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Passive radiator subwoofer and two way in one enclosure

Archer60xArcher60x
in DIY
This is my current project.

I picked up some passive radiators and a DVC driver that matched them.  I did some initial testing in a test box to see how the radiators worked with the driver. Some of my findings are here.

So as i kept looking at these radiators and drivers and the shape they made.  I thought this would make a good tall speaker.

I remembered seeing someone doing kerf cuts to bend sheets of wood so i wondered if MDF would be a good candidate for it.  It ended up working really well!  I placed kerf cuts at the areas that needed to bend.  The baffle will be hardwood of some kind.  I will cover the MDF with a wood veneer or paint it.

Right now the plan is to use a plate amplifier to power the DVC driver for subwoofer.  Then i need to come up with a tweeter and about a 7" driver for the two way side of it.

This box kind of came before the two way drivers.  So we will see what i can find that will work well in this volume.  If anyone has a two way design using about a 7" driver and tweeter let me know.

Thanks for reading!
Chad


D1PP1NGowadynamo

Comments

  • D1PP1ND1PP1N
    Looks great. I like the overall design. 
  • ThumperTomThumperTom
    How are you guys calculating the curf.  Are you adding up the angle of each cut and depth to reach the desired angle?
  • Archer60xArcher60x
    I am not sure what you mean.  Kerf is the thickness of the saw blade.  I knew my tightest radius was the top portion.  So i did a test board to figure out the spacing between cuts.  You can see on that 1/2" MDF it is about 1/4 of an inch between each kerf cut.  I found this good video on the process.  
  • Tom_STom_S
    This seems a lot easier than bending sheets of 1/8. I've played around with kerfs on scraps of mdf and was surprised it didn't break. Do you plan on filling the slots to increase rigidity?
  • tajanestajanes
    thanks for posting this, very interesting
  • GowaGowa

    Kerfing Plywood Jintani Speaker Project


    Archer60xjholtz
  • Archer60xArcher60x
    Hi Tom, Yes you cannot really tell from the pictures, but i used Bondo in the kerf cuts.  I did not use enough to fill all of them.  It started drying faster than i expected.  So i am going to go back and add some more bondo where it is needed.   --Chad
  • rjj45rjj45
    Mother-effer that's a pretty sweet design/build!
    I just did my first kerf project with 18mm Baltic Birch ply. Used Gorilla glue to fill the kerfs, and had some problems filling all the voids, but resulted in a very strong bend.
    But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
  • rjj45rjj45
    ThumperTom said:
    How are you guys calculating the curf.  Are you adding up the angle of each cut and depth to reach the desired angle?
    I've heard (Javad S) that there are kerf bend calculators on the web, but I haven't found any.
    You've got to play around with some scraps to figure out spacing and depth.
    If the depth is not enough, bending is really difficult - if the depth is too deep, you will get cracking or splitting.
    I found that about 1 1/2 layers of Baltic Birch worked well for me. One nice aspect is that once you have your jig set up,
    the cuts can go very quickly.You will need some strap clamps to make the bends on your production box.
    Hope this helps.

     
    But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
  • dcibeldcibel
    edited March 2019
    rjj45 said:
    I've heard (Javad S) that there are kerf bend calculators on the web, but I haven't found any.

    I didn't find it hard to find on the web:

    First result:

    In any case, it doesn't look like Chad did any calc to determine the bend radius, just closely spaced the cuts so he has more than he needs, and the bend radius is determined by the board it's wrapped around. This may actually have some benefit, as cuts with a wide spacing may make for a less curvy bend with points where the kerf cuts are.

    I'm not deaf, I'm just not listening.
  • rjj45rjj45
    edited March 2019
    dcibel said:
    rjj45 said:
    I've heard (Javad S) that there are kerf bend calculators on the web, but I haven't found any.

    I didn't find it hard to find on the web:

    First result:

    Oh great, now I find that I'm "google challenged".  <grin>

    Thanks dB!

    When I started to look at kerfing, every example showed bends where the inner part of the cuts all touched.
    I felt that the bend would be plenty strong if filled with Gorilla Glue even if the inner parts were not touching, 
    and allowing for "extra" bending capability gave a little more leeway when gluing up the bend.
    That looks like a correct assumption.
    dcibel
    But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
  • Archer60xArcher60x
    Some initial theoretical models of the drivers i have on hand.  The Usher driver is in a sealed box.  I am leaving the F3 pretty high on the Usher 97Hz. 

    Once i get Soundeasy i will get some real measurements.



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