 has the same sensitivity than the 4540, I suppose that the 2406 has a slightly higher sensitivity. Anyway, to my knowledge no BMS drivers with 44mm coil has a corresponding JBL type. The same for the 90mm 1.5" and 2" throat coax drivers. However, BMS has a new driver whose diaphragm is front-mounted just like the 2408. It has a tiny voice coil (1" diameter) and a small ceramic magnet. It should not be used below 1.9 kHz

Oh, and I just noticed that JBL is making a 2407H (8 Ohms) and a 2407J (16 Ohms version, to be found on older VRX932) Same for 2408: 2408J only on (newer) VRX932.
On the PRX512M I found a 2408F (4 Ohms?) version.

2407H is 8 Ohms nominal. I just measured the DCR on one at 4.3 Ohms.

Though I couldn't swear to it, I've likely posted the impedance curves here previously....

[scott fitlin]

I'd rather have a BMS. Scan-speak = toys.

Arent you the one who told me that just because a driver is designed for a certain application, doesn't mean it wont work in another application the driver wasn't intended for?

Scan-Speak, Vifa, and Audax drivers are used in many speaker systems.

Implemented correctly, they do work!

[Old Pink]

Arent you the one who told me that just because a driver is designed for a certain application, doesn't mean it wont work in another application the driver wasn't intended for?

Scan-Speak, Vifa, and Audax drivers are used in many speaker systems.

Implemented correctly, they do work!

No, that wasn't me. And I cannot agree to that.

[scott fitlin]

No, that wasn't me. And I cannot agree to that.

Are you A9X?

He knows what Im talking about.

[Old Pink]

Are you A9X?

He knows what Im talking about.

no