A new Ring Radiator?

[Joe Alesi]

Hello All,

I hope everyone is happy and well and looking forward to the Christmas break.

The Scanspeak ring radiator is widely used in various high end speakers. How about a JBL version:blink:? What? Yes a JBL version. Why? Just for the heck of it- because we can. Sure we would loose considerbale efficiency, but we would also gain wider dispersion.

Take a humble JBL 2402 (you have sitting around doing nothing- I have a few) and make a new face plate for it (or remachine the JBL front horn:screwy:) and do the same for the phase plug, completely removing all the horn loading. I am not sure where this would now place the sensitivity, but I would guess it would be sub 100dB/1W/1m.

Take a lok at the pics:

[A9X]

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

[subwoof]

JBL did it 45 *years* ago and called it the 030. It is used in the minigon and a few others.

sub

[Robh3606]

JBL did it 45 *years* ago and called it the 030. It is used in the minigon and a few others.

The 030 was not a ring radiator. It just used a common motor. It was a rather large conventional cone tweeter with an aluminum cone .

Rob:)

[edgewound]

The 030 was not a ring radiator. It just used a common motor. It was a rather large conventional cone tweeter with an aluminum cone .

Rob:)


If nothing else....the 030 sure looks pretty.:applaud:

I don't remember how they sound...I've only had the chance to repair one pair about 17 years ago when parts were available.

Wharfdale had a similar design with a purple plastic diaphragm and a huge voice coil that sounded mighty good. I think I still have it in the boneyard for reference....doesn't work though.

[Joe Alesi]

I'd rather have a BMS. Scan-speak = toys.
But you can have a JBL..........:D

Hello A9X

[John W]

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.

[Joe Alesi]

I was trying to find any info I could on the 2408H and came accross these pictures of the diaghragm and phase plug.


Hello John,

Thanks. WOW that is some phase plug.

[A9X]

But you can have a JBL..........:D

Hello A9XHey 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.

[Joe Alesi]

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.

Hello A9X,

I have had a look at the BMS site- some very interesting high spec drivers there for sure, but they are all compression drivers.
http://www.bmspro.info/?&show=item&usbid=10267

What I was suggesting with the 2402 mod (just for kicks) was to remove all the horn loading turning it in to a direct radiating ring radiator similar to the Scanspeak design.

I will do it just for fun and eventually post the before and after response.

Thanks- I will check DJK AA posts

[A9X]

What I was suggesting with the 2402 mod (just for kicks) was to remove all the horn loading turning it in to a direct radiating ring radiator similar to the Scanspeak design.

I will do it just for fun and eventually post the before and after response.Be interesting to see the results, but not sure it'll work all that well. Efficiency will be a lot lower.

[Joe Alesi]

Be interesting to see the results, but not sure it'll work all that well. Efficiency will be a lot lower.

Yes A9X- I agree and I would expect to loose something like 10dB, but gain considerable dispersion and possibly increase bandwidth and lower distortion/colouration somewhat. Although the distortion would be hard for me to quantify at the moment (I have ETF and another package- I have forgotten).

Only experiment will know for sure.

[A9X]

Yes A9X- I agree and I would expect to loose something like 10dB, but gain considerable dispersion and possibly increase bandwidth and lower distortion/colouration somewhat. Although the distortion would be hard for me to quantify at the moment (I have ETF and another package- I have forgotten).

Only experiment will know for sure.Experimentation will be the test. But, I would expect distortion to increase as to get the same amount of SPL there will need to be more displacement. Compression effects in the throat should be minimal at sensible domestic levels. Dispersion is something that I prefer to be controlled and matched to the driver below so I'm not a fan of that aspect.

I'm going to be doing a bit of testing and measuring, as I'm getting Soundeasy and ARTA in the new year as well as an IBF calbrated measurement mic.

After my experiences with DR and CD HF drivers I could never see me going back to DRs.

Cheers

[Joe Alesi]

Experimentation will be the test. But, I would expect distortion to increase as to get the same amount of SPL there will need to be more displacement. Compression effects in the throat should be minimal at sensible domestic levels.

Good point

[Mike Caldwell]

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

[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 webspamI 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