JBL 4311b gift

[asilker]

Happy Thanksgiving, everybody. I hope you've all had some good time with your families. I've had some great time home with the in-laws, and my nephews are running about as I write this

Just thought I'd drop a line and let you all know I scored HARD yesterday. My wife's uncle has talked to me here and there over the past few months about stereo gear. We were at his house yesterday for the holiday and he brought up a pair of Advents he'd had in college that needed a refoam. So of course I said "let's take a look at 'em!". When we get down the basement stairs, lo and behold he's also got a pair of JBL 4311b's stacked in a corner. So of course I start pushing the woofers and checking the foams and whatnot, and he tells me he got them on an insurance claim because somebody insisted that they had water damage. Obviously they hadn't, so he had kept them instead of letting them go to waste. Anyway, he says he's never used them and if I can refoam his Advents and get them back to him, the 4311b's are mine to take.

I made sure to express to him that they were valuable and offered to pay him, but he insisted. And hey, who am I to say no? I loaded them into the car as fast as I could and they're still down in the hatch. Really looking forward to getting them home and giving them a refresh. All of the woofers move freely, foam is fine around the tweeters. The aluminum caps on the mids are all pushed in, so I imagine I'll have to cut them out and install new ones. 12" woofers are in great shape. I'll upload pics as soon as I'm able to pull them out of the car and put them somewhere.

So of course, I'm also looking for opinions (That's why we're here!!)
Q1) One of the mids has a small puncture on the outside of the cone. I have owned 15" JBL woofers before where people repair tears with rubber cement or similar adhesives. For the time being, can I gently dab the puncture closed, or are they only usable after a recone?

Q2) The crossover of course! I'm still reading up on the stock network but like I said, I've been involved in parting out JBL gear before and have considered rebuild projects, so I am (vaguely) aware that people achieve much better results with creative crossover rebuilds. I have saved the thread that gives different options for the 4311b crossover build (improved, refreshed, etc), but I'm still interested to hear who would recommend a crossover build from scratch?

PHOTOS TO COME...

 

[elitopus]

I voted for a simple crossover recap. You can fix the woofer with a piece of coffee filter and aileens (or similar) glue on the back of the cone
Nice score!

 

[Jeffery]

I wouldn't sweat a small puncture in the mid, or pushed in dustcaps. Just keep an eye peeled for a nicer pair of LE5-10 to pop up, they can be had for a reasonable price.

There are other models that use the same cone kit, but differ cosmetically, etc.



http://www.audioheritage.org/vbulletin/showthread.php?5706-The-LE5-Matrix

 

[GerryC]

Congrats on a great find, JBL 4311B's are what first started my interest in vintage audio, as I grew up listening to them. My father bought a pair new in the late 70's and still uses them today. A few years ago the crossovers were rebuilt to original specs, with better film caps than were available at the time of their manufacture. There IS an audible difference/ improvement. I am a big JBL fan, and almost all my JBL's have benefitted from a crossover rebuild/recap. I personally prefer to keep them close to original specs, they ALL sounded better afterwards, particularly my L300's. The tiny hole in the mid is an easy fix, and IMHO only requires reconing or replacement if cosmetics and pristine condition are that important to you. Hope you had a great holiday, great find. Fortunate thing for you he likes his Advents more than his JBL's. I dare say most members here would prefer the opposite.

 

[asilker]

Left:


Right:


Left tweeter isn't making any sound, I suspect it's just an Lpad or connection issue. Don't have time right now to disassemble it right now, but I think I heard it spark in once when I moved the Lpad...


Left mid puncture


right mid paper fold


Running with an Ortofon Omega cart and an NAD 3150 integrated. So far, John Bonham's drum hits feel like they're in the room. These are definitely a rock monitor; I think they'll compliment my Infinity Ref Five's well as the Five's are extremely neutral and "live" sounding, but not as forward and vivid as the 4311. If my ears are correct, the roundness and lively character of the vocals and acoustic strings are due to a bit of a peak in that area. That being said, I am pleased with the EQ coloration of these monitors and I think I'll try to maintain that filter.

Other observations (I'm sure this will echo what's already been said a hundred times here and on the Lansing Heritage forums): Mids are a bit beamy, the sweet spot is definitely directly in front of them. Bass isn't hugely extended, but feels very full. According to the spec sheet, the tweeters fall off around 16k; doesn't feel as airy as the ribbons I typically hear, but still feels very bright and natural.

 

[donprice]

Other observations (I'm sure this will echo what's already been said a hundred times here and on the Lansing Heritage forums): Mids are a bit beamy, the sweet spot is definitely directly in front of them. Bass isn't hugely extended, but feels very full. According to the spec sheet, the tweeters fall off around 16k; doesn't feel as airy as the ribbons I typically hear, but still feels very bright and natural.

Sounds like you are thinking real hard about the crossover mods to flatten out the mid range. Someone did it and added a couple of switches to be able to flip between the original and hot-rod (Dennis Murphy?) crossover.

 

[asilker]

Sounds like you are thinking real hard about the crossover mods to flatten out the mid range. Someone did it and added a couple of switches to be able to flip between the original and hot-rod (Dennis Murphy?) crossover.

Oh that's a great idea. I do have a number of mini switches around.

Honestly now that I've heard them, and as I'm aware of the high end constraints and the low end roll off associated with most JBL 12's and 15's, I think I may just keep em Classic and use em as a "reference" sort of piece.

Wife heard them last night and said "wow these sound more like a concert"

 

[GD70]

Awesome score! The dust caps may be fixed with the toilet tube & suck method. Tweeters I'd leave alone, maybe use some blue painters tapu very gently and see if they will pop out, otherwise, leave them.

How are the cabs? lets see some pics, and did they come with the grills?

Great way to start the holiday season!

Cheers!

 

[asilker]

They did come with grills! One grill has snapped in the middle but a bit of wood glue should fix things right up. I think I might replace the cloth with some old school gold textured cloth.

Cabs definitely need a sand and stain, there's a small chunk missing from one of the corners above the woofer side, but as I'll be positioning them tweeter up that shouldn't be too big an issue.

More pics to come as they're packed away in the car again

 

[Goldjazz]

Recap and clean the L-pads. Really improved my 4311's. Genuine recone kits are way too expensive, its generally cheaper to source a whole driver. I haven't messed with the non genuine recone kits so not sure if that's the way to go. I like my 4311's hope you enjoy them.

 

[asilker]

Recap and clean the L-pads. Really improved my 4311's. Genuine recone kits are way too expensive, its generally cheaper to source a whole driver. I haven't messed with the non genuine recone kits so not sure if that's the way to go. I like my 4311's hope you enjoy them.

Thanks for the heads up. I definitely will not be messing with recones until the crossovers are redone. But even if recone kits set me back a little bit, I only have $0 into the pair right now lol. It's tempting to do a really thorough driver refresh

 

[Zonker92]

Fantastic score! I haven't read all the posts above but here are a few random thoughts, based on my own experiences with L100s and 4311s:

The Dennis Murphy crossover may be a good upgrade, but there is no reason to do it yet. I would listen to them recapped first and see how you like them. The parts for the Murphy will be fairly expensive. (And there is no reason to use the elaborate switching arrangement; that was just for experimental purposes as far as I can tell and it would be a big hassle.)

On eBay you can find lovely replica grill covers in many great colors; check out the offerings from Huntley Audio.

Also, spend some time Googling the work Troels Gravesen has done on these speakers and related models. You will see who he has fixed the dented domes, done crossover work, etc.

 

[Jeffery]

Thanks for the heads up. I definitely will not be messing with recones until the crossovers are redone. But even if recone kits set me back a little bit, I only have $0 into the pair right now lol. It's tempting to do a really thorough driver refresh

I doubt you will find JBL recone kits for the mids or woofers, that leaves you with aftermarket recone or used drivers. Used drivers pop up now and then for reasonable prices.

 

[jlovda]

Awesome score! The dust caps may be fixed with the toilet tube & suck method.

I wish I knew how you do that. I have tried that countless times and all it does is make my face turn blue.

 

[Jeffery]

I wish I knew how you do that. I have tried that countless times and all it does is make my face turn blue.

According to the "LE5 Matrix" posted above, the LE5-10 has an aluminum dust cap (surprised me, I would have thought paper), so suckling the dust cap out probably won't happen. And those look pretty gnarly.

 

[asilker]

I will be researching. Thanks for all the comments on crossover options. I've replaced the aluminum domes on some D130's before and it was pretty easy, so if I can't find a suitable method for popping out the ones attached, I'm considering a careful cut and replacement. I've found suitable caps and I've done the job before so I'm not too worried. I am suspicious of the "suck" method with aluminum caps but hey I'll give it a try.

1 mid and 1 tweeter have fold marks in the cones. Is that something I should be worried about? The fold-ey tweeter is the one that isn't connecting, but again I suspect an L-pad problem and not a tweeter malfunction; to my ears the fold-ey mid driver sounds just fine. My hunch would be that these are pretty rough drivers and that they'd take a lot more than a little wear and tear to keep 'em down.

I suppose I should add that if anyone has more minty drivers they'd like to get rid of I may be interested in purchasing. I'll have to take stock of finances this week, but I am interested in cleaning up the small details here.

Here's another question: Can I thoroughly deoxit the Lpads and just keep the originals or is it highly advised that I purchase new ones?

 

[asilker]

Opened up the cabs this morning. First off, let me say it was VERY difficult to get the woofers loose. I have never experienced a speaker so stubbornly attached to the baffle. From the beginning it's been a fight. Similarly, I was attempting to slip off the attenuation knobs in order to spray out the Lpads, but after deoxit spray and channel locks, I still cannot get one of the knobs loose. YEESH!

A few other issues: I cannot move the mids out of the baffles to check them out. This is frustrating. The functional tweeter measures around 5 ohms, the nonfunctional one at 28 ohms. I'm assuming this means it's cooked. Finally, one woofer does not have the model nameplate on the back (who knows why, it doesn't feel like these have ever been opened) and they measure difference resistances. One is above 5, the other around 3 ohms. Is this a problem?



The speakers are not consecutive serial numbers...

 

[Zonker92]

Looks like there's adhesive residue on one woofer from where its foilcal fell off (is it lying in the bottom of the cabinet?). No big deal. 28 ohms is strange on that tweeter. I would examine the terminals to make sure the connections to the tinsel leads are solid.

It may help, in removing the midranges and that one L-pad knob (does it really need to come off?), to warm them up with a hair dryer.

 

[asilker]

The nameplate actually was caught up near the crossover I'll reassemble that in a minute. After over 30 minutes of effort, I still cannot figure out a way to pop the tweeter out. Hair dryer method is next. And unfortunately, I do need to get that knob off. I've tried to poke my head in and just spray the cleaner, but there's no way I can see into the corner like that.

EDIT: After using a hairdryer to get the faceplate off, I found 2 phillips head screws which allowed the crossover board to slip out. After spraying the Lpads, they still feel awfully sandy so I probably will be replacing them.

Still cannot get the tweeter off.

 

[donprice]

Tweeter removal often requires some brute force (as you already know). A chisel to get under an edge to break it free is one method. Obviously you can booger up the tweeter frame and cabinet this way. A block of wood and a hammer to tap away at the sides is less aggressive and less likely to result in damage. You might be able to get a hook under the frame through the screw holes and lift...not much to work with little risk of visible damage.