A Few Questions I hope someone can answer...

VR3
VR3 Posts: 28,654
I am wanting to build a subwoofer, and I wish to build it sealed (no ports) ---

SO.... here is my question

1) A sealed subwoofer isnt as loud as a ported one, right? If this is true, if I build the subwoofer to the exact size for the required volume, would I still lose output? If so, how much?

2) Will a rear firing subwoofer mess with the sound quality of the bass in anyway?

Thank you in advance.

- Trey
- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
Post edited by VR3 on
«1

Comments

  • gatemplin
    gatemplin Posts: 1,595
    edited August 2004
    1. Sort of. A port is used to extend the frequency response of a driver, not increase the output over the whole operating range. The port will produce most of the output near (a little above and below) the tuning frequency but above that, the woofer is on it's own just like a sealed sub.

    If you want the most extension and output pick a box design with a Q of 0.7

    2. With subs, it doesn't matter which way the ports or drivers are pointed. The exception to that, is some drivers can't be mounted in a down-firing position.

    This is the sub for PA use right? You wont find a sub with more output for the dollar than this: http://adireaudio.com/TextPages/TempestHornPageFrameText.htm
    It would be hard to make but it is worth taking a look at.

    Also, you can read up on subs at www.diysubwoofers.org
    Graham
  • VR3
    VR3 Posts: 28,654
    edited August 2004
    I am planning to build a 15" Home Design

    With a 6.60 Cu foot box

    35 inches tall, 18 inches wide and deep...

    Rear firing, 250 watt amp.

    Wood wont cost much at school, they get alot of free wood...so I can work myself around that

    The budget is no more than 300...

    I want to use a 15" Dayton woofer, which is like 90 dollars...

    Then a 250 watt plate amp from PE -- so 130 + 90...

    Here is what I got planned....or one of my plans -- I keep thinking up stuff...

    I also plan to turn the Pioneers into a similar design - with the wrap around grill and oak caps and corners
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • gatemplin
    gatemplin Posts: 1,595
    edited August 2004
    Dont forget about bracing the enclosure. Consider copying the bracing seen here.
    Is this sub going to be used in a system or as a PA sub? If you are going to be toting it around consider making it one layer MDF, that sum **** will be heavy. Take a look at what others have done with that driver aswell.
    Graham
  • VR3
    VR3 Posts: 28,654
    edited August 2004
    Hey,

    This subwoofer will be kept in one spot at all times...

    It is going to be used in the Den of my Mom's house probally, it is 30x15x8 (guesstimate)

    I don't understand the PDF, I was looking at that earlier and it all totally blew my mind, which part of it is the bracing?

    I will probally do 1 layer of MDF if the wood costs alot...

    all depends on cost - I want a REAL dense cabinet - the top and bottom caps will probally be cut 1/8" larger than the rest of the cabinet, then the corners will be put in place -- not sure I wanna get all technical with it with slants, etc

    Ah, I see the bracing now! -- Will study this further -- THANKS!
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • gatemplin
    gatemplin Posts: 1,595
    edited August 2004
    Originally posted by Vr3MxStyler2k3
    Hey,

    I don't understand the PDF, I was looking at that earlier and it all totally blew my mind, which part of it is the bracing?

    I will probally do 1 layer of MDF if the wood costs alot...

    all depends on cost - I want a REAL dense cabinet - the top and bottom caps will probally be cut 1/8" larger than the rest of the cabinet, then the corners will be put in place -- not sure I wanna get all technical with it with slants, etc

    The pieces with the small circles are the braces.

    Bracing will add a lot of strength for a minimal increase in weight and material.

    The MDF is cheap though, about $20 for 4' x 8' IIRC.
    Graham
  • VR3
    VR3 Posts: 28,654
    edited August 2004
    ah --

    I think the school gets a discount or helps - I dunno, so hopefully wood wont be a huge dent..

    Hmm, so would a circle braces from top to bottom and side to side (in the middle) work?

    4" in diameter...

    thank you for all your help!
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • gatemplin
    gatemplin Posts: 1,595
    edited August 2004
    Have the braces running in the middle of the longest sides, vertically. Only top to bottom. This is what Adire recommends to keep the unsupported areas as narrow as possible.
    Graham
  • VR3
    VR3 Posts: 28,654
    edited August 2004
    So basically, I would need bracing running from top to bottom of the subwoofer?

    Since that is the longest side -- right?
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • gatemplin
    gatemplin Posts: 1,595
    edited August 2004
    Correct sir. You would need to make three pieces. They will make the enclosure very solid.
    Graham
  • VR3
    VR3 Posts: 28,654
    edited August 2004
    Alright, sounds good to me. I will do that ---

    this woofer has clips, like car audio woofers - where you press down or w/e and they open up and then you put the wire through and the amp comes with wires with the 'terminal things' on the end, so do I pull these off or cut them loose and then strip the wire and run it through the woofer terminals?
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • gatemplin
    gatemplin Posts: 1,595
    edited August 2004
    I would go to radio shack an buy some spade terminals (flat thingys?) and make some extensions using old speaker wire instead of cutting the amp leads. The extensions would fit into the amp leads, and then strip the extension to fit into the speaker terminals.
    Graham
  • VR3
    VR3 Posts: 28,654
    edited August 2004
    alright, will do that!

    Thank you very much for all your time and patience!
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • gatemplin
    gatemplin Posts: 1,595
    edited August 2004
    Your welcome.
    Graham
  • VR3
    VR3 Posts: 28,654
    edited August 2004
    Ok, I went on Home Depot and figured that I will need 2 sheets of MDF to do the cabinet and bracing at most if I do the cuts completely right...

    Then I will need 1 sheet of 1/4" Oak ---

    The price of Oak is EXPENSIVE, SO - I decided to do the caps in MDF with an Oak overlay....

    Woofer - http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-560

    Amplifier - http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-794

    Grill Cloth - http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=260-335

    Cabinet Materials will be 60 + Tax

    Woofer will be 85 + S/H

    Amp will be 128 + S/H

    Grill Cloth will be 7 + S/H

    Total - 280 + Tax and S/H

    I believe I will be real close to my budget of 300, maybe a tad over.

    Hmm, I wonder if it can compete with SVS's 400 dollar monster in output??
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • VR3
    VR3 Posts: 28,654
    edited August 2004
    Forgot to attach pic..
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • Dr. Spec
    Dr. Spec Posts: 3,780
    edited August 2004
    (sigh)

    Sid, read up on how the box volume, stuffing, and the driver specs all interact.

    Do you have any idea what the final Q of the system or the F3 will be with that driver, your box, the bracing, and xyz ft3 of stuffing?
    "What we do in life echoes in eternity"

    Ed Mullen (emullen@svsound.com)
    Director - Technology and Customer Service
    SVS
  • VR3
    VR3 Posts: 28,654
    edited August 2004
    Nope, But I am all ears :D

    I would much prefer design my own box and subwoofer than use plans. I wanna rightfully call it mine....

    So any help or know how someone can share, I am open to it...
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • VR3
    VR3 Posts: 28,654
    edited August 2004
    Ok, I went on PE's speaker box program --

    And I chose a different woofer since they didn't have mine and here is what I have come up with....

    Woofer - http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-130

    PE Recomends - 34.23x21.16x13.07 for internal volume or 5.48

    However I plan to change those dimensions to come up with the same volume, because that looks like an incredibly wide and tall, yet insanely shallow speaker. I don't want that...

    It will have 1 vent - 4.70 inches in diameter - can I use a 5 inch?

    It will be tuned to 22hz and should hit down to 24hz, theoretcially...

    Now do I have all of my bases covered? The program mentions nothing about Polyfill - but they did in the sealed design which was tuned to 40hz!! #_# -- So I am guessing it requires none?

    I went on PE's calculator and got the following....

    New Internal Dimensions - 18x18x29.25 = 5.48 Cu Ft

    Port Dimensions - 4.70" D
    Port Depth - Straight Tube - 13.73 IN
    One End Flared - 13.18 IN
    Both Ends Flared - 12.62"
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • gatemplin
    gatemplin Posts: 1,595
    edited August 2004
    Well to do it right you should first learn about the thiele/small parameters and how they affect eachother. A book like the Loudspeaker Design Cookbook will do and www.diysubwoofers.com . Then use that knowledge to pick the right driver for the application. Then get a program like WinISD, LSPcad, and learn how to use the T/S specs to design the box for the Q and F3 you want.

    The Cookbook will also teach you about bracing, materials, dimensions and stuffing.
    Graham
  • VR3
    VR3 Posts: 28,654
    edited August 2004
    Hey Gatemplin - thanks for the reply, I am curious as to what you think about the above idea - I will have to check out those books and read into this more....
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • VR3
    VR3 Posts: 28,654
    edited August 2004
    Here is what I got now basically...
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • gatemplin
    gatemplin Posts: 1,595
    edited August 2004
    I suggest you dont use that woofer. Step up to a Shiva for $125 or one of the DVC Daytons. That woofer has a mediocre 8 mm Xmax (although Sd is high), and doesn't look very robust to me. You will probably run out of excursion at around 30-40 Hz quickly. Also, it is 8 ohm so it will drop your 270W amp down to 180W. If you stick with the more popular drivers, you can copy other tried and true designs.

    I attempted to make my own sub, so I could say I designed it, but it sucked. I then copied Adire Audio's design to the letter, and it made a world of difference. Speaker design ain't easy and the more research you do, the better the results will be.
    Graham
  • VR3
    VR3 Posts: 28,654
    edited August 2004
    Hey,

    You have convinced me, SO - I will take your advice and go word for word on a Shiva design...

    I was on Adire's website and I had zero luck of finding design plans??

    Do you have access to a cabinet design for a vented Shiva?

    Thanks for all your help...

    You wouldnt happen to have AIm would ya? It would make this entire process a tad easier eh...
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • gatemplin
    gatemplin Posts: 1,595
    edited August 2004
    Here are the Shiva plans, they were under the technical link on the website.
    http://www.adireaudio.com/Files/VentedShivaApplications.PDF
    Here is the white paper
    http://www.adireaudio.com/Files/ShivaWhitePaper-V2.PDF

    Check out some of the sites people have made while constructing their Shivas. The three vented designs are like the three SVS cylinders. The bigger you go, the more extension, but lower max volume. Going with the Adire plans will ensure good results, Dan Wiggins knows his stuff.

    www.creativesound.ca has the Shiva on sale for $110, www.acoustic-visions.com has it for $125 shipped, they sell amps too.

    I still recommend you check out some speaker design books from the library. Learning as you build is one of the biggest rewards of DIY.
    I dont have Aim or any other message thing and am not on the computer very often for very long, but feel free to PM me.
    Graham
  • VR3
    VR3 Posts: 28,654
    edited August 2004
    Thank you Gate and thank you Dave (Phoneisbusy) he was helping me in IM...

    I am going to make the Adire Alignment Shiva....

    Going to be constructed of MDF all around, with double layered MDF top - and a MDF platform wrapped in black textured vinyl, same for the 'pegs'

    The cabinet itself will have a Oak top, and a 'ring' going around the bottom of the cabinet - the cabinet itself will be wrapped in a black grill cloth, the back will be open MDF, painted black (as will be the entire cabinet under the cloth, with the 250 watt plate amp from PE powering the subwoofer in it's own enclosure attached to the back of the sub.

    Sound good?
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • tryrrthg
    tryrrthg Posts: 1,896
    edited August 2004
    Although the Shiva is a great driver... for an extra $25 I'd get the Tempest ($150 shipped)! Much more woofage there!

    And why are you putting the sub amp in it's own enclosure? why not just put it in the sub's box?

    and why the double layer top? If you're going to double up something it should probably be the baffle...
    Sony KDL-40V2500 HDTV, Rotel RSX-1067 Receiver, Sony BDP-S550 Blu-ray, Slim Devices Squeezebox, Polk RTi6, CSi3 & R15, DIY sub with Atlas 15
  • VR3
    VR3 Posts: 28,654
    edited August 2004
    Because putting the amp in there would change the internal volume, no? - If it wouldnt matter that much, then I will put it in the enclosure itself....

    Bigger woofer = Bigger cabinet = more money

    Doubling the top to apply the Oak overlay to -- much cheaper than buying a complete 3/4" oak...

    The bottom will have the 1/4" oak overlay around the bottom of the cabinet...

    I might just do it where the 1/4" Oak overlay goes directly on top of the first layer of MDF to save money...

    The bottom platform for the woofer to fire into will be 3/4" MDF wrapped in textured black vinyl ---

    I downloaded the plans, and I looked at em for about 10 minutes and with my limited drafting skills, here is what I have come up with based on the drawings. I hope they are right....
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • VR3
    VR3 Posts: 28,654
    edited August 2004
    I have one last question, how would I wire the shiva woofer to get a 4 ohm load so I can get all of the 270 watts the PE amp has to offer?

    Thanks in advance, and thanks for all the help so far..
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • gatemplin
    gatemplin Posts: 1,595
    edited August 2004
    Looks good
    That drawing is right, except I think the port goes in the right rear corner. In the PDF it looks like there is a brace on each side of the port. You can add the sub amp to the box, no problem. You are not really changing the volume very much with that amp. I would add the amp to the side that has no brace.

    As for the DVC, wire them up as shown in the first diagram here which is the parallel method. Also, just in case you missed it, Adire says dont use polyfil in that enclosure.

    Here is another way to do the feet, just giving you another option. I find that these are the strongest.
    Graham
    Graham
  • VR3
    VR3 Posts: 28,654
    edited August 2004
    hey
    thanks for the fast reply...

    Ok, I will mount the amp on the sub --

    As for the feet, I plan to use the feet in the design but with a bottom plate like SVS uses, just the same size as the box...

    I like the platform look on speakers and that will probally help the output instead of it firing into carpet I would think....

    So that looks good, I will try my best to follow the specifications in the PDF - but the person that laid it out did it confusing, I wish he did a 3-D view...lol, woulda helped me alot...lol
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.