Shielded 8" subwoofer?

Discussion in 'Home Theater Projects' started by BenSC, Sep 29, 2003.

  1. BenSC

    BenSC Stunt Coordinator

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    So I've got a guy who likes my Dayton III's, but wants me to make him towers that use the bottom halfs as 8" subs. He has a small area to work with, so he'd like placement in close proximity to his TV.

    Are there any options other than the AV8 from Adire in the sub $100 price range? A shame they don't make a shielded Dayton Quatro 8", as I really like that speaker, not to mention they're 30% cheaper. Not to mention its going to take 3.5 ft^3 to get the AV8 down to an F3 of 30htz.

    Also, I'll be using the PE 120 watt plate amp to power the two 8's, then his amplifier will power the Dayton III's on the top half.

    Thanks in advance.
     
  2. Brian Bunge

    Brian Bunge Producer

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    Ben,

    The 8" driver used in the SCH towers is shielded and only costs $37. It can be used as a subwoofer in not too big of a box. It doesn't have the Xmax of a Quatro 8 but still a damn nice driver.

    http://www.speakerpage.com/S08911.htm
     
  3. DanWiggins

    DanWiggins Second Unit

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    An AV8 in 1.5 cubic feet, tuned to 30 Hz does a really good job as a small subwoofer. Gets you into the 25-30 Hz range in-room quite well.

    Dan Wiggins
    Adire Audio
     
  4. Brian Bunge

    Brian Bunge Producer

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    Dan,

    Two of them work great in a 3-way center channel as well! [​IMG]
     
  5. DarrenK

    DarrenK Extra

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    Hi Ben,

    They're not quite ready yet, but I'm working on a new Dayton 8" shielded subwoofer driver. Xmax will be about 6 mm, and should do a vented F3 of just about 30 Hz in around 1.2-1.5 cu. ft. per driver. Cost will be pretty darn good.

    But, unfortunately, it'll likely be a month and a half before they are in stock. I don't know what your timeline is like, but I just wanted to let you know in case you won't be doing this for a while.

    See ya!

    Darren
     
  6. BenSC

    BenSC Stunt Coordinator

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  7. DanWiggins

    DanWiggins Second Unit

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    Ben,

    Must be something wrong with your software, then... To get an F3 (anechoic, without an XO) of 30 Hz, 2 cubic feet and a 30 Hz tune will do it.

    BUT, don't forget the effect of the crossover! Include a low pass filter at 100 Hz, and the 1.5 cubic foot/30 Hz tune will get you down to 30 Hz without a problem. Without the XO, your F3 should be 40 Hz. But since subs rarely run without an XO, it should be considered in your design from the get-go.

    And as Brian confirms, you can use a small vented box (even with a pair of AV8s) to play pretty darn low...[​IMG]

    Dan Wiggins
    Adire Audio
     
  8. BenSC

    BenSC Stunt Coordinator

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    OK, so I use WinISD, which is something I've used forever. But this is the second time I've been told that my numbers aren't right.

    Here is my graph with a 3.5 cu ft enclosure and tuned to 30htz. I find it odd that my measurements are off because I've used this software numerous times and my speakers have tested pretty spot on.

    [​IMG]
     
  9. Matt Dolejsi

    Matt Dolejsi Agent

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    just as a thought, dont limit your choice by whether a driver is shielded or not...large cancellation magnets and a little superglue can go a long way...just my 2 cents
     
  10. David Giesbrecht

    David Giesbrecht Second Unit

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    How about a Hi-Vi M8N its about $50 bucks at parts express and will play very low in a vented box.

    Vas 1.88 cubic ft
    Qts 0.45
    Fs 29 hz
    Xmax 5.8 mm

    If you give each driver about 2.5 cubic ft to work with and a port tuning of 20 hz you would have an F6 of about 20 hz wich would easily be flat in room down to 20 hz.

    Remember to consider room gain in the design! The anechoic F3 doesn't mean squat when you stick them in a closed space! The anechoic F3 of my Tempest subs are about 37hz and the in room F3 is 18hz and the F10 is at 8 hz!

    The 8" driver Brian suggested would perform very similar to the M8N in the same box configuration as well.
     
  11. BenSC

    BenSC Stunt Coordinator

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    Very good points. Wow, that Hi-Vi is an.. intresting looking speaker to say the least. Does it glow? [​IMG]

    I've got all these 8's on my list, and I've convinced him to hold off until the Dayton that Darren mentioned arrives. I'll make the decision based on that. Thanks again everyone.
     
  12. BenSC

    BenSC Stunt Coordinator

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    Well, I've convinced him to go farther away from the TV so he can use the Quatro as long as they don't have to be TOO far away. How far do you think I could get away with being? I'll place the sub's as low as possible in the towers.

    I'm hoping for placement around 1.5-2 feet from the TV. which would put the quatro magnet at about 2 to 2.5 feet from the bottom corners of the TV, and about 3 to 3.5 feet from the upper corner (where color problems seem worst on that particular TV).
     
  13. Dennis_H

    Dennis_H Stunt Coordinator

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    DarrenK,

    How is that new 8" Dayton coming? Any timeframe or specs yet? I'm looking for a small sub for a bedroom system and am considering this driver along with the AV8.

    Thanks,
    Dennis Hoenich
     

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