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Car speakers for a bass cab?

Discussion in 'Amps and Cabs [BG]' started by Intrepid, Feb 28, 2002.


  1. Intrepid

    Intrepid

    Oct 15, 2001
    Has anybody tried use car speakers on a bass cab...I suppose there is more competion, but you can get a equally powerful car speaker for much less then a bass speaker for exampe...does it work? Not to mention having a bass cab made out of those pretty showcar speakers would be cool...
     
  2. Paul A

    Paul A

    Dec 13, 1999
    Hertfordshire U.K!
    No,
    Don't do it! - The efficiency of car speakers is very, very low.
    About the best you could say is they look pretty (if you like that kind of thing)
     
  3. Premium grade automobile subwoofers will reach way down into frequencies where bass guitar commercial cabinets just won't go. There is a misnomer about car subs being for just for cars. This is poppycock. A sub is a sub. Where you use it is up to you.

    Most subs are intentionally inefficient by design to keep the size down. The three components of a driver are Loud, Low, and Size. These three can be juggled around by the designer but the sum cannot be more than 100%. You cannot have Loud, Low, and Small in the same cabinet because the laws of physics prevent this. You can trade off one, to gain the other two.

    Typical subs are designed for Low and Small, and trade away Loud. These are found most often in cars because this is where they sell the most, and for the small size. The opposite end of the spectrum are JBL 2241 and the Eminence Kilomax Pro 18" that are both Low and Loud, and require huge Size.

    I run a pair of Rockford RFR-2215 subs as 1x15 cabs. The have SPL 89 which is awfully inefficient, and I use a 1,200 watt amp channel to drive them. I found that one is not enough for a loud bar venue and an over-loud guitarist, so I use both now. The pair is less than half as loud as the average value of most bass cabs, and probably 1/4 as loud as an Eden D410XLT. But... they will go FAR lower than the commercial cabs. If you are playing a 6 string with low F#, you need true subs because the commercial cabs won't cut it at all.

    True subs have to be bi-amped because they are all done above 100 Hz. This means an active crossover in your rack, a stereo power amp, etc.
     
  4. Bruce Lindfield

    Bruce Lindfield Unprofessional TalkBass Contributor Gold Supporting Member

    Having read the last comment I tend to agree with Paul A - if you need 1200 watts to power them, you are not going to be saving any money!

    I don't find that extreme lows are very useful either and I am usually trying to cut this part of the sound out - might be good for some kind of heavy metal band; but not for acoustic Jazz! ;)
     
  5. Bryan_G

    Bryan_G

    Apr 28, 2000
    Austin, Texas
    Well car subs are designed to be in cars. If you take them out of that environment they lose alot of power. Car subs are optimized for very small rooms, because as I understand it when the frequency becomes low the wave length becomes long. In cars the wavelength can become longer than the actual room, and when the wave gets too long it'll reflect off the walls and amplify itself. Car sub designers use this fact to greatly enhance bass responce. This gain is quite noticable. I don't know exactly but it starts somewhere around 80hz, sometimes as high as 100. It increases bass response by 12db per octave. So assuming it starts @100hz, you get 12db+ @ 50hz, 24db+ @ 25hz, and 36db+ @ 12.5hz.
    WOW, now take that sub out of the car and your bass responce goes way down.

    I don't know alot about the physics of sound so if somebody who knows this stuff would back me up or shut me down, it would probably help everbody out.
     
  6. Intrepid

    Intrepid

    Oct 15, 2001
    Well also take into account that I usually play in a very acoustically sound room, so possibly maybe I really don't need a whole lot of power....just very good tone and moderate power to get over a horn section, piano, drums, and guitar. I work at Circuit city and I get the speakers at discount(factory price) so in reality, I could buy all these parts very cheap...I was just wondering...
     
  7. Mr_Pink

    Mr_Pink

    Nov 30, 2000
    Belgium
    Are you shure the SpeakerPower for cars is measured in Watts RMS?
    I know for shure that car-amplifiers are measured in Peak power .
    Dunno for the speakers
     
  8. All drivers have three design points: Size, Loudness, and Low Frequency response. Subs used in cars require small cabinet size and compensation for cabin gain.

    The sub is required to go Low (duh, it's a SUB) and required to be Small, to fit inside the vehicle. These two requirements force the 3rd parameter (Loud) to be sacrificed. Small and Low cannot also be Loud in the same box.

    Cabin gain is the significant amount of bass boost and low frequency extension that occurs inside the enclosed space of a vehicle. A tiny, sealed box that rolls off at 55 Hz will have significant low bass extension below 30 Hz because of cabin gain. Plotting this box inside the cabin shows a flat response below 30 Hz. The same box measured outside the car sounds anemic and has no low end.

    Sealed boxes offer significantly tighter bass and a much smaller box than vented cabinets. They also roll off much higher up, and in general don't go down nearly as low as vented boxes. Sealed boxes eat more power than vented boxes because they are not as efficient. However, vented boxes are not appropriate for in-car use because they are too large, and have too much bass due to cabin gain.

    Vented boxes are entirely appropriate for live music production because they offer low frequency extension this is absent in sealed boxes. Vented boxes do not have the long cone excursion required by sealed boxes at very low frequencies, so vented boxes can get much louder.

    Car subs are drivers whose Thiele-Small characteristics let them perform well in small, sealed cabinets combined with cabin gain. Many of these subs will perform well in usable-sized vented boxes outside of automobile cabins. The trick is understanding the T/S numbers and finding the correct driver for this use. If you want a really loud subwoofer, it is going to require a huge box.