Vintage HiFi Audio Forum

Audio Discussion => General Discussion => Topic started by: scorpio333 on April 06, 2019, 04:44:03 PM

Title: JBL 4311b Control Monitors
Post by: scorpio333 on April 06, 2019, 04:44:03 PM
I rarely scroe anything...a few weeks ago my wife says she
Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on April 06, 2019, 04:47:02 PM
That is a very compelling story.

PEPE!!!
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Title: Re: JBL 4311b Control Monitors
Post by: scorpio333 on April 06, 2019, 05:26:16 PM
So compelling I posted it twice...

Happened on my phone. I was able to go back and copy the text.

I rarely scroe anything...a few weeks ago my wife says she
Title: Re: JBL 4311b Control Monitors
Post by: scorpio333 on April 06, 2019, 05:28:34 PM
DAMMIT...now I tried to post it from the computer...still cutting it off.
Title: Re: JBL 4311b Control Monitors
Post by: scorpio333 on April 06, 2019, 05:31:33 PM
.
Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on April 06, 2019, 05:38:39 PM
Text me.
Title: Re: JBL 4311b Control Monitors
Post by: gdv on April 06, 2019, 05:53:48 PM
Sean, I am sure it is a good story!  Would be interested in hearing it...
Title: Re: JBL 4311b Control Monitors
Post by: Jim Pittsburgh on April 06, 2019, 06:33:59 PM
inquiring minds want to know lol
Title: Re: JBL 4311b Control Monitors
Post by: scorpio333 on April 07, 2019, 12:36:50 AM
Sorry, had to go out for a concert. Let
Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on April 07, 2019, 12:39:24 AM
Sorry, had to go out for a concert. Let

Now you're just screwing with us, right?
Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on April 07, 2019, 12:40:30 AM
Who did you
Title: Re: JBL 4311b Control Monitors
Post by: scorpio333 on April 07, 2019, 10:44:29 AM
Whitey Morgan and the 78s.
Title: Re: JBL 4311b Control Monitors
Post by: scorpio333 on April 07, 2019, 12:23:18 PM
Going to try this one more time...at this point the whole post is anti climatic.

I rarely scroe anything...a few weeks ago my wife says she's bringing home her dad's stereo. First thing I think that pops in my head is my buddy who inherited a AR XA turntable. Nope. It's a MCS all in one junker. Today she texts me he has speakers. UGH. I'm thinking particle board pair of misery. Nope. JBLs. They're not home yet, crossing my fingers they aren't destroyed. Any opinions on these? Haven't looked them up yet.

She got home and they are rough. Grilles are shot. One mid is ripped. The cabinets are poor. Then she tells me he mostly used them in his Bronco. DOH!

The MCS is going to the ecycler next Saturday, unless by some chance someone wants it.

Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on April 07, 2019, 01:49:40 PM
All of that is pretty standard for vintage JBLs.   Grills are usually missing (discarded when they invariably break or rot), so simply "shot" at least gives you a template to work from.   The torn mid is also not unusual and an easy fix.   Depending on how bad it is, you can simply use thinned Aileens and an artists brush or if it's bad, use a piece of coffee filter paper from behind and the thinned Aileens.   Think of the Aileens as Bondo and the filter as sheeting.   You want to add as little mass to the cone as you can get away with.   Mids don't have much excursion, so you are really only concerned with eliminating any possible paper buzz at the tear.   As for the cabinets, JBL was generous with the thickness of their veneers, so they tend to be easier to work on that most.   If your tweeters aren't pushed in, you've avoided the biggest headache in restoring a legacy JBL speaker.
Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on April 07, 2019, 01:58:18 PM
All of that is to say, yes, absolutely worth the time and effort of restoring.
Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on April 08, 2019, 04:51:12 PM
If you decide they aren
Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on April 08, 2019, 04:52:06 PM
Crap
Title: Re: JBL 4311b Control Monitors
Post by: scorpio333 on April 08, 2019, 08:39:58 PM
Here's some pics.
(https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/021042486451/media/84496532254/medium/1554769293/enhance)

(https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/021042486451/media/84496532249/medium/1554769112/enhance)

(https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/021042486451/media/84496532278/medium/1554769114/enhance)

(https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/021042486451/media/84496532286/medium/1554769114/enhance)

(https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/021042486451/media/84496532305/medium/1554769116/enhance)

(https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/021042486451/media/84496532310/medium/1554769116/enhance)

(https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/021042486451/media/84496532326/medium/1554769117/enhance)

The cabs can be fixed, I'll need a tetanus shot update. I guess the next step is determining which drivers work. I don't think that mid can be saved, maybe I'm wrong? 
Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on April 08, 2019, 11:35:23 PM
Well, I looked at it and thought "that mid is no problem but I don't know if that cabinet can be saved", so we each must have different specialties.   Get rid of the mold from the drivers with a dry paintbrush then let them sit in the sun for a day.   The cabinets are cleaned easily enough, I just don't know how to repair the water split joint.   The bottom front edge of the one can just get a new piece of veneer glued in.
Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on April 08, 2019, 11:36:58 PM
What I was going to say before and it cut me off is that if you decide to not restore them I would trade you a defective Dual for them as is and we can each play to our strengths.

I may even have two Duals for you to use that jig on.
Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on April 08, 2019, 11:38:15 PM
Oh, and not tetanus, but wear a mask.   Mold can be dangerous.
Title: Re: JBL 4311b Control Monitors
Post by: Comten on April 09, 2019, 07:03:33 AM
<snip>
The cabinets are cleaned easily enough, I just don't know how to repair the water split joint.   The bottom front edge of the one can just get a new piece of veneer glued in.

Please advise if you find a place in SW PA that can repair the cabinet split at the joint.

Thanks!
Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on April 09, 2019, 08:12:48 AM
<snip>
The cabinets are cleaned easily enough, I just don't know how to repair the water split joint.   The bottom front edge of the one can just get a new piece of veneer glued in.

Please advise if you find a place in SW PA that can repair the cabinet split at the joint.

Thanks!

Speaking only for myself, I would be exploring options of how to do it myself.   I wouldn't be looking to pay someone else to do it.
Title: Re: JBL 4311b Control Monitors
Post by: MacGeek on April 09, 2019, 08:23:48 AM
Considering the moisture to which these must have been exposed, I am concerned about the condition of the x-over and pots.  Also, any damping material inside the cabinets is suspect, as is the back of the drivers.

If these were mine, I would start by completely disassembling them to fully assess any damage.  The cabinet split might be repaired from the inside while they are apart.
Title: Re: JBL 4311b Control Monitors
Post by: Comten on April 09, 2019, 09:13:29 AM
Considering the moisture to which these must have been exposed, I am concerned about the condition of the x-over and pots.  Also, any damping material inside the cabinets is suspect, as is the back of the drivers.

If these were mine, I would start by completely disassembling them to fully assess any damage.  The cabinet split might be repaired from the inside while they are apart.

Time and tools... Have neither.
Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on April 09, 2019, 09:30:43 AM
Considering the moisture to which these must have been exposed, I am concerned about the condition of the x-over and pots.  Also, any damping material inside the cabinets is suspect, as is the back of the drivers.

If these were mine, I would start by completely disassembling them to fully assess any damage.  The cabinet split might be repaired from the inside while they are apart.

Absolutely.
Title: Re: JBL 4311b Control Monitors
Post by: scorpio333 on April 09, 2019, 08:03:32 PM
I'm hoping to get these apart tonight/tomorrow. While wearing a mask. I got enough issues with the pollen explosion, don't need to double down with inhaling mold. MacGeek brings up a good point that the guts of these could be a horror, I'm hoping the mold is mostly on the outside.

I've got the tools here...time is the hard part. I'm no pro woodworker, but you don't get there without trying. At first glance, I planned to remove that wasted bottom and try to replicate as close as possible.

STaL, I appreciate the offer of the Duals. My wife would like me to try and restore these, if possible. It would be payback for a 40 yr old rifle I gave her dad to restore. I let him keep it when he was done, I'd be too tempted to do some backyard pest control. That said, if I get to the point of frustration with them, I'll let you know.
Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on April 09, 2019, 09:14:56 PM
I'm hoping the mold is mostly on the outside.


Hissing cockroaches are more likely on the inside of a ported speaker.   I never bring a dodgy ported box into the house without tearing it apart first and making sure it's all clear.
Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on April 09, 2019, 09:16:35 PM

STaL, I appreciate the offer of the Duals. My wife would like me to try and restore these, if possible. It would be payback for a 40 yr old rifle I gave her dad to restore. I let him keep it when he was done, I'd be too tempted to do some backyard pest control. That said, if I get to the point of frustration with them, I'll let you know.

I'm happy to provide an escape hatch should you need one.   I know it's very unlikely that I will ever get to the Duals.
Title: Re: JBL 4311b Control Monitors
Post by: scorpio333 on July 22, 2019, 10:15:31 PM
Couple of new pics.
(https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/021042486451/media/84643445440/medium/1563847208/enhance)

(https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/021042486451/media/84643445445/medium/1563847208/enhance)

(https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/021042486451/media/84643445464/medium/1563847209/enhance)

Yeah, yeah the grain on the new bottom...or is it really the top  ??? isn't going the right direction. It's what I had lying around that was close to the correct thickness. Couple passes through the planer and it fit right in. Plus, I doubt it affects the sound.  >:D

More coming including a fairly ratty cone repair. The ripped mid may need replaced, the dustcap surrounds are aluminum and this one is real wavy. I think I got it glued back together, but we'll see.

The crossovers look good, minus some corrosion on the one that was wet. I'm going to hold off doing caps until I get them put back together and listen to them. The caps in there look pristine, but we'll see how they sound.
Title: Re: JBL 4311b Control Monitors
Post by: MacGeek on July 23, 2019, 08:31:06 AM
Nice work so far.  I don't have some of the tools, like a planar, but if I did I might not have the ambition.
Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on July 23, 2019, 10:04:16 AM
Yep.   That was a lot more work than the pictures may lead one to believe.
Title: Re: JBL 4311b Control Monitors
Post by: scorpio333 on July 23, 2019, 01:28:47 PM
Definitely not fun raising sawdust on hot, humid days.
Title: Re: JBL 4311b Control Monitors
Post by: scorpio333 on July 25, 2019, 08:52:59 PM
Put them all back together today, except one woofer screw. JBL used T nuts for the woofers. If you over torque or put too much pressure on them removing them you get a nice little mess. I tore the t nut right out of the particle board. Used sawdust and glue in multiple layers to fix the missing chunk. Anyhow, all back together to check the L pads and drivers. Everything works. I
Title: Re: JBL 4311b Control Monitors
Post by: scorpio333 on July 25, 2019, 08:54:27 PM
Ack, got cut off. Pics later.

Any cap recommendations? Need 3.0 and 8.0.
Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on July 25, 2019, 10:25:52 PM
I've done that before.   I cut a piece of 3/4" plywood and glued it into the space.   I figured it was something to grab into and extra bracing.   I just had to find a 1" longer bolt.
Title: Re: JBL 4311b Control Monitors
Post by: scorpio333 on July 30, 2019, 05:03:33 PM
I had other photos, not sure where they went. Anyhow, here's a few of the Lpads and one of my "fixed" mids. All four L pads work great, pretty surprised. New caps should arrive tomorrow.

(https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/021042486451/media/84654581025/medium/1564519542/enhance)

(https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/021042486451/media/84654580926/medium/1564519540/enhance)

(https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/021042486451/media/84654580924/medium/1564519540/enhance)

(https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/021042486451/media/84654581087/medium/1564519544/enhance)

(https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/021042486451/media/84654581093/medium/1564519545/enhance)

(https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/021042486451/media/84654581141/medium/1564519546/enhance)

After the caps go in I need to make a set of grilles. While I didn't ruin the foilcals removing them, they were pretty ratty. I may not put them back on and instead make grilles that cover the whole front of the cabinet with some holes for the knobs. The cabs are ok enough, but there are some other swells and veneer damage. That said, I think I'll call it a day and enjoy the sounds they make. While the JBL purists may go bonkers over that decision, effort vs result is hitting diminishing returns and new cabinets won't make them sound better.
Title: Re: JBL 4311b Control Monitors
Post by: Sir Thrift-a-Lot on July 30, 2019, 10:16:43 PM
IIRC, there is somewhere on the internet that you can buy repro foilcals.

The folks at Lansing Heritage would know for sure.