Help me with this WinISD Plot

Discussion in 'Home Theater Projects' started by Greg_L_C, Mar 30, 2005.

  1. Greg_L_C

    Greg_L_C Stunt Coordinator

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    I have Been having a lot of fun playing with winISD and plotting diffent drivers and box configurations. Take a look at this graph.

    Plot WARNING may be slow loading.

    Green line - Adire Audio Shiva Subwoofer MkIV
    Yellow line - Titanic 12" MkIII
    Orange line - Stryke AV12MKII
    Blue line - Acendant Atlas 12 High qts

    All are ploted in a 5qf 4" vented box tuned to 18HZ.

    I'm looking for some help it understanding what I'm seeing. To me it seems that the Titanic is the best for the box I would like to build. Also why would the vent mach change for diffent drivers?

    What vent mach should you stay under for a single 4" port?

    How much of the vent length can you take off for a dual flared port?

    Thanks

    Greg
     
  2. Stephen Hopkins

    Stephen Hopkins HW Reviewer
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    While the Stryke AV12 MKII has about a 1.5db dip around 35hz it does go a bit lower than the Titanic and its biggest advantage is its 23mm excursion allowing it to go louder before bottoming out. I replaced a Shiva w/ a AV12 and while the Shiva was great for the money at the time it bottomed out much easier than the AV12. I'm yet to bottom my AV12 w/ my PE 272w amp.
     
  3. Brent_S

    Brent_S Second Unit

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    You probably also want to look at the SPL graphs using your amp's power as input to see which driver meets your goals. There's also a Max SPL graph to show you the potential output for each driver.

    For a 250 watt input all 4 drivers are within about .5 db at 20 hz.
    At 30hz/250watts, the Shiva (mark 2 in my model) has about a 2.5 db edge over the AV12 & Titanic.

    From 20hz-40 hz, all fit into 4db window at max SPL.

    Just for fun, I threw the Dayton DVC12 into the mix. In your box, it's almost identical @ 250 watts and Max as the Shiva and I believe it's also the cheapest option of the 5.
     
  4. Stephen Hopkins

    Stephen Hopkins HW Reviewer
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    WinISD SPL plots don't take into account that you may be bottoming out the driver before you reach a given SPL. With 250 watts there's a good chance you'll bottom out both the Shiva (mine did in a 5.3 cu ft enclosure tuned to 20hz) and the Dayton DVC.
     
  5. Greg_L_C

    Greg_L_C Stunt Coordinator

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    Thanks for the comments. I guess I don't understand what it means to bottom out a driver. I plan on using either a PE 250w amp or a Rythmik Audio A250.

    I had planned on using a Shiva, but availability seems to be up in the air on them, so I started looking at other drivers.

    I also couldn't find if the Titanic was suitable for down firing.

    Also good for me, I noticed in my test that small variations in box size didn't seem to make any diffence. Being a first timer I think its going to be hard to get the internal volume exact with the bracing and amp.

    Thanks
    Greg

    P.S. I'm hoping to crush the JBL PB12 I'm using now.
     
  6. MarkRoberts

    MarkRoberts Stunt Coordinator

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    I have a Dayton 12" DVC and you can bottom it out with the rythmik A250 amp. I would go for the Ascendant Audio atlas 12" or even a 15".If you got 5 cu.ft. in mind a 15" maybe an option. You should fire an email to Chad at Ascendantaudio and see what can be done with the 12" and the 15" with that volume. The motor design is like adire's tumult, it has a xbl^2 motor. Which is much better than the shiva or most others from what I understand. It is only a $20.00 difference. I don't think you can get AV12 or shiva right now either so it kinda narrows it down. The atlas 15" isn't much more than the Titanic driver. Just my 2 cents.
     
  7. Mitch N

    Mitch N Stunt Coordinator

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    The Dayton can be downward mounted. Well at least my last MKII 10" could.. It says so in the user manual.
     
  8. Jack Keck

    Jack Keck Second Unit

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    "How much of the vent length can you take off for a dual flared port?"

    You have to ADD for it. I have no idea how to figure out exactly how much, though. Precision Ports has th einfo for their ports, but if you construct your own, then you're on your own. Then again, the difference that it makes could very well be negligible.
     
  9. Dave Poehlman

    Dave Poehlman Producer

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    Here is a good article explaining the importance of port/box tuning.

    Anytime you see a hump at the lower end of the curve, the driver is under-damped and you risk bottoming it out.
     

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