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Building a cab

Discussion in 'Amps and Cabs [BG]' started by JMS, Feb 25, 2003.

  1. Although most persons I have asked have said that it's better to buy than build from a price / quality perspective, I have wondered about the suitability of commercially available sub-woofer drivers designed for the car-audio market in a bass guitar cabinet. I know the eyes have probably started to roll, but could someone give me a reasonable answer as to why this would be a bad idea (or a good one)? As there is such a huge market in the car audio industry, I would imagine that competition might drive quality up and prices down. The market is not as broad in the music industry and quality components are quite expensive. I can hear my neighbour's truck's 2x10 boom-box a block away. Surely an 8x10 cab with the same components might power up a stage??? :confused: Constructive feeback please.
  2. kirbywrx

    kirbywrx formerly James Hetfield

    Jul 27, 2000
    Melbourne, Australia.
    Merlin has built all his amps. I think he has a 4x10 and a 1x15, so sending a PM his way may be a good idea. He's a sparky aswell :D
  3. Lovin Bass

    Lovin Bass

    Feb 8, 2002
    Los Angeles
    I had some car audio components laying around and was wondering the same thing so I did a search here on Talkbass.

    What I found out from other post were that car bass drivers are designed more for a narrow and "extreme" low frequency range (5-30 Hz.) "kick-drum" bass where as bass guitar drivers are designed to handle somewhat higher and broader frequency ranges (30 - 700 Hz. - ?).

    However, I am NO expert so try a search and you will be able to find more information on this. The above could be wrong and I my intent is not to mislead you.
  4. The main disadvantage of car sub is their extremely low efficiency. While a good commercial 4x10 will output far over 100 dB at 1W if input power, a car sub will most likely not get over 90 dB. You'd need 10-20 times as much power to get as loud as the 4x10. You'd need a separate amplifier on top of your existing amp system to do this, and an active crossover.

    If you're into relatively low-volume things (acoustic/jazz), then go for it, you'll get by with 100 W. But don't expect to be heard in a rock band this way.
  5. Bruce Lindfield

    Bruce Lindfield Unprofessional TalkBass Contributor Gold Supporting Member

    Of course Joris is the expert, but I think it's pretty obvious, even to someone like me, that a car speaker is only looking to project the sound within a very small space and short range. Whereas playing in a band you really want the sound to "project" a bit further than that!! :rolleyes:
  6. Bruce Lindfield

    Bruce Lindfield Unprofessional TalkBass Contributor Gold Supporting Member

    You were right!! ;)
  7. TxBass


    Jul 3, 2002
    Frisco, Texas
    agree with these guys, however there are some bass/PA drivers out there that are affordable and if you can build your cab to suit what it needs to get a sound decent you can still do it. To get some of the higher end stuff you'll pay (as it should be) but i've built 2 cabs with Madison speakers and they sound nice for rock. Run a search for Madison on here and you'll find others that have used them. They have a site but sell through other vendors (exp: speakerhole.com). No, they are NOT the high-end driver, but it doesn't sound like you need that. If you do, buy a cab--it would be less frustrating.

    good luck with it!
  8. ESP-LTD


    Sep 9, 2001
    Yes, but Ampeg uses 32 ohm drivers in parallel to get to a 4 ohm final load. Most car audio drivers are 4 ohms and 8 of them together would pretty much smoke any amp out there short of an arc welder (and it would probably only need 4,000 watts to get going well).

    It's a contradiction to get low and loud out of a speaker; it won't happen. However, you may get "loud enough" for your purposes with 500-1000w to power them (not such a big trick these days). I doubt a car audio sub will work much above 500hz or so.

    Car audio SUBWOOFERS will not make a general purpose bass cab; they will make SUBWOOFERS.

    My solution is an Avatar B112 sitting on top of (2) homemade JBL 12" subs, crossed over at 100-300hz. The Avatar is about a 96db sensitivity cab, and my 2 subs together are about 95db (with luck). I only fnished it all a few weeks back and haven't pushed real power in yet to see "how loud" that will get but the tone is excellent. My total investment in the pair of subs is about $300. My design goals were:

    1. Flat down to 30hz
    2. Small, light boxes (40#)

    I would suggest it's very doable, but don't do it unless you really want to go LOW. Loud isn't part of the equation with car audio speakers. They are loud in cars because of the cabin effect which boosts low end a LOT.
  9. ESP-LTD


    Sep 9, 2001
    From the specs published by JBL on my 12's for a suggested alignment, they suggest a flat response from 30-200hz +/- 2db or so (JBL GT120 ).

    I would disagree about the "5-30hz" part but it's only in the matter of degree. I agree- these are subwoofers, not full-range speakers. Typical 15" bass guitar speakers commonly are flat from about 50hz-1,500hz or so (broad generalization). If you expect car audio subwoofers to run full-range you will be very disappointed. As subwoofers however, they do reasonably well.
  10. Also, rubber surrounds (car drivers) tear apart pretty easily. PA drivers w/ paper surrounds last much longer and are more appropriate for bass guitar.
  11. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Low efficiency would be the killer.

    Keep in mind that car boom boxes do so well because they're pressurizing a very small volume...and the signal is really compressed when it hits the amps.

    I believe that Bruce Gavin swears by his subs of car audio origin. I'm sure that he'll join in shortly...

    I suppose that you could build a HUGE 8x10 subwoofer box with 4 ohm speakers and have a system impedance of 2 or 8 ohms...or build a 9x10 subwoofer box and have a system impedance of 4 ohms (three parallel banks of three drivers in series):bassist:D :bassist: