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  • Hi guys.  I was able to mount and measure these new SB15CAC30-8 woofers on my 48" x 48" infinite baffle today.  Far field is 25" mic distance.  Near field is ~1/4" from dust cap.  1/48th octave, 5 ms gate.

    Far field frequency response:



    Far field distortion:



    Near field frequency response:



    Near field distortion:


    kennyk
  • Very good! Distortion is low and the response range is great. This will be a really easy driver to work with.
  • 10k may still need a notch. other wise, looks smooooo
  • Near field distortion lol.

    The 25" distortion test isn't at a level high enough to really discern the driver distortion from the noise floor. You'll want to test at a high level to get a meaningful result, like 90+dB. FWIW Zaph tested 5.5" drivers at 96dB@0.5m.
    I'm not deaf, I'm just not listening.
  • What I am reading into it is they suffer the same drawback as a lot of other very stiff coned drivers - the nearfield reveals the breakup does not really go down in magnitude in the off-axis so will probably require an aggressive notch. These days, though, it is pretty easy to pinpoint these filters. 


    I have a signature.
  • Distortion at ~95 dB at 21"



  • Thank you, that is a more meaningful plot as you can see that the harmonics have been brought above the noise floor.
    I'm not deaf, I'm just not listening.
  • Looks like a nice driver and the price is not terrible either.
  • Thanks Craig! It looks like it would make a great mid in a 3-way.

    Jim
  • My current plan is a medium sized 2 way with a time aligned baffle.  Now I just need to make a final decision on which tweeter.
  • What are the choices?
     John H, btw forum has decided I don't get emails
  • Nice that there doesn't appear to be a lot of distortion by-product from the cone break-up. You can see a slight rise at 5K in 3rd order but it's not that bad compared to other stiff cone drivers.

    I don't know what SB does with their woofers to achieve this but I saw the same thing on the little 4" aluminum cone. 
  • edited December 2017
    My guess is that it has to do with the "geometric reinforcing". I believe this is radial ribs they have on the back of the cone. Perhaps they function similar to the slits on the Revelators?

    Looks like an excellent mid to me. Am I interpreting the distortion correctly that it's greater than 50 dB down from around 300 Hz through 4k?

    I wonder if the 8" is as good.
  • edited December 2017

    It's hard to see in the pictures but there are 5 radial creases that start a little outside the dust cap and extend all the way to the surround.  From my hot rod days I know that a little crease, bend, bead, etc. can really help stiffen a sheet metal panel.  I would surmise that these creases help move breakup modes even higher.  I seem to remember that the aluminum cone SB driver that Ani used had those same 5 creases.

    EDIT:  I just looked at SD DIY event page and see that it was Jason P's project that used the SB aluminum cone with creases, not Ani's.  Here is a pic:

    Looks like Jason used the XT25!

  • What are the choices?


    Some same-old/same-olds that I already have on hand, like the RS28A or RS28F, or the Peerless XT25TG30-04.  Maybe my pair of Dynaudio D28/2.  Also considering the Seas 22TAF/G but I would have to purchase those.  The TL's ceramics look awesome but they would push this project way beyond budget.

  • Hi Paul, looks like we were posting at the same time this morning.

    My box modeling of this driver indicates it will also make a great mid bass driver with an F3 in the mid 30's in about 12 L ported. 

    The distortion measurement I did was really loud and the driver had zero reinforcing help from an enclosure!  I could see and hear the driver in distress under 50 or so Hz.  It was hitting its mechanical excursion limits for sure.
    isaeagle4031
  • See where the blade is ground? If it were a finish the color wouldn't go through the grind. 

  • The standard aluminum "NAC" are still on sale as well.
    I'm not deaf, I'm just not listening.
  • Change of plans...  I don't need yet another 12ish Liter 2 way bookshelf.  What I really need is a largish 3 way LOL!  Think 2 piece enclosure like my "Trials" project or Paul C's Tarkus.
    Nicholas_23Turn2
  • What are you thinking for woofer duty ? 
  • Peerless 830668.  I bought a pair when they were on sale for $50.
  • Gonna spray some clear gloss lacquer today on some curly maple baffles.  Fingers crossed!
    jhollanderkennyk
  • Beauty Craig ! Howd it go ?
  • They turned out beautiful!  Gave me one heck of a headache though.  Pics to follow soon.
    kennyk
  • PWRRYD said:
    They turned out beautiful!  Gave me one heck of a headache though.  Pics to follow soon.
    uhh... spray only with adequate ventilation.....

    But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
  • Im going to install one of these fans in my garage for spraying stuff. You can get a smaller one for a little less with a speed control. You can shove a filter on one end so your not blowing pant through it. 

    iPower 6 Inch 442 CFM Duct Inline Fan Vent Blower for HVAC Exhaust and Intake, Grounded Power Cord https://www.amazon.com/dp/B009LCEUEK/ref=cm_sw_r_cp_apa_EOvNAbS1A0FJZ
  • D1PP1N said:
    Im going to install one of these fans in my garage for spraying stuff. You can get a smaller one for a little less with a speed control. You can shove a filter on one end so your not blowing pant through it. 

    iPower 6 Inch 442 CFM Duct Inline Fan Vent Blower for HVAC Exhaust and Intake, Grounded Power Cord https://www.amazon.com/dp/B009LCEUEK/ref=cm_sw_r_cp_apa_EOvNAbS1A0FJZ
    Where do you mount it? 
  • The motor is in the air stream which is a no-no for solvent fumes.  You can push more air with a $20 box fan.
     John H, btw forum has decided I don't get emails
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