Kairos Speaker Build

Discussion in 'Audio Visual' started by Eclipsor, Sep 10, 2018.

  1. Eclipsor

    Eclipsor Member

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    I decided at the start of the year to build some speakers. I'll post updates here as I go.

    Planning:
    My only previous experience was assembling a LSK M4 kit probably 12 or so years ago. So not a lot. After spending many hours researching plans and kits I decided on the Kairos bookshelves from Meniscus Audio in the USA.

    After some pretty poor initial communication from Meniscus I eventually managed to place the order for the parts and plans. I opted for the "premium" parts upgrade, unassembled crossover and they also left out the drivers for me to keep shipping down a bit. I was able to order the drivers from WES components for cheaper through work anyway.

    I also got the woofer kits so that I can build them in the future too.

    I decided to go with the recommended materials of 18mm MDF, 12mm ply for bracing (I used marine since birch was too expensive) and 25mm MDF for the front baffle (I laminated 18mm and 9mm so I didn't have to buy a whole sheet of 25mm). I would have liked to go with birch ply all round, but that shit is expensive!! And I knew I'd probably make too many mistakes.

    Workshop Prep:
    Before I started making the speakers first I had to setup a workshop. I moved into this house last year, so haven't had a lot of time to set up any kind of work space so far. I also had to acrue most of the tools that I'd need since I haven't really done any woodworking before.

    In this photo you can see:
    - All hardwood Gumtree workbench for $50. Awesome score. I added the shelf underneath.
    - Added the big shelf up on the left for storing sheets and other stuff
    - Ozito track saw. This has since been returned for my money back. It was pretty horrible to use and faulty.
    - Ozito wet and dry vac. So far as been pretty great.

    [​IMG]

    In the photo below:
    - Triton table saw that I've since moved on. It was too annoying to use. Not really suitable for accurate results.
    - More storage added
    - Made a cutting table/portable workbench to take outside if needed
    - Scored a router and laminate trimmer from my brother who doesn't have space to use them

    [​IMG]

    Now this is what I'm talking about!! Finally found a nicer table saw second hand for a reasonable price. More lighting added along the way too.

    [​IMG]

    Made a crosscut sled for the saw:

    [​IMG]

    Made a tenon cutting jig for the crosscut sled:

    [​IMG]

    The saw didn't come with a mitre gauge, so I made one of them too for doing the angled crosscuts:

    [​IMG]

    So after a few false starts (particularly with crappy tools), now I could actually start making the speakers!!! To be continued...
     
    Last edited: Sep 10, 2018
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  2. OP
    OP
    Eclipsor

    Eclipsor Member

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    Even with a half decent table saw with a heavy top and a wide cutting capacity, breaking down full 1.2 x 2.4m sheets of 18mm MDF is hard. So I rough cut with the handheld circular saw first.

    With the prep work of the crosscut jig done, cutting down the rest of the panels was fairly straight forward and quick.

    The angled cuts for the front of the side panels I did with the handheld saw and finished with a flush trim bit on the router and a straight edge.

    Rebates I cut with the table saw using multiple passes, and the rebates for the corner joins were cut using the tenon jig pictured above. I had to finish these with a chisel though as my blade isn't a flat kerf one. So leaves little bunny ears in the rebates.

    I'm not going to lie. The joints aren't the best. I think I'd do a better job second time around, but hopefully they'll hold.

    All panels cut:

    [​IMG]

    Test fitting before I cut the braces and before doing any of the angled crosscuts for the front. Starting to actually look like something:

    [​IMG]

    Internal bracing cut out with a jigsaw. Edges rounded over with the router. You'll see the first major mistake I made here. The horizontal braces should match up with the solid bit in the vertical brace. I'm not too concerned. The amount of total cutout is correct, so internal volume isn't really affected. Vertical brace still to be trimmed to final height here too.

    [​IMG]

    [​IMG]

    Laminating the 18 to 9mm MDF for the baffles. These are cut oversized and glued with one straight side protruding from the rest. This makes it easy to do final cuts on the table saw:

    [​IMG]

    Baffles, trimmed and top/bottom angle cuts made. Test fitting:

    [​IMG]

    Spent some more time with test fits and some final trims. Here's the bits for one ready to start glueing:

    [​IMG]

    First glueing done. Top, bottom, sides and vertical brace done first. Back piece is placed without glue to help keep it square. Need to get some better clamps. I broke two doing this haha.

    [​IMG]

    Meanwhile, I started assembling the crossovers. Zippys for holding the heavy parts:



    RTV sealant adhesive used to help reduce vibration and glue down the resistors:
     
    Last edited: Oct 8, 2018
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  3. newynut

    newynut Member

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    Wow nice.
     
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  4. Hi-end Head

    Hi-end Head Member

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    This is not a criticism , just a question. At what point do you intend to cut the Baffle for the speaker inserts, and do you intend to surface mount or inset the speakers.

    I see by your photo's it would appear that the front baffle is simply glued, to the front edges of the cabinet, It is really advisable to double the thickness of the front baffle, By way of having another sheet of MDF, [ Hardwood would be far better ] cut to the exact size of the of the internal dimensions. This not only improves the sound it also helps stabilise the drivers in the cabinet.

    You haven't said what drivers you are using. Really when you go to that amount of trouble with the cabinets, it pays to use the best drivers available. Might I suggest you look at WES [ with ABN business account ] or Wagner [general public ] for suggestions on what's available
    https://www.wagneronline.com.au/5-bookshelf-speaker/speaker-kits/audio-speakers-pa/3269/fl/

    It would be a shame to go to all that work , and then use cheap Chinese speakers
     
  5. Stooge007

    Stooge007 Member

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    OP already got drivers from WES
     
  6. DangerMaus

    DangerMaus Member

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    The baffle is already thick enough from the look of it, especially for a relatively small cabinet. He's laminated two sheets together 18mm and 6? or is it 18 and 9? 18mm is fine for most speaker builds, you might want 25mm on wide panels. If the baffle is too thick you have to chamfer the back of the driver cutouts. MDF is better than hardwood for cabinets and baffles in most cases.

    If you mean that the baffle should "plug" into the front of the cabinet it does look like it's rebated to allow for that.

    He has said what drivers he's using, theyre in the link for the kit he chose.
    • Satori, TW29R, Ring Dome Tweeter
    • Satori, MW16, 6.5″ Papyrus Cone Woofer
     
    Last edited: Sep 11, 2018
  7. Hi-end Head

    Hi-end Head Member

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    The OP also said he was buying the drivers from WES, and WES don't retail the Satori brand. I read all there blurb, typical American hype. An example of that is there driver discription, " Papyrus cone drivers" Normal people would simply say "Paper" cones. The OP is a wise man, buying from WES.

    I really don't want to get into an argument about the use of MDF, But the reason it's used, extensively in speaker construction is the cost factor, and the fact is readily available, and easy to use. Unlike hand built cabinets made from selected hardwoods. Of cause it does not need to be said the the cost factor of hand built high end manufacturers is a major consideration. Of cause budget brands all use MDF, which keeps the cost down and some manufacturers get outstanding results
     
  8. OP
    OP
    Eclipsor

    Eclipsor Member

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    Thanks for the other replies to some of these points. I'll be cutting the speaker holes before attaching the baffles to the box. Much easier to use the router while I can lay the flat. The plans from the kit I linked are quite detailed and being my first build I'm sticking pretty closely to these (apart from avoiding mitre joins). So based on these I'll be flush mounting the drivers.

    As I mentioned above regarding the baffles. The photo is just a test fit for the outer dimensions. They will be rebated slightly into the cabinet. This was probably the most complicated part of the cutting since everything is on an angle.

    I looked into hardwood for the baffles, I even bought some beautiful slabs of silver wattle to use, but decided against this. From everything I read unless you've got access to some very old and dry timber, using solid hardwood can be fraught with issues due to expansion and contraction. This is made worse by using it in thicker and larger slabs. Especially when combined with flush mounted metal drivers which don't contract with it.

    There seems to be equal people who have had success, and those that have had splits. Local climate can also play a part. Some use trickier techniques like using screws rather than glue and elongating holes to allow for expansion. Also allowing for expansion in the driver holes too.

    Either way, MDF is much more stable and cheaper for me to stuff up. It is specified in the design too, although I've gone slightly thicker at 27mm (18 + 9). I'll probably be chamfering the inside of the driver holes. I'm hoping the 18mm plus fairly generous bracing will be enough for the reset of the cabinet to be solid.

    I've ordered a sheet of wattle veneer to finish them.

    As mentioned by DangerMaus the drivers and and crossovers are specified in the plans linked. Definitely not skimping on the drivers.

    The Kairos design and the SB Accoustics Satori driver line are fairly well established and highly regarded so I'm not really doing much guess work there. It really just comes down to how good my workmanship is I think.

    Gorgeous drivers waiting patiently for their time to shine:

    [​IMG]

    Glued up the second cabinet this morning:

    [​IMG]
     
    Last edited: Sep 11, 2018
  9. DangerMaus

    DangerMaus Member

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    Hardwood won't expand or contract that much if it's seasoned properly, over the width of a normal baffle the movement isn't really that bad. The issue is that each material has a resonance and hardwood resonates at a higher amplitude and frequency than MDF.

    MDF is used because it is a stable, consistent and relatively dead cabinet material, the low cost is a bonus. It's used in plenty of high end brands, sometimes layering MDF and HDF.
     
    Last edited: Sep 11, 2018
  10. Hi-end Head

    Hi-end Head Member

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    SB Acoustic brand speakers are there low end budget brand, Do all there Tweeters come with dented centre cones. I don't understand why you would spend all that time and care and then buy
    shit cheap drivers. While I'm not suggesting you use Scanspeak, The Vifa tweeters are very good as are Peerless
     
  11. DangerMaus

    DangerMaus Member

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    So you want him to scrap the crossover and try to design his own?

    Just build it, enjoy it. You'll catch the bug and upgrade or make more speakers later :p.

    Jasper circle jig will help unless you've already built your own. Your work looks good to me, just make sure it's all staying square when you're clamping it down.
     
    Last edited: Sep 11, 2018
  12. OP
    OP
    Eclipsor

    Eclipsor Member

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    Yeah fair enough. The pieces I got are still moving so would have needed much more drying time. I didn't have a simple way of flattening them either so MDF was the simple choice.

    I bought another brand circle cutting jig. Will be giving it a go soon on some scrap.
     
    Last edited: Sep 11, 2018
  13. Hi-end Head

    Hi-end Head Member

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    The amount of so-called movement would not be measurable. I'm fortunate in the fact I live in an area where huge amounts of hardwoods where milled in the past and there are still some sawmills working, extensively with hardwoods. I can buy at a low cash price were-as should I have to buy retail, the costs would blow out.

    Here's a small example of a near finished cabinet [​IMG] [​IMG]
     
  14. DangerMaus

    DangerMaus Member

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    So-called movement? Timber expands and contracts. It's a fact.

    You would have been better off forming plywood or MDF for the curved sides. The woofer cutouts need the backs chamfered, at least in a flower petal pattern around the screw holes. Do you have internal bracing of the sides? Do the panels have any lining, deadening material? Any filling? The sides extending past the baffle would be producing some diffraction and lobing issues.


    Keep them out of the sun.
     
    Last edited: Sep 11, 2018
  15. OP
    OP
    Eclipsor

    Eclipsor Member

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    lol. Obviously you and I have different concepts of cheap. I'm already a little uneasy with how much I've spent on this as a first project. I thought I was really splashing out by even using timber rather than foamcore. :lol:

    Given the plentiful reviews of this design I'm reasonably confident that I'll improve on my little B&W's. Which I've pre-emptively sold to pay for more materials. haha
     
  16. sebbyreddan

    sebbyreddan Member

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    Has someone pushed the dome of the tweeter in?
     
  17. DangerMaus

    DangerMaus Member

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    It's intentional, ring radiating design without the nipple or spike.
     
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  18. sebbyreddan

    sebbyreddan Member

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    Oh, ok. Though it looked uneven hence my thinking it was pushed in.
     
  19. oculi

    oculi Member

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    just make one out of 6mm plywood
     
  20. DangerMaus

    DangerMaus Member

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    The lighting in that pic makes the dimple look wonky.
    [​IMG]
     
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