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View Full Version : 2234H, 2235H, and Mass Controlling Rings



4313B
07-02-2003, 01:01 PM
From a post by PSS AUDIO in this thread:

http://www.audioheritage.org/vbulletin/showthread.php?s=&postid=2742#post2721

”What do you mean by removing the mass rings from the 2235?

Can you give me/us information about it?”

A 2235H has a 35 gram mass controlling ring centered at the apex of the cone at the top of the voice coil former as shown in the attached photo:

4313B
07-02-2003, 01:03 PM
A 2234H is a 2235H without the mass controlling ring:

The effects of this reduction in mass can be seen by inspecting the Thiele/Small Parameters of both transducers:

4313B
07-02-2003, 01:11 PM
Some people feel that by leaving the mass controlling ring out of the 2235H, and thereby creating a 2234H, they end up with a better sounding transducer. In reality, the 2235H and 2234H are both extremely viable transducers with different loading requirements. Depending on application, one would be preferred over the other. They are not technically interchangable. e.g. If you pull a 2235H out of a 4430 and put a 2234H in instead, the result will be less than ideal.

The only production JBL loudpseaker system that I know of which used the 2234H is the 4435 Studio Monitor. These links might be of interest:

http://www.jblpro.com/pages/components/2235h.htm

http://www.lansingheritage.org/html/jbl/specs/pro-speakers/1981-4430-35.htm

http://www.jblpro.com/pub/obsolete/443035.pdf

http://www.jblpro.com/pub/technote/tn_v3n01.pdf

4313B
07-02-2003, 01:20 PM
Here are graphs showing the 2234H and 2235H in free air. It is easy to see the results of a change in effective moving mass. Note that all other physical aspects of the 2235H transducer are held constant, only the mass controlling ring is removed to create a 2234H.

4313B
07-02-2003, 01:31 PM
The following graphs illustrate how one particular software package interprets the Thiele/Small parameters of the 2234H and 2235H to arrive at what it considers to be the proper vented enclosure volume and tuning for each transducer to provide maximally flat response:

4313B
07-02-2003, 01:40 PM
Finally -

The 2234H and 2235H in a 5.0 cubic foot enclosure tuned to 30 Hz as recommended here:

http://www.jblpro.com/pub/manuals/enclgde.pdf

Guido
07-02-2003, 02:54 PM
Wow!!!

One Question left:

From the graphs there is not soooo much difference.

Why could we not use the 2234 instead of a 2235?:confused: :confused:

4313B
07-02-2003, 03:52 PM
Oh that's just Great! :eek:
Make fun of the crappy resolution of my little graphs! :p

If you look at the Normalized Amplitude Response in the 5.0 cubic foot volume tuned to 30 Hz you will notice roughly a 20 Hz difference in the 3 dB downpoint between the 2234H and the 2235H, meaning the 2235H is enjoying a 20 Hz extension over the 2234H in this particular situation. At 6 dB down the difference shrinks to roughly 5 Hz. Another way to look at it is the 2234H will require almost twice the power input to reproduce low E on electric bass in order to match the output of the 2235H.

BTW, the response of the 2234H in this situation is more along the lines of the type of bass response popular in Japan.

Guido
07-02-2003, 04:07 PM
Youre right like always!

6dB difference is more than not soooo much.

And all becuse of the small massring.

Thank you

4313B
07-02-2003, 04:16 PM
Here's how Winspeakerz interprets the 2234H and 2235H T/S parameters in 5.0 cubic feet tuned to 30 Hz:

sa660
07-04-2003, 10:34 AM
Giskard.

I do not understand how you can see 6dB difference at 5hz and only 3dB difference a 20Hz

I was thinking of buying a pair of 2234 to place them in a pair of 4628B and use the E145 for other application. A long time project is the harsfield.

The volume is 5cu-ft and the efficiency is very close.

Can you comment on this?

4313B
07-04-2003, 11:56 AM
"I do not understand how you can see 6dB difference at 5hz and only 3dB difference a 20Hz"

Hello sa660,

Here's what I said:

"you will notice roughly a 20 Hz difference in the 3 dB downpoint between the 2234H and the 2235H"

Explained another way, the 3 dB downpoint of the 2234H occurs at ~ 56 Hz and the 3 dB downpoint of the 2235H occurs at ~ 36 Hz. That's a difference of 20 Hz giving the 2235H a 20 Hz extension into the VLF region.

"At 6 dB down the difference shrinks to roughly 5 Hz"

The 6 dB downpoint of the 2234H occurs at ~ 34 Hz while the 2235H has it's 6 dB downpoint at ~ 30 Hz. Therefore I was in error. The difference is 4 Hz instead of 5 Hz.