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DIY Bass Cabinet Design

Discussion in 'Amps and Cabs [BG]' started by JehuJava, Oct 20, 2004.

  1. JehuJava

    JehuJava Bass Frequency Technician

    Oct 15, 2002
    Oakland, CA
    I'm gonna try to build a bass cabinet. Not to save money or anything like that, just for my own personal pride and satisfaction.

    Here's what I came up with:

    Emminence Omega 18" 4 ohm model

    Interior dimensions:
    24"W x 20"D x 28"H

    (2) 6"Dia x 12" Long (approx to tune)

    I was planning on using 3/4" MDF for the wood with dowel bracing between sides and top/bottom.

    My goal was to be able to rock all the way down to the low E (41hz).

    any thoughts?

  2. r379


    Jul 28, 2004
    Dallas, Texas
    Don't use MDF. Spend the money to buy good void-free 3/4 inch birch plywood. Building/tuning a ported cabinet will require making sure the size of the cabinet and port(s) will be apporiate to the frequency you wish to tune the cabinet for. The easiest way to do this is to copy a cabinet you like and use the same driver or to use software to do the calculations for you. Software is available from Eminence and Harris Technologies.
  3. I would build this cool, folded horn design and scrape the 18, or make it with the 18. Second order ported design is kind of boring for a DIY. At least do something a little original. Is the 18 a sub in a biamp or is it full range. If you are using for low-end reinforcement, then build this:


    That will give you pride if your wood skills are up for it.

    Use birch ply and at least 1" for the baffle plan, or plan the driver is mounted to. Use speakon connector and good cable.

  4. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    I appreciate the plug, but Tuba 30 isn't really well suited to electric bass. It's intended as a large main PA sub, with extension and output capabilities far beyond what anyone could possibly need from a backine cab; it will run to an octave lower than E41. That won't stop some people from building one for bass anyway, but to each their own. In any event, being a sub it's intended for use up to 100-120 Hz and would require a separate midbass/HF speaker.

    I agree with the idea of not going with either an 18 or a same-old same-old cabinet; if you're going to the trouble of building you own why settle for the ho-hum performance that you get with a factory made box? DIY means not only saving money but also getting performance that you simply can't buy ready-made, at any price.

    The cabinets on my site that do make sense for electric bass, and were specifcally designed for that purpose, are the DR250a full range cab (equal in output to a 4x10) and Tuba 24 sub (equal in output to a 2x18).
  5. Jim Ingraham

    Jim Ingraham Supporting Member

    Nov 14, 2002
    Heres the Tuba24... Highly recommened :bassist: :
  6. I can't argue with the designer. Just didn't want that guy to spend so much time and energy laboring on a 1960s design. Y

    our comment about how it is not suitable for bass is going to send more bass players to the lumbar yard and Parts Express than anything I said.

    And my 36" scale 5-string goes down to low A, 27hz with the hip shot lever and stands open at low B, a taut 31.5hz fundamental.

    Why aren't there any commercially produced COMPACT horns?
  7. JehuJava

    JehuJava Bass Frequency Technician

    Oct 15, 2002
    Oakland, CA
    Thanks for the responses.

    While I am in favor of building something unique, I wanted to build a standard run of the mill 18" cab for two reasons:

    1. I would like to use it in conjunction with my Aggie GS410 for more bottom. (The reason for the 18) I would use my Eden Navigator's crossover.

    2. I have no real woodworking skills. (The reason for the standard design)

    I have checked the website for the tuba24 many times. I love the design! I'm not sure if my skills are up for it or not. Although, I would have some experienced folks offering me assistance from time to time.

    Bill, do you think I could accomplish the Tuba 24?
  8. JehuJava

    JehuJava Bass Frequency Technician

    Oct 15, 2002
    Oakland, CA
    I used the formulas from David Weems and G.R. Koonce's book "Great Sound Stereo Speaker Manual."

    I used the FAT BOX ratio 4:5:6 to determine my measurements.

    The port measurements were calculated from Kbapps.com calculators.

  9. Look dude, in case you haven't figured it out, we don't want you to build that 18. It's going to be big, ugly, heavy and will probably muddy up that premium name-brand 410.

    Build a horn, bandpass or something else. That tiny $100 tuba 24 design might be overkill anyway for your 410-too much air moving. Use your head to crossover so the aggies will just play above 100hz or so.
  10. ESP-LTD


    Sep 9, 2001
    At least in my neighborhood, a lumber yard will make simple cuts for .50 cents each. With a little careful planning, they will cut out your whole project for under $5. Make/reinforce the joints by tacking down 1x2 as an interior frame; glue and drywall screws.

    MDF is sonically superior to plywood, and easy to work with. But, your 1x18 cab will be pretty heavy, and MDF is more subject to damage if you drop in on a corner; plywood is pretty forgiving.
  11. JehuJava

    JehuJava Bass Frequency Technician

    Oct 15, 2002
    Oakland, CA
    I know, I know. I want to build something cool also!

    What do you mean the tuba 24 might be overkill?
  12. You'll have to have one of the other guys answer that for you on why the tuba 24 may be more bass than your ready for. I din't own one but if I could pay the guy at home depot 10-20 bucks to cut the whole project then consider me in.

    Maybe this is the sound your after in a DIY:
  13. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    While the DR cabinets are quite complicated and require both a well equipped shop and a high degree of skill, the Tubas are not much more difficult than simple boxes, they just have a lot more parts. A high degree of accuracy isn't required, you can even build one with only a circular saw and electric drill for tools. All you have to do is take your time, understand what you're trying to do, and if you run into problems just ask myself or the other guys who've built them for help at my forum.

    Tuba 24 is a good match for either a 2x10, 2x12 or 4x10, going at least a full octave lower than they can reach. From a technical standpoint it has extension and sensitivity superior to even an 8x10 and would be a reasonable addition even to that if the player finds the bottom end lacking.

    Tuba 30 is overkill even for 5 string to low A bass for the simple reason that while the fundamental may lie at 27 Hz the power band lies in the second and third harmonics, not the fundamentals. On average the power requirements for electric bass in the fundamentals are 20dB less than that for the second/third harmonics.Even for low A maximum output is required above 54Hz, not below it.

    There are no commercially available compact horns for one reason: cost. To make a reasonable profit they would have to be priced at least twice what comparable direct radiator cabinets cost because they take about four times the labor to build. Where cost is of no concern and performance is everything horns dominate. In the $5k and up range horn subs account for at least 75% of sales.
  14. slinkp


    Aug 29, 2003
    brooklyn, NY, USA
    Bill, I've been looking at your site, and I have a couple kinda dumb questions... about the size, when you say e.g. "22 inches cubed" for the DR250A, does that mean roughly 22x22x22 or what?

    and, if I buy plans, do they come with recommendations for drivers including tweeters?

    How easy is it to change drivers in one of your horns if you ever blow one?

    Is it possible to add a tweeter attenuator?
  15. JehuJava

    JehuJava Bass Frequency Technician

    Oct 15, 2002
    Oakland, CA
    You'll have to ignore my ignorance on folded horns...

    So one 10" driver will effectively replace an 18" driver and ported cabinet? That seems amazing.

    Regarding power, suppose I use a 10" driver that can handle 500W RMS. How would that work with the whole project? Most of the discussion refers to 100W. Is the folded horn design not as effective with loads of power?

  16. What are the external measurements, weight, and recommended driver for the Tuba 30?
  17. ]

    With longer scale lengths the power band decreases closer towards the fundamentals. The difference on my 36" scale seems dramatic compared to a regular 34" scale. A std upright or EUB with a 42" scale definetly has more power down towards the fundamental. Who could possibly disagree?

    I still think that if the consumer can build the tuba 24 for $150, then a Chinese factory could build a couple thousand and sell them for a decent profit. I don't know. It just seems far fetched that there are no petite horn subs on the market that costs under 500. I have seen the little E.V. and Cerwin Vega PA horns but have not heard them. Obviously, they can be massed produced and sold cheaply. But they aren't loaded with modest 10" drivers, nor do they boast that they are overkill for most application.

    Beyond all that, I am thinking of giving it a shot. Is it efficeint enough for 150 watts RMS? That's all I have to work with if I slave it off my Eden CXC110 Combo at 4ohms.

    I can understand why people don't mess around with more transmission line enclosures, however.
  18. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Yes. Plans come with complete instructions and photos of the buiding process and recommended drivers. Tweeter attenuators could be used, but it's better to series wire them for less sensitivity and thus higher power handling.

    No. It can replace a dual 18 ported box.

    100 watts into a folded horn can give the same output as 1000 watts into a direct radiator. Horns don't use a lot of power because they don't need to. 300 watts is more than enough.

    Tuba 30 is 30 inches cubed, weighs about 100-120 pounds, recommended driver is the Eminence Magnum 12 HO; JBL2206 is OK if you can afford it, Eminence Delta Pro 12 if you want to keep the cost as low as possible.

    Me. Aside from designing speakers I'm also a professional consulting audio engineer; I conducted RTAs at a major concert venue over a two year period that conclusively back up my statements. It was the result of those 60 odd RTAs that allowed me to design small subs that more closely duplicate the real word requirements of pro-touring sound than any other speakers that I'm aware of, concentrating the highest sensitivity in the frequency bandwidth where it's actually required and not wasting space and weight trying to go with more first octave sensitivity than is actually necessary, but not giving short shrift to the lowermost fundamentals either. Even if you have an 18 right now chances are its response is down 30dB at 27Hz.

    As for the Chinese factor, look at what almost all the posts on this and other forums talk about when it comes to speakers: cheap sealed or ported boxes than can be assembled by a chimpanzee in fifteen minutes and sold at a high profit; the only thing that's moving to China is the assembly of these same boxes. Horns are out there and they cost a lot; as long as there are plenty of pros willing to pay $5k for an EAW BH760 you're not going to see them selling them for $2k, no matter what it cost to build them.

    Transmission lines are interesting but they don't work well with low Qts high fs pro-sound drivers, though those characteristics are ideal for horns.

  19. I Concede Defeat. Great answer!
  20. JehuJava

    JehuJava Bass Frequency Technician

    Oct 15, 2002
    Oakland, CA
    So when choosing a 10" driver for the Tuba 24, what driver parameters should I be most concerned with? I have heard, whether it's true or not, that a larger Xmax is desired for a folded horn.