Reconing Klipsch Forte II passive radiator

Discussion in 'The Klipsch Korner' started by Speedbump71, Jan 9, 2018.

  1. Speedbump71

    Speedbump71 Klipsch Guy Subscriber

    Messages:
    624
    Location:
    Dandridge, TN
    I bought a ratty set of Forte II's that need some love. One of the passives had a big chunk missing in the accordion surround. I ordered some recone kits from SS and got down to business.

    The slugs used for mass are encapsulated in glue, and the whole thing wont fit back into the cone/spider. I think I will need to cast another slug by building a little paper bowl where the spider/cone meet, and filling it up with glue like the original.

    What glue should I use to encapsulate the slugs? The original stuff still had some flex to it. Clear, yellow, rubbery stuff.

    Anybody ever done this on the Forte radiators? Help is welcomed.

    Speed
     
  2. Speedbump71

    Speedbump71 Klipsch Guy Subscriber

    Messages:
    624
    Location:
    Dandridge, TN
    OK. No help to be had. I'm gonna wing it.

    I got the first speaker disassembled, stashed the drivers in a safe spot and then tore apart the bad passive. I dug the metal slugs out of the old glue and decided I would just cast epoxy plugs that weighed what the old glueball weighed.

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    A couple of bathroom Dixie cups fit the hole in the cone just right, so I made little "volcanoes" with the cups and some black card paper. Slugs on top of black paper, 5 minute epoxy over the whole mess. Slug came out looking good:

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    Test fit into cone/spider assembly looks promising. I will get the spider/cone glued into the frame, then mix up a bit more epoxy and bond the slug to the cone/spider.

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    Last edited: Jan 9, 2018
    IndyDucati, Bigboi33 and dmckean like this.
  3. DavidF

    DavidF Active Member

    Messages:
    298
    Location:
    San Jose, CA
    It looks like you are proceeding quite well without any help from the gallery. Some good tips I may need to borrow from.:D
     
  4. Bigboi33

    Bigboi33 AK Subscriber Subscriber

    Messages:
    133
    You are very brave! I wish you the best of luck in this endeavor. I'm very curious how this turns out.
     
  5. Speedbump71

    Speedbump71 Klipsch Guy Subscriber

    Messages:
    624
    Location:
    Dandridge, TN
    Not too brave. It was already broken, so worst case I was out the cost of the kit and back where I started.

    Progress for today: I glued the spider/cone to the frame, and bonded the slug to the assembly. I left the slug a little light, so I can add epoxy over the top of the whole thing to give it a really good bond to the cone. The dustcap will cover the ugly, although the original with the yellow wood glue looking plug was no beauty queen. I put the cap and gasket on to see what it will look like finished.

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  6. 851 SP3

    851 SP3 Active Member

    Messages:
    158
    Location:
    Canton, Ohio
    I have yet to get around to doing the same to a passive I 'rescued' from a dilapidated FII. Hard to say what the original glue is. Looks like you've gotten along well with yours.
     
  7. Jirachi

    Jirachi Member

    Messages:
    64
    If all else fails, Forte III passives will work also. Roy said so himself
     
  8. Speedbump71

    Speedbump71 Klipsch Guy Subscriber

    Messages:
    624
    Location:
    Dandridge, TN
    That is good to know. I was told by my "inside guy" at Voxx that they wouldn't fit properly. Regardless, this was a $45 fix. I'm trying to decide if I should do the other one so they match, or just replace the dustcap. I have the second cone.....

    Original on left vs Recone on right:

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    Rear view of epoxy slug:

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    Front View:

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  9. mkline

    mkline Active Member

    Messages:
    108
    Location:
    Lewisburg, PA
    That passive looks exactly like the one in my SW-15. Back in the late '90s I was hearing a curious "rattle" coming from the direction of the sub. I zeroed in on the back of the sub and figured it was the passive. I pulled it but didn't find anything. Then I got to thinking about the weights in it and removed the dust cap. Sure enough they were rattling, so I dug through the yellow glue and reglued them, putting a layer of glue between each one.
    It worked perfectly. That passive eventually self destructed and I replaced it with one from Parts Express. The old sub is still working great. There is one difference to yours, mine had a rubber surround.

    Mike
     
  10. Speedbump71

    Speedbump71 Klipsch Guy Subscriber

    Messages:
    624
    Location:
    Dandridge, TN
    Odd factoid: My passives have thicker steel on one frame than the other. Almost 4 oz difference. I used the same amount of weight for each slug, and the finished product with identical cones/spiders plugs is heavier by a quarter pound on one passive.

    I will add weight to one or the other to fine tune them once i have everything mounted back up. Should just be able to sweep the low frequencies and find the tuning frequencies easily enough. I am also wondering if I should seal the cloth surrounds. They seem a bit more porous than the originals.
     
  11. Speedbump71

    Speedbump71 Klipsch Guy Subscriber

    Messages:
    624
    Location:
    Dandridge, TN
    Did a little work on the cabinets today. Decided to go with a bit of stain instead of just the oil finish to help cover any flaws. The first cabinet turned out really nice.

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  12. DavidF

    DavidF Active Member

    Messages:
    298
    Location:
    San Jose, CA
    Did you replace both cones, after all?

    I would hesitate to alter the surrounds but I understand the concern for leakage. Any added stiffness could really change the compliance on the cone assembly and work against you in the end.
     
  13. Speedbump71

    Speedbump71 Klipsch Guy Subscriber

    Messages:
    624
    Location:
    Dandridge, TN
    I did replace both cones. I am interested to see how the box tuning is changed, and if it is the same for both boxes.

    I will post more pics when I get home today. Cabinet #2 is ready for oil.
     
  14. Speedbump71

    Speedbump71 Klipsch Guy Subscriber

    Messages:
    624
    Location:
    Dandridge, TN
    OK. Speakers are reassembled. Time to be sure the recone is tuned properly for the enclosure.

    I notice that just by sweeping the frequencies from 25hz to 35hz, that I seem to get the most movement from the passive, and the least movement from the woofer about 34HZ on one side, and about 30Hz on the other. That seems pretty close. This enclosure is tuned to 32Hz right??

    Some pics of the side I am finishing up....

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  15. Sound Dragon

    Sound Dragon AK Subscriber Subscriber

    Messages:
    1,089
    Location:
    Valley Stream. NY
    Looks good. How's the sound?
     
  16. Speedbump71

    Speedbump71 Klipsch Guy Subscriber

    Messages:
    624
    Location:
    Dandridge, TN
    They sound like Forte IIs. I have had a few pairs of Chorus/Forte I's and II's.

    I do like these very much, but both my Chorus and my Fortes were displaced by the Ohm Model I's behind these in the pics. I had this set out in the shop and needed some space so I decided to finish them up.

    It seems like the Simply Speakers recone kits get you pretty close to the original. The surrounds are a bit more porous than the originals, but with all of the torn Forte/Chorus passives out there I thought this was a worthwhile exercise.

    I'm not sure I can hear the difference in the tuning between the two sides, so they are likely to stay as is.
     

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