Jbl 2245

[Ear4life]

Hello everyone!

I´m about to build a B460 next summer as a DIY project. And I have some technical questions about the 2245H that goes in. Does that speaker have the same massring under the dust cap like in the 2235?

Best regards
Martin

[ivica]

Hello everyone!

I´m about to build a B460 next summer as a DIY project. And I have some technical questions about the 2245H that goes in. Does that speaker have the same massring under the dust cap like in the 2235?

Best regards
Martin

Hi Ear4life,
As I can remember, from my C8R2245 JBL Kit, there is no mass-ring included in the recone kit,
from some forum posts about the mass ring from JBL bass drivers 2245 was not mentioned there.

Regards
Ivica

[Ear4life]

Hi Ivica

Thanks, I´m just surprised that the 2235 has a mms at 155 grams and on the 2245 it´s 185 grams. The mass ring weight is 50 grams. So in other words, without the mass the weight it´s 105 grams (15") and 185 grams for a 2245 cone (18"). So going from 15" to 18", is 80 grams of cone material, or is it included air load?

Regards
Martin

[4313B]

The LE14H, 2235H and 2245H use the same voice coil and magnetic assembly. The LE14H and 2245H use aquaplas for increasing the mass (resulting in a very stiff cone) while the 2235H continues the 124/2203/136/2231 tradition of using a mass ring. The mass ring weighs ~ 35 grams.

There was a second mass ring available weighing ~ 95 grams and it was only used on the 121. The 121 used the same coil, cone, surround and magnetic assembly as the 124/2203 but it required a stiffer spider to handle the additional mass.

[Ear4life]

Hello!

That makes sense! Thanks for sharing! I remembered something about the 35 grams, but was not sure. I looked at the differences between the 2234 and the 2235´s mms. I´m glad there is a reason why there isn´t a mass ring in my 2245 recone kit ;)

Regards
Martin

[4313B]

I remembered something about the 35 grams, but was not sure. I looked at the differences between the 2234 and the 2235´s mms.Yep. So does it mean that the mass ring is glued in using 15 grams of glue? :p

I did aquaplas several pairs of 2235 cones instead of using the mass ring. It took me several weeks and something like eight coats of the stuff to come up with the correct mass. The coats have to dry fully. The process can be hurried using a blow dryer but I just did the whole process in a room with a dehumidifier running.

[Ear4life]

Yep. So does it mean that the mass ring is glued in using 15 grams of glue? :p

I did aquaplas several pairs of 2235 cones instead of using the mass ring. It took me several weeks and something like eight coats of the stuff to come up with the correct mass. The coats have to dry fully. The process can be hurried using a blow dryer but I just did the whole process in a room with a dehumidifier running.

Interesting! :) Did you discover a change in the tonal characteristics? Of codes there is a change in the curve, but I´m thinking in the upper bass. Not "mass-ring vs aquaplas" but with and without aquaplas?

Regards
Martin

[4313B]

I only used them up to ~ 300 Hz so I didn't bother to measure the response change.

If you don't use aquaplas or a mass ring then it's just a 2234H with ~ 2 dB greater efficiency.

[4343]

Yep. So does it mean that the mass ring is glued in using 15 grams of glue? :p

I did aquaplas several pairs of 2235 cones instead of using the mass ring. It took me several weeks and something like eight coats of the stuff to come up with the correct mass. The coats have to dry fully. The process can be hurried using a blow dryer but I just did the whole process in a room with a dehumidifier running.

A few years back I bought a 2235H off the 'bay, it had been coated in black aquaplas. Needed a refoam and a new dome,so the price was reasonable. During the dome replacement, I noticed it had the mass ring in also. Seemed like a professional job...

Not having a coated dome make it look a little odd, but that's what grilles are for.

[4313B]

All mine were coated on the back of the cone and all of them were fresh recones. No mass rings.

[4343]

All mine were coated on the back of the cone and all of them were fresh recones. No mass rings.

It came from southern California, so it may have been a factory experiment, or not.

[ivica]

The LE14H, 2235H and 2245H use the same voice coil and magnetic assembly. The LE14H and 2245H use aquaplas for increasing the mass (resulting in a very stiff cone) while the 2235H continues the 124/2203/136/2231 tradition of using a mass ring. The mass ring weighs ~ 35 grams.

There was a second mass ring available weighing ~ 95 grams and it was only used on the 121. The 121 used the same coil, cone, surround and magnetic assembly as the 124/2203 but it required a stiffer spider to handle the additional mass.

Hi 4313B,

Unfortunately I am not so good informed about the JBL driver construction, but as I remembered:

-voice coil length for the 2235 is about 0.75-inch, while 2245 VC is about 0.96-inch, about the
-magnet assembly, I have find (somewhere) that TP thickness for 2235 is about 0.28-inch, while for the bigger "brother" 2245 is about 0.35-inch ,
-magnet assembly weight differs too, ( 8.5kg fro 2235, and 9.1kg for 2245)


All of the data are from published JBL

http://www.jblpro.com/pages/components/2245H.pdf
http://www.jblpro.com/pages/components/2235h.htm
http://www.lansingheritage.org/html/jbl/specs/pro-comp/2235.htm


2235.pdf add 2245.pdf, but may be in the reality JBL has decided to change all of the mentioned data.
Regards
Ivica

http://www.audioheritage.org/vbulletin/showthread.php?10651-2235H
http://www.audioheritage.org/vbulletin/showthread.php?10654-2245H

(http://www.audioheritage.org/vbulletin/showthread.php?10654-2245H)

[4313B]

Ok, thanks.

I'm a real stickler for correct data and we all appreciate the corrections.

My memory isn't what it used to be. G.T. and I were joking about faulty memories earlier this week. :D I guess it's time to start using IIRC. :rolleyes:

[Ear4life]

Yep. So does it mean that the mass ring is glued in using 15 grams of glue? :p

I did aquaplas several pairs of 2235 cones instead of using the mass ring. It took me several weeks and something like eight coats of the stuff to come up with the correct mass. The coats have to dry fully. The process can be hurried using a blow dryer but I just did the whole process in a room with a dehumidifier running.

What kind of aquaplas did you use? Something you sprayed or painted on? Got some ideas you know... ;)

Best
Martin

[Ear4life]

Hello!

Did JBL use aquaplas on all the 2245 drivers, I thinking the monitors as well? I see no reason why not, but I have one here that tells me that not all of them were coated with aquaplas... Is he teaching me bad stuff?

Regards
Martin

[grumpy]

I've seen back-of-cone white and black/gray aquaplas on 2245 drivers with JBL cones.
I don't think it would really be a 2245 without it (different T/S parameters).