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Building a Cab...

Discussion in 'Amps and Cabs [BG]' started by Mike, Nov 20, 2002.

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  1. Mike


    Sep 7, 2000
    I'm considering building a 2x12 cab with a tweeter. I wouldn't mind modeling it after the Aguilar GS212 b/c that's probably a pretty safe template. Does anyone know if the GS212 is chambered? Also,if I use Eminence Kappa 12's, can the Aguilar be safely used as a model or will I need to design a cab specifically tuned to my chosen speakers? This will be my first venture in cabinet making and I don't wanna end up with a lemon...

    Thanks for any info...
  2. OsQ


    Jun 13, 2002
    yeah, it wouldn't hurt if you come up with the cab like that... i think that aguilar even uses some kind of eminence speakers, but that doesn't help the fact that you need to spend time on your drawing board...

    there are very good cab modelling softwares on the web ie. WinISD that i use. it has speaker spec database - you don't need to spend your youth looking for them.

    software will also quide you to find optimal measurements to your cab... enjoy:)

    btw, what's wrong with lemons?
  3. Mike


    Sep 7, 2000
    btw, what's wrong with lemons? [/B][/QUOTE]

    Lemons are great! Lemonade, Lemon Meringue, Lemonheads... I'm just not convinced they would faithfully reproduce the natural tones of my Status basses. ;)
  4. Educate yourself first.

    Buy a copy of "Vance Dickason's Loudspeaker Design Cookbook". You can get it discount from www.partsexpress.com for a decent price.

    Once eduated, you can make decisions about what to build. First, how low do you have to go? Are your requirements for a 4-string, 5-string, or even lower? This is a fundamental decision. Next, does it have to be really loud, or have to be really small cabinet?

    Me personally, I don't like multiple driver cabinets. A pair of 1x12 is preferable to a single 2x12. The singles are smaller overall, easier to move, easier to get the optimum volume, and they look cool when stacked.

    The Eminence Kappa 12 Pro will do just fine in a net volume of 1.06 cubic feet, tuned at 37 Hz. It has a gentle rolloff and the -3dB point is 96 Hz. Nice tone, but it won't have a massive bottom. This is the SBB4 alignment and will give the best transient response (punch). The 37 Hz tuning is a good compromise that works well for 4-string and 5-string basses. I expect it will have a bass response similar to Fender combo cabs I've played.

    Link to Kappa 12 Pro Plot in SBB4 alignment
  5. I'll go ahead and point out that if this is your first cabinet project, it will cost more, look worse, and sound worse than a professionally made one, unless you are a really good cabinet builder, and then it will still sound worse and cost more.

    Sad but true in most cases. I just thought I'd go ahead and bust your bubble so you wouldn't get your hopes up.

    Now, if you don't care about those shortcomings I listed above, and are willing to pay some money and sweat a lot to learn how to do something that is very hard but worthwhile, then you're doing it for the right reasons and by all means full steam ahead.

  6. Mike


    Sep 7, 2000
    I kinda had a feeling that might be the case. It sure sounded cool! I read regularly, so, the book suggestion mentioned by another was good. I want better bass cabs than I have. I'm just not that satisfied with the Eden products I own. I hate using power tools and performing manual labor. Spending money is never a problem but $ down the drain isn't all that cool. I checked the software mentioned by another. It was interesting but the shape and dimensions of the generated cab seemed to cater toward home stereo equipment. Maybe I oughtta buy one. Trying 'em out is always cool.;)
  7. That is the clincher, right there.

    Buy one, and save yourself mountains of grief and expense.
  8. Seeing as how I use the kappa Pro 12 as my main cab, i thought I'd chime in. Allow me to touch on some points made earlier:
    I find this statement not quite right (if in the right cab) I bought this driver as a replacement for my Nemesis's orig driver. It is more bottomy and gutsy that the Gs112 (if that says anything. In fact they are very very similar (as the GS uses the Gamma series) tonewise, but mine has more headroom. My cab is just over 1.2 Cu ft with a 4" deep 3.5" dia port. It is very tight sounding with GREAT lows - defineltly moves a lot air. If anything i could say is that it is a bit scooped sounding - Im thinking it could use a mid driver in the array (one day).

    Eminence has a great simulator that includes all of the specs (general+T/s) of thier drivers already loaded. It seems to be pretty accurate. I simulated my cab in the prgm and got the graph, then used my buddy's studio to comapare it's results with a test tone and analyzer. The results were very close. Its pretty cheap as well

    My thoughts on building vs buying is that the building is a bit more pricy and difficult compared to the offerings of companies such as Avatar and the like. Dave at avatar will load his cabs with any driver you like at an affordable price. It seems to me that you would be better off if you modify an existing cab using a simulator than from scratch.

    $.02 deposited :)
  9. Mike


    Sep 7, 2000
    Yeah, that's the problem. I have a 2x10 and a 1x15 now. I'm very much interested in 12's and a tweeter (can't live without one). I've spoken with Dave at Avatar and, unfortunately, he has no plans to manufacture a 2x12 bass cab. I really don't want his 1x12 because then I'd have to buy 2. I could pick up his 4x10 for less than 2 1x12 cabs. Gear is a damn headache...

    How much is the Eminence software?
  10. Alrighty. I'm not too scared of power tools, but I know that anything I turn out would look like crap. So I designed a custom cab and had Armadillo Ampworks build it for me. Very economical, and you can get your dream cab built by a professional. Go here for details:

    Here's the one I had them build. The largest Bass combo ever I think. 2x15 sealed cab that I loaded with Altec Lansing 421A speakers, and a Bassman 50 Watt tube amp slid in to power it. Exactly what I wanted. They did the grill cloth and all that. Packed it up extremely well and shipped it to me on Greyhound since it was too big for UPS. Everything turned out perfect.


  11. I can see the issue, what about getting a blank 15" cab and put a new baffle in? I'd get the software and put in some of the parameters and see what it comes up wiht (iow, a lot of times it can fill in the missing parts of the equation for you)

    How much is the Eminence software? [/B][/QUOTE]
    I think its like $50, but I "procured" mine independently:)
  12. The Gamma 12 is a crappy driver for electric bass. It has a miniscule Xmax, too high a resonant frequency at 57 Hz, and a very high Qts, which provides crappy transient response. In short, the Gamma 12 is better suited as a PA speaker.

    Is your cabinet 1.2 cubic feet *net* internal volume? Deduct about 0.12 cubic feet for the driver volume, deduct more for bracing and the port itself. The Kappa Pro 12 in SBB4 is 1.06 cubic feet, for optimum transient response (read: tight sounding). It will have a nice bottom, but it won't have the massive bottom of a sub.

    All the design programs operate on the same principles, but they do require the operator to understand what he is trying to accomplish. Vented boxes have a wide variety of different alignments. It all depends upon what you want. Most design programs assume flat response (WinISD, et al). I favor superior transient response. The SBB4 alignment rolls off higher up, but offers much better transients (read: punch) when applied to the right driver. The extended bass shelf (EBS) used by the Delta 10s in the Avatar 4x10 extends low bass response, but sharply spikes the group delay which makes for worse transient performance near the tuning frequency.

    The plots below shows the classic shelf that occurs when a driver is put into a cabinet that is too large for its requirements. It does extend the bass response, but there is an associated price to pay with more sloppy transients.

    Link to Delta 10 in EBS Alignment

    Link to Delta 10 in SBB4 Alignment

  13. Now that you are done showing us that you know something, it wouldn be a bad idea to adjust the the condescending manor in which you delivered the message.

    No, im not trying to start a flame war, i was merely stating my experience for someone who asked. My calculations on volume was based on the simulations of the Eminence Designer. I made no claim, otherwise. To my fault, I meant to say " I believe" that Aggie uses the Gammas. I was going off of memory (which isnt that sharp today...or any day, for that matter) and i was wrong.

    If your specs say that my cab has insufficient lows, OK, but the producers and bandleaders that hire me for my tone are saitisfied, so are other bassplayers that witness it and I am elated to have it. Isn't that what matters most?

    Please accept my apologies for being a layman with experience, i didnt mean to tread on your ground (no sarchasm intended)
  14. ESP-LTD


    Sep 9, 2001
    I always appreciate your posts, even though it is a constant reminder of the Calculus classes I fought with...

    I was looking around at 12" drivers and was surprised that there were no "great" choices, since a 1x12 is a pretty convenient and scalable size.

    Have you run into any favorites drivers and/or alignments in a 12" ?
  15. No condescending tone was intended. My apology if that was your perception. Tone of voice is a problem with non-verbal message boards. If we were having a face-to-face, you would have understood my tone about the crappy driver. The Gamma 12 IS a crappy driver for bass, and for all the reasons mentioned above.

    Most major manufacturers do not use off the shelf Eminence drivers, but purchase custom designed units. Eminence has a catalog of thousands of different designs that are available to OEMs. I'd be very surprised if the publicly available Gamma 12 is used by a major manufacturer, because it isn't much of a bass driver.

    I never mentioned "insufficient lows", nor unsuitability, bad tone, your band leader will hate it, or anything else of the sort. I said "no bottom", and that still stands: -12dB at 41 Hz and -16dB at 31 Hz is "no bottom". It bothers me to see somebody set themselves up for failure by undertaking a project they don't have the knowledge to complete. It is much more involved than sticking a driver inside a box.

    All the commercial cabs I've played through and tested don't have much bottom. The reason is they are all designed to be loud, and this accentuates the mid-bass. The famous Eden hump. The manufacturers all do it the same way: they stuff an acoustically large driver(s) into a too-small box. This cause a big hump in the mid-bass, and a corresponding steep rollof in the low range.

    The Acme probably has the most bottom of all commerical cabs, but it isn't very loud. It has more difficulty cutting through a loud mix because it has a more of a flat response design type. But... this is what EQ is all about. I'd like to have a cab that will produce whatever I feed to it. If you want hot mids, turn up the EQ.

    The Omega Pro 12 in 1.23 cubic feet at 39 Hz is nice for a 4-string.

    Link to Omega Pro 12 Plot
  16. Mike


    Sep 7, 2000
    What about the Kappa not Gamma 12? Is there any right choice? !:confused:

    I don't know why I post where the tech heads answer. All I ever do is become more indecisive... ;)

  17. Firstly, since you are illiterate, i replaced a faulty driver in my nemesis cab. I did not just "slap a driver into a box" I did research it. I take great offense that you speak with such contempt right off. I hope your personal life doesnt suffer too much by this.

    But for my dollars (read: I did not want to spend the national debt on my small gig cab - but it turned out to be tquite the opposite), the Kappa Pro was ideal for my uses, (i have a 3.6 cu ft box, i was at work when i frist posted) that fact that it does roll off at ~50hz is nearly ideal to the cabs that I modeled it after. I got a clear objective and used the resources made available to me and exectued them to what I feel is perfection.

    See attached for more detail.

    Further, it is not optimal in bass guitar reproduction to have a perfectly flat response- if that was the case, wouldnt you think it would be doen and successfully marketed? Certainly ampeg and eden's business would be shot, right?

    I was trying to be cordial enough in my last post so we could at least be in agreement, but instead you felt the need to be superior. Im glad for you. please, go on about the subharmonic, power robbing, unneccesary frequencies. Im intrigued.

    to the rest of TalkBass, i am sorry for causing a ruckus, i was trying to be helpful before this donkey decided to show the farm that he can call louder than the rooster.
  18. /German accent on/

    "Hey fun boys, get a room!"

    /German accent off/

    Sorry, I just had to say that. :D

  19. flacko


    Dec 6, 2001
    Surrey , UK

    What are the technical reasons behind this.
  20. Suburban


    Jan 15, 2001
    lower mid Sweden
    Partially true.
    The optimal response of an amp-cab system would probably be according to the "phon"-curve, aka F-M or F-W curve after the inventors. This shows the relative disability the human ear has to percieve lower and higher frequencies.

    However, a flat response will carry the same information as the acoustic image the instrument sends out. Hence, it will be known as "transparent".
    Now, if you do some simulations, you will find that it is very hard to design a speaker-box system that can give flat response. There will probably be a bump somewhere. And manufactorers want to make cheap gear, more than anything (for which they charge a lot...).

    Eden, SWR, and especially Ampeg would be dead ducks by now, if they hadn't fooled the musician to sought for their respective bumps, rather than the sound of the instrument strings.:rolleyes:

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