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brianlun
08-31-2006, 11:33 PM
hello to every members in this forum :) ( I love this forum. it keep teaching me a lot of thing about jbl ) My name is Brian I,m a diy newbe & a former 4425 owner (sold my 4425 11 years ago, big mistake! I miss jbl sound very much .) lucky or not. i got a pair of unknow condition 4333a from a lady neighbourhood ,she said the speaker was in working condition many years ago. now I would like to test the speaker is it in working order ( the woofers doesn't have any edge foam, it all fall off ), should i hook it up to try? i have a cheap mini stereo, but I"m afaid I might blown them all up :blink: should I call tech service frist ,any recommend ? please help & wish me luck

speakerdave
09-01-2006, 12:08 AM
hello to every members in this forum :) ( I love this forum. it keep teaching me a lot of thing about jbl ) My name is Brian I,m a diy newbe & a former 4425 owner (sold my 4425 11 years ago, big mistake! I miss jbl sound very much .) lucky or not. i got a pair of unknow condition 4333a from a lady neighbourhood ,she said the speaker was in working condition many years ago. now I would like to test the speaker is it in working order ( the woofers doesn't have any edge foam, it all fall off ), should i hook it up to try? i have a cheap mini stereo, but I"m afaid I might blown them all up :blink: should I call tech service frist ,any recommend ? please help & wish me luck

I would suggest you do not try to use the woofers with the edgefoam gone. It is a relatively inexpensive job to replace the foam, but without the surround the woofer cone is tilted and if used the voice coil may rub and become shorted out. If that happens you will need to replace the whole cone/voice coil assembly, a much more expensive job. You should, however, give the woofers a continuity check to determine that the voice coils work before you go through the trouble and expense of refoaming them.

If you are handy it is possible to refoam the woofers yourself, but it is also possible to have them done at a shop. Try to find a shop that does JBL work conscientiously. If the woofer cones (2231) are the original cones (they probably are) I would advise you to not let anybody persuade you to 'update' to a 2235 recone because although it makes somewhat better bass it is not a good match to the original in the midrange. This is my opinion and the opinion of some others (but not all) on this forum who have owned this speaker and tried the change. I prefer the original cones.

If the speakers were used in a private home and have been in decent storage since being taken out of service it is very unlikely there is anything else wrong with them besides the foam (the foam rot was cause enough for many people to stop using their speakers). These speakers are a great find and will provide many enjoyable hours of listening. Use the search function in the tool bar above to search for 4333, 4333A and 4333B and you will find lots of reading in the earlier LH forum threads about this speaker.

David

brianlun
09-01-2006, 02:09 AM
Nice to meet you David:) . You just stop my dum move, thanks. but how can i find out my woofer is still in working order can be re-edge . I did try some test use my finger gentlely pass the dust cap, one woofer cone is still moving ok,smoothly bouncing, but the other unit is not, the voice coil is not in the central ,feel a little bit of scartch ,not bounce much , is that unit blown before? or it just not align? can it repair ? please help .

speakerdave
09-01-2006, 09:19 AM
Nice to meet you David:) . You just stop my dum move, thanks. but how can i find out my woofer is still in working order can be re-edge . I did try some test use my finger gentlely pass the dust cap, one woofer cone is still moving ok,smoothly bouncing, but the other unit is not, the voice coil is not in the central ,feel a little bit of scartch ,not bounce much , is that unit blown before? or it just not align? can it repair ? please help .
I wouldn't push on the dust cap. You'll end up with a dented dust cap. If you must push on the cone assembly at all push on the cone near the dust cap.

But I would try to avoid doing even that. As you say, you hear a "scratch", but you do not know if that means the voice coil is bad or if the cone is misaligned. If you are doing this with the woofer in the speaker and the speaker standing upright chances are (the surround being gone) the cone is misaligned.

Lay the speaker on its back. To make it easier to get it upright again the best way is to have it on a hand truck and lay the hand truck down with the speaker on it. If you don't have a hand truck place some old thick books or something similar on the floor to catch the back of the speaker top when it's lying down so you can get your fingers under it when it comes time to pick it up. If you are not working on a carpeted floor, put something under the speaker to pad it so you are not dinging the corners and edges as you roll it around.

To test the continuity of the voice coil get a multimeter (can be purchased inexpensively at Radio Shack and other places) that has the capability of testing DC resistance. Remove the woofer mounting clips. Place a small piece of cardboard or an old paperback book on the baffle next to the woofer so you can set the woofer on it without marring the baffle or the back of the woofer. Lift the woofer out of its hole and set it on your pad. Note how the wires are connected and disconnect them. Use your meter to check the DC resistance of the coil. An 8-ohm voice coil typically shows between 6 and 7 ohms direct current resistance. If resistance is infinity the voice coil is open; if it is zero, or much less than 6-7 ohms it is wholly or partially shorted.

You also should check to see if the cone has been hanging out of position for so long that the spider has become permanently torqued. With your fingers gently hold the edges of the woofer cone in the position you think it will be in when the new edge is in place and examine the spider. You may need to hold a small penlight in your teeth to see in there between the woofer cone and the frame. If the spider looks high on one side and low on the side opposite, it is distorted and neither the movement of the voice coil in the gap nor the damping provided by the spider will be exactly right, and you may want to consider having the woofers reconed.

David

John
09-01-2006, 04:57 PM
Are these the 4333A that just sold last weekend on ebay from the left coast of Canada?:blink:

brianlun
09-02-2006, 03:45 PM
Thanks again David. just check the woofer spider this morning .it's doesnt look level flat, its a little bit sit back like a wide v shape. & i did trid hold the woofer in the new edge position, the spider both side havent look side high & side low. I'm think im agree the spider( voice coil too?)really has been permanently torqued. can the service shop fix that problem ?

speakerdave
09-02-2006, 05:25 PM
There might be some shops that would attempt it, but I wouldn't suggest you try it. The cost to you for labor begins to be unreasonable for a patched-together woofer. JBL supplies its recones as an assembly--the cone, voice coil, spider and surround all together, and does not support partial replacements (not even surrounds, actually).

On the other hand, if the spider is not twisted, but is only slightly depressed, I'm not so sure I would get the woofer reconed. I personally would be inclined to refoam and let it go at that.

David

brianlun
09-02-2006, 08:03 PM
Hello David. is it the only thing I can try is re-edge? give the cone some surround support then test it again? if the cone problem is just not align ,does it made hum noise only when it sing ?can that cause damage to the other speaker parts (crossover ? woofer itself ? ) and I had heard some info( i dont know is it true, but it sound logic) its about some age woofer drive ,when it made noise, what we do is turn the unit up side down 180 degree, the cone will back to normal ? am i facing that tricky problem thing ? wish me luck.

speakerdave
09-02-2006, 09:30 PM
Nice to meet you David:) . You just stop my dum move, thanks. but how can i find out my woofer is still in working order can be re-edge . I did try some test use my finger gentlely pass the dust cap, one woofer cone is still moving ok,smoothly bouncing, but the other unit is not, the voice coil is not in the central ,feel a little bit of scartch ,not bounce much , is that unit blown before? or it just not align? can it repair ? please help .
About two years ago I was fortunate enough to come across a pair of 4333A's that were in good condition except the foam surrounds were rotted off the woofers. I installed new surrounds and have been listening to them happily ever since. I suggest you do the same and cross the next bridge when you come to it.

David

norealtalent
09-02-2006, 10:02 PM
...On the other hand, if the spider is not twisted, but is only slightly depressed, I'm not so sure I would get the woofer reconed. I personally would be inclined to refoam and let it go at that.

David

I would be inclined to refoam. Not only do you want to maintain the original coils for proper midrange integration but more importantly, you need to keep both woofers balanced. If you recone one to 2235, you really should do them both so they match. I bought a pair of 4333's that somebody had reconed only one woofer and they didn't sound the same. I MEKed the spider and pulled the cone to install a 2235 for a proper match. I have one pulled 2231 cone if you get in a jam.

Good luck, Dave :)

brianlun
09-02-2006, 10:04 PM
:) I'll keep trying. It' look a bit complicate for me. but I still hope the process made a good lesson experince for me .

speakerdave
09-02-2006, 10:29 PM
:) I'll keep trying. It' look a bit complicate for me. but I still hope the process made a good lesson experince for me .

Please understand, I've been working with my hands from a kid and feel confident about taking on many projects, but I don't try things that I'm not sure about, especially if it involves delicate and expensive stuff. So, unless you have a background in working with your hands, or making models or something, you should find a shop to do the work for you. When I say "refoam" I mean do it or have it done for you.

Try to find a shop that is experienced with refoaming JBL woofers and make them explicitly promise you they will not glue the new foam to the front of the cone.

Where are you? Perhaps we can help you find a shop near you. You could always send your woofers to LH forum member edgewound, who does factory authorized JBL service and does good work.

David

brianlun
09-02-2006, 10:54 PM
Yes;) , I'll go to a authorized JBL service for sure. because not much skill I have for now .