1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  
     
    TalkBass.com has been uniting the low end since 1998.  Join us! :)

Building a couple of 1x12 cabs

Discussion in 'Amps and Cabs [BG]' started by Kenson, Jun 27, 2018.


  1. Kenson

    Kenson

    Apr 27, 2017
    Willard, MO
    Hey all, going to be building a couple of bass cabs for my V4B RI. I'll be posting on here with stuff getting put together so you all can laugh at me when I mess up :) hopefully I won't tho.

    Reason behind this is there are few 1x12 cabs that match the demintions of my head and I didn't want to fork out the dough for ampeg 1x12s. So I'm going to save myself $700 after this gets done. If your curious I'm modeling them after the svt 112. If you all have any suggestions along the way I'll take them and if I'm not too hard headed I'll listen.

    What I'll be using is Birch ply and eminence legend BP 112 speakers
     
    Pbassmanca likes this.
  2. DukeLeJeune

    DukeLeJeune rational romantic mystic cynical idealist Commercial User

    Nov 24, 2008
    Princeton, Texas
    Owner & designer, AudioKinesis; Auth. mfg, Big E (Home Audio only)
    The BP-112 is a very good sealed-box woofer. I suggest making your cabs approximately 24" wide by 15" wide by 12" deep. Use no more stuffing than is necessary to prevent boxiness. This will give you a true sealed-box low-B, and when you stack the cabs on their sides the amp will sit nicely on top.
     
    Last edited: Jun 28, 2018
  3. Kenson

    Kenson

    Apr 27, 2017
    Willard, MO
    why does more stuffing give you boxiness? My original plans were 24L x 16w x 17h

    I was planning to port the cab
     
    Pbassmanca likes this.
  4. Stumbo

    Stumbo Wherever you go, there you are. Supporting Member Commercial User

    Feb 11, 2008
    the Cali Intergalctic Mind Space
    Song Surgeon slow downer software- full 4 hour demo
    Heighth x Width x Depth are usual measurements.

    What is "L x W x H"?
     
    Pbassmanca likes this.
  5. Kenson

    Kenson

    Apr 27, 2017
    Willard, MO
    Length width hight
     
  6. Kenson

    Kenson

    Apr 27, 2017
    Willard, MO
    So it would be
    17 high 16 deap 24 width
     
    Stumbo likes this.
  7. mapleglo

    mapleglo Gold Supporting Member

    Sep 7, 2013
    phoenix, az
    Curious how the 12" Legends will do.
     
    Pbassmanca likes this.
  8. Kenson

    Kenson

    Apr 27, 2017
    Willard, MO

    Me too :) Again this is going to be an adventure, but I'm sure I'll be happy either way things turn out
     
    Pbassmanca and mapleglo like this.
  9. Rick James

    Rick James

    Feb 24, 2007
    New Jersey
    That's OK if the cab is at least 12 cu ft tuned to 25-30Hz, but in the size cab you want to use ported is a bad idea. I assume you didn't use speaker modeling software to come up with the box size, driver choice and the idea of porting it.
     
  10. Kenson

    Kenson

    Apr 27, 2017
    Willard, MO

    no I didn't, is there web based software that I can use for free?
     
  11. BogeyBass

    BogeyBass

    Sep 14, 2010
    We're talking about a BP122 ?
     
  12. Kenson

    Kenson

    Apr 27, 2017
    Willard, MO
    Yes sorry I probably typed the wrong set of numbers
     
  13. DukeLeJeune

    DukeLeJeune rational romantic mystic cynical idealist Commercial User

    Nov 24, 2008
    Princeton, Texas
    Owner & designer, AudioKinesis; Auth. mfg, Big E (Home Audio only)
    Sorry my wording was ambiguous! Should have said something like this:

    Stuffing reduces boxiness by absorbing internal reflections, but too much stuffing can make the midrange sound wooly and congested, and can reduce low-end impact. So don't use any more than you need. Some trial-and-error is probably called for.

    Imo that size will work fine.

    I estimate your internal volume at about 2.75 cubic feet, before subtracting for the woofer and ports and bracing. Ballpark 2.6 cubic feet net internal volume, taking into account woofer and ports and bracing.

    I would suggest two 3" diameter ports, each 5.0 inches long. Make sure the internal diameter of the ports is very close to 3.0 inches so that you can plug them with expandable plumber's test plugs.

    With both ports open, the box is tuned to about 42 Hz. This is a lower than normal tuning, but because the BP-122 is optimized for sealed box use, imo you want a low tuning frequency other wise it'll be too boomy. It will probably still be too boomy for some rooms. That's where port plugs come into play:

    Plug one port and the tuning frequency drops to 31 Hz, tightening up the low end a bit. Plug both ports and - you guessed it - you now have a sealed box.

    I would guess that both ports open will be most useful for outdoor gigs, and that otherwise you will probably want to have both ports plugged.
     
    Last edited: Jun 28, 2018
    wave rider, Kenson and yodedude2 like this.
  14. BogeyBass

    BogeyBass

    Sep 14, 2010
    I'm assuming 3/4 or .75 ply being used
    And setting back the baffle 1.5 inches or so for the grill.

    Be around 2.4 to 2.6 cubic feet per driver

    The ampeg dimensions work out well for the head size. Likewise gives a somewhat larger box which the BP likes. It can be boomy in small boxes and kinda typical behavior of all the BP series

    Is the driver selection set in stone? Being you already purchased them

    The BP does fine ported or sealed. Does well for sealed with very low fs. Think only fun part will be port length to get tuning around 35hz. The Fs is low which is actually very nice for ported it won't tune high like typical 12". But sensitivity is kinda poor. there is other options for a ported 12" box.
     
    Last edited: Jun 28, 2018
  15. SactoBass

    SactoBass A retired civil engineer who likes all-tube amps! Supporting Member

    Jul 8, 2009
    Sacramento CA
    Duke is a class act all the way, and IMO, one of the most knowledgeable bass cab builders on the planet! :thumbsup:
     
    Last edited: Jun 28, 2018
    Roccafella, wave rider and Kenson like this.
  16. Kenson

    Kenson

    Apr 27, 2017
    Willard, MO

    Correct I'll be using 3/4 with room for the speaker grill. I did already purchase the drivers.
     
  17. Kenson

    Kenson

    Apr 27, 2017
    Willard, MO

    I did purchase the wrong size ports due to rushing my ordering. So those will be sent back. I will probably use a different porting system. Would pvc be a bad choice?

    Also with the porting, can I get away with just one port per cab? That was my original plan
     
  18. Coolhandjjl

    Coolhandjjl Supporting Member

    Oct 13, 2010
    Appleton
    1/2”Baltic Birch is fine if you brace it properly. No need for 3/4”.
     
    BassikBrad likes this.
  19. BogeyBass

    BogeyBass

    Sep 14, 2010
    I would definitely go with minimum of 2 ports. Velocity is very high with a single port. And will cause distortion called chuffing
     
  20. Pbassmanca

    Pbassmanca In the pocket n' thumpy. So woody, so greasy...

    Well sir, I certainly admire your willingness to work hard to build your own cabs and save some money. My humble suggestion is that you take the advice of expert builders like @DukeLeJeune at their word and learn as much relevant information and knowledge as possible. I believe there are even software programs that will tell you what the appropriate size box is for your driver as well as porting and other information. If you are patient and take all of the relevant information into consideration, I believe that you cannot fail at this project. It's my understanding based on my limited knowledge of the subject, that cabinet design in conjunction with driver selection and porting etc, is strictly a numbers game ; and so if you get those things right I think you cannot but succeed! :thumbsup:
     
    Christine, SactoBass and Kenson like this.

Share This Page