JBL 2231A - has anyone tried it? (in open-baffle)

[hasselbaink]

This driver is up for sale and I am considering buying a pair.
I intend to cross it at ca. 150-200hz to a full range Hemp Acoustics driver in an open-baffle configuration. I'm interested in opinions on this alnico bass unit.

Kris

[chops]

Originally posted by hasselbaink
This driver is up for sale and I am considering buying a pair.
I intend to cross it at ca. 150-200hz to a full range Hemp Acoustics driver in an open-baffle configuration. I'm interested in opinions on this alnico bass unit.

Kris

Don't know for sure. The only thing I found of any use is the tech sheet on it, no T/S parameters though. The 2231A does have a nice low Fs of 16Hz however, which would really be nice for OB use!

http://www.jblpro.com/pub/obsolete/2231a.pdf

[Robh3606]

Watch the x-max on it. It's a nice driver the pedesosor to the 2235. If it has been reconed recently it will have a 2235 kit which significantly increases x-max. The T/S are in the T/S document on the JBL Pro Site in the Technical Documents Section. The 136A is the same woofer

Rob

[chops]

Yes, the T/S parameters for both the 2231A and 136A are identical, except the SD for the 136A is 0.008 whereas the 2231A is 0.088.

The 2235 is a bit different than the other two drivers.

Either way, with a Qts of only 0.21-0.25, these would not be ideal for OB and would need a serious amount of EQ, Xmax and power to get any bass out of them.

[Robh3606]

"except the SD for the 136A is 0.008 whereas the 2231A is 0.088."


It's a typo with the large difference. SD is effective piston area. There are several mistakes in that table.

Rob

[hasselbaink]

Originally posted by Robh3606
Watch the x-max on it. It's a nice driver the pedesosor to the 2235. If it has been reconed recently it will have a 2235 kit which significantly increases x-max. The T/S are in the T/S document on the JBL Pro Site in the Technical Documents Section. The 136A is the same woofer

Rob

Wouldn't it be enough to just change the surround rather than the whole cone to achieve a higher x-max?

[Robh3606]

"Wouldn't it be enough to just change the surround rather than the whole cone to achieve a higher x-max?"

What about the spider?? You need to change all the suspension elements and maintain the same mechanical properties as the original or the T/S will change.

Rob

[hasselbaink]

Originally posted by Robh3606
"Wouldn't it be enough to just change the surround rather than the whole cone to achieve a higher x-max?"

What about the spider?? You need to change all the suspension elements and maintain the same mechanical properties as the original or the T/S will change.

Rob

Good point, they both have foam surround so changing it would not make a vast difference. A new spider would be overdoing it, I should think.

Kris

[Robh3606]

"A new spider would be overdoing it, I should think."

Well no not in this case. The spider change in the 2231-2235 was significant. The 2235 uses a progressive spider and it alowed for more travel. You can easilly see the diferences in the spider pleats between the 2 drivers. Also spider stiffness is a key element in determing the Fs of a driver.

Rob

[lhoward]

Originally posted by Robh3606
"A new spider would be overdoing it, I should think."

Well no not in this case. The spider change in the 2231-2235 was significant. The 2235 uses a progressive spider and it alowed for more travel. You can easilly see the diferences in the spider pleats between the 2 drivers. Also spider stiffness is a key element in determing the Fs of a driver.

Rob

One other consideration is that the xMax defines linear travel so that accurate frequency response is maintained. Two things the tables don't show is the height of the magnetic gap and the width of the voice coil windings. Although the suspension might be altered to allow the extra travel desired, in the end all that would be accomplished is increased levels of distortion when the ends of the voice coil travel out of the magnetic field on each half cycle, thus that portion of the magnetic field generated by the signal throught the voice coil would not add any inter-reaction with the magnetic field of the speaker magnet existing in the gap and non-linear signal response would ensue.

Personally IMHO, I don't consider this driver suitable for use in an OB system. Put it in a box with proper loading for the cone and maybe, depending on what you want for an F3.

L. Howard