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My 20-20 Indy theme project

edited January 25 in DIY
To date I have designed and built two hybrid open baffle projects.  The first one was a simple two way with a ND105-4 in a ported enclosure and a single TC9FD above on the open portion of the common baffle.  I loved how that little project sounded and it received lots of positive comments from folks that heard it at DDIY and Iowa.  After that I upped the game a bit with a three way design using a NE225W-04 woofer in a ported bass bin with a separate open baffle sitting on top.  That open baffle had a Tang Band W4-1320SIF woofer for mids and a Beston RT002A-bipolar tweeter.  I really liked that project but I didn't feel that the dipole tweeter added all that much.  In fact it forced a crossover point that was a bit compromised  :(  A couple of you heard this project in Iowa two years ago.  Unfortunately it was the last project to play on Saturday and many folks were either already gone or busy carting out their projects.

Anyway, fast forward to now...  The theme build for Indy this year is 20-20.  A purrrrfect excuse to try and step up my hybrid open baffle journey another notch :)

For this design I have chosen to invest a significantly larger portion of the allotted budget towards the mid driver and the tweeter.  For the bottom end I am using a 2 cubic foot bass bin on each side that uses two MCM 55-5670 8" woofers, in a push-pull configuration, wired in parallel for a 4 ohm load.  In my opinion these are fantastic performing woofers considering their low cost.  Their regular sale price is only $39 each.  I bought mine when they were on sale for $26 each.  SCORE!

I think I've nailed down the mid and tweeter for this design, but I'll wait to share their details until I've built a prototype baffle, taken some real measurements, and simulated a crossover design.

So why not, here are a couple of pictures of one of the unfinished bass bins with a mock cardboard baffle sitting on top:



Wait, what???  Two cubic feet and I only see one 8" woofer???

Peek-A-Boo, here's the other one on the backside, in a recessed cavity so the magnet/frame doesn't stick out visually:


hifisideGowajhollanderdynamosquamishdrocNicholas_23Turn26thplanetS79104thtryand 2 others.
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Comments

  • Interested in how those compare to the rs225. 
  • That recessed woofer is a cool idea.
     John H, thanks to JP I did get that email
  • I used that TB 4 incher in a MTM with a NeoCD 3.0 ribbon and a wide roundover kerfed baffle like yours. Closed box. 
    Extremely smooth on and off axis response. I'm very happy with the result. 
    Don, Donno, or "Hey you" all work for me, But never "Mr Johnson"
  • edited January 26
    I love that TB W4-1320SIF!   I'm hoping I like my OB mid choice just as much or even more.  It's a 5" with a lower Fs and higher sensitivity so hopefully it will have a bit more umph.
  • Uh oh, I am using the same combination of 4"TB and Beston dipole for my OB..... Hmmmm.... Too late to change anything now....
  • Very interesting...push-pull woofers. I'm guessing you mean the one on the back is pushing out, to it's magnet, while the other is pushing forward? The inset rear woofer is a cool idea.

    * Do I spy a vintage Marantz receiver on the floor?


  • Tom_S said:
    Very interesting...push-pull woofers. I'm guessing you mean the one on the back is pushing out, to it's magnet, while the other is pushing forward? The inset rear woofer is a cool idea.

    * Do I spy a vintage Marantz receiver on the floor?


    Yes.

    And yes, a model 2230.  I am going to repair it and recap it for a friend.
  • Why not just flip the speaker around so it faces outward on the back, instead of building a crevice to hide the frame and motor?
    I'm not deaf, I'm just not listening.
  • It wouldn't be a push-pull design and gain the advantages of non-linear suspension travel cancellations.
  • edited January 28
    ...and it's cool to see zee motor assembly.  B)
    My buddy, Adam did this to his towers...

    R-CarpenterkenrhodesGowaPWRRYD4thtrysquamishdrocThumperTom
  • Those look awesome!
    R-Carpenter
  • Not only do they look awesome, they sound awesome too! Adam has some skillz!
  • Yeah, those are really something! IIRC they were crowd favorite at MWAF.
  • 6thplanet said:
    ...and it's cool to see zee motor assembly.  B)
    My buddy, Adam did this to his towers...

    Is Adam on this forum?  If not, you really need to invite/encourage him to join.

    Are those Viawave ribbons?
  • Yes- he won crowd fave. He SHOULD have won the 200+ class as well.
    Adam isn't on the forums much. He keeps a low social media footprint methinks. I think he'd get along here.
    Yes- Viawave 850.
  • Quick update my friends.  I decided to go with a single 8" MCM woofer in a 1 cubic foot bass bin.  If anyone remembers me talking about how great and smooth my sound bar project went...  Ummm this project has gone complete sideways every step of the way!!!  :s.  I had my first DIY injury today.  It sucks but the duct tape seems to be stopping the bleeding.  Hopefully this project will be in Fort Wayne with or without finish.  Never say "Uncle" right?  B)
  • Until ya gotta take it off...  good luck, and
    keep us up on the modeling and adjustments for the 8" MCM- thx
  • PWRRYD said:
    Quick update my friends.  I decided to go with a single 8" MCM woofer in a 1 cubic foot bass bin.  If anyone remembers me talking about how great and smooth my sound bar project went...  Ummm this project has gone complete sideways every step of the way!!!  :s.  I had my first DIY injury today.  It sucks but the duct tape seems to be stopping the bleeding.  Hopefully this project will be in Fort Wayne with or without finish.  Never say "Uncle" right?  B)

    Thats pretty good that it’s only your first DIY injury, I think you will find blood stains somewhere on everything I’ve ever made! 

    Why the change to one woofer?
  • It gives me more room to shape (attenuate) the mid's response.  The smaller single woofer bass bin will also be easier to fit in my car.
  • Easier to fit in your car?......weak.
    kenrhodesPWRRYDbrek81dynamo
  • edited March 11
    Thought I'd post a pic of my Indy 20-20 project.  It actually looks a little bit better in real life.  Sorry for the somewhat blurry cell phone pic:


    jhollanderdynamoTurn2ThumperTom4thtrysquamishdrocGowa
  • nice !
    what did you end up for your X-over slopes, and freqs ?
  • Still working on the XO.
  • Nice driver combo
     John H, thanks to JP I did get that email
  • Lookin good! Is that an H1212?
  • edited March 12
    DA25TX-08 corundum tweeter.  The mid is a TB W5-2143 paper/bamboo cone.  The woofer is MCM 55-5670 with a rubbber surround lol.
  • Looking good!
  • I finished simming a prototype crossover early this morning.  Parts count is not too bad for a 3 way, 17 parts so far.  It's nice to have a stash large enough that I can actually build the prototypes without having to place a PE order  B)  Might be listening to this project later today.  Crossover points right now are 400 Hz and 2000 Hz, BW3 and LR4 respectively. 
    hifisidetajanes
  • I finished the prototype crossovers.  Just had my first listen... very impressive right out of the gate.  I don't think the're gonna need too many tweeks.

    Couple initial comments:
    - These Tang Band mids are everything I hoped for.  Their light weight bamboo/paper cones yield amazing detail.  
    - Just like my last two hybrid OB projects, I love the openness of the midrange.
    - The DA25TX sounds great just like the DA32TX I previously used.  So far it's my favorite dome tweeter.
    - I can't believe how good these cheap MCM 8 inch woofer are.  I wouldn't hesitate to recommend them.


    brek81jhollander6thplanet
  • edited March 29
    I've been listening, tweeking, listening....  I think the crossover voicing is done.

    After critically listening to these as well as going through all my music and just enjoying them for almost two weeks, I don't know if I will ever go back to standard midranges in sealed/stuffed boxes  =)

    I wish large film caps weren't so expensive.  I have a 125 uF NPE in series with the mid.  I wonder how much different a film cap would sound there.
    kenrhodesjholtzMartyH
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