Refurbishing 4333a

[ngccglp]

Hi,

I saw a pair of 4333As, the drivers are all in good condition. Only problem is the sound of one of the speakers come on and off, sounds like intermittent connection. But when the sound do comes on, I was blown away by the classic JBL sound. The grill cloth was also torn.

I would like to request for some advice before I commit to the purchase:

1. Are the parts of 4333A still available, so that in case if the crossover or the control switches are really damaged, I can replace them.

2. How do I clean the switches and cable binding posts?

3. Where can I get replacement grill cloth?

All advice are welcome. Thanks in advance.

David

[Tom Loizeaux]

There were many parts used in making these 4333s. Some are still available from JBL. Others can be found, used, and many from members of this Lansing Heritage Forum.
I've restored a pair of 4333s myself and came to know these very intimately (see photo at left). If you get these, I would start by cleaning and tightening the connectors (inside and out) and spray pot cleaner into the L pads.
As you progress with these steps, keep us posted on this forum and you will find a wealth of knowledge and support.

Tom

[boputnam]

Originally posted by ngccglp
1. Are the parts of 4333A still available, so that in case if the crossover or the control switches are really damaged, I can replace them.

Hey, David - welcome.

Here's a brochure on the 4333A's (4333A - Link), if that's of any help.

If you do decide to get these (you should follow Tom's advice! ), then start working on them with the Forum's help, and many here can help diagnose with you.

Grill cloth is near impossible to find (or replicate ), but let us know if you find any over there!

[ngccglp]

Dear Tom and Bo,

Thanks for the advice. I will go down to the shop today and have another round of inspection of the speakers to make sure I can pin-point the defects.

BTW, what is L pads? Is it the two knobs found at the front used to adjust the frequency?

Also, how does 4320 compare with 4333A? Honestly, I cannot bear to see these beauties fall in the wrong hands.

Thanks.

David

[lpd]

As a proud owner of 4333's I will beging to say, I tried to clean the l-pads with ill effects and decided to replace them. What a difference, real clean sharp highs and the intermittent music has ended. The l-pads are the knobs in the front upper left corner for lowering, raising mid horn and tweeter levels. I would check the condition of the foam on the bass drivers and you may have to replace it. Not impossible to repair, but I wasn't comfortable with 15 inch drivers and had a professional repair mine. Check all leads and if you really want to be anal, check the driver and tweeter to see if the wax seals are still intact (mine were).

Great sounding speaker, but will need some TLC to get up and running, as most vintage gear is.

Peter

[boputnam]

Originally posted by ngccglp
BTW, what is L pads? Is it the two knobs found at the front used to adjust the frequency?

Also, how does 4320 compare with 4333A? Honestly, I cannot bear to see these beauties fall in the wrong hands.

Firstly, , but not frequency, per se, but relative gain (i.e., "pad").
And second, well, it's easy to guess that JBL increased the numeric designation with increased engineering. IMO, you won't go wrong with any 43xx-series - but higher number seems to equate with higher "understanding" on JBL's part...

[ngccglp]

Dear all,

1. How do I remove the L Pads for cleaning? Is it from the front or rear? I notice a warning behind stating that there is a seal in the rear panel and removing them will affect the performance of the speakers. Can I replace the seal?

2. There are two panels at the rear which I can open. Which one should I open to gain access to the interior of the speakers? The outer one or the inner one?

3. One of the speakers the JBL label is peeling off and is held by masking tape. What do I used to stick it back?

4. What do I used to fill up the small opening at the cabinet joints?

I'm getting quite excited about this speaker. I have not bought it yet becuase there are still too many 'what if'.

Thanks

David.

[Tom Loizeaux]

Originally posted by ngccglp
Dear all,

1. How do I remove the L Pads for cleaning? Is it from the front or rear? I notice a warning behind stating that there is a seal in the rear panel and removing them will affect the performance of the speakers. Can I replace the seal?

2. There are two panels at the rear which I can open. Which one should I open to gain access to the interior of the speakers? The outer one or the inner one?

3. One of the speakers the JBL label is peeling off and is held by masking tape. What do I used to stick it back?

4. What do I used to fill up the small opening at the cabinet joints?

I'm getting quite excited about this speaker. I have not bought it yet becuase there are still too many 'what if'.

Thanks

David.

You don't need to to remove the L Pads to clean them.
When you get these you might want to carefully remove the woofers. You can reach the L Pads through the woofer cut-outs. The upper panel on the back holds the compression driver. If you carefully remove this panel, you will be able to see the back of the L Pads...sort-of. Spray a little burst of cleaner (made for potentiometers) into the little openings in the sides of the L Pad housings, and then rotate them all the way, back and forth.
A contact cement will re-glue JBL lables.
There shouldn't be any openings at the cabinet joints!
If the driver all work (not blown), the crossover works, and the cabinets are "restorable", then I think you have a managable project without committing to any major expense. Of course, anything can be restored, repaired or even replaced, but the cost just goes up!
Keep us posted.

Tom

[Speakertown]

Be sure to point out all the defects to the seller, so you
can get them for very cheap!.

[ngccglp]

Last but not least, based on my description of the speakers, how much do you think I should pay for them?

David

[Mr. Widget]

The market for them in Singapore will help determine that, but here in the US they would probably go for $500-$1500 depending on condition. While they are acoustically identical (more or less) to the L-300 the consumer models tend to go for much higher prices.

Good Luck!

[ngccglp]

Currently in the process of price negotiation with the dealer...I am really quite excited about the whole project.

BTW, are the speakers supposed to be placed against the wall?

David

[ngccglp]

Hi everybody,

Seems like the deal may come through. I went back to scrutinize the speakers again and these are the new faults:

1. The L Pads only works at one or two specific positions. Will cleaning solve the problem or where can I get replacements?

2. For me to clean the L pads as Tom suggested, I need to remove the bass drivers. But I noticed the bass drivers are attached to the baffle with a thin layer of 'something'. When I take out the screws, how do I lift the bass driver up?

3. When I play vocals really loud, the right mid range 2420 gives off the siblance sound that might suggest that it has already worn out and need repairs. Where can I get it repaired or replaced?

I am really impressed by the JBLs. Driven by just an old Audiolab 8000A and a cheap source, many speakers costing more just could not reproduced that kind of deep bass and air around the vocals. It is like you are there at the recording studio!

Thanks.

David

[Tom Loizeaux]

[QUOTE]
1. The L Pads only works at one or two specific positions. Will cleaning solve the problem or where can I get replacements?

2. For me to clean the L pads as Tom suggested, I need to remove the bass drivers. But I noticed the bass drivers are attached to the baffle with a thin layer of 'something'. When I take out the screws, how do I lift the bass driver up?

3. When I play vocals really loud, the right mid range 2420 gives off the siblance sound that might suggest that it has already worn out and need repairs. Where can I get it repaired or replaced?

The L pads can often be cleaned to work fine. Sometimes they need to be replaced. These are still available.
The woofers are supposeed to be resting on a flat cork gasket. If these are still stock, then, once you remove the clamps, the drivers should pull free.
You need to inspect and clean these up before you know you've got a problem that might require replacement. Diaphragms are still available for the 2420. I think they are called D162421 from JBL (they're not cheap!). We can help you with all this if you determine that you need to replace your diaphragms.

Tom

[Alex Lancaster]

ng:

You are in the process of getting a great pr of speakers; In addition to the other advice:

the D16R2421´s are better, and as mentioned, very expensive, I would try the replacement for 2425´s from P.Audio, I´m sure there is a dealer near You, I have used about 30 of them.

In pre owned speakers You might find the woofers glued on, take a real sharp razor blade, and slowly cut around it.

Congratulations!.

Alex.