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Thread: Building new sub/mid box

  1. #16
    Senior Member maxwedge's Avatar
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    Ah, turning on the piston band responce really changed things. Yes, I have a lot of learning to do still.

    Here's the graph now: red is 2242, green is 2202 wo/ piston band responce and yellow is 2202 w/ piston responce. I take it the piston band responce mostly effects the on axis feild?

    Ported dog box looks good also. Would I loose any 'punch' by going ported? I have room for the port but I need to keep the dimensions for w and h at 20.5 and 14.5 (want to tie into one wall and top of the sub box). Right now I have depth at 9.25 for 1.5 cu ft. Is there a minimum depth that I need to be aware of that could cause problems? (these are all inside mesurements)

    Thanks again, I've got to get back to working on these now.
    Scott
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  2. #17
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    Originally posted by maxwedge
    I take it the piston band response mostly effects the on axis field?
    Yes
    Originally posted by maxwedge
    Would I loose any 'punch' by going ported?
    Yes, but you might prefer the overall sound of ported instead of sealed. It's a preference and you should give both a listen to see which you prefer. The Qts of the 2202H is intentionally low so that any reasonable size enclosure (1.5 to 2.0 cubic feet) you put it in that is sealed will result in maximum transient response. That's what the JBL midrange transducers are designed for - maximum transient response in sealed enclosures. You might want to look on the Internet and read about Acoustic Suspension versus Infinite Baffle. The 2202H in a 1.5 to 2.0 cubic foot sealed volume behaves like an Infinite Baffle design whereas a transducer such as the LE10H in the same size volume behaves like an Acoustic Suspension design. Most JBL midrange transducers are intentionally designed to operate in sealed enclosures as Infinite Baffle systems to maximize transient response.

    You can also play around with BB6P and see how different sized sealed volumes affect power handling, efficiency, response, group delay, etc. A Qtc of ~ 0.5 is critically damped, anything below that enters the realm of an Infinite Baffle design (the transducer begins to act as if it were in "free air" and the enclosure volume begins to have diminishing effect on the transducer). A Qtc of 0.577 is a Bessel response and a Qtc of 0.707 is a Butterworth response. It's probably best to stay away from anything higher than 0.707 in general.
    Originally posted by maxwedge
    Is there a minimum depth that I need to be aware of that could cause problems?
    Sure, your internal physical dimensions for any midrange enclosure should follow the "golden ratio" as midrange is the most critical and you want to avoid reinforcing internal standing waves like the black plague. There have been several discussions on this forum about the topic and numerous solutions worthy of investigation. Sonotubes, non-parallel sides, non-parallel baffle and back, etc.

  3. #18
    Senior Member maxwedge's Avatar
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    Exclamation Progress

    Ok, I'll cut a port and make a removable pannel to try both ported and sealed. I don't think I'll be going for tilted sides and all....I'm having a plenty of a hard time without a table saw. But I will look up the threads.
    Thanks.
    Here's a few pic's . All the main pannels are cut out and I'm starting to fit one together. Working on the dog box now.
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  4. #19
    Senior Member maxwedge's Avatar
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    Talking I can sleep in there

    Inside
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  5. #20
    Senior Member maxwedge's Avatar
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    Love that router

    Back
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  6. #21
    Super Moderator Hofmannhp's Avatar
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    Re: Graph

    Originally posted by maxwedge
    here it is
    Hi Max,

    which kind of measuring software do you use?

    and how's the handling of this?

    Thanks for comments.

    HP

  7. #22
    Senior Member maxwedge's Avatar
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    Hi Hofmannhp,
    The graph is from BassBox 6 Pro: http://www.ht-audio.com/.
    It's a bit pricey but you can get the lite version for less. You have to import your own specs and I think there are less options...you'll have to read about them.
    I kinda of new with it, so I still on a learning curve if you know what I mean.

    Once I get the box's built I'll fine tune them with a RTA. I don't have a rack mount unit but I found this pc software thats pretty cool. I still need to buy the full version so I can fine tune better but the free version is ok.
    http://www.trueaudio.com/
    I use a Behringer calibration mic (cheep one, lol) and a small Behringer mixing board for my pc. It's kind of tricky to set up but once you get it right it works pretty well.

    Scott
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  8. #23
    Senior Member maxwedge's Avatar
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    Update

    One is almost done...need to work on the port area now. Pannels for 2nd are all cut out so this moving along fairly nice.

    The baffle fits flush and is 1" thick. It sits 1/2" into the cabinet with a 1/2" lip all around it. The dogbox fits into a grove that is cut on the inside of the baffle.
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  9. #24
    Senior Member maxwedge's Avatar
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    Inside

    Braceing
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  10. #25
    Senior Member maxwedge's Avatar
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    Question Bracing dog box

    You guys think I should brace the dog box more? It's 20x14.25x10 inchs (1.5 cu ft) and .75" mdf. All the edges are lap joints. You can see it is supported by those 2 2x4's and there's about 6" to the back of the cabinet (hard to see in the pic). I think I'm ok since it's for midrange. It is going to be ported also.

    Scott
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    Last edited by maxwedge; 01-15-2004 at 06:56 PM.

  11. #26
    Senior Member maxwedge's Avatar
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    Thumbs up Drivers

    One Last pic. Thanks to Giskard for the 2242HPL's I'ts on it's back so they don't fall out, lol.
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  12. #27
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    Holy Rolling Donut Batman! That 2242HPL looks pretty groovy

    I've really come to love those beasts.

    Nice work dude!

    *****

    BTW - Speaking of Mopars, you ever ride in a 440 six pack?
    Last edited by 4313B; 01-15-2004 at 07:34 PM.

  13. #28
    Senior Member maxwedge's Avatar
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    Yep, passed a chp at 160 mph in a 68 GTX 440 six pack 4-speed! No, I wasn't driving. Yes, we got away! The guy was giving out a ticket and boy you should have seen his neck snap, LOL!

  14. #29
    Super Moderator Hofmannhp's Avatar
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    sub/mid project

    Hi Scott,

    your cab looks very nice. Have you calculated the crossover...if yes ...can you tell the parts you want to use.
    I calculated the crossover for my similar cabs and found out:
    4mH and 76uF for Woofer, 90uF and 5,6mH for midbass, 14uF and 3,2m for Mid/high

    HP

  15. #30
    Senior Member maxwedge's Avatar
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    Hello HP,
    I use Rane active crossovers, so I can try any crossover points I like. They have 24db slopes and delays for the drivers to aline them electronicaly.

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