should I make this sub?

Discussion in 'Speakers' started by hoamskilet, Oct 9, 2008.

  1. hoamskilet

    hoamskilet Extra

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    I'll try to make this as short as possible. I've always been into car and home audio, but more the car side. Well now I'm starting to upgrade my home theater equipment that is several years old/lower end (just picked up a denon 3808 yesterday [​IMG] ). Right now I've got a Sony SA-WM40 for a sub (which I know is a joke compared to what most are running on here). I have a pair of Image Dynamics IDMAX car subs just collecting dust, so I was contemplating taking one of them and making a sub for my home theater. Here's some info/specs on the sub:

    Impedance: 2 or 8 ohms
    Re: 3.0/6.0 ohms
    Fs: 20 Hz
    Qes: .40
    Qms: 2.1
    Qts: .34
    Vas: 5.81 cuft.
    Xmax: 24.9 mm
    Sd: 545 cm2
    Spl: 93.1dB/88dB
    RMS Power: 1000 watts

    I've got all the tools I need and I've built several boxes for my vehicles, so I'm not afraid to tackle the project. I guess I'm just looking for advice from the pros on if this would be worth it (or even work since it's a sub meant for car audio). I absolutely loved these things in my truck, so I'm hopin I can pick up an amp and some wood and make a damn nice sub for not a ton of money. Any help/advice is appreciated.
     
  2. Gerald LaFrance

    Gerald LaFrance Supporting Actor

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    Well from what I have Read using a Car Sub for Home Theater is Not a good Idea. It can Not acheive the Low HZ usually needed for Home viewing.

    I would try over at AVS forum they have a DIY Sub Section with some very knowledgable DIY Sub Builders:


    AVS Forum
     
  3. Cpt.America

    Cpt.America Agent

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    I don't think that's entirely true. Look at JL for example... the W7 is used in car and home theater. The W6 plays even lower than the W7 and I doubt would have any problems hitting all the necessary lows that a movie can put out. Granted I know nothing about the sub he is referring to specifically.
     
  4. Robert_J

    Robert_J Lead Actor

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    And there are a lot knowledgable subwoofer builders here as well. I frequent that forum and a few others.

    Nate,
    What is your amp budget and size limitations? Can you go with a massive box or a smaller, sealed box? Do you want a box or a cylinder sub like SVS? From here we can start to work on a design for your subs.

    -Robert
     
  5. hoamskilet

    hoamskilet Extra

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    I haven't had much of a chance yet to find out what's available as far as amps that would work in this setup, I'm not sure what's a reasonable price to be looking at. Off the top of my head I guess I'd like to keep it within the 2-300 dollar range if that's possible (the cheaper the better, but I'm not one to buy junk just cus it's cheap). That's nothing set in stone though.

    As far as size goes, I don't really have the room to have something ginormous, but it doesn't have to be terribly small either. It's going to be going in the back/right corner of the listening area (which is a corner of the room) and there's a love seat angle in the corner. The footprint of the triangle area made by the back of the loveseat and the two walls is roughly (very roughly haha)

    ------------
    . 47" .
    .31" .
    . . 58"
    .


    I hope that makes some bit of sense haha. It can be as tall as the ceiling though and obviously I can adjust the loveseat a bit to make a little more room if needed. Sealed boxes are certainly easier to build, but I would definitely port it if it would make a big difference. I really don't know much about the cylinder subs as of this point, so I can't really comment one way or another about it, but I'm always up for tryin something new. Any other questions let me know. Thanks a ton for the help.

    Oh, btw...at this point I'm leaning more towards getting a pro amp rather than a plate amp, but I'm not opposed to a plate if it would work better
     
  6. hoamskilet

    hoamskilet Extra

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    .
     
  7. hoamskilet

    hoamskilet Extra

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    Sealed boxes are certainly easier to make, but I'd definitely port it if it was worth the extra work. I can't really comment on the cylinder tubes as I don't know much about em. I'm always up for something new though.
     
  8. hoamskilet

    hoamskilet Extra

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    As far as box size goes, I don't really have the room to make a ginormous box, but it doesn't have to be tiny either. It's going in the corner of a room with a loveseat angle in the corner. The very rough dimensions of the triangle shape footprint that the back of the couch and the two walls makes is 47"/31" (those are the two wall distances) and 58" along the back of the couch. Obviously I'm not going to make a triangle shape box, but was hopin that might give a good idea of the footprint I'm aiming to fit the box into. It can be as tall as the ceiling and I can move the loveseat a bit to make more room if needed.
     
  9. Robert_J

    Robert_J Lead Actor

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    Can you at least post a picture of the triangle so I can get the angles? From that, I can determine the area. From there I determine the enclosure volume available based on diffenent heights. But from the description, you should have more then enough room for both subs.

    Is your amp budget at least $350 for a decent pro amp? A Behringer EP-2500 can easily push both subs. And ported isn't difficult. For construction, it only requires that you cut an extra hole or two (or 3). The design part is easy.

    -Robert
     
  10. hoamskilet

    hoamskilet Extra

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    Here's a rough sketch of the triangle. Like I said earlier too, the loveseat can be adjusted a bit to make room if needed:

    [​IMG]

    I had actually originally planned on using just one of the drivers. Thought two might be overkill for my basement. Thoughts? I could probably swing 350 for that amp if needed.
     
  11. Robert_J

    Robert_J Lead Actor

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    You have a LOT of room to work with. Do you want front firing or downfiring drivers/ports? There is no acoustical difference just asthetics and placement of the furniture around the sub. You need to give the ports room to breathe if you have the on the front. If you have kids, I recommend downfiring everything.

    And there is no such thing as overkill, just headroom.

    As for not knowing about cylinder subs, that is just another shape. Construction is easier since you just have to cut circles. I'm running a family member's cylinder sub in my house now. I just finished construction and running it as a test before painting. He wants it to blend in. Difficult for a 4' tall sub. To try, I'm painting the top and bottom white to match baseboards and other trim in the room. The body of the sub will be painted the same color as the wall.

    How tall can your triangle enclosure be? You mention ceiling height but we don't need that much room. Where would you like it to be? End-table height? You can always go that route and put a decorative top on it made from glass, granite or marble.

    -Robert
     
  12. hoamskilet

    hoamskilet Extra

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    Well headroom sounds better than overkill, so I might as well build it for both subs then haha. The shape of the enclosure doesn't necessarily have to be a triangle. It could be a square, rectangle, cylinder, whatever...the goal is to just have whatever shape it is fit within the outline of the triangle. I'm not terribly worried about aesthetics either since it will be completely hidden by the loveseat and two walls in the corner. I'll put a nice black finish on it, but how it looks definitely isn't one of my bigger worries. I guess if I had to put a cap on the height of it, I would say try to keep it not much taller than your typical couch/loveseat (will have to wait till i get home to get a rough measurement of that). I have no real preference on the firing position. Whatever will give the best performance is the way I wanna go.
     
  13. Robert_J

    Robert_J Lead Actor

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    I played around in Unibox with a pair of your subs in a single enclosure. A sealed 200L box will give you a Qtc close to .5. With 800w of input power, you don't reach xmax until 16hz. Real world, you probably will never reach it.

    A 350L, ported enclosure tuned to 14hz is a bass monster. You wouldn't need the full output of a Behringer amp. In fact, full output at 12hz will send the driver past its mechanical limits.

    As an example, I'm testing a sonosub I finished building last weekend. It uses a Dayton 12" driver and a Dayton 275w amp. I could easily feel the vibrations through the concrete floor. A dual IDMAX sub will have more then 3 times the output of my sub.

    Besides the Behringer amp, I always recommend an EQ. Their Feedback Destroyer is one of the most flexibleEQs on the market. And at just over $100, it's a bargain. It's certainly not the easiest EQ to set but you only have to set it once.

    -Robert
     
  14. hoamskilet

    hoamskilet Extra

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    Alright. I ordered the amp earlier today. Do you think I should go with the sealed or ported? You suggested getting the eq....what exactly is that going to do in this situation and how would I set it? Thanks again for all the help.
     
  15. Robert_J

    Robert_J Lead Actor

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    Even though your T/S parameters didn't list it, almost all high excursion drivers also have high inductance. This will lead to a boomy sound in the 50 to 60hz range. My TC-3000 drivers had the same thing. When calibrated via my Pioneer's built in mic, it had a good higher bass sound but lacked the low end. Adding the EQ flattened my sub's in-room response down to 17hz.

    Setting the EQ is easy. All you need is a Radio Shack SPL meter, Microsoft Excel to run a free spreadsheet and a test tone CD (free if you have a CD burner). You play each tone through the sub and measure the SPL with the meter. When done, you type in your values into the spreadsheet. From there you can tweak your sub's frequency response in software. Once you get a response curve that you like, you just take the software settings and enter them into the Feedback Destroyer.

    Another option is free software called Room EQ Wizard. Running it on a laptop with a quality sound card with a MIDI interface will allow you to connect directly to the BFD and change EQ settings on the fly.

    I know that adding an EQ was not part of your original budget but you are using a pair of drivers that can easily beat retail subs costing thousands of dollars. But only if you build it correctly. Buying the Behringer amp was just the first step.

    Sealed or ported are just your choice. Ported is larger and has more output. Sealed is smaller with less output. Hoffman's Iron Law best explains the trade-offs you have to make when building a sub or any speaker for that matter.

    Finally, do you have an equipment closet? Because that amp has quite a noisy fan. Mine sits in the front of my room on top of my sub. When I first installed it, it sounded like a small airplane. I swapped the fan for a quiet model and I can barely hear it.

    -Robert
     
  16. hoamskilet

    hoamskilet Extra

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    I actually just picked up a spl meter a week ago, so I've got that. Sounds like getting the eq would definitely be worth it. Since I'm building the sub using both drivers, I don't think output will be an issue by any stretch of the imagination, so I think I'm going to go with a sealed enclosure. I have space behind one of the walls that it will sit by for access to the fish tank i built into the wall and storage, so the amp will go back there.
     
  17. hoamskilet

    hoamskilet Extra

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    eq has been ordered
     
  18. Robert_J

    Robert_J Lead Actor

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    The quickest way to get started is with Tony Gomez' PEQ software - link. All you have to do is create test tones to match the frequencies in the software and burn them to a CD.

    Since you have chosen sealed, all that is left is building. MDF is the best value as a material for the enclosure. Use a duble thick baffle and don't skimp on the bracing.

    -Robert
     
  19. hoamskilet

    hoamskilet Extra

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    You said earlier that your program said to make the enclosure 200 liters. Does that include the drivers or not?
     
  20. Robert_J

    Robert_J Lead Actor

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    200L is net internal volume. You must account for displacement by the drivers as well as all of the bracing.

    -Robert
     

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