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

Hello,I was given a pair of JBL 4311B from a close friend and I am in the process of restoring them,they need work specialy on the outside wood!
this forum helped allot.
I just ordered Jantzen caps like EF and will try to upgrade the crossover ,i was also suggested to get read of the fiber glass damping and used
bitumen pads and 40mm Egg-case foam.
What i wanted to ask if any one has done it ,is you first cover all the internal walls (except from baffle ) and the on top of them you glue the foam ?
What about the bass reflex tube this was also covered in fiber glass with a tape holding it.

Cheers to all
 
Hello. Great thread, and hope to dive deeper into it some day. But for now, I noticed it did not touch on the topic i'm about to drop. If there is a better thread for this, please direct me there. Driver polarity.



I recently found a pair of 4311B's at Value Village for $19.99. That's right, and I actually had to think about it for a second. They are in great shape, other than some replacement tweeters (had a pair of Audax 24010 tastefully installed), and the woofers are somewhat brownish, but at least they don't smell like smoke.

I managed to find a pair of LE25-4 tweeters on CanuckAudioMart for $115 CDN shipped. I thought that would be the better option for a replica pair of LE25-2's that would cost me at least $250.

First thing I noticed was that one of the woofers (2213H) was rotated 90 degrees, assuming to get a more symmetrical look, so I popped that one open first. To my surprise, the GREEN/BLACK wire was connected to the RED terminal. I found a link somewhere to the technical manual, and it showed the GREEN/BLACK goes to the '-' terminal on the woofer, and I would assume that the Black terminal is '-'. So I thought they must have hooked it up wrong when they rotated the woofer.

I found and started reading a thread on here saying the many jbl's will have a driver out of phase. That thread had a ridiculous amount of info, but no real answers about how exactly different models should be hooked up. There was actually little talk about the 4311B for that matter also.

So I thought to myself, well maybe that was actually hooked up correctly, and the black terminal is actually '+' (or something like that).

BUT then I popped out the tweeter on the other one, and I saw that the GREEN/BLACK was hooked up to the BLACK terminal !!! So at this point, I'm a little confused.



Does anyone have photos of their hookups on a re-build, or can any nice 4311B owner crack one open to look? There doesn't seem to be any schematic available regarding this.

Looking forward to sorting this out. Thanks.
 
I would trust the JBL manual on the proper wiring for the 4311b. It sounds like the previous owners already messed around in the speakers, considering that there was a rotated woofer and a replacement tweeter. It doesn't take much effort to change the wiring on those speakers, so just go by color-- Red wire to red terminal, black/green wire to black terminal. I would pull the midrange as well and make sure it is hooked up correctly as well, as well as pulling all the drivers on the other speaker to make sure everything is connected properly.
 
Shrugg said:
I would trust the JBL manual on the proper wiring for the 4311b. It sounds like the previous owners already messed around in the speakers, considering that there was a rotated woofer and a replacement tweeter. It doesn't take much effort to change the wiring on those speakers, so just go by color-- Red wire to red terminal, black/green wire to black terminal. I would pull the midrange as well and make sure it is hooked up correctly as well, as well as pulling all the drivers on the other speaker to make sure everything is connected properly.
Click to expand...


Thanks for your reply. There are no red wires, the 2213H driver has a green wire, and a green with black stripe wire. See the attached technical manual. The problem is, it doesn't tell you if the '+' is the red or the black terminal on the 2213H.

I did the battery test, and the positive end on the battery to the red terminal, makes the driver go inwards. So I guess the 2213H drivers are 'innies'? Would hooking up the wires conventionally (GREEN/BLACK to BLACK terminal, and GREEN to RED terminal) make this driver out of phase? Is that how a 4311B is when it is connected 'properly'? No one seems to know.


Here is the forum that I found that had everyone confused. You will see it is not as simple of a topic as you might think.

http://www.audioheritage.org/vbullet...p/t-37337.html

I popped off both mids. They look like they have never been removed, and still have what I believe to be the stock male and female disconnects soldered on, so there is no switching them without re-soldering. I think I'll be leaving those.
 

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Thanks for posting that thread @Thrifty HiFi . It really seems to be somewhat confounding as to what jbl intended with the woofer polarity.
The red terminal is almost universally the positive one. After checking the manual, it also shows the drivers from the back side with the wiring diagram and the driver polarity, so you can use that as a reference as needed. Just make sure that all drivers are connected identically between the two speakers for now. I would stick to what jbl did originally for the tweeters, but you can experiment with woofer polarity if you like, as long as you change the driver's polarity so they match each other. IMHO, I would stick to what Jbl did originally for the woofers as well.
 
Shrugg said:
Thanks for posting that thread @Thrifty HiFi . It really seems to be somewhat confounding as to what jbl intended with the woofer polarity.
The red terminal is almost universally the positive one. After checking the manual, it also shows the drivers from the back side with the wiring diagram and the driver polarity, so you can use that as a reference as needed. Just make sure that all drivers are connected identically between the two speakers for now. I would stick to what jbl did originally for the tweeters, but you can experiment with woofer polarity if you like, as long as you change the driver's polarity so they match each other. IMHO, I would stick to what Jbl did originally for the woofers as well.
Click to expand...

You have a manual??? Please share if it is not the two page 'Technical Manual' we referenced earlier.

If that is the one you are referring to, It is not very helpful as a reference for a few reasons. That back view is not very representational of the LE25-2. The male and female disconnects are on either side, 180 degrees of each other, not paired at the bottom like in the illustration. Although I was able to find this attached schematic for the L100, Century/4311 which tells me the "Male terminal is PLUS" on a LE25/26. Fingers crossed it is the same for the LE25-4 (not too confident in that actually, but that's all I got). I needed to know this because the original disconnects were cut off to solder on the Audax tweeter, and I'm about to install new disconnects on the yellow wires to hook up one of the LE25-4.

JBL L100, Centur, 4311 Schematic.gif

Secondly, the rear view illustration of the 2213H woofer show the '+' terminal where the black one actually goes. See the attached image I found.

JBL 2213H image.jpg


I'm about to hook up one of the LE25-4 tweeters, and I have the woofers hooked up the same, in a conventional Green to the Red terminal, and Green/Black to the Black terminal. Really curious to hear it up against the Audax. Also to see if the bass has improved from when I first got them. Listened to them for about a week or so. Was fairly impressed, but thought the bass was a little weak from a pair of 12" woofers. Little did I know one we hooked up out of phase. The question is... which one was right?
 
I also found this JBL Technical Notes on Polarity Conventions document last night. It describes Negative systems, and I had already tested this with a AA battery, and the positive going voltage to the red caused a 'negative pressure' on the 2213H woofer (goes inward).

Then I scrolled down to see if my 4311B's were listed as 'positive' or 'negative', and there it... ... ... (crickets)...

NO MENTION OF THE 4311B'S OR 2213H !!!

I love the note at the bottom of page two:

" making the polarity inversion anywhere else in the system is an invitation to confusion."
 

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This might have been asked before ,apologize if that's the case, the capacitors on the 4311xx series are Non Polarized ?This means that we replace with non polarized right?
Just making sure i ordered the proper ones (Jantzen Ones)
 
Alou said:
This might have been asked before ,apologize if that's the case, the capacitors on the 4311xx series are Non Polarized ?This means that we replace with non polarized right?
Just making sure i ordered the proper ones (Jantzen Ones)
Click to expand...

Yes, crossover caps are non-polarized.
 
Hello again. Sorry for disappearing for a while. It's summer, and well... not much time to fiddle around.

So this schematic I posted, led me to hookup a female connector to the yellow wire, and put it on the male terminal on the LE25-4 (and yellow-black to the female on the LE25-4). I did this to one speaker, assembled it, and compared it to the Audax. The result was what I was hoping for I guess. The LE25-4 was way more crisp and had more volume.

And that's where I got distracted and put this whole thing aside.

To get myself in the mood, I was looking online at refinished JBL monitors. The I stumbled upon this attached pictoral hookup diagram.

I thought... this is exactly what I was looking for... except not what I did. So If both are right, I guess the yellow/black needs to go to the male terminal (Plus).

So does this make sense? Are the woofer and midrange in phase with each other, and the tweeter is out of phase?
 

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  • Pictoral Driver Hookup.jpg
    Pictoral Driver Hookup.jpg
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Ignore any reference that includes the L100 series, the 2213H and LE25-2 were never used in that speaker, there are three versions of the L100 with two of them using a negative woofer, just confuses this unnecessarily.

The 4311 and 4311B are also different beasts, again ignore any reference to the non-B.
 
Giovanni68 said:
Ciao Glenn,

that's a good idea, thank you! I think I will delay attempts to when I have extra speakers ;) I am dealing for a pair of L220 :cool: which needs the passive to be refoamed and also some fixing to a crossover, if I menage to get and resurrect them I would sure give a try at recapping the 4311B and follow all of the precious advice out of this thread.

Grazie

Giovanni
Click to expand...

Giovanni, hai trovato il coraggio ? :)

Hi friends, I'm tempting a recapping as well, I run my 4312 with a marantz 2235b, and the sound of classical music is the worst I've ever heard... murky, muddy, confused, just like behind a damping curtain...
With rock/pop turns out to be better, but still unsatisfactory...
The guy where I bought these from said he had just deoxited the L-pads, not recapped because "those caps last forever"...
Since I am getting very frustrated, I can't understand whether it's a problem of
- power low amp
- caps kaputt
- positioning (using the wood lincoln stands, gently reproduced by father-in-law)
- God knows what

I'd like to give a try...
By the way, does someone knows where to source good caps here in Europe ?

I'll let you know when I'll find time and guts :)
 
The system that you have is vintage, very old and should be restored to sound as good as it did new.

Having said that, neither the 4312 (non-A) nor the 2235 are really known for brightness nor speed, especially in the higher octaves. It is one of the reasons I have no vintage marantz, it is more of a "warm" sound where I prefer more detail.

Was your 2235 a better sound on brighter speakers? The 4312 is a nice collectible speaker, but lacks the sizzle of a modern unit, the 4312A was much better at producing HF as were any of their dome-tweeter speakers.

Yes there is an electrolytic cap in the crossover that should be replaced, not sure but I think that the cap in the sand-filled tube is a film cap.
 
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