JBL 12" Woofer

[speakerdave]

Discussions about the L65 and the 4425 and other speakers have often centered around need for a 12" JBL woofer. I would suggest people consider the 252G. It is a modern woofer with neodymium magnets, differential drive, dual voice coils with a third braking coil to dampen excursion overrun, and a no-rot rubber surround (yes!), etc. We JBL nostalgists need only overcome our attachment to 12" drivers with 4" voice coils.

I have been listening to this woofer in the LSR32 for several months and think it is quite impressive. I have not found a data sheet on it, but you can find some description of it in the panels on the LSR32. In that speaker the 252 is crossed over to the midrange at 250 Hz; so I have a question about what it's upper limit should be. As a twelve inch woofer you would not want to try to use it much above 1000 Hz anyway.

I know that also George Augspurger has used this woofer in custom monitors. In more than one he used it with the TAD 4002. I don't know what crossover frequency Mr. Augspurger used, but Pioneer gives the 4002 a minimum specified crossover of 600 Hz. Mr. Augspurger included an 18" subwoofer in this monitor system, so I would think that would free the 12" to be used at least up into the high hundreds.

Giskard ran the numbers on this woofer once and it looks to be a suitable replacement for the much mourned 2203 in a cabinet of about 2.5 cu. ft. It's in this thread discussing the LSR 32.

http://audioheritage.csdco.com/vbulletin/showthread.php?s=&threadid=822&perpage=15&highlight=252g&pagenumber=2

I think the 252G would likely be an improvement over the stock woofer in the L65, although crossover modification would be required. Note that the L65 cabinet is probably just under 2 cu. ft. net, so Giskard's plots would not apply directly to that use. In the smaller LSR 32 cabinet it is down 3 dB at 53 Hz in a half space. It has a 28 Hz tuning, which I think gives it a roll off with little knee, a tuning that works well playing to room rise, especially in a smaller room, which, after all, is the kind of space a small monitor is designed for. In a larger space, like my listening room, you would want to plan on a larger cabinet or the addition of a subwoofer.

Retail price on the July 1, 2004 list is $233 and change.

David

[johnaec]

I've often thought the differential drive technology with 3" voice coils is probably the wave of the future. JBL uses these in their Vertec speakers, and JBL's three top of the line car audio subs also use this. I know people associate both the Vertec and car audio drivers with high output more than accurate response, but the technology DOES actually point to more accurate reproduction. I'm actually really curious how those car subs would work in an studio/HT situation. The price alone shows how much JBL must put into their design, and the published specs are great. It'd be nice to see more, though, such as distortion readings, etc.

I was able to pick up the 10" W10GTI to play with, but it's still in the box right now. 'Really impressive unit, though...

I know this "heritage" forum is more concerned with keeping older premium speakers up and running, but what better place to also discuss/compare the alternatives, especially as replacement parts get harder and harder to come by?

John

[Valentin]

speaker Dave

Have you ever thought you could do a mtm configuration a la k25800 with 2 252g and the midhigh section of the lsr

it is a wild thought but the 1200fe in the k2 are the same woofer in the century gold and that speaker has the same volume that the lsr32 and the same response

the bigger difference between the century gold and the lsr is in the crossover that the mid and bass are done at650 hz

by your previous comments the 252g can be crossed at this frequencies

[toddalin]

I've often thought the differential drive technology with 3" voice coils is probably the wave of the future. JBL uses these in their Vertec speakers, and JBL's three top of the line car audio subs also use this. I know people associate both the Vertec and car audio drivers with high output more than accurate response, but the technology DOES actually point to more accurate reproduction. I'm actually really curious how those car subs would work in an studio/HT situation. The price alone shows how much JBL must put into their design, and the published specs are great. It'd be nice to see more, though, such as distortion readings, etc.

I was able to pick up the 10" W10GTI to play with, but it's still in the box right now. 'Really impressive unit, though...

I know this "heritage" forum is more concerned with keeping older premium speakers up and running, but what better place to also discuss/compare the alternatives, especially as replacement parts get harder and harder to come by?

John

I've have nothing but good things to say about the W15GTI that I use for a sub in my home theater.

I recently acquired a pair of 2425s on generic butt cheeks and would like to replace my surround speakers. They are currently Cerwin Vega 10" 3-ways and the boxes are about 1.4 cu ft. I was thinking that the W10GTI with the 2425s could be nice replacement for the existing components and I wouldn't need to redo cabinets to match the ceiling or figure out how to hang the new speakers. I think that the 1.4 cu ft volume is right in the range for the suggested cabinet size for the W10GTI. I don't know if the cabinet construction is up to teh thump, but internal bracing is possible. Still, at >$250 each for the W10s, four surrounds get costly.

Let me know how these work out for you.

[mikebake]

Good thread topic, and worthy of attention and further exploration. It does appear to be quite a good driver.

[sa660]

I am very interested.

I did not beleive that the 252G was that good for low response and could go as low as the 2203! I was looking for 2203 and may now start looking for 252G
I alos beleive that JBL as a modify version of the 252G for the subwoofer only 252F.

[Maron Horonzakz]

Are the 252G, 252F 4 ohm or 2 ohm ?

[10 Watt Street]

252G is 4 Ohms, used in the LSR32 three way.

252F is 2 Ohms, used in the LSR12P subwoofer.

[Valentin]

Allaire Studios

has

5.1 Augspurger Custom Monitors
LF- (4) JBL 252G 12" woofer
HF - TAD 4002 HF Driver with Wood Horn
Subwoofers - (4) JBL 2241 H 18" woofer


http://www.allairestudios.com/studios/studios_greathall.html

[4313B]

...

[4313B]

qxlxp asked that this be posted so I am posting it along with the 252F above.

[sa660]

What is the advantage of the 252G for low frequency only?

Regards,

[LowPhreak]

Great thread! I'd like to see more on the 252G in a 3-way config.



I've have nothing but good things to say about the W15GTI that I use for a sub in my home theater.



Also would like to see more on the W-series drivers being used as a DIY home sub.

toddalin, is yours sealed or ported, etc? I've seen a couple of reports that the transient response of the W's is not so great.

[speakerdave]

Great thread! I'd like to see more on the 252G in a 3-way config.
Read up on the LSR32 and 6332. There's also a thread somewhere with charts by Giskard comparing the 252G with much-mourned 2203, and they show a very similar profile in 2.4 ft cab, if you want to go a little lower.

David

[toddalin]

Great thread! I'd like to see more on the 252G in a 3-way config.




Also would like to see more on the W-series drivers being used as a DIY home sub.

toddalin, is yours sealed or ported, etc? I've seen a couple of reports that the transient response of the W's is not so great.

Mine is ported. Woofer is in a 4 cu ft chamber that has a 4" dia x 14.75" port to baffle board. Also ports to a central 2 cu ft chamber that also has a 14.75" port to the baffle board. Port between the two chambers is 4" dia x 9.5".

Previously all ports were 9.5" and woofer had more volume and boom, but wasn't as "tight."

It does consume considerable power to push to it loud, but my Crown PSA-2XH bridged for mono has plenty, even at 12 ohms.

[LowPhreak]

Read up on the LSR32 and 6332. There's also a thread somewhere with charts by Giskard comparing the 252G with much-mourned 2203, and they show a very similar profile in 2.4 ft cab, if you want to go a little lower.

David

I've read all of the LSR blurb before, dave, but I'd like to know what DIY's ppl may have done with the 252G and other drivers/X-O's/cabs.

[LowPhreak]

Mine is ported. Woofer is in a 4 cu ft chamber that has a 4" dia x 14.75" port to baffle board. Also ports to a central 2 cu ft chamber that also has a 14.75" port to the baffle board. Port between the two chambers is 4" dia x 9.5".



So is that not actually a bandpass box?

[toddalin]

So is that not actually a bandpass box?

No not a bandpass box.

[timc]

Does anyone know what modifications would be needed in the L65 crossover if i change to the 252G driver? I recon i dont have to change the damping on the mid/tweeter since the potentiometers have a lot to go on. Is this correct.

Tim