Want to build my own sub... some advice needed. (im a NEWB)

Discussion in 'Home Theater Projects' started by Anthony_I, Sep 11, 2003.

  1. Anthony_I

    Anthony_I Stunt Coordinator

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    Ok i will be using a rhythmik audio plate amp to power the sub, and it will be running from a Pioneer XV-HTD520.

    Now here is my problem, if im going to build the sub (and the rest of the speakers) im naturally assuming that i should buy speakers that match the frequency response of my unit.
    IE the sub channel on my unit has a response range of 30Hz - 2000Hz. I want to use a Phoenix Gold Octane R12d as the speaker for my sub. But ill be damned if i can find out what the response range of that speaker is... and the only place by me that i knows sells them wont fucking tell me cause "it doesnt really matter"

    well to me it does. I've fallen in love with this speaker, the way it sounds, and looks.... its all flashy and shit lol. but i dont want to buy it if its freq response is going to be like 40Hz - 160Hz, cause then i would be missing a whole lot wouldnt i?

    So what kinds of things do i need to know to build a sub and speakers for my unit.
    and can ANYONE find any info about the freq. response of said speaker?? cause i cant find shit.
     
  2. Jack Gilvey

    Jack Gilvey Producer

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    Somebody needs a good mouth-washing.
     
  3. Joe Tilley

    Joe Tilley Supporting Actor

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    Anthony, I dont think youll get any positave responces from a post like that.
     
  4. David Giesbrecht

    David Giesbrecht Second Unit

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    Wow [​IMG] you gotta calm down bud.
     
  5. Rory Buszka

    Rory Buszka Supporting Actor

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    (black guy from Spaceballs): "Maaannn, we ain't found s***!"

    Here's how it is, yo
    Get a good driver, like a Dayton Titanic from Parts Express. Get the 12". I know it's like $150, but you have to shell out to get the performance, yo. With the Rhythmik amp, you should have plenty of power. Put the driver in a box with a big 4" flared port and you should be in business. To see how big the box will have to be, download WinISD from http://www.linearteam.org (not the Pro, because it is really technical for someone who is new to all this.) Once you have WinISD on your computer, go to the Utilities menu and select Database Maintenance. Click New and type Titanic Mk II 12" into the very top entry field. Then pull up the Titanic driver on http://www.partsexpress.com/ and input its electro-mechanical parameters (Qts, Vas, Fs, Qms, Qes, Z/Impedance, Re/Voice Coil Resistance) into the spaces below the input field. Make sure you get the units straignt or your box will not work. You can change the units by clicking on the unit symbol beside the entry blank. This will convert units on the fly. Then click OK. Now WinISD knows how to model enclosures with that particular driver. Close the Database Maintenance window. Click on the New button in the toolbar and choose to design an enclosure with oen of your own drivers. Select the Titanic from the list and click Next. As the program guides you through the next steps before you get to the response graph, enter that you will only be using one driver in Normal configuration, and that your driver will probably work with both a vented and a sealed box. Ported boxes will have more output, and sealed boxes will have better transients and be more tuneful, but you can't drive them as hard as you can a vented box. Once you get into the project window, and the frequency response curve appears on the graph, then switch the units on box volume to cubic inches. This makes it easier to model. Go into your Calculator and pick some dimensions that give you a box with an internal volume of right around two cubic feet. Then go into the ports section and change the units for the port size and length to inches and enter that you will be using a 4" port. Once you have a good frequency response curve (no peaks or dips greater than +/-3dB) and a bass cutoff point (where the graph crosses the purple line) that you like (shoot for 20-25 Hz) then you can write down the dimensions of the box and buy the parts. From Parts Express you will want to get the sub (Titanic Mk II 12") and the port (4"-Diameter Precision Port) and then you can build the box. Use graph paper to design the actual enclosure using the dimensions you came up with while entering volumes into WinISD to try them out.Make sure you figure all the panel dimensions properly. If you have no experience with woodworking then find someone who does and at least get them to help you. Build the box out of MDF (Medium Density Fiberboard) that is 3/4" thick or greater. MDF is the most acoustically-dead wood for building speakers, so you won't gat nasty panel resonances. Make sure to build an internal brace that will keep the walls rigid under bass transients. When you cut the panels for the enclosure, measure very precisely. Then when you put them together, use both screws and Elmer's Wood Glue in the joint for a very tight hold. You can use a jigsaw for cutting the driver hole and port hole. This is important for a good subwoofer. You can use a jigsaw for cutting the driver hole and port hole. At this point you should paint or otherwise finish the enclosure if you want to. This is the point during the construction at which it should be done. Following the instructions in the Precision Port package, cut the port tube to the appropriate length and attach the flares as directed. Install it in the box. Also in the box, line the walls with some damping material. Fiberglass insulation will work ok for this. Try to make sure that the material is not so close to the port that a big bass transient won't rip off little pieces and eject them through the port. There might be people walking barefoot around this sub and if you know what it's like to get fiberglass stuck in your hand you know that it's important to keep people from coming in contact with the fiberglass. The last thing is to install the driver using T-nuts and machine screws, which are available from Parts Express in their Cast-Frame Driver Mounting Kit. Ordinary screws will pull out of MDF when the cone recieves a big input signal. Once the driver and port are installed, then you are ready to go subwoof. Invite some friends over. They'll all think that it is the s***!

    If all this seems a little involved for your newbieness, Parts Express sells kits and enclosures that will work with the Titanic and still give good results.
     
  6. Anthony_I

    Anthony_I Stunt Coordinator

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    what did i do wrong? i wasnt being rude was i??
    If i was i didnt mean for it to sound that way.
     
  7. Patrick Sun

    Patrick Sun Moderator
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    Please tone down the use of curse words.
     
  8. Jack Gilvey

    Jack Gilvey Producer

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    You weren't rude, we just try to keep the level of discourse well above that of the various car audio boards...of which I'm sure you're a member.
     
  9. Rory Buszka

    Rory Buszka Supporting Actor

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    That Phoenix Gold sub is designed for car use where the cabin gain phenomenon boosts the bass. In a house, you don't get that extra bass boost and the Phoenix Gold will not work real well. Get the Titanic instead. You will be mich happier.
     
  10. Frank Carter

    Frank Carter Screenwriter

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    Do you have the T/S parameters of the Phoenix Gold sub? If not, try and get them from PG. This will help find out whether the driver will be suitable for home use.

    Like Rory said, it probably would be better to go with a driver intended for home use, see if you can sell the PG and check out drivers from companies like Adire Audio, Stryke, Dayton(partsexpress.com), Blueprint(audioliquidators.com).
     
  11. TimForman

    TimForman Supporting Actor

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  12. Anthony_I

    Anthony_I Stunt Coordinator

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    Yeah i just bought the speaker tonight, i was told by a damn smart guy at the shop that it would work with my home stereo, and be good for it, but i would require a larger box to get the same sound out of.

    PG reccomends a 0.9 Cu. Ft box, so how much larger should i go?

    and yes i have the T/S.

    And from now on i will do my best to respect others on the board and tone down the language.
     
  13. Dan Hine

    Dan Hine Screenwriter

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  14. Frank Carter

    Frank Carter Screenwriter

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    It can work, but will it work well?

    How much did you pay for the woofer?
     
  15. Anthony_I

    Anthony_I Stunt Coordinator

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    It will work, though without a box it barely makes any noise at all when hooked up to run at 8 Ohms, also my amp is only outputting 114W to it.

    it will work much better when my plate amp arrives and its all in a box. then it will run at 250W like its supposed to.

    I paid wholesale for it, $139 CAD.

    As for the T/S Params, here they are

    Code:
     Octane-R12d
     T/S Parameters
     Fs . .23.640 Hz
     Re . .7.24 Ohms
     Qms . .8.190
     Qes . .0.499
     Qts . .0.470
     Vas . .117.7807 liters
     Mms . .135.9013 grams
     Cms . .318 uM/Newton
     BL . .8.6628 Tesla-M
     SPL . .91.74 dB
     Sd . .511 sq cm
     Xmax. .25mm Point to Point
     


    Thats the specs of the speaker.
     
  16. Brian Bunge

    Brian Bunge Producer

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    It looks pretty good in a 3ft^3 sealed enclosure or about 4.5ft^3 ported, tuned to 20Hz. I think the Xmax is a little low though. I think a Shiva would be a much better choice and could be purchased from Creative Sound for only $35 CAD more.
     
  17. David Giesbrecht

    David Giesbrecht Second Unit

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    If the shiva is 30mm point to point and this sub is 25mm point to point how much difference is that 5mm's going to make in the real world? Just wondering.
     
  18. Brian Bunge

    Brian Bunge Producer

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    Well, for one thing, we don't know for sure if the PG driver truly has a 12.5mm Xmax or if that is actually the limits of the driver's suspension. If it's latter, then that would mean that Xmax will more than likely be substantially less.

    For $35 CAD more you would at least know what you're getting.
     
  19. Anthony_I

    Anthony_I Stunt Coordinator

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    Sounds good, but how exactly do you come to that conclusion, and what difference in sound exactly would it make to go from 0.9 Ft^3 to 3Ft^3, and how is sound affected by a port/tuning frequency? (ive never understood this "box tuning frequency" thing)
     
  20. Anthony_I

    Anthony_I Stunt Coordinator

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    also i had it hooked up out of the box, and running at 2 Ohms to test it, cause apparently running it at 8 Ohms unpowered doesnt provide enough wattage to drive it... now it sounds alright (obviously a box is needed) but after certain volume levels i can hear the speaker cut out, and my stereo makes a "click" noise like relays kicking in, im guessing this is the protection circutry kicking in from overloading breifly, and/or the speaker bottoming out?? cause no sound comes out of the speaker when this happens. and that this wont happen in a box.
     

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