JBL 4311's = system complete... for now.

Brainwashed

Brainwashed

Active Member
Well, I bought a pair of 4311's. I got them from the 'bay, mostly because I wanted them... he he. And now I finally have a bare system of a reciever, TT, and speakers :banana: ... sorta.

Ok, so I went and picked up the JBL's, and brought them home, and hooked them up to my SX-980. They sounded good together at low levels, :music: and so, I turned the balance all the way to the left/right, and listened to each individual speaker (woofer/mids/tweeters) and had to fiddle with the Presence/Brilliance knobs (which are loose) to get them to work. No big deal, I'll just take the crossover out and clean the the pots right? Um. No. I failed my attempt.

So, here's my question... how in the world is that crossover plate attached to the cabinet itself? I took the woofer out, and can stick my head in and see that it 'should' (in theory of course) come out... but can only see one screw with a round washer type thingummy on it, which is going to be a pain to get to, yet alone a hidden second one.

I'll probably spend the next couple of hours, uploading some pics so you can see what I'm actually talking about.

Oh, and thanks for reading!

EDIT:: To make it simple for people who search for 4311's in the future, I'll just put all the parts links in this first thread. The blue text is a clickable link. All parts are from www.partsexpress.com except the clarity caps. Those are available at www.e-speakers.com

This is what the FRONT side of your crossover should look like:
3112ju3.jpg


This is what the BACK side of your crossover should look like:
3112backgz4.jpg


REPLACEMENT L-PADS
4 x L-PAD 15W MONO 3/8" SHAFT Part Number 260-248

CAPS FOR REBUILDING A PAIR OF JBL 3112 NETWORKS YEILDING "IMPROVED ORIGINAL" SOUND
4 x AUDIOCAP PPT THETA .010µF-600V FILM/FOIL CAPACITOR Part Number 027-700
2 x DAYTON PMPC-3.0 3.0µF-250V PRECISION AUDIO CAPACITOR Part Number 027-220
4 x DAYTON PMPC-4.0 4.0µF-250V PRECISION AUDIO CAPACITOR Part Number 027-226

CAPS FOR REBUILDING A PAIR OF JBL 3112 NETWORKS YIELDING A "BRIGHT" SOUND
2 x SOLEN 3.0uF-400VDC POLYPROPYLENE CAPACITOR Part Number 027-542
2 x SOLEN 8.2uF-400VDC POLYPROPYLENE CAPACITOR Part Number 027-564

CAPS FOR REBUILDING A PAIR OF JBL 3112 NETWORKS YEILDING A "MELLOW" SOUND
ClarityCap PX range
You'll want to select the Value from the dropdown menu, and type in the quantity:
Value=1.5uf Quantity:4
Value=3.3uf Quantity:2
Value=4.7uf Quantity:2

SPEAKER CAULKING
Also, in removing the woofer, I noticed what appeared to be a caulk of some type. In trying to keep everything as it was, I assumed that 30 year old caulk isn't exactly up to snuff, and found some more. I ordered 4, but at 36" lengths, you could probably get away with less, but I'd rather have extra than not enough, so for now it's:
4 x 36" SPEAKER SEALING CAULK Part Number 269-300

FOAM TWEETER DISCS
Available directly from JBL
Number is 818-894-8850
Hours are from 8-5 PST Mon-Fri, and best hours to call are from 8-12 and 2-5 PST.

LE25 :: #50402 - $1.97 ea (used in 4311 and older L-100)
LE25-2 :: #53363 - $2.04 ea (used in L-100A and other models)

JBL SCHEMATICS FOR ALL VARIATIONS OF '3112 CROSSOVER NETWORK' FOUND IN 4311's
3112 :: <<CLICKITY>>
3112-A,B :: <<CLICKITY>>
3112-C :: <<CLICKITY>>
3112-D :: <<CLICKITY>>
 
Sure will.

I just got done shoving my camera into the cabinet and snapping some photos. I'll upload a couple of the better ones so people can see what I'm talking about.

 
Are the attenuator/pots loose from their main mounts, or are the actual internal pieces dirty or loose? You can pull the pots out by pulling the knobs off and use a pair of needle-nose pliers or a deep socket (preferred) to tighten up the shaft retaining nuts, or take those same nuts off to remove them all together to clean or replace them. If that doesn't do the trick, you may have to very carefully heat the thin aluminum foilcal/badge that reads "4311x Control Room Monitor" with a blowdryer, while gently lifting it off the enclosure with a 1" "full elastic" blade putty knife. That will expose the retaining screws that you see coming in through the front and from behind the aforementioned foilcal/badge. Go to www.audioheritage.org for the replacement numbers, or contact member Zilch about the proper replacement attenuator pots. To replace the foilcal/badge, spread a small amount of contact cement as per directions, and reattach them after you R&R the pots. Sometimes you can just re-heat them with the blowdryer and press them back down. Either way it takes a great amount of patience and care to prevent damage to them.

BTW, you have what I consider to be the best of all the 4311 models. Your 4311's have the wonderful LE5-2 Alnico mid. Nice find, I hope you get them up to spec.
 
HOLY COW!

Thanks for the info! I was hoping they were the good mids, and not just a set with pushed in dust caps! ha ha

I'll get to work and take snap some pictures while I do it so other's can see what's in them.

THANKS AGAIN!
 
No sweat. You won't be able to see the back of the LE5-2's because they reside in their own little cardboard tube sub-enclosure. If they are the original mid's, that's what they are for sure. I think Zilch also recommends plugging up the port with a 3" plumbers temporary expandable plug that can be found at most hardware stores. I understand that it will tighten up the bass response.
 
Ok, so I found dad's ancient heat gun, figured it would go a bit quicker than with a blow drier!

I pulled the mid to disconnect it from the x/o network and they are indeed LE5-2's.

Also, one of the pots has a real gravelly operation, like little bits of stuff are bouncing/tumbling around in it, and the other is smooth. I think I'm going to have to replace at least one, and depending on price, I may just order 4 and be done with it.

I don't have any way to test the caps, is there some way I can check if they are indeed doing what they are supposed to be doing while I've got the network out of the cabinet?

I'm uploading some pics again.

Oh, and it is safe to deoxit the attenuator pots correct?


Picture of the procedure I used.


Picture(s) of the results


And some pictures of the networks themselves.

 
Way to go dude! I am cautious when recommending that blowdryer deal becuase it is so easy to damage the foilcals. A heat gun is a major piece of hardware, and it takes a lot more than the average tinkerer knows to pull that off, literally and figuratively. Damn, I should have told you to try Deoxit on 'em, my bad. I'm glad you already knew about it. Zilch would know exactly what to do wrt the crossovers. The guy is probably #1 when it comes to JBL crossover work, modifications and upgrades. Once you talk to him, you will understand what I mean.
 
Brainwashed: I'm watching this thread like a hawk. Gonzo and Zilch are aiding me in getting the "right sound" from my 4311's.

I'm still in need of the 3" plumber test plugs. HD and Lowes didn't have them. Nor did the local plumbing supply stores. I just returned from Spring Break and tomorrow will put them on order at a local hardware store. Zilch recommended I get them....will make them more of an 'Acoustic Suspension' system than a 'Bass Reflex'. (At least for testing purposes).

Nice job, so far. Great pix, too! Looking forward to your progress.

Regards,
Rick
 
Well, I tried Deoxit, on the atunneator pots... let them dry for a couple of hours and reassembled. Pfft now they don't pop so much when you turn them, they just cut completely in and out. Ha ha.

Ok, so time to take them back apart and order pieces.

I'll post an update with pics part numbers and links when I get the parts in.

Oh, and thanks to those who gave advice or support!
 
That's not a problem at all, but I didn't really do much except what 'zilch' and 'gonzomeep' reccommended.

Perhaps they deserve a thanks too. :thmbsp:
 
Brainwashed: I had a little problem with the part Nos for Parts Express: Items 1 and 3 have the same part #. Item 2 (027-220) results in a dead end search.
I think I should recap my 4311's, too.

Rick
 
My apologies, my older sister is in the hospital, and as I was posting that message, my little sister came in and told me that mom needed to take her into the E.R. for hives or something, and could I watch the 2-year-old nephew. He was asleep, but he was at the older sister's house, so I had to leave and go over there, and didn't get a chance to proof my post.

Anyways, I have a new nephew a month before schedule, and my lil' sis doesn't have any hives any more. AND, most importantly to you, I have the parts-express pages in my history folder yet!

CAPS FOR REBUILDING A PAIR OF JBL 3112 NETWORKS YEILDING "IMPROVED ORIGINAL" SOUND
4 x AUDIOCAP PPT THETA .010µF-600V FILM/FOIL CAPACITOR Part Number 027-700
2 x DAYTON PMPC-3.0 3.0µF-250V PRECISION AUDIO CAPACITOR Part Number 027-220
4 x DAYTON PMPC-4.0 4.0µF-250V PRECISION AUDIO CAPACITOR Part Number 027-226

Also, in removing the woofer, I noticed what appeared to be a caulk of some type. In trying to keep everything as it was, I assumed that 30 year old caulk isn't exactly up to snuff, and found some more. I ordered 4, but at 36" lengths, you could probably get away with less, but I'd rather have extra than not enough, so for now it's:

4 x 36" SPEAKER SEALING CAULK Part Number 269-300

Hope those links work for you, I used IE7 to do the initial search, and posted them in Firefox, and then used firefox to confirm that they point to the places I intended them to, and all was well. Let me know if something doesn't work!

I also sent an e-mail to JBL to see if they have the L-pads or if they know where I can find a suitable replacement, I'll either post or edit again when responded to by them.
 
Thanks, Brain. I hope I can copy all those numbers without a mistake!

You gotta get that family of yours under control!

Rick
 
Yep, the non-standard colored text is a hyperlink to the product page.

If I get really frisky, I may go back and edit in all the variations that zilch recommended for the different sound qualities.

EDIT: I got frisky... sorta

CAPS FOR REBUILDING A PAIR OF JBL 3112 NETWORKS YIELDING A "BRIGHT" SOUND
2 x SOLEN 3.0uF-400VDC POLYPROPYLENE CAPACITOR Part Number 027-542
2 x SOLEN 8.2uF-400VDC POLYPROPYLENE CAPACITOR Part Number 027-564

CAPS FOR REBUILDING A PAIR OF JBL 3112 NETWORKS YEILDING A "MELLOW" SOUND
ClarityCap PX range
You'll want to select the Value from the dropdown menu, and type in the quantity:
Value=1.5uf Quantity:4
Value=3.3uf Quantity:2
Value=4.7uf Quantity:2
 
Again, thanks brain and gonzo. I've already check out parts express. I found the correct items using brain's descriptions. This got me the correct part numbers. PE looks like a valuable site, too!

Maybe someone more qualified should do the recapping for me is what I'm thinking...

Rick
 
Absolutely not Rick, you really need to take a leap of faith here and get your feet wet. Trust me, the 4311 crossover is very simple and just the right project for a budding experimenter. I actually believe that the woofer runs full range, without a single thing in it's path. You have the original placement to serve as a guide. Remove and replace. Not a problem at all. And, if you do one speaker at a time, and get lost somehow, you can always refer to the stock one to refresh your memory. I say that this is where you'll look back and remember where the "good stuff" began.

I see that you are willing to try top improve your system. Let Zilch guide you. Get those plugs and get those caps, and Git-R-Done! I'll keep an eye on this thread and your other one. It's gonna be fun!
 
You must log in or register to reply here.

Similar threads

doji
JBL 4312A speaker crossover recap
Replies
9
Views
2K
toxcrusadr
toxcrusadr
oldsmobuick
Crossover recap questions. Ohm Walsh 2
Replies
11
Views
1K
oldsmobuick
oldsmobuick
xoaphexox
JBL 4311 Crossover
Replies
2
Views
6K
xoaphexox
xoaphexox
Lastplace
Just passed on JBL L-100's and 4311's
2 3
Replies
41
Views
3K
Lastplace
Lastplace
N
aDs L-810 vs. JBL 4311
Replies
13
Views
4K
gonzomeep
gonzomeep
Back
Top Bottom