Renovation of my KLH 17's is complete (long)

Discussion in 'Speakers' started by specialidiot, Feb 23, 2007.

  1. specialidiot

    specialidiot Break Glass, Smoke Lucky Subscriber

    Messages:
    10,029
    Location:
    Mendota Heights, MN
    A couple of weeks ago I won an ebay auction for a pair of KLH Model 17s. The price was quite cheap, and the seller charged actual shipping so my cash outlay was about $45 shipped. Unfortunately, the speakers sounded like crap when I gave them their first listen. No highs at all, what sound was there was quite muddy. To make matters worse, the seller taped directly to the cabinet and they looked like crap. Luckily there was no cabinet damage and to my surprise were built from solid walnut.

    A quick check on the AK forums indicated that they were definitely worth rebuilding. So began my first speaker renovation project.

    I used to work as an electronics tech in the early 80's, and my wife generously assesses my tinkering around the house skills as "handy", so I looked forward to this effort.

    The first step is to approach the speaker in a confident manner. Here's the subject:
    [​IMG]

    Remove the KLH badge and set it aside for later
    [​IMG]

    Carefully remove the grill. Mine was fastened by velcro, I've heard of them being glued on too. The grill is a thin piece of fiber board - like peg board without the holes - that has the speaker openings cut out and the grill cloth stapled to the back.

    I used a 1-1/2 inch flexible putty knife. Use a towel where the knife meets the cabinet.
    [​IMG]

    Once you can get your fingers under an edge, just start lifting it out
    [​IMG]

    remove the screws from the tweeter
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    catch a fingernail under the tweeter and lift it out. Yep, that's fiberglass insulation in there!
    [​IMG]

    Label the wiring as you remove it. Failure to do so could cause some head scratching later
    [​IMG]

    remove the wirecaps, set them aside for later, unsolder the leads, and put the tweeter in a safe place. I tested mine out with a sine sweep file provided by spkrdood. Make sure you put a 10MF cap in series with the positive lead of the tweeter to block the lower frequencies. Thankfully both of the tweeters worked great.
    [​IMG]

    Remove the 8 screws holding in the driver and pull it out
    [​IMG]

    One thing I forgot to take pictures of and thanks to AK'r neilsvanm2, I've added this part in. The drivers have cloth surrounds, not foam. The good news is that cloth doesn't disintegrate like foam, but it does need to be re-sealed. I used some standard household latex caulk, thinned with 2 parts water. I used a glue brush and real lightly coated the surrounds. I then set the drivers aside for a couple of days as I waited for my parts to come in.

    There is a piece of black fabric under the woofer, looks kinda like a shroud to me. Remove it and set aside for later. Label and unsolder the red and black wires
    [​IMG]
    [​IMG]

    Here's the cabinet with the tweeter and driver removed, wires labeled.
    [​IMG]

    Put on some gloves and remove the blocks of insulation. A paper shopping bag is large enough to hold the stuffing for one speaker. Put the "shroud" in the bag too.

    When you get the stuffing out, you can see the crossover (XO) mounted to the back of the cabinet.
    [​IMG]

    Remove the tape holding the XO together, make note of how the caps are connected. Note that these are some type of dual caps. The black lead is common, and the red lead goes to each side of the 2 pole switch. The switch lets you set how much high frequency you want to pass to the tweeters.
    [​IMG]
    [​IMG]

    Part two coming up
     
  2. specialidiot

    specialidiot Break Glass, Smoke Lucky Subscriber

    Messages:
    10,029
    Location:
    Mendota Heights, MN
    Part two

    Here are the old and new caps side by side.
    [​IMG]

    I purchased the caps from Parts Express at http://www.partsexpress.com. It only took 3 days for the caps to arrive, and I added in a few other items I needed too.

    Here's what I ordered:
    027-414 DAYTON DMPC-2.0 2.0uF-250V PO .. qty 4 $1.52 ea.
    027-421 DAYTON DMPC-4.0 4.0uF-250V PO .. qty 4 $1.85 ea.

    Here is the reassembled crossover with the new caps. I used hotmelt glue to fasten the double caps. Note that the two 4MF caps are in parallel, giving a total of 8MF.
    [​IMG]
    [​IMG]

    Solder and wirecap the tweeter leads, and put it back in it's place
    [​IMG]

    Before you put the driver back in, its time to put the stuffing and shroud back in place. Don't forget the gloves.
    [​IMG]
    [​IMG]

    Solder in the driver leads, and mount it back on the cabinet with the 8 screws that you haven't lost.
    [​IMG]

    With any luck, here's how it looks! Note that I cleaned and oiled the cabinets.
    [​IMG]
    [​IMG]

    Just a couple of steps yet. Since the cabs were filthy, I figured the grills were too. They were in perfect shape, so instead of replacing the grill cloth, I used a fabric cleaner to freshen them up. Screw the logo back in place and you are DONE!
    [​IMG]

    Here are a couple more shots of the finished product.

    [​IMG]
    [​IMG]

    I must say that I'm VERY pleased with how these turned out. Total time invested was about 4 hours, including taking pictures. I've moved them up to my home office, driving them with my Marantz 1060 being fed by iTunes via a dbx 3BX-DS. I had planned on selling them, but oh my they sound mighty nice!

    I've listened to a nice variety of music as I've put this together. I hope someone can find this post useful and maybe it will inspire someone to take on a project like this themselves.
     
  3. nielsvanm2

    nielsvanm2 Active Member

    Messages:
    411
    Location:
    Guelph, ON
    Nicely done! I'm on the verge of doing my KLH 20's, which are the same as 17s but 4 ohm. I've heard they're sweet sounding speakers. The only other thing you might want to do is re-dope the surrounds. Seems like they need it after 40 odd years.
     
  4. specialidiot

    specialidiot Break Glass, Smoke Lucky Subscriber

    Messages:
    10,029
    Location:
    Mendota Heights, MN
    Uh, yeah I forgot - I DID THAT! I thinned some latex caulk with water and brushed it on real lightly, and let them dry for a couple of days while my parts came in.

    Thanks for reminding me..... I've edited the post to include that step - but no pictures.
     
    Bdbras84 likes this.
  5. jpdylon

    jpdylon non-active member...

    Messages:
    7,275
    Location:
    LaMesa (San Diego)
    Those look fantastic.

    Enjoy them. one of KLH's great bookshelfs
     
  6. dshoaf

    dshoaf That high voltage buzz

    Messages:
    9,605
    Location:
    Santa Cruz, CA
    Very nicely done and well documented, too. That should help others who have been thinking about stepping up to redo a set of speakers.

    I've got a set of KLH Model 5's that I redid with surprisingly excellent results much as you report with your 17s.

    So, what's the next project? I can tell you these sorts of projects get addictive by themselves.

    Cheers,

    David
     
  7. cubdog

    cubdog banging through drywall Subscriber

    Messages:
    21,167
    Location:
    Oregon IL.
    Thanks for documenting your project. They look great.

    cubdog
     
  8. specialidiot

    specialidiot Break Glass, Smoke Lucky Subscriber

    Messages:
    10,029
    Location:
    Mendota Heights, MN
    Indeed - there is a high payback for relatively little effort. I may have vastly over estimated the amount of time spend on this one, too. I probably spent 2.5 - 3 hours total.

    My next DIY is to build a panel to mount to the back of my desk that I can mount my cable modem, router/wireless AC, Vonage router, mess 'o cables, and all the other junk that is on my floor. Sorta audio related I guess, since I'll have my audio system stuff there too.
     
  9. gkarelitsky

    gkarelitsky AK Subscriber Subscriber

    Messages:
    1,381
    Location:
    Ridgewood, NJ
    Great job. I'm sure you'll enjoy them all the more.

    I have a pair that I picked up from the curb that sound decent as is but the cabs are trashed. Someday I may tackle them.
     
  10. Urizen

    Urizen Lunatic Member

    Messages:
    25,705
    Excellent post on some fine sounding classics. Apart from the Model Six, these are (IMHO) the best sounding classic KLH.

    My restoration was very similar to yours. They are keepers, that's for sure!

    [​IMG]

    [​IMG]
     
  11. Ausjoe

    Ausjoe Super Member

    Messages:
    3,408
    Location:
    South of the Colorado, Texas
    Great job on the speakers. I've got 2 pair waiting for me to recap. Few things I'll add for anyone else. The shroud is to keep fiberglass from the drivers so shake it out and mark the front side. I wouldn't store it with the fiberglass to keep one side as clean as possible. Anal maybe but fiberglass and paper don't mix. I'd suggest water based silicone caulk , not the vinegar smelling kind. That's acetic acid which while I don't know the effect would worry me a little. Most people don't change out the sandcasters with some mills resistors but since I hate fiberglass I might. Did you mention replacing the mordite and foam My foam is trashed. Lastly these were voiced back in the tube days. A tweak by BoldEagle over on AA was to run a 1? ohm resistor to the speaker taps to smooth out the highs if my memory is correct. You made such a good start with your post that I was inspired to add this in the hope it would help someone else out. Anybody else want to share?
     
  12. OMI

    OMI Super Member

    Messages:
    1,981
    Location:
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    NICE!!!

    I am "electronically" challenged, so the more pictures the better... As long as I can see what folks have done I can do it also...
     
  13. Urizen

    Urizen Lunatic Member

    Messages:
    25,705
    I have tried this tweak, and it only works on amps with capacitor-coupled outputs. It does help a little, the effect is subtle.

    On direct-coupled outputs, the effect is null, other than lowering the volume some.

    I used 1/2 ohm resistors in series with the neg speaker tap.
     
  14. Eunomians

    Eunomians Diggin' 4 LP's Worldwide Subscriber

    Messages:
    1,506
    Location:
    SoCal
    What a great thread. Thank you for the step by step detailed pics.

    And nice speakers by the way!

    Best regards & happy listening :music:
     
  15. specialidiot

    specialidiot Break Glass, Smoke Lucky Subscriber

    Messages:
    10,029
    Location:
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    Well thank you!

    and I have been listening to them all weekend. The sound has mellowed and become more balanced.

    They are going to have to stay.
     
  16. PoppaSteve

    PoppaSteve Your what hurts?

    Messages:
    567
    Location:
    Woodbury, MN
    This should be a sticky.

    Great photos and clear instructions. This would be an inspiration to any number of us who want to tackle a speaker rebuild.

    Thanks for sharing that with us.
     
  17. joelongwood

    joelongwood No more room at the inn

    Messages:
    875
    Location:
    Wading River, LI, NY
    My sentiments exactly............a truly GREAT thread! :D
     
  18. pmsummer

    pmsummer simul justus et peccator

    Great looking (and now great sounding) speakers! Really great pics, too.

    Note to self: Get those KLH 23s out and get to work on them.
     
  19. dat521gatherer

    dat521gatherer current projects

    Messages:
    92
    Location:
    tacoma,wa
    exellent now i can recap my 17's. great pics. those are the cleanest/nicest model 17 woofers i've ever seen. cabs are clean too!!
     
  20. wiredbecker

    wiredbecker AK Subscriber Subscriber

    Messages:
    1,937
    Location:
    Albany Landfill, CA
    Great thread. Totally takes the fear out of recapping the 17. I was wondering what the guts of the 17s at my local thrift looked like. I tested them in the store and they obviously need a recapping. I may go back and get them if they're still available.
     

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