Makie a JBL 2234 with a 2225

[SilverSurfer]

Hello,

I read a lot of things on this forum. (many interresting informations)

Actually I have a pair of 2225H, and I would like to know if I can transform them on 2234H ?

- by replacing the cloth surround by a new foam surround...

Considering that 2231 2234 2235 2225 have the same basket / engin, and that JBL sould prefere to save money and produce the same cone / coil:

"is someone on the forum know exactly what are the differences between the 2225 and the 2231 ?" ( Cone / coil / spider / surround )

Many thaks for your help

[RMC]

Hi Surfer,

Welcome to the Lansing Heritage Forum.

Sorry, but i'm not convinced this would be a worthwhile undertaking. I think you will end up with an imbalanced woofer. Coil, spider and surround were designed for a specific performance and excursion level in mind.

Usually sound reinforcement woofers (e.g. 2225) have stiffer suspension system and hi-fi/monitor woofers have a more compliant one. What you're trying to do would be a mix of both: a more compliant foam surround allowing more cone excursion, working together with a stiffer spider trying to restrict such increased displacement.

Can the coil and spider travel the extra distance afforded by the foam edge? And without increased distortion? i doubt. Some driver parameters may also change in the process.

The other way around (from foam to cloth surround) might have been somewhat more logic, though still an imperfect solution.

Richard

[SilverSurfer]

Hello Richard,

Thanks for your reply... I understand you must be right !

It sould be logic, but, "Are you shure that the spider and the coil are not the same ? "

[1audiohack]

Hi All;

I don’t think that any of the moving parts are the same. Well the dust cap and maybe the tinsel leads.

From a George Augsperger note I have: The cone is specific to the 2234/2235. They are made by Hitachi from very hard paper. Most other JBL woofers of the age have cones manufactured by Hawley.

If the goal is to lower the FS of the 2225 then changing the surround may bring it down a little but as has been mentioned a moving system is a system and there is a possibility of creating unforeseen problems by changing components of that system.

That said, 2225’s are still plentiful and inexpensive here in the states and few would worry about experimenting with them.

What's the worst thing that could happen? Reconing them with C8R2235 kits and you end up with what you want anyway.

Barry.

[1audiohack]

I forgot to mention, the coils are not the same. The 2225 is 0.63” / 16MM long where the 2234/2235 is .75” / 19MM.

The only thing I don’t know for certain is the spider rate but I have to assume that the 2234/2235 is one letter softer than the 2225. I believe there are A through D spiders with A being the softest. However my memory could use some work!

Also, I measured the FS of four 2234’s that I replaced the surrounds on and the difference with no surround and new surrounds was less than 3Hz. So the 2234 surround contributes little the the resonant frequency of the 2234. Measured with the driver vertical of course.

Based on that information you could measure the 2225’s FS, cut one of the 2225’s surrounds out remeasure and get an idea of where the FS would land with a thin foam surround.

Barry. Who’s not afraid to hack.

[RMC]

Had this already in the making.

The JBL driver listings i have don't give the specific part number for each component that goes into a driver (e.g. no coil or spider part number mentioned). The only sure way to know if the exact same.

But lets assume the voice coil and the spider are the same for 2225 and 2234 as you mention. Apart from knowing or not if the foam installed is the same or not as the original one for 2234, you still have yet another problem.

Changing the surround to a more compliant one (cloth to foam) will cause the driver's Vas and Qts parameters to shift (as per Eargle) and both of these influence the proper cabinet volume. Then you need to measure the new and actual woofer parameters that are impacted, with a software program such as DATS or Woofer Tester before building a box.

Also, a member who tried a surround change from foam to cloth saw his driver's Fs parameter increase markedly, while some others varied less. Based on this, one might expect that, from cloth to foam surround, there could be a shift downards of driver Fs, therefore modifying some box ratios like the tuning factor and the F3 factor, both of which take into account the driver's free-air resonance frequency (Fs).

So not an easy call. These are things one should know before jumping in to avoid regrets.

Richard

[SilverSurfer]

Hummm.... ok guys!

If “cone + coil + spider” are not the same ... it's dead! . I imagined that It was a wonderful option, but there is no miracle.

- I'll keep the 2225 basket and I'll recon with a 2235 recon kit, if it's the only one solution, it would be 'tip top"


Many thanks for all these "very interesting" information

[toddalin]

Buy the 2235 kit, if you can find a pair, but leave off the mass ring leaving it a 2234. I wish I would have had this done to mine when I had the 2205s reconed as 2235s.

Ultimately, I am far happier with a pair of 2241Hs which don't require that much larger of a cabinet.

[Ian Mackenzie]

https://jblpro.com/en/site_elements/2225h-j-information

Modelling the 2225 driver with its 97 db sensitivity gives a QB3 alignment with a box volume of 50 litres and a port tuning of 56 hertz and F3 68 hertz. Depending of what your doing this driver could be used for a mid bass application to a large horn from 500-1200 hertz. The jbl spec sheet suggests a response out to 1200 hertz.

It’s high 97 db sensitivity in a compact enclosure mid bass ported enclosure is the best attribute for a home diy situation using a low power hifi amplifier. Simply use a sub woofer below 80 hertz and you have a workable system. A driver with 97 db sensitivity and a lower Fs typically requires a physically large enclosure of 170-240 litres but the bass response F3 is still limited to 40 hertz. The x max of 5.00mm means it’s really only useful as mid bass driver.

The 2234 will require some bass boost to achieve a similar response to the 2235.

Something to think about.

[SilverSurfer]

https://jblpro.com/en/site_elements/2225h-j-information

Modelling the 2225 driver with its 97 db sensitivity gives a QB3 alignment with a box volume of 50 litres and a port tuning of 56 hertz and F3 68 hertz. Depending of what your doing this driver could be used for a mid bass application to a large horn from 500-1200 hertz. The jbl spec sheet suggests a response out to 1200 hertz.

ItÂ’s high 97 db sensitivity in a compact enclosure mid bass ported enclosure is the best attribute for a home diy situation using a low power hifi amplifier. Simply use a sub woofer below 80 hertz and you have a workable system. A driver with 97 db sensitivity and a lower Fs typically requires a physically large enclosure of 170-240 litres but the bass response F3 is still limited to 40 hertz. The x max of 5.00mm means itÂ’s really only useful as mid bass driver.

The 2234 will require some bass boost to achieve a similar response to the 2235.

Something to think about.

Many thanks Ian,
I'll keep that in mind ! ... I think that I will recon directy with a 2235 recon kit ! .


- I have a paire of 4430 and for me the sound of the 2235 is the better a never heared.

I never heared the 4435 ( 2 x 2234 ), but a lot of peoples told me that it was mutch better that the 4430 ( 1x 2235 ). i'is for this reason that I asked this question (2225 to 2234) It was just to test it!

- I also have a paire of 4645C with the 2245h (original, with the aquaplast) It's more low but less reactive as a 2235 H.

After that, I planed a do a cabinet with 2 x 2235 ( apolito style ) to keep the reactivity of the 2235 but the 2245 sound level.

What do you thing about that ?