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    Want to learn Acoustics/Mechanics of box building

    Before you pound your head on your keyboard thinking "Oh great, another noob wanting to know everything about something" let me clarify the goal of this thread. Simply put, I'm just seeking the information regarding the acoustics, mechanics and mathematics of box building (I'm mainly interested in ported/vented box building).

    Here's the story: I currently run an Sundown SA-12 on a Rockford T500-1BD @ 1ohm in my trunk adjoined with the cabin. While the custom box the original seller built me sounds great, I think there's room for improvement. Rather than using a box builder I wanted to build something totally custom and understand the acoustics behind it so I know exactly how it should sound before I ever turn on my ignition. What I found was a lot of basic information about ported vs. sealed vs. bandpass boxes and the pros and cons of each but nothing that actually told me how to build one other than using software to do the work for me. I've read about guys who really know what they're doing building amazing boxes for their applications and I'm guessing they don't just sit down and follow 5-step instructions. I understand that port tune, material, volume, port surface area, etc all help determine how it will actually sound, but I want to know the math behind that software and how those numbers affect the performance.

    Here's the catch, I'm NOT asking for somebody to sit down and spend the next two hours of their life teaching me quantum physics. I'm just asking for help finding the articles and explanations I need to learn. I'll do the reading, but if somebody could provide book titles, web links, thread links or any insightful information that will help me learn beyond an entry level, that would be awesome. Thanks guys.







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    Re: Want to learn Acoustics/Mechanics of box building

    This is far from my area to talk about specifics but Every sub is different its a lot of trial and error with each box to find the box specs for a sub. My buddy built 6 boxes for competition before he was happy.




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    Re: Want to learn Acoustics/Mechanics of box building

    Quote Originally Posted by Silverado SS View Post
    This is far from my area to talk about specifics but Every sub is different its a lot of trial and error with each box to find the box specs for a sub. My buddy built 6 boxes for competition before he was happy.
    Yeah I know every sub wants a different box...at least of the most part, but is that really all there is to it? Just trial and error?




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    Re: Want to learn Acoustics/Mechanics of box building

    hell no but maybe double 07 or buck can chime in




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    Re: Want to learn Acoustics/Mechanics of box building

    Loudspeaker Cookbook

    I think you're on the wrong forum. Most people on this site only care how loud X woofer is vs O woofer. To be totally honest when working with car audio, you can throw most acoustical properties out the window. It changes way too much to get accurate results. Simply moving a seat forward and inch can have drastic changes.

    The math behind most box programs is easy. It a simple algebra equation. I (and many others)wrote out in detail a couple of years ago how to do it using pencil and paper. LINK It's the exact equation used in Bass Box Pro and many other box programs.

    To get a frequency response graph I'm afraid you'll have to use software, unless you want to crunch numbers for a single woofer over a weeks period and have all those numbers mean squat when you put it in your car. Graph numbers like WinISD and other programs provide are just a guideline to see how X woofer reacts to different designs/configuration in an open room. Throw it in a trunk and the results could be similar or totally different.

    Also, don't over think things. It's a SUBwoofer box for crying out loud. Sub bass is >10% of music bandwidth. IMO your brain power should focus more on the other 90%.




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    Re: Want to learn Acoustics/Mechanics of box building

    Quote Originally Posted by thehardknoxlife View Post
    Loudspeaker Cookbook

    I think you're on the wrong forum. Most people on this site only care how loud X woofer is vs O woofer. To be totally honest when working with car audio, you can throw most acoustical properties out the window. It changes way too much to get accurate results. Simply moving a seat forward and inch can have drastic changes.

    The math behind most box programs is easy. It a simple algebra equation. I (and many others)wrote out in detail a couple of years ago how to do it using pencil and paper. LINK It's the exact equation used in Bass Box Pro and many other box programs.

    Also, don't over think things. It's a SUBwoofer box for crying out loud. Sub bass is >10% of music bandwidth. IMO your brain power should focus more on the other 90%.
    I'll check out that link when I get a chance. I'm working on school right now. And already on that. Running 4 tweets, 2 coaxials and 2 drivers off a 4 channel with DTA. The problem is I'm broke and can't afford the obvious upgrades like better components, better wiring, better amps etc. But I can afford 50 bucks on materials. I just like my hobbies and figure if I can build a box that will be louder deeper and cleaner, why not? I think you're right in that I'm probably overthinking this, but shoot, it's a hobby and I'm willing to learn.




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    Re: Want to learn Acoustics/Mechanics of box building

    This could turn out to be a great and in depth thread if the right people start posting here.
    Saying "don't waist your time" defeats the purpose of this website.



    "When I listen to a stereo loudspeaker playback in my room and an auditory scene has formed in my mind, how would I know that what I hear is an accurate replica of an auditory scene that could be had at the recording venue? Or more generally, that this is an auditory scene that could have existed at all?"


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    Re: Want to learn Acoustics/Mechanics of box building

    Hoàng Quân Chuyên cho thuê xe cao cấp, xe tháng hàng đầu Hà Nội
    Tel: 04.66.83.66.07 – 04.62.69.45.42
    Hotline: 0987.999.222 – 0983.838.553
    Địa chỉ: Số 02 Trúc Khê – Đống Đa – Hà Nội




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    Re: Want to learn Acoustics/Mechanics of box building

    Quote Originally Posted by budgetkiller View Post
    I'll check out that link when I get a chance. I'm working on school right now. And already on that. Running 4 tweets, 2 coaxials and 2 drivers off a 4 channel with DTA. The problem is I'm broke and can't afford the obvious upgrades like better components, better wiring, better amps etc. But I can afford 50 bucks on materials. I just like my hobbies and figure if I can build a box that will be louder deeper and cleaner, why not? I think you're right in that I'm probably overthinking this, but shoot, it's a hobby and I'm willing to learn.
    What are you trying to achieve? Loud music with low hitting bass? Running 8 drivers off a 4 ch amp? Technically rules are more space/tune lower to get lower bass than what you already have, keep in mind power handling will go down and the sub might get quieter because it doesn't have the same peak it had in the previous enclosure. Programs like winisd will help but remember cab gain has a huge affect on how it will actually sound and will probably be to your benefit(lower bass)



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    Re: Want to learn Acoustics/Mechanics of box building

    Quote Originally Posted by supermaxx123 View Post
    What are you trying to achieve? Loud music with low hitting bass? Running 8 drivers off a 4 ch amp? Technically rules are more space/tune lower to get lower bass than what you already have, keep in mind power handling will go down and the sub might get quieter because it doesn't have the same peak it had in the previous enclosure. Programs like winisd will help but remember cab gain has a huge affect on how it will actually sound and will probably be to your benefit(lower bass)
    I'm not really worried about power handling of the woofer. My understanding is if anything I should be running it off a bigger amp. As for the 8 drivers off a four channel, I've already got that taken care of, I only mentioned that in response to the suggestion that I should work on the rest of my system before I worry too much about the <10% the subwoofer actually plays. I'm hoping to achieve a SQL set up that hit's CLEAN and low. A flat response would be nice but I also like my stuff to slam when I'm in the mood. My current box is tuned somewhere in the 30-35hz range but has trouble hitting some of the lows other systems can and also has a slight midbass dropout. I would like to fix both of those while having as deep of bass as possible. and don't get me wrong, I definitely have my basshead moments so if I could gain SPL by running a larger box I'm willing to do so. Basically I want SQ first, deep resonating non-directional bass next, and if possible, SPL gains as well. It's a lot to ask I know, but keep in mind that's why I started this thread. I want to know what can be done.




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    Re: Want to learn Acoustics/Mechanics of box building

    If your looking to build an SQL set up, I personally think the sub stage should be the last thing on the list. You could very well find that; after doing your sub stage first, front stage second; you did your sub stage wrong to begin with.
    To me, SQ can be achieved best by getting your mids and highs correct with an implemented, temporary sub stage. And after getting mids and highs dialed in, then working on a SQL sub stage.
    Someone correct me if im wrong....



    "When I listen to a stereo loudspeaker playback in my room and an auditory scene has formed in my mind, how would I know that what I hear is an accurate replica of an auditory scene that could be had at the recording venue? Or more generally, that this is an auditory scene that could have existed at all?"


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    Re: Want to learn Acoustics/Mechanics of box building

    ignore people who say acoustics doesn't play a role in car audio. it certainly does, especially with placement. and enclosure design is deeply routed in acoustics and mathematics. i have solved problems and improved systems using acoustics theory.

    i agree the Loudspeaker Design Cookbook is your first step.



    have you been helped by me? i'd love to know. shoot me a PM.

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    ***My YouTube Channel https://www.youtube.com/channel/UCkYUo2EShW9lgtrfXiDvLNQ/videos
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    Re: Want to learn Acoustics/Mechanics of box building

    If you want to "iron man" box calculations don't use a calculator and use the long formulas. I really don't see the point. The formula underneath the skin is the same and the graphing programs save time and are quite accurate.

    To make much use out of them you'll need some measuring equipment so you can compare actual response to predicted. Once you can make a few boxes, try some different locations for things, you can start to get a feel for what effects the vehicle will have on response and what effects firing a port up as opposed to back or subs forward versus up will have. From there you can look at a response curve and immagine what it'll look like after you add the peaks and nulls from other variables.

    The people who design boxes for a living don't have any more magic at their disposal than the formulas used to make any of the software out there.... what they do have is a lot of experience actually testing various things in a lot of different car cabins so they have a good feel for what will work. There is no substitute for trial and error and a lot of testing.




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