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1x10 Cab Build Help

Discussion in 'Amps and Cabs [BG]' started by xjoebradshawx, Dec 29, 2015.

  1. xjoebradshawx


    Dec 29, 2015
    Hi there!
    I'm knew to talkbass, and cab building in general. I've been interested in building speaker cabinets for a while and have done tons of research on building guitar cabinets. My lovely girlfriend decided to help me get started by buying me tons of hardware to build cabs for christmas, including a speaker. But her lack of knowledge on anything music related led her to buy me a bass speaker, specifically an Eminence Legend B1P102 . I decided its not a big deal, because I could use a smaller bass practice amp, than my SVT810, but upon doing more research I've come to learn that bass cabinet design is a whole different beast, and I really don't know where to start. As for the look I want something simple and as compact as it can get. So my questions are this..

    Realistically how small could I make this cab?
    Obviously the volume of the cabinet will affect the sound, but the Eminence cab design PDF doesn't help me much, because I honestly don't know what I'm looking at. So if somebody could help me out with good interior dimensions for the cab or how I could find good dimensions, that would be wonderful. I know that the choice of having a completely sealed or a ported cabinet will affect the dimensions of the cabinet, which leads me to my next question...

    Sealed Vs. Ported?
    If I'm looking for something compact to fit in my apartment for practice, will porting the cabinet make a big difference?
    In general this project is a) for me to have a portable practice amp, and b) for me to get started into cab construcion, so the cabinet doesn't have to be perfect. Does placement of the vent make a big difference? I've seen some DIY cabs built with the vent facing the rear of the cabinet, vs coming out the front.

    Is a tweeter necessary?
    I would like to think no, and hope thats the answer because from the research that I've done over the past days, it seems as though having to build a crossover is more of a pain than I want to deal with. Any insight here would be a big help.

    Cabinet Finish?
    Does the exterior of the cabinet have a major affect on the sound?
    I see most DIY cabs covered in carpet, I think it looks terrible, and perfer the look of a stained cabinet. Would leaving the bare wood affect the sound of the cabinet in a major way? I also have a roll of tolex if having the wood covered to some degree is a necessity.

    I think that's all I have for questions right now, I'm sure that more will come with time but I think this should be enough to get me started. If you have any other insight to send my way that would be a big help. I thought I knew everything that I needed to, but like I said bass cabs are a whole different ball game than guitar cabs.

    My hope is to come out of this build with a cabinet that looks something like this one:
  2. http://www.parts-express.com/pedocs/more-info/290-471-eminence-legend-bp102-more-info.pdf

    It will be a pretty "dark" sounding cab without a tweeter or midrange (but then you also need a crossover). The upper response rolls off at only 2KHz.

    Finish of the cab makes no difference to sound. Porting extends the low end output, but means a larger box. The cabinet volumes in the spec sheets are internal volume so add panel thickness into your cut dimensions as well as any internal bracing and the volume the speaker takes up http://www.parts-express.com/pedocs/specs/290-471--eminence-legend-bp102-specifications.pdf.
    Last edited: Dec 29, 2015
  3. Alivefor5

    Alivefor5 Supporting Member

    Jul 17, 2006
    Karl Kaminski likes this.
  4. mbelue


    Dec 11, 2010
  5. Eminence publishes a pdf of designs for each driver. A sealed cab leaves little to the imagination whereas the ported ones need a bit of design to match the volume to the ports.

    A bp102 is a bit old fashioned as a bass speaker but fine for your purposes. Loads of bass cabs use them.
  6. mbelue


    Dec 11, 2010
    Your easiest path to a working cabinet would be the sealed Eminence design.

    Your choice large or small. I would do large so you can add a Xover and tweeter later.(This speaker will be too dark without.)

    I like 1/2" Baltic Birch plywood, but with that you'll need to oversize the box so you can brace the baffle.
    3/4" ply you can avoid bracing but the cabinet will be overly heavy.

    The box you have pictured is a guitar speaker. The ratio of depth to width is off when used for bass.

    When determining height x width x depth look up golden ratio. Use these guidelines to determine the dimensions of the box.

    Edit: in light of the particulars surrounding this speaker's midrange response, disregard my comments concerning golden radio. Construction with this driver may benefit greatly from baffle step adjustment.

    I recommend Duratex covering. Durable and very easy to achieve professional result. Although no covering is necessary for function.

    DIY speaker boxes can bring much satisfaction, but once you build you'll never be satisfied.

    Reviewing the cabinet construction pictured above some possible considerations.
    It appears that box is built using cleats. While a cleat may make for a sturdy joint they do little to brace against panel flex and vibration.

    Minimising vibration is the purpose of internal bracing.(which is sometimes avoided by using thicker panels) Vibrating panels is lost output. You want your driver moving air not its enclosure.

    Standard butt joints are more than sufficient if using a modern adhesive such as PL Premium. Sturdy and air tight. Air tight being an important detail.
    Bass cabinets(like subwoofers) whether sealed or ported should be airtight along all joints, allowing air to escape only through a port(if used).

    Cleats are not only unnecessary they take up internal space better used for bracing.
    Last edited: Dec 30, 2015
  7. xjoebradshawx


    Dec 29, 2015
    I was looking at the small sealed design from the eminence website, im just it really sure what I'm actually reading when I look at it. Maybe I'm just missing something? Is the total volume of the box .508 cu. ft, and .44 cu ft with the speaker in it? How would I calculate the interior dimensions of the box based just on the volume of the box? Also is any soundproofing nessecary with the cabinet? I do have some soundproofing foam that she bought with all the other hardware
  8. mbelue


    Dec 11, 2010
    Yes you read those dimensions correct.
    Soundproofing isn't really the intent of the foam. In a cabinet foam is used to minimize interior sound reflection. In the case of the design you are considering one of the particulars is "heavy fill".
    Generally Poly-Fil is a commonly used product.

    In a sealed cabinet the air inside creates a spring like effect for the speaker. Filling material changes the "tension" of this spring. This tension is used to control the way the speaker moves and prevent damage or poor quality sound.
  9. mbelue


    Dec 11, 2010
    If you notice some of those designs are labeled "bass guitar" while some others are not.

    Other designs are more suited for subwoofer use.
  10. xjoebradshawx


    Dec 29, 2015
    so if i look at this design it shows i need a volume of .999 cu ft. and 1 round port. is Dv, the diameter of the port?

    I wish I knew better what I was looking at when reading the box properties hahah.

    If I'm understanding what I'm reading right, based on this calculator, if i make a box thats 13x15x11.75" the box will have a volume of 1 cu ft". My inputs looked like this. Am I missing anything or did I input any of the information in incorrectly?

    Will I run into any major sound issues building a cabinet with those dimensions? Also is there more to the port than just drilling a whole in the front speaker baffle? Also, does port location have any affect on the sound?

    Again, sorry I'm so full of questions all of this stuff is just so confusing to me. Maybe I should just let the cabinet companies build my cabs, and I'll stick to plugging in and playing haha.
  11. you need to account for the port length and driver displacement, using the same calculator I've got a volume of 0.82 with port length and driver displacement factored in. Otherwise, it seems like you get the idea.

    I think that what a lot of people do is just make the cabinet %10 bigger and call it a day, but in my projects so far I've been particular enough to do the math to account for those volumes. Whether you want to punch those numbers in there or not is up to you.
    Last edited: Dec 30, 2015
  12. Dv is the diameter of the port and Lv is the length of the port. So a 3 1/2" ID port tube that is 10" long flush to the front sound board. Your depth is not enough for the port length.
  13. mbelue


    Dec 11, 2010
    A port(vent) is a combination of Dv=Diameter and Lv=Length. Which is pretty much what you're missing in all of these.
    Length of port, which in Eminence's PDF is 10.01".

    Ish. you need to input the length of the port into that calculator. As well as the driver displacement. Check here.

    Beaten to the punch.
  14. xjoebradshawx


    Dec 29, 2015
    How deep does the box need to be to fit the port? Would 12.75" be enough?

    If I change my dimensions a bit, and input all the right info I'm able to come up with a volume of .99 for the box, but when I'm looking at the cab design from eminence theres two different volumes, the total volume should be .999 cu ft, which i believe is the volume of the box without the speaker in it. If thats the case should I not worry about entering in the speaker displacement in the calculator. The new calculations I came up with look like this
  15. For what it's worth, the best sounding 110 cabs I've played have all been front ported cabs, not sealed
    red_rhino likes this.
  16. FerruleCat


    Mar 29, 2014
    Tulsa, OK
    In general terms, the tradeoff is that a ported cab will go lower, but porting can make it easier for a driver to shake itself to death unless the math is right. The math varies from driver to driver depending on a set of characteristics called the Thiele/Small parameters. Bass cab design is really just an expensive form of jigsaw puzzle.
  17. Right you are, didn't think about that. You should be fine then.

    another rule of thumb: Don't put the woofer in the centre of the baffle, keep it off centre of the baffle both vertically and horizontally. If you're going to put a tweet or a mid, then you could put the woofer towards one corner, with the port occupying another, and the tweet/mid (or at least space for it) in the third. staying away from the centre of the baffle helps to canel out vibrations both inside of the cabinet and on the panels of the cabinet. This helps to minimize the need for bracing, though if you're going with 3/4" ply you'll be more than fine without it.
  18. I would not mount the driver in the centre of the baffle but offset it towards a corner. This will allow placement of a high range driver later if you feel the cabinet is too dark.
    spaz21387 likes this.
  19. Rick James

    Rick James Banned

    Feb 24, 2007
    New Jersey
    Save yourself a lot of headaches and get the Simplexx 10 plans. The BP102 is a recommended speaker for it.

    If you don't want to cut your own wood I think you can get a flat pack from Leland at www.speakerhardware.com.
  20. xjoebradshawx


    Dec 29, 2015
    Where's the fun in just buying plans?!
    Passinwind, mbelue and B-string like this.

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