KLF-20 Repairs and Upgrades. Looking for suggestions

Discussion in 'The Klipsch Korner' started by grindfix, Feb 8, 2019.

  1. grindfix

    grindfix Full time hobby Subscriber

    Messages:
    679
    Location:
    New Albany, OH
    I have a pair of Black Satin KLF-20 that are NOT consecutive serial numbers but both untouched.
    According to sticker on the tweeter horns, one speaker was made in March of 1998 or after and another one is from August of 1997. Newer one does not seem to have any issues but older one does.

    1. Mid horn cracked from threading it too far.
    2. Front (motor board?) panel is loose and wouldn't take much to remove it.

    Crossovers and drivers look identical between the speakers.

    My plan is to re-cap crossovers, repair cabinet(s), repair or replace cracked horn and soundproof both units.
    Soundproofing is where I need some advise. Foam stuffing is different between speakers and I'm sure there are better ways to silence those cabinets. I read here that people use material called Dynamat?
    Does whole inside of the cabinet need to be covered with it? Are there different thicknesses of this product?
    Before I read about Dynamat I was thinking to use foam drawer liner material from Home Depot. It is about 3/16" thick but does not have adhesive side, so I was thinking to use carpet seam tape which sticks to about anything. I'd like to hear suggestions.

    Tweeter diaphragms. Should I consider replacing them with Crites Titanium? Big difference?
    Mid diaphragms. Anything to improve there?
    Anything else?

    Thanks
     

     

    Please register to disable this ad.

  2. moray james

    moray james Super Member

    Messages:
    3,115
    Location:
    Calgary on the Bow
    you can attempt to adhesive bond your cracked horn but it would be easier to find a replacement. If the adhesive in your front baffle is problematic then in all likelihood all you baffles are the same or are going that way. You should bite the bullet and remove all the baffles and repair them once an be done with it. If you have a Dremel tool use a small drum sander with a coarse grit and remove the melamine where ever you have a joint then you can re assemble with good old white glue (PVA) which is stronger than the wood and will last forever is dirt cheap and non toxic. I won't say more than that. You can take the opportunity to install all your bracing while the baffles are all out which makes this job an easy one.
    You can apply some 1/16" thick dynamat on the back side of the mid and treble horns. If you brace your cabinet that will make it solid and non resonant. The foam inside the top portion of the box is there to damp any upper range resonance that is driven by the woofers. It is fine up there doing that job you don't need more, the woofers are damped by the reflex vents.
    Switching to the Crites Ti tweeter will be a massive improvement so do that. I also use the Klipsch Ti mid diaphragm only available from Simply speakers. to me this change transforms the speaker to a whole new level. Some think you need to mod your network to include this diaphragm I do not agree believe who you like or experiment for yourself. I have listened both with and without the network and I choose not to use the network, I also modify all my drivers but that is more than most want to do or are capable of doing. You can look to further mods after you are done with your cabinets and have hew capacitors and tweeters installed and see what you think then. You should be more than pleased when you are done as these speakers are well worth the effort.
     
  3. grindfix

    grindfix Full time hobby Subscriber

    Messages:
    679
    Location:
    New Albany, OH
    Thank you for your input!
    Would you recommend going with Crites capacitor kit or there is a better and possibly less expensive alternative?
    I already repaired cracked horn with Plastic Weld from hobby store. I will also drill 4 holes and reinforce threaded section with screws and nuts on both mid horns. I think that horn plastic shrinks with age and weight of the driver and tension of threaded nipple is too much to take.
    I was thinking to dampen backs of all horns with Dynamat as well as to line all large flat surfaces with it and get rid of original foam insulation. What do you think of that plan?
     
  4. Dingman

    Dingman Do you know where your towel is? Subscriber

    Messages:
    2,594
    Location:
    Des Moines, Ia
  5. moray james

    moray james Super Member

    Messages:
    3,115
    Location:
    Calgary on the Bow
    congratula
    Congratulations on repairing your cracked your horn. Dynamat applied to your interior cabinet walls is not going to have any effect upon wall damping because the wall panel is too massive this would be a horrible waste of time and money. If you want to deal with the walls then brace them, This will push the wall resonance up above the pass band of the woofer meaning the woofer will no longer be able to cause the wall to resonate as the wall with brace work will now have its first resonant point above any frequencies which the woofer can generate. If you want to take advantage of your dynamat then place a layer of it on the inside of the woofer basket struts.
    To brace your box use braces made from 3/4 inch plywood make them 1.5" wide. This width is already a little wider than optimum so any wider and you will not make a stiffer brace you will only take up cabinet volume which is a bad thing and you will gain no benefit so far as cabinet stiffness goes. Place a vertical brace on each side (attach the braces on the 3/4" edge) one on the top front to back (make sure to leave room for the tweeter magnet) leave the bottom alone you may need that space for an upgraded xover later and I like to place two vertical braced on the back baffle. That takes care of the vertical braces. Net you need to install some horizontal braces on the front baffle one below and above of each woofer and on the rear baffle above the vents and above the terminal cup. Finally you want to tie the side braces to each other and the front baffle braces to the rear braces.
    You can see how removing the front and rear baffles makes this a much easier job to do. You must also remember to remove all the melamine where ever you intend to install a brace.
    The caps which Bob will sell you are very good quality caps and they are all the right voltage and will physically fit the board. If you go shopping for other caps you may well end up paying more especially if you have to purchase from multiple vendors then shipping will cost you a lot and as mentioned you will need to make sure all your new parts will fit or you will incur more costs to replace them. Bob will send you great parts that fit and you will pay only one shipping charge. The caps he will sell to you are very much superior to the parts Klipsch installed stock, your call do what you think best. Hope this helps.
     
  6. grindfix

    grindfix Full time hobby Subscriber

    Messages:
    679
    Location:
    New Albany, OH
    I wonder if anyone ran into this. Two out of four woofers are not centered. Voice coil rubs badly in one and slightly in another one. I believe they came from older speaker cabinet. Their dust caps look different from the ones in newer cabinet. There is no indication that woofers were re-foamed. Am I dealing with improperly centered spider or just surround? Spider does not seem to be detached as I’ve seen in Klipsch subwoofer drivers due to basket rusting. I was able to peel off the surround from the cone and can attempt to recenter using low frequency signal. What adhesive would be recommended for this type of cone?
    I have good experience with paper cone reforming but never done poly type.
    Thanks
     
    Last edited: Feb 13, 2019 at 12:39 PM

     

    Please register to disable this ad.

Share This Page