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Project CS24 - MTMW

edited March 13 in DIY

This project idea has been brewing in my head for years now. It should be finished by Fall, in time to demo in Iowa DIY 2024. The bass bins are already built but they have no finish yet. They sport a single RS270P-4 10" woofer per side in ~ 1.5 ft^3 boxes that are ported with 3" diameter flared ports. Awesome bass extension, great impact, and good sensitivity.

The MTM section sitting on top of those will be a pair of Tang Band W3-1364SA on each side that I bought from JR. They are the bamboo/paper blended cones with the neo magnets, a copper shorting ring, and underhung motor design. The tweeters are the awesome CSS LD22 units.

The weather here today was simply awesome for early March. 72F and sunny. I rolled out my wood working workshop (table saw/router table on casters) to the driveway and cut the 5/8" thick Menards shelf boards for the top units. These will sport 5" diameter cardboard tubes to create 2.5" radius round overs on the sides. I've done this before and the on axis and off axis diffraction is extremely smooth.

ugly_wooferSilver1omojr@macrjj45hifisideEggguyjohnny5jzSteve_LeeTurn2Nicholas_23and 1 other.


  • Are you going to keep the baffle widths the same or narrower for the MTM?

  • Look like he’s putting monsters round over on it.

  • Correct. 2.5" roundovers on the MTM section so it will have a total width of 11.5" which is the same width as the bass bin.

  • I'm interested in your detail and finish work on the sonotube . . .

  • I used the rs270p-4 in my last retro build and absolutely love it. I would like to hear that CSS tweeter.

  • The LD-22 tweeter is great. work good as is or in a waveguide

  • Yes, I used these RS270P-4 bass bins in another project and their bass performance is way better than their price would suggest. There is just something more "real" when using a large SD woofer compared to 5.25", 6.5", or even 7". I also like 8" woofers when there isn't room for a 10".

    I bought these LD22's when CSS switched to aluminum face plates. They sold off their remaining stock of plastic face plated tweeters for half price. That's what these little honeys are. I love them! I used them in another project and they sound fabulous to me.

    Another beautiful day of weather so I'm going to wheel out my saw and cut those cardboard tubes in half. I'll share some pics later.

  • This is how I cut the cardboard tubes perfectly in half:

    First set up the table saw's fence to be exactly the same as the tubes' OD:

    Then I cut four scrap pieces of MDF square to that dimension:

    A few small dots of hot glue attached them to the ends:

  • With those two ends done I layed the tubes down on the table saw and tight against the fence, then hot glue tacked the other ends to the tubes:

  • Then just set the table saw's fence to (tube diameter - blade width divided by 2).

  • edited March 13

    That’s frinkin’ slick
    Do you then spray in expansion foam, or ???

  • I'll do some shallow rabbits with my table saw so that the tubes have some more glue surface, not just their thin ends. I plan to fill those cavities with dried play sand or kitty litter to dampen the enclosures.

  • Sitting here thinking more about it... I could have flipped those assemblies 4 times and made 8 perfect 1/4 round over pieces instead of 4 halves if that makes sense.

  • It is amazing how dead the cabs get with those half rounds fully mass filled. Added 10# to my 'Tudes cabs.

  • Dude that's a pretty amazing idea for cutting tubes! I hope this translates to PVC. That is a real PITA as it wants to close the gap the whole time.

  • @PWRRYD said:
    Yes, I used these RS270P-4 bass bins in another project and their bass performance is way better than their price would suggest. There is just something more "real" when using a large SD woofer compared to 5.25", 6.5", or even 7". I also like 8" woofers when there isn't room for a 10".

    Agree 100%!
    I made some 3 ways a few years ago with sealed RS270 woofers and passive LT - wonderful impact.
    So much so, that I passed on JR's beatiful Rival 8 inch carbon woofers. I need more these days!

    But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
  • I used that tweeter in a build with a SB paper cone 5" that I named Vermillion. Awesome tweeter.

    I have a signature.
  • Weather has made a turn here. This project may move forward at a snall's pace for a while :(

  • Yeah it was a nice break, but geez, last night's thunderstorm and hail sure sucked! A tornado hit up in Madison.

  • Yeah I was sad when I saw the news of those souls lost to the tornadoes.

    It's actually kind of nice out right now (55 F, sunny, slight breeze). So I might just get the driver rebates machined before dinner.

  • edited March 16

    I was able to get all the driver rebates machined as well as all the through holes cut and rear chamfers applied for the mid drivers. So after my haircut this morning I started to glue up the rectangular boxes. Hopefully the glue joints are strong enough by later this afternoon because it's supposed to be another nice day and I'd like to get the rabbits cut for the roundover tubes. We'll see. Pictures at five.

  • Before the roundovers:

  • Those look fantastic and I bet they are going to fantastic, as well. Should be an ultra-low distortion system when all is said and done.

    I have a signature.
  • edited March 17

    A few more pictures, because who doesn't like pictures?

    jr@macSteve_LeekenrhodesNicholas_23silverDugly_wooferjohnny5jzrjj45hifisidetajanesand 3 others.
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