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View Full Version : Stuffing a 2312 into a L200



subwoof
03-12-2008, 06:55 PM
In a nutshell, The 2312 / 2420 ( or H92 / LE85 ) will not fit into the venerable L200 cabinet so an access must be made on the rear panel to allow the driver to stick through. The 2420 / LE185 and the later 2425/26/27 are all 5.75" diameter

SINCE this an angled cabinet, the hole size, centering and angle precludes any simple "jigsaw" approach unless a significant amount of material is removed. The goal here was to make it "doable" with basic power tools and supplies available from the local home depot or next-door neighbor who is in general construction.

If carefully done, the gap around the driver is an even 1/8 inch on the inside AND outside...:) I did this in less than 30 minutes on the living room floor so no special "shop time" is needed.

Tools required:

1/2" chuck GOOD electric drill ( I used a Milwaukee hole shooter )
6" holesaw ( standard ceiling light fixture diameter )
6" or longer 1/4 diameter drill bit for the hole saw pilot.

In order to find that magical location for the pilot hole, I mounted a 2312 horn into the cabinet, installed an 18" long 1/4 diameter bit into the drill and used a plastic bottlecap to center it deep in the horn. Using a straight edge on the horn face between 2 mounting holes I drilled through the back panel.

This worked out well and the exact measurement for the pilot hole ( 11 7/8" ) is shown in one picture ( and is of course centered ).

NOTE that the hole goes into the cabinet at an UPWARD ANGLE that is the same as the cabinet sides when viewed from the back.

The Hole saw was then used ( note the angle that it cuts into the cabinet ) to make the hole. This is where the extra long pilot bit is REQUIRED!

After vacuuming out the debris and trimming the insulation, the horn was mounted and then the driver. Unfortunately the horn mounting flange is *just* a little larger than 6 inches otherwise the whole assembly could be mounted from the rear.

Now as you can see by the measurement, the top edge of the driver protrudes 1 3/8" so a cap needs to be placed over the whole driver OR a rubber / neoprene thin hose could be jammed into the 1/8 gap around the driver. Do not use silicone or the heritage members will hunt you down and noodle whip.

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toddalin
03-13-2008, 10:02 AM
Nice idea on the bottle cap! ;)

My idea was to slip a piece of stiff paper around the driver on the short horn, slide it to the back wall, trace it, then measure the center. I think I like your way better. I would just put a PVC cap over the driver back. :)

hjames
03-13-2008, 10:05 AM
VERY cool!! Not sure when I'm going to bore mine out tho ... but the technique is quite neat!

But ... what kind of Ale comes with a bottle cap?? :applaud:

SMKSoundPro
03-13-2008, 12:31 PM
A 2312 TEASE!

I am ALL over this!!!

I'll take 2 2312's, please!

If only I could find some.

scotty.

toddalin
03-13-2008, 12:55 PM
A 2312 TEASE!

I am ALL over this!!!

I'll take 2 2312's, please!

If only I could find some.

scotty.


Still an hour to go:

http://cgi.ebay.com/PAIR-JBL-2312-HORNS-ORIGINAL-RARE-FOR-4333-L-300_W0QQitemZ250222054140QQihZ015QQcategoryZ73372Q QssPageNameZWDVWQQrdZ1QQcmdZViewItem

subwoof
03-13-2008, 02:50 PM
When power tools are concerned, Mountain Dew is the strongest. Besides, the metal ones scratch...

LATER it's the double india pale ale ( 10% )

Anyways, here is the back chamber initial construction. 8 X 8 X 1/4 oak plywood and 1 5/8 X 3/4 pine make an effective enclosure. Later we sand, paint, install T-nuts on cab and install.

A 6" PVC cap wouldn't cover the driver because it would have to be angle cut and would become not deep enough.

And then there isn't enough "meat" around the driver for the cap to attach. Remember this IS 30 year old particleboard....

The pine and gasket material was less than 5 bucks at home depot.

It's also hard to work when the KITTEN HAS TO INSPECT EVERYTHING.

:o)

toddalin
03-13-2008, 04:04 PM
When power tools are concerned, Mountain Dew is the strongest. Besides, the metal ones scratch...

LATER it's the double india pale ale ( 10% )

Anyways, here is the back chamber initial construction. 8 X 8 X 1/4 oak plywood and 1 5/8 X 3/4 pine make an effective enclosure. Later we sand, paint, install T-nuts on cab and install.

A 6" PVC cap wouldn't cover the driver because it would have to be angle cut and would become not deep enough.

And then there isn't enough "meat" around the driver for the cap to attach. Remember this IS 30 year old particleboard....

The pine and gasket material was less than 5 bucks at home depot.

It's also hard to work when the KITTEN HAS TO INSPECT EVERYTHING.

:o)

I never said a 6" cap. ;) (They also have 8" which are both bigger and deeper.)

That looks nice too and far more "stock."

I could do it with the 6" cap because I use an LE175 and the thinner diameter would allow for the space of the driver tilt.

I hope that you don't let the cat inspect the woofers or grills!

subwoof
03-13-2008, 05:23 PM
That kitten found it's way into a port within 1 MINUTE of the cabinets arriving into the living room. Lost one life right there and then.

I thought you said 6" - I know I saw it somewhere on the many 200 / 300 threads...maybe the reading glasses fooled me.

If you need any of the larger drivers, I have a LOT of 1" drivers to be sorted ( here are *just* the ferrites ) and all of the 16 ohm Ti's will be aquaplassed so I don't have to worry about expensive aluminum dia's when the teenagers stomp on the systems I have put in the den.

I think there are about 6 2420/2470 drivers here that are not part of any dissasembled monitors

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toddalin
03-13-2008, 05:42 PM
That kitten found it's way into a port within 1 MINUTE of the cabinets arriving into the living room. Lost one life right there and then.

I thought you said 6" - I know I saw it somewhere on the many 200 / 300 threads...maybe the reading glasses fooled me.

If you need any of the larger drivers, I have a LOT of 1" drivers to be sorted ( here are *just* the ferrites ) and all of the 16 ohm Ti's will be aquaplassed so I don't have to worry about expensive aluminum dia's when the teenagers stomp on the systems I have put in the den.

I think there are about 6 2420/2470 drivers here that are not part of any dissasembled monitors

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Thanks for the offer.

BION, I like the LE175s and have tried both the LE85 and 2425s and still prefer the LE175 on the HL91 when crossed over to the tweeter.

Zilch even ran the curves and the LE175s were smoother with as much or more low end extension than the LE85s. They just don't go as high. But so what..., that's what the tweeter is for.

Now if you have any extra H-92 or 2312s..., that's quite different. ;)

My four surround speakers use the 2425s in a two-way system.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/index_011.jpg

subwoof
03-13-2008, 06:19 PM
I made 4 stage monitors ( hung ) that used the 2425 / 2342 and the 10" GTI1000 woof with great results. The damn things were only 12" wide and biamped with a CT810 on each. Lotsa bang for a small footprint.

I'd like to find some 10" Nd woofs and duplicate that here with the newer PT 1.5 horns and 2435HPL drivers but too many projects and too little capital anymore..:o(

BTW, some time ago I took apart the 175 and 2420's I had in the shop with weak magnets ( that I now use to demonstrate driver workings to sound guys ) and determined that the magnets themselves were in fact identical. Just the larger iron circuit made for higher gauss and then HF response.

Back when I had alnico's in PA systems the 2461 was my driver of choice for just about everything. They never died, behaved well on stage and were the lightest I could find for compact cabinets.

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subwoof
03-14-2008, 03:08 PM
ALMOST ready for the final assembly. 136A's at the reconing station, 077's to be picked up and dia's to be aquaplassed...

Need more beer though.

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subwoof
04-06-2008, 07:33 PM
Finished the driver "doghouse" which heather calls the "hump"...cat not included.

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toddalin
09-03-2008, 11:42 AM
I'm getting ready to do this now that I've acquired the longer horns.

A couple questions:

I assume that 11-7/8" is where the horn centers on the back particle board? I assume that this was measured down from the back top of the cabinet and that the hole is centered side-to-side?

Wasn't the hole saw unnecessary? Except for the stability of the driver actually sitting on the wooden "cradle," couldn't you just have used a saber saw to cut an 8" square hole that would be totally within the rear extension you made and wouldn't this allow for rear mounting of the horn?

Your back cover looks to be kind of thin. Have you noted any rattles/vibrations/buzzes from this panel when played at high levels? (I was going to use 2"x2" to make the frame and 3/4" particle board for the back plate but have 1/2" particle in stock.)

Wouldn't a larger cutout/back plate have added cabinet volume extending the low frequency response?

Thanks :)

toddalin
09-04-2008, 09:01 AM
Yesterday I constructed the two "dog house bumps" for the cabinets. I used 2"x2" (actually 1-1/2" x 1-1/2") to make the frames and covered them with 5/8" high density pressed board. I still need to sand these and paint them primer grey to match the cabinet backs.

Subwoofs photos clearly show that this is enough depth to house the driver. The internal square hole is 5-7/8" so if I ever find a pair of LE85s that sound as nice as my LE175s, I can simply change then out. The dog houses will be held to the cabinets using 1/4" machine screws and T-nuts inside the cabinet.

Also, the cabinets will receive a 6" square hole in the rear so the horns can be installed though this hole if desired.

Doc Mark
09-04-2008, 09:06 AM
Hello, Friends,

I was wondering, what is the internal volume of the L200's? Are they that much smaller than the L300's, that the horn/driver won't fit inside, as it does in the L300's? This is an interesting thread, and it's made me wonder about the actual internal differences between the L200 and the L300. Thanks, very much, and God Bless!

Every Good Wish,
Doc

pos
09-04-2008, 09:27 AM
I measured mine at 140L.
I think the L300 is also 140L, albeit a little deeper :
http://lansingheritage.org/images/jbl/specs/home-speakers/1975-l300/page3.jpg

toddalin
09-04-2008, 05:32 PM
Hello, Friends,

I was wondering, what is the internal volume of the L200's? Are they that much smaller than the L300's, that the horn/driver won't fit inside, as it does in the L300's? This is an interesting thread, and it's made me wonder about the actual internal differences between the L200 and the L300. Thanks, very much, and God Bless!

Every Good Wish,
Doc

The L200 baffleboard is about 22" x 28" and I assume that the L300 is similar. Whereas the L200 recesses the components such that they all sit behind the grill (including the slant plate, the L300 adds about 3" of depth at the baffleboard requiring that the grill have a stand-off frame. You could take an L200 and move the baffleboard out 3" (has been done by someone on this forum), but the dog house bump is far simpler and for me at least, more sturdy.

22" x 28" x 3" =~1,848 cubic inches =~1.07 cubic feet larger. Of course the extra horn length and tweeter take up some of this additional volume, so figure ~1 cu ft larger.

Of course, this assumes that the L200 and L300 are the same height and width. L200 is ~5 cu ft so L300 should be ~6 cu ft.

subwoof
09-05-2008, 08:30 PM
On a jobsite but need to reply. You CANNOT use a simple jigsaw to cut the hole if you want an even 1/8 clearance because the hole is ANGLED...you need to think in three dimensions here.

The sides of a jigsaw cut are right angled to the surface it rides on. The hole I added is required to be angled at every part of the hole.

The extra cabinet does not rattle. It does not add ANY additional volume to the cabinet since the 1/8 gap is sealed. I do not use particle board for any project for any reason. The plywood is veneer core hardwood.

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toddalin
09-05-2008, 10:44 PM
On a jobsite but need to reply. You CANNOT use a simple jigsaw to cut the hole if you want an even 1/8 clearance because the hole is ANGLED...you need to think in three dimensions here.

The sides of a jigsaw cut are right angled to the surface it rides on. The hole I added is required to be angled at every part of the hole.

The extra cabinet does not rattle. It does not add ANY additional volume to the cabinet since the 1/8 gap is sealed. I do not use particle board for any project for any reason. The plywood is veneer core hardwood.

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If I make the hole in the cabinet 6-1/4" diameter square, there would be plenty of clearance such that the angle becomes moot. (Its moot anyway due to the extra clearance of the LE175s, but I always look to the future.) The frame has a 5-7/8" ID, but an 8-7/8" OD so would easily cover a 6-1/4" hole.

Plus, because the hole is bigger than the horn flange, I can install it from the rear. (I could do this with even a smaller square hole because I could angle it in on the diagonol.)

I really don't see a need to seal the gap as I used 1-1/2" x 1-1/2" to make the frame and a 5/8" thick high density fiberboard back plate and this chamber will be sealed to the cabinet through close tolarance/gasket. The added volume is insignificant. The LE175 isn't so heavy such that it needs a cradle, and if I replaced it with an LE85 and if it did, its a simple matter of putting a shim/shelf on the back plate. And, this saves me buying a big hole saw that I would only use twice.

Right?

subwoof
09-06-2008, 10:02 PM
In the immortal words of buckwheat: Otay...

I was looking for minimal impact and wanted to keep the original size drivers.

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Robh3606
09-07-2008, 07:57 AM
In the immortal words of buckwheat: Otay...


You forgot Spanky

Rob:)