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Bass cabinet design

Discussion in 'Amps and Cabs [BG]' started by Prostheta, Aug 19, 2012.

  1. Prostheta


    Mar 19, 2010
    Pori, Finland
    Hi everyone - over the period of the next year I intend on putting together a "convenient" bass cab as part of my studies in woodworking. The structural and material sourcing aspect of the build is no problem, however I would like to get the specs for the speakers (and hence volume/porting in WinISD) sorted early. Budget is limited given that I am in a study period of my life so suggestions on speakers choices should bear that in mind.

    If my thinking is true, I should hit a combination giving me either 4Ω or 8Ω. The amp to be used with the cab will happily put 800W or so into 2Ω and I have no use for stupid high volumes with this cab or for that matter amp shopping! I think it is logical to have a cab that doesn't load the amp too heavily with a low Ohmage or necessitate the master volume forever living right at the bottom of the range.

    The design of the cab needs compactness hence the initial rough idea being a 2x12 in a deep wedge or kickback style rather than being a bootshaker.:smug:

    A 1x15 with a horn crossed my mind, however cost is again a factor with the crossover and the large speaker pumping up the cost, etc. Constructive commentary on this choice is welcomed of course.

    Choice of speaker and cabinet volume/porting specifics are of course dictated by the programme type. The muse in my playing style is a mix of pick, finger and percussion (in that order of prevalence) with a brighter up-front tone than as not. My former favourite cab was a Trace Elliot 4x10 however my main instruments are 5-string basses in "normal" B and also open C (GCGCG). The bass response is not that much of an imperative as I prefer punch and presence to big warmth.

    The initial idea for speaker choice is a pair of Gallien Krueger 082-0590-A. These 12" drivers are rated 200W at 4 Ohms, so two in series hits my target weight of 8Ω at 400W. I seem to remember some recommendation about not installing speakers in series however. Hmm.

    Unwarranted scathing criticism of my approach, logic or anything else for that matter is not welcome. I am happy to admit I am learning, so all egos can be left in the basket at the door. Complimentary nibbles at the bar, don't pee on the seat etc.:D
  2. 1958Bassman


    Oct 20, 2007
    Find some used drivers if you want to keep the price down. There's a ton of them on ebay, Craig's List and in music stores. If it's more of an exercise than a quest for the best sounding design, buy something safe- Eminence, JBL, Altec, Peavey Black Widow, Celestion, etc (not trying to make anyone mad if I left out their favorite brand), get the Theil-Small parameters and free the beast on it. You could also call a local shop that re-cones speakers- they usually have several left overs that weren't picked up. I think a pair of 4 Ohm would be most practical and flexible- your amp will drive an 8 Ohm load and if it has two channels, you could run one speaker off of each. Additionally, your amp can drive a 2 Ohm load, so that option is still available if needed. You may have drivers made by other manufacturers form Europe that would work well and I know many good manufacturers are on your side of the pond.

    You can wire speakers in series, but the voice coil inductance will decrease the highs a bit. If you don't need ear-splitting levels and want to use more of the volume controls' range, go with 8 Ohms if you have the power for it.

    Unless you like the sound of a bass to be really bright, I would stay away from a horn with a 15". Most 15" don't do well high enough to make the transition work well, regardless of what people say about Piezoelectric horns not needing a crossover. They still sound like garbage when the frequency is too low. Better to use a 6" or 8" instrument driver for the upper range. It will do upper-mid well (it IS a bass, after all) and should blend with the 15 better without being overly harsh. You can use a passive crossover for this, but it will need to handle lots of power.
  3. PlungerModerno


    Apr 12, 2012
    AFAIK you need to choose drivers very carefully. You'll need a lot of xmax to get deep deep lows very loud - most drivers are very limited in that regard (esp. vintage or guitar cones).

    If you check these out you'll find some well presented, extremely well tested info and ideas: http://billfitzmaurice.info/forum/


    You can't go wrong by looking at greenboy's stuff either - http://greenboy.us/fEARful/

    It seems to me that to make a great 2 or 3 way cab costs a fair bit (the components that are awesome cost a bit to make) but a good 1 way cab (Hi-Fi enough for a lot of bassists) can be done with no huge price. At least nowhere near what a great off the shelf cab would cost new.

    Happy building! :D
  4. +1

    May I also add that 12" speakers are not necessarily cheaper than their 15" counterparts, when you get into premium drivers. As an example a 3012LF costs as much if not more than a 3015LF. If you are not looking to go with premium drivers, then you spend a lot more money re-inventing a crappy cab.
  5. Prostheta


    Mar 19, 2010
    Pori, Finland
    Well, I can't afford premium drivers as I stated. These GK drivers are pretty affordable at about €75 each. Inasmuch as a driver budget three times that would of course bring all kinds of "premium" units into range, that just can't happen here really I'm afraid. The two points of the project is for me to use the cab for course credit and also to end up with a useable compact wedge, crappy re-invention or not. If anything, the design of the structure is the focus and perhaps sometime later I will take the experience of this project to build something better specced and with a wider budget. This will certainly not be the ultimate cab. :)

    Some great reading on the links provided, thank you very much. I've been through Bill Fitzmaurice's site before however the size and scope are quite out there in comparison to my aims. Plenty of food for thought in translating those ideas down of course. The fEARful site is now in my bookmarks and I will no doubt absorb that over the next few days. The crossover builds on there are of particular interest....I think you might well be on the money with a big single and mid if the crossover components are not too expensive in comparison.

    I'll do a bit of investigation as to who might have overstock of drivers....Uraltone have bulk and second hand plus they list the Eminence Basslite S2012 (8Ω, 150W) and Eminence Legend CB15 (8Ω, 300W) which sound promising. I'll throw these into WinISD to play around with volumes and dimensions using the specs for those two and compare.

    So tired. Thank you again.
  6. PlungerModerno


    Apr 12, 2012
    If I had a workshop I'd be doing this myself - you can get awesome cabs put together with 'non - super' drivers. They'll never handle the same power though, driver for driver.

    Remeber... Post pics! :hyper:
  7. Trying to design an enclosure around cheap drivers is not a simple task. I assume at the end of the exercise you want a cabinet that will actually work very well. Side stepping the design process and going with an established and tested design should have no impact on the woodworking process. I have built many speaker cabinets during my playing career. Some worked very well, others meh!
  8. In a similar situation I kept my eye on ebay and Craigslist and scored a brand new Eminence Delta Pro 15A for cheap. I'm going to build a cabinet tailored to the Kappalite 3015 and use the Delta in the cab until I can afford the Kappa.

    For the purposes of your carpentry class I presume any old speaker will do. For you own long term purposes you might consider designing for the speaker you want to buy 6 months from now.
  9. PlungerModerno


    Apr 12, 2012
    Nice thinking... You can get a good cab and then go downright awsome with a straightforward switch.

    You can also put in some 'temporary' port tuning you can have a nice balance for both drivers without serious modding to the cab.

    Rock on! :bassist:
  10. 1958Bassman


    Oct 20, 2007
    Have you thought about contacting some of the European instrument/PA speaker manufacturers, to find out if they have something that might work in the enclosure you're considering? Tell them that it's a school project and they may go above & beyond the call, as a PR gesture.
  11. Phendyr_Loon


    Sep 4, 2010
    If you're not looking for a super high wattage 12" driver, the S2012 is a good choice.
    It has roughly half the power handling, weight, Xmax, and price of say the 3012LF Kappalite. The Basslite has a slightly higher sensitivity, with decent db's into 4.5hz.
    I've played around with the S2012, it performs most efficiently in the ported box, though some folks make it work in a sealed application.

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