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Thread: DIY 4344 MKII using Beyma TPL-150

  1. #61
    Senior Member Ian Mackenzie's Avatar
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    Quote Originally Posted by Drummerboy2 View Post
    Ok, so lets see if I got it.

    2420 with 8 Ohm diaphrams (measure 6.0-7 Ohms) remove the 20 Ohm resistor from the network?
    2420 with 16 Ohm Diaphrams (measure 12 Ohms) leave the 20 Ohm resistor in?

    Does this rule still apply if I want to use the "Super 3145" network?

    Thank You for all the help!
    If you are referring to measured impedance YES and YES (referring to charge coupled I assume)

    The thing to understand is that a multi meter will only give you a dead or alive resistance which is always much lower than the actual AC impedance of the driver. Its only possible to measure the impedance with Clio or the Dayton Dtas or LMS.
    JBLs labelling conventions and polarity conventions have always caused confusion so don't stress.

  2. #62
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    Quote Originally Posted by Ian Mackenzie View Post
    If you are referring to measured impedance YES and YES (referring to charge coupled I assume)

    The thing to understand is that a multi meter will only give you a dead or alive resistance which is always much lower than the actual AC impedance of the driver. Its only possible to measure the impedance with Clio or the Dayton Dtas or LMS.
    JBLs labelling conventions and polarity conventions have always caused confusion so don't stress.
    Thanks, for the help and info. I wasn't really stressing, just wanted to make sure I didn't have to do anything else if the driver impedance wasn't correct. So now I think I have a better understanding of this network and drivers. so I can concentrate on ordering the network parts and can start build them while waiting for other items to come.

    I still need to receive my 2405's from Jammin Jersey. Once this is in I can start on the Front baffles and making everything is measured correctly before I start on the cabs. I still need the knobs like the originals and get some L-Pads. I'm seriously thinking of doing the external Xovers for these speakers.

    Things will start to slow down on this build due me starting a new job on Monday. So hopefully I can do a little at a time.

  3. #63
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    Some bad news on the one of the 24220 CD.

    Today I opened up the 2420 CD's to check them out. I found that they had different driaphrams as you will see in the pics, but that wasn't all I found. The one diaphram that looks after market was damaged. Good thing I bought the replacements. The foam was a little bad on one more than the other.

    here's the pics:
    Attached Images Attached Images     

  4. #64
    Senior Member grumpy's Avatar
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    Foam looks pretty typical. The broken dia just looks original and busted. The other could be from a 2421 (Al) or 2425/6 (Ti).
    Good time to refresh the insides

  5. #65
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    Quote Originally Posted by grumpy View Post
    Foam looks pretty typical. The broken dia just looks original and busted. The other could be from a 2421 (Al) or 2425/6 (Ti).
    Good time to refresh the insides
    really? I thought the diamond shaped suuround of the diaphrams was the original one and the broken was after market. If you look closely the foam that was covering the damaged diaphram says it all. Look at how the wire that connects the diaphram to the cover is going over the diapram so when it was screwed down it was resting on the edge of the diaphram, it's imprinted on the foam perfectly.

    The seller want to refund the amount of the diaphram which is cool. Everything else is in good shape.

    I guess when I replace the diaphrams in both it will be a good idea to use some masking tape and fold it with the sticky side outside and run it through the gap where the voice coil is inserted to pick up any loose particles that may rub on the new diaphram.

    Ok, the foam looks like that normally for it's age. I will be careful not to dislodge any more of it. It would be great to replace it with newer type of foam.

  6. #66
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    Take the chance and get some
    https://www.parts-express.com/radian...6-ohm--294-722
    those are quite good.
    The dia with the diamonds is the newer type, often titanium.
    The turbine pattern is the old and aluminum.
    Replace in aftermarket is also "Altec 604 802 804 806 808 904" on ebay but they look like titanium and the turbine pattern goes the other way round.

    Foam is sticky and will fall apart by touching it, any open foam or felt will do,
    just to upsorb backward reflection.
    looking for a JBL 2346 horn

  7. #67
    Junior Member GUYGELLA's Avatar
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    8 ohm version:

    https://www.parts-express.com/radian...8-ohm--294-720



    Quote Originally Posted by rogerjulien View Post
    Take the chance and get some
    https://www.parts-express.com/radian...6-ohm--294-722
    those are quite good.
    The dia with the diamonds is the newer type, often titanium.
    The turbine pattern is the old and aluminum.
    Replace in aftermarket is also "Altec 604 802 804 806 808 904" on ebay but they look like titanium and the turbine pattern goes the other way round.

    Foam is sticky and will fall apart by touching it, any open foam or felt will do,
    just to upsorb backward reflection.

  8. #68
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    Quote Originally Posted by Drummerboy2 View Post

    The seller want to refund the amount of the diaphram which is cool. Everything else is in good shape.

    Have you any idea what an original tangential diaphragm would cost..., if you could even find one?

    Tell the seller that the damaged diaphragm would cost as much/more than you paid for the driver(s) so actually, if he wants to make good, he should give you a complete refund, at least for the one.

    BTW, I have an original aluminum 2421 (aluminum diamond surround) sitting in the closet that I was able to find an original tangential diaphragm (that had been mislabled) replacement. This is in my center channel and my mains have the tangential diaphragms so I was extremely jazzed to find this one..., and for only $65.

    The seller had it in a 2425 box and listed it as a 2425. I figured someone blew out a 2420, replaced the pair, and stuck the good one in the box..., which was the case.

    Right after the sale, I got a message from the seller saying that there had been a mix-up, and this was not a 2425 diaphragm, and I could cancel the sale if I wanted. Yeah..., Right!

    I think he figured it out and recognized the true value. (Perhaps hundreds of $$$, or more, to the right buyer.)

  9. #69
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    Quote Originally Posted by rogerjulien View Post
    Take the chance and get some
    https://www.parts-express.com/radian...6-ohm--294-722
    those are quite good.
    The dia with the diamonds is the newer type, often titanium.
    The turbine pattern is the old and aluminum.
    Replace in aftermarket is also "Altec 604 802 804 806 808 904" on ebay but they look like titanium and the turbine pattern goes the other way round.

    Foam is sticky and will fall apart by touching it, any open foam or felt will do,
    just to upsorb backward reflection.
    Yes, I had already purchased the Radian 1225-16's a while back when I had purchased the 2420's just incase. Glad I did.

  10. #70
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    Quote Originally Posted by rogerjulien View Post
    Take the chance and get some
    https://www.parts-express.com/radian...6-ohm--294-722
    those are quite good.
    The dia with the diamonds is the newer type, often titanium.
    The turbine pattern is the old and aluminum.
    Replace in aftermarket is also "Altec 604 802 804 806 808 904" on ebay but they look like titanium and the turbine pattern goes the other way round.

    Foam is sticky and will fall apart by touching it, any open foam or felt will do,
    just to upsorb backward reflection.
    Thank You for the info on the foam. I just need to find some new foam and then remove the old foam. Just one more thing to do but I was already ready for this. LOL!

  11. #71
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    Today my JBL 2405H super tweeters came in. They do show some signs of wear and are missing the JBL model decals but are in good condition.
    Attached Images Attached Images   

  12. #72
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    Here are my Kenrick Lenses.
    Attached Images Attached Images   

  13. #73
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    Diaphragm replacement procedure anyone?

    I'm planning on replacing the diaphragms in my JBL 2420s this weekend and wanted to know what is the proper procedure for doing this. I have never done this before on a CD and don't want to make a mistake and cause them to accidentally rub.

    Anyone here have any suggestions on how to do this?

    I have brand new Radian 16 ohm diaphragms.

    Im still looking for some foam for the back cap. Kendrick had some but we're really expensive for the two.

    Thanks.

  14. #74
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    I would suggest that you be very careful handling the "horseshoe" clips. While they are silver grey in color, they are ferrous and will be drawn toward the magnet, right though the diaphragm, and leave a pair of "vampire bite" marks in your diaphragm.

    This is a very common mistake and you see these "bites" all the time.

  15. #75
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    Cool

    Quote Originally Posted by toddalin View Post
    I would suggest that you be very careful handling the "horseshoe" clips. While they are silver grey in color, they are ferrous and will be drawn toward the magnet, right though the diaphragm, and leave a pair of "vampire bite" marks in your diaphragm.

    This is a very common mistake and you see these "bites" all the time.
    Wow, I didn't know that! Thank You for the info! Glad I asked here!

    I did find an older thread about felt for the back cap, there was a link to McMaster-Carr for that item. I ordered it just a few mins ago.

    I'm slowly getting there with my parts and repairs!

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