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jbl
07-25-2008, 07:30 AM
Picked up a pair of 2235H yesterday.:applaud:JBL Pro had a few pair of their latest production run. I plan to use the 2235H as subs with my present system at a later date. For now, I'll replace the 2225H with the 2235H in the 4507 cabinets.
A special thank you goes out to both Bo and Zilch for their efforts.
I hope to have time this weekend to make the change.
The 2235H is supplied with a thin rubber gasket. I don't think I'll use it. I would think that it will 'melt' over time and glue the 2235 to the baffle making it difficult to remove the woofer in the future. I'll stay with cork.
Anyone have experience with the rubber gasket?

Ron

grumpy
07-25-2008, 07:35 AM
little spaghetti gasket? Other than not always going where you think they went, I've not
had a problem with them regarding getting a good seal (when installed right), or with
removing a driver.

I think you're going to have some fun :)

jbl
07-25-2008, 07:52 AM
Hi Grumpy,
Yes, the spaghetti gaskets. I didn't get the chance to fool with it yet.
How do you suggest placing them on the 2235H for the best seal?

Ron

grumpy
07-25-2008, 08:13 AM
With 4507's the hole should be the right size (can be a problem if oversize).

The gasket fits under the 2235 lip... inside the bolt-hole pattern.
Just make sure none of it slips down the hole while you're mounting the driver.

jbl
07-25-2008, 08:39 AM
With 4507's the hole should be the right size (can be a problem if oversize).

The gasket fits under the 2235 lip... inside the bolt-hole pattern.
Just make sure none of it slips down the hole while you're mounting the driver.

The woofer cutout was never a problem with the 2225H. The 2235H is the same basket. I don't think it will be an issue.

The cork gasket is the peel 'n stick type. Much easier than the rubber gasket.
The rubber gasket offers a cleaner look that I like. I'll try that first.

Ron

grumpy
07-25-2008, 11:10 AM
cool. what I meant about the hole size was relevant to the o-ring type gasket, but
sounds like you're good to go. :)

jbl
07-25-2008, 11:17 AM
Thanks Grumpy.
I'll try the rubber gasket. I like that it allows the woofer to be flush with the baffle. I put some wire mesh behind the grille fabric. The rubber gasket may eliminate the slight bluge of the grille that the cork causes.

Ron

grumpy
07-25-2008, 12:57 PM
Hmm... :hmm: you might want to somehow shim out your grille... don't want the 2235 surround
whacking wire mesh during extreme sub duty.

jbl
07-25-2008, 01:21 PM
Good thinking Grumpy.:applaud:
I may have mispoken. It's been some time since I last looked.
I doubt I would have let anything be in direct contact with the woofer. In fact, I know I wouldn't.

The cork gasket when compressed is only 1/16" to 1/8" deep.
Here's what I did;
Tacked the mesh to the outside of the grille.
The fabric is stretched over the front of the grille and glued to the grille frame so there's no chance of the woofer cone making contact.
The slight bulge is the mesh itself.
Not an issue.

Ron

SMKSoundPro
07-25-2008, 01:25 PM
Are the 2225's available?

Scott.

jbl
07-25-2008, 01:38 PM
Are the 2225's available?

Scott.
No. Sorry.

Ron

Russellc
07-27-2008, 04:18 PM
Please keep us updated on this project. I am particularly interested in this as I am in the same boat. I have JBL 4647, which is a box identical to yours loaded with 2225H. I have a spare pair of 2225H which I am ( if I ever get around to it! get reconed to 2235H. I am using them in a two way system
with a JBL wave guide and a selenium driver as outlined in a Zilch project on another site.

I also have interest in cloning 4430, so the need for this blasted recone is pressing! So little time!

Russellc

jbl
07-28-2008, 08:49 AM
Replaced the 2225H with the 2235H in the 4507 cabinet over the weekend. First, a little history of my listening position. The left speaker is located in a corner having a solid wall behind the cabinet and a sliding door to its left. There is a great null in this location. The right side speaker is located next to two solid walls enhancing bass respones.
I removed the left side 2225H and replaced it with the new 2235H, closed off 2 of the 4 ports and played some unfimilar CDs so that I would not know what sounds to listen for, only the female voice and some upper bass as well as much VLF as the new 2235H would offer at the moment. My thinking here was that the new 2235H would require some break in period. I wanted to check the difference between the two drivers in the important cross over region. The 2235H would be lacking enough low end out of the box to not 'color' the sound difference between the two different woofers.
This method worked well. There was no noticable difference in the upper bass up to the crossover point. Both drivers had the same tonal quality. A tribute to JBL tolerance standards. These woofers have 23 years difference between them.

Replaced the second 2235H. Played some music. WOW!!! What a difference!! With the 2225H I had excellent high frequency, mid range and bass. With the 2235H I now have the same HF, midrange, bass ... but I now have VLF bass!!:applaud:
With the 2225H I was missing the last note of a bass guitar. The sound would drop out at that point.
After listening for 2 days, the 2235H is now producing excellent VLF bass. It will only get better as the surround works in.
Here are some pictures of the 2235H in the 4507 with 2 ports closed off. I used the tops of some spray cans, rolled some air conditioner filter foam to get an air tight fit. Worked great.
The first pic is of the 2225H. The next 2 are of the 2235H with the 2 ports closed . The one on the right is the same as the left. The flash is what caused the distorted image in the second picture.

The picture of the spray can top wraped in foam didn't down load properly. I'll take some shots this evening and post tomorrow. Sorry.

P.S. Forgot to mention that the 3110A crossover has a three position switch for both the mid and HF response. I didn't have to touch these controls to compensate for the 4 dB fifference between the 2225 & 2235. Another plus.:applaud:

Ron

doodlebug
07-28-2008, 10:03 AM
Excellent job, jbl. I've been following a similar path myself with the 4508s I have, which also have 2225s in them.

I've wondered if a set of 2235s would work if I closed off the 2nd 15" hole and adjusted the port structure much as you've done.

Sound like you're really enjoying you 'new' speakers.:applaud:

Cheers,

David

jbl
07-28-2008, 10:12 AM
Hi David,
Enjoying them very much. Too bad going to work got in the way.:D

If you close off one of the 15" cutouts and seal it up well, you can mount one 2235H in your cabinet. Retune the cabinet and you're set.

It's interesting how the bass extends as the drivers break in.
As far as break in is concerned, I listened as I usually do to various CDs. By Sunday evening I was hearing bass I never heard on familar CDs.:applaud:
The 2225H is a great woofer as well when 'used as intended.' It was intended for movie as well as PA.

I intend to keep my 2225H as they are for future use.

Ron

sergelisses
07-28-2008, 10:37 AM
In the JBL PROFESSIONAL ENCLOSURE GUIDE :
For single 2234,2235,2215/LE15 used as hifi low-end or subwoofer :
The cabinet caracteristics are :

Volume 5.0
Height 25.3
Width 20.7
Depth 17,9

2 Events 4.0 lenght 11.0

Tuned Frequency=30hz


Is it possible to have the size of your 4507 cabinet and the events lenght?


Best regards

Serge

Zilch
07-28-2008, 11:39 AM
I've measured and documented 4507 tuning several times in these forums.

Here's my recollection, but y'all can look it up to be sure:

4 ports open = 40 Hz, the stock tuning for 2225H, E140, and similar.

One port closed = 34 Hz, stock 4430 tuning.

Two ports closed = 28 Hz, extended bass or sub duty, which is how I run them mostly.... :yes:

jbl
07-28-2008, 12:26 PM
Hey Zilch,
I'm running it with 2 ports covered. Smoothest response. With one port covered, the dropoff is steep from what I see on WinIsd.

Ron

Russellc
07-28-2008, 02:44 PM
For a bit more finished port plug, use the infamous "Zilch plugs". these are available at your local building/plumbing supply. You need 3" test plugs. wont sound any better but cool never the less!
Your report on the effectiveness of the 2235H is just what I wanted to hear. I must get my spare 2225Hs reconed. Now to dig up some spare coinage!
Russellc

jbl
07-29-2008, 07:26 AM
Here's some pictures of the port plugs. The foam prevents damaging the port tubes. The tubes support the plug. Removing the tubes would be a mistake.
The port tubes supply the proper compression of the foam around the cap. The plastic cap is soft enough for the foam to press against it forming an air tight fit.

Ron

Russellc
07-29-2008, 10:58 AM
If you've never seen "Zilch plugs" they are sort of a soft rubber tube which has accordian folds in it, when the screw is turned, they expand to fill the hole. Loosening the screw allows easy removal with no damage done. I would supply a pic, but I'm at the office right now. Your method looks just fine as well.

Russellc