Restoration of 4301B

[stanghello]

Hi, I am very new in this business, but I need help to repair my JBL4301B professional series monitors. I acquired them 20Years ago, and recently noise detriorated, Opening the grille I noted that the woofer (suspension ?) foam has almost completely deteriorated and disappeared in crumbles.

What can I do?

Cheers,
.:(

[ratitifb]

:D

or 116A or H on ebay ...:p

depending on money you have for :blink:

[rutabaga]

sure you can by 116A on eBay (or116H, if it's the case...)

but I suggest you to repair it yourself ...

The JBL foam surround life is approx 15 years...

time to have news :bouncy:

it's not so easy the first time but you CAN do it !

Better buy the surrounds on eBay.com ... the best are from
rick cobb

he is looneytune on ebay.com (USA)... and it's not expensive ...
even the ship price to Europe... it will cost you the same price than buy a kit in Germany and you will have the RIGHT kit( right dimensions),
the best quality surround and glue

and at last , an easy method to do it right :
you will receive a CD that you must play when you do the job,
your 116A connected to the amp ... a 30 Hz sine wave test tone...
you will appeciate! easy to repair, even if you :banghead: a bit, you will :p
at last
the kit is for 2 surrounds, the glue , the cd and a good notice...

everybody here will say you to buy this kit... and not another...

good luck and amaze the job... you will not regret.. your 4301b
will appreciate too:spin:

rutabaga

[boputnam]

What can I do?:wave:

Typical problem with vintage cabinets.

You should get a recone done if you have access to good workmanship - someone here might recommend someone in your region.

If you get stuck, and are handy, you could follow the Resurround Step-by-Step and at least get them back functioning until you can get a proper recone.

A recone is always the preferred path...

[brutal]

Playing them in that condition can possibly damage the voice coil, so a thorough inspection and test is in order before attempting a refoam. More than likely, you'll be better off with a full JBL factory recone.

[Zilch]

Recone kit for 116A/H is $146 MSRP....

[mech986]

sure you can by 116A on eBay (or116H, if it's the case...)

but I suggest you to repair it yourself ...

The JBL foam surround life is approx 15 years...

time to have news :bouncy:

it's not so easy the first time but you CAN do it !

Better buy the surrounds on eBay.com ... the best are from
rick cobb

he is looneytune on ebay.com (USA)... and it's not expensive ...
even the ship price to Europe... it will cost you the same price than buy a kit in Germany and you will have the RIGHT kit( right dimensions),
the best quality surround and glue

and at last , an easy method to do it right :
you will receive a CD that you must play when you do the job,
your 116A connected to the amp ... a 30 Hz sine wave test tone...
you will appeciate! easy to repair, even if you :banghead: a bit, you will :p
at last
the kit is for 2 surrounds, the glue , the cd and a good notice...

everybody here will say you to buy this kit... and not another...

good luck and amaze the job... you will not regret.. your 4301b
will appreciate too:spin:

rutabaga

And be sure to get all the old foam surround off of the back edge of the cone, and then glue the new surround to the back of the cone like the original was. The cone will then look and function like originally engineered.

Good Luck!

Well worth saving/repairing, some have also advocated changing the crossover capacitors to newer polypropylene types, some like bypasses along with them, or you could go all out and build charge-coupled types.

Regards,

Bart

[stanghello]

:)Many many thanks for your detailed answer. Being soemwhat a handyman (I used to build alos model ships etc, model airplanes) I will most probablt attempt myself.
There is still a question I have:
looking in ebay for offers I found somebody (musicfriends) which claims to use polipropylene (PE) because this was the closests to the original material and others who says that it is better to use the modern rubber parts, because anyway the sound has changed due to capacitors etc. but that rubber last longer and produces better damping (this last issue I doubtm being originally a structural engineer) .
I would suspect that PE is better for sound and it will anyway come closer to the original....but, I am a bit scared at the possibilty of having to do it again in 10 years....

I assume you have a very clear position on this.....

Thanks,

Stanghello:)




sure you can by 116A on eBay (or116H, if it's the case...)

but I suggest you to repair it yourself ...

The JBL foam surround life is approx 15 years...

time to have news :bouncy:

it's not so easy the first time but you CAN do it !

Better buy the surrounds on eBay.com ... the best are from
rick cobb

he is looneytune on ebay.com (USA)... and it's not expensive ...
even the ship price to Europe... it will cost you the same price than buy a kit in Germany and you will have the RIGHT kit( right dimensions),
the best quality surround and glue

and at last , an easy method to do it right :
you will receive a CD that you must play when you do the job,
your 116A connected to the amp ... a 30 Hz sine wave test tone...
you will appeciate! easy to repair, even if you :banghead: a bit, you will :p
at last
the kit is for 2 surrounds, the glue , the cd and a good notice...

everybody here will say you to buy this kit... and not another...

good luck and amaze the job... you will not regret.. your 4301b
will appreciate too:spin:

rutabaga

[rutabaga]

'looking in ebay for offers I found somebody (musicfriends) which claims to use polipropylene (PE) because this was the closests to the original material and others who says that it is better to use the modern rubber parts, because anyway the sound has changed due to capacitors etc. but that rubber last longer and produces better damping (this last issue I doubtm being originally a structural engineer) .
I would suspect that PE is better for sound and it will anyway come closer to the original....but, I am a bit scared at the possibilty of having to do it again in 10 years....'

:hmm:

I have 2 pairs of 116A with rubber surrounds...

(They come from Germany)

Some says that with rubber surrounds you will have a rubber sound

:rotfl:

I just don't like it because of finding it unaesthetic... but I cannot
really find an acoustic difference...

I will remove it and place foam ... with the lip of the surround UNDER
the paper cone... THAT's really important, yes...

for the aesthetic , sure - but especially for the acoustic result...

I'm not an expert, here ... Just try to save some damage cabinets...

If there was JBL foam surround for the job, I'll buy it !
( but never from new old stock!)

those from looneytune (ebay.com) are the best I find....

http://cgi.ebay.com/BEST-Speaker-Foam-Surround-Kit-for-JBL-12-L65-L150-2203_W0QQitemZ180204162194QQihZ008QQcategoryZ3276Q QssPageNameZWDVWQQrdZ1QQcmdZViewItem

In Europe, too many foam kits China made with wrong dimensions...
pitty...

So many drivers that needed simply new foam were thrown away
(or pick up :nanana: ) by professionals...

Just try to respect the original way...

Here in France, the people speak about or goes to a shop in Paris called "la maison du haut-parleur " ( the house of the loudspeaker)...
I have drivers repared there (eBay) it's a shame.... bad surround ... paper dust cap removed and changed with awful polypropilen one.... screws in the alu frame... etc...

no respect.... vintage stuff got the money value ... but also the sentimental and historical value....

Some says to put away the JBL imput terminals to upgrade quality with gold plated one...

I don't care about that...even if it is a bit the truth...
that's just no funny to do that...

the fun is to find the right grill cloth to restore the old ones...

etc etc .. :blah:

so so.... maybe forget the rubber...

and let to the pretty 4301B their terrific JBL look.....


With the looneytune method refoam, you don't need to remove the dust cap... It's so easy... you'll be happy to refoam in 2023 !

good luck to you

rutabaga

[rutabaga]

have a look at this 4301B restored...

with a rick cobb kit

http://www.audioheritage.org/vbulletin/showthread.php?t=14481