JBL 4311 - tweeter problem

[ballpein]

Hey,

I just scored a pair of these, in pretty fair cosmetic shape, cones are good, but nothing from the tweeters, not even scratching when I turn the brilliance knobs. The woofers and midranges seem to work fine, the mids respond when I tweak the presence knobs.

For folks in the know, is this likely to be a problem with the tweeters themselves, or with the crossover? Word on the web is that one should replace the caps on these, as they're prone to failure after 20 or 30 years.

These have been stored without climate control since about early August, probably saw some pretty extreme heat, as well as a couple days of subzero before I saved them. Apparently they saw enough heat to melt some glue around the woofers, as there is a large drip of glue on both speakers, running down from the woofer towards the soundport. This drip is now solid, but a little tacky - consistency wise, a little stiffer than caulk. I understand the woofers can be tricky to remove, and I imagine these could be extra tricky given the afore-mentioned glue issue.

I'm going to try and pull the tweeters and mids off tomorrow night to have a look and poke around with a multimeter. Any tips on what I should look for / test would be much appreciated.

Also, if anyone can direct me to specs, schematics, repair guides, it would be greatly appreciated.

By the way, they sound pretty balls, even without the tweets.

[???????]

Those are great speakers. I like them for home hi fi listening use.

The tweeters, even if bad, are fairly inexpensive to find used.

I'd try recapping the crossovers first.

Check the resistance across the leads of the tweeters. If it reads 0 ohms or more than about 10 then you probably have bad drivers.

[ballpein]

Thanks, uh, nils ? I'll try that.

As much as I'd like to, I don't think my neighbours would forgive me if used these at home. I'll probably end up using them for playback in our live room, which should be a huge improvement over the stage monitors we've been using.

I found a ton of tech info on these units here, in case anyone else is looking:

http://audiokarma.org/forums/showthread.php?t=106180

[???????]

for more/better info/advice, go to the Lansing Heritage forum.

http://audioheritage.org/vbulletin/

[themagicmanmdt]

my 4311b's are the best speakers i've ever laid ears on.

and i've listen to really big, really expensive monitors, and really small, really expensive monitors.

and these just sound so *real*!





do the speakers come up as having an ohmage on a voltmeter?

try hooking them up to the connections on the midrange. (turn the volume all the way down, and just ease it up to see if you get signal. you won't hurrt them, just don't turn them up loud at all.) if that works, then there's some strange crossover issue. give it a recap. you should recap them anyways. there's only 4 caps total for the monitors.

if you still don't get sound, maybe the wires got pulled off the cone. or it's just a bum speaker. or possibly demagnetized!

[ballpein]

thanks magicman,

I'm going to do some testing over the weekend, hopefully I can get the tweeters out without completely mangling the front of the cab, they're really reluctant to come out of there.

A recap is definitely in the plans too, I can't wait to get these babies up and running.

[firby]

I run a pair of 4311s as my bigs in my control room. The pair I got had bad tweeters with bad foam around the tweeters. I thought that they were just party speakers or whatever, then I replaced the crossover in one and the tweeters in both.

They really sound beautiful now. So, if you have not heard a pair in great condition don't stop with them until they are pristine. The bass is a little slow in them but they are really charming, great speakers and you could definitely mix a fabulous record on nothing but those speakers. In fact, its been done a few thousand times.

The foam around the tweeters helps them too. They are good speakers!

[???????]

I agree with firby, they are great speakers.

Don't get me wrong when I said they are great for hi fi and home listening. That was not meant to denigrate their ability as monitors, where they have worked great for decades. I just find them especially pleasing to listen to records on.

I agree with firby also that the bass can be a little slow, and the tweeter technology isn't the most current. But they certainly sound pleasing. They are very similar to the L100 Century.

I don't find them to be the most honest sounding speakers, but they're nice sounding. JBL always tuned by ear rather than more objective means, for whatever that's worth.

[Jim Williams]

I used them to mix on in the 1980's. The aluminum tweeters are a bit zippy, that did create listening fatigue after several hours. Replacing the crappy mylar crossover caps does help, I like MIT, InfiniCaps, Mundorf silver foils, VTV ultra caps (silver foil, paper in oil).

Also replace the coils with Alpha or Solen air foil inductors. Replace the sand resistors with Mills MRB-12's.

Now yer talkin!

[ballpein]

Okay....

so, bad news, looks like the tweeters are shot. Any thoughts on where, besides ebay, I might look for replacements? (ebay pricing seems pretty high to me, at close to $250 a pair).

I would definitely like to get these back into good condition, and had planned to recap with Daytons. Seems like the L-pads might need replacing too - they're not noisy, but they feel gravelly and one is intermittent. I wasn't planning on replacing the other components but maybe I'll look into it.

[???????]

Okay....

so, bad news, looks like the tweeters are shot. Any thoughts on where, besides ebay, I might look for replacements? (ebay pricing seems pretty high to me, at close to $250 a pair).

I would definitely like to get these back into good condition, and had planned to recap with Daytons. Seems like the L-pads might need replacing too - they're not noisy, but they feel gravelly and one is intermittent. I wasn't planning on replacing the other components but maybe I'll look into it.

ask on the lansing heritage forum. You might even have success with a WTB post there, or someone might know where you could get them repaired. JBL might even still repair them.

[nclayton]

The aluminum tweeters are a bit zippy, that did create listening fatigue after several hours.

Was there a version of 4311b with aluminum tweeters? I thought they were all paper.

If your tweeters aren't aluminum but paper, I might have a spare set. I've had a few but sold some on ebay myself, I'm just not sure how many. If I do have some, I probably don't need $250 for them. Let me know.....

Ned

[???????]

I was wondering about that. All the 4311s I've ever known have had paper tweeters.

And they are NOT worth $250, at least they weren't when I sold a pair for I think about 40-50 bucks over the summer on eBay. One had a creased dustcap but still.

[ballpein]

Well, there's a couple pair going for around $230 CDN on ebay.... which is around $180 or $190 USD... still way overpriced, I'm thinking... like all things "vintage" on ebay.

These definitely look to be paper tweets. Ned, if you've got a pair kicking around I'm definitely interested.

Dave.

[themagicmanmdt]

i've got a spare set ofthe ceramic midranges, just for the record. one needs a recone, but i know a guy in town here that recones JBL and Jensen speakers.