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A question about cabs

Discussion in 'Amps and Cabs [BG]' started by hdracer, Dec 20, 2012.

  1. hdracer


    Feb 15, 2009
    Elk River, MN.
    I have a question about cabs that has been bothering me for wile now.

    I have seen a lot of threads about using a PA cab as a bass cab.
    Usually the thread is started by a younger player with limited funds and has found a good deal on a used PA cab with 1 or 2 15's.
    The usual reply's are DONT USE IT!! It will sound like crap!!!

    I also see a lot of people that say they don't need a amp or cab. Just run through the PA with a DI box.

    What am I missing here?
    If a PA cab sounds bad with a bass head why will it sound good using a DI and relying on FOH and a little 210 monitor??? :confused:
  2. jlepre

    jlepre Supporting Member

    Nov 12, 2007
    Parsippany, NJ
    Good question
  3. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    Maybe because cheap pa cabs sound like crap for bass or pa.
  4. Subs...
  5. hdracer


    Feb 15, 2009
    Elk River, MN.
    I have seen a lot of very good PA cabs sell used for a couple hundred dollars.
    I got my PA cabs used in nice shape for $300 for 2 115 with horns.
    I have tried plugging my amp right into the and using a DI and going through the mixer.
    It sounded okay but nothing like my "real" cabs.
  6. skychief


    Apr 27, 2011
    South Bay
    Generally speaking, PA cabs use "full-range" drivers, which typically have much less cone excursion than a proper bass driver. i.e., a 12" PA driver wont push as much air as a 12" bass driver(@ same power input). So the PA cab will need to be pushed harder to achieve the same perceived loudness of a bass cab.

    So it basically comes down to efficiency.

    But many bass players are content playing through FOH and use a small 210 for monitor purposes. Different strokes for different folks.
  7. CL400Peavey

    CL400Peavey Supporting Member

    Nov 7, 2011
    Grand Rapids Michigan

    Its usually in response to just mains, or a sub. Not both, with a stereo power amp, and a cross over.
  8. Try plugging your bass amp in. Mind out you don't flap them!

    PA cabs have the benefit of subwoofers to do the hard work. Hopefully we get a toneful sound into the mixer and the net effect after some more EQ is rocking.

    There was a young fella reporting back last week about his bargain Yamaha dual 15 thing. He was very happy with it.
  9. This is the reason for Sansamp DI, Reddi, etc.
  10. CL400Peavey

    CL400Peavey Supporting Member

    Nov 7, 2011
    Grand Rapids Michigan
    PA mains are not subs, and subs are not PA mains. You need both to cover bass guitar.
  11. Tuned


    Dec 6, 2007
    Bass cabs are only good at providing low end to a small area directly near them. They are essentially PA speakers with narrow treble dispersion and better low end extension than full-range PA speakers thanks to longer excursion capabilities. PA subwoofers are designed to deliver low end to large areas, and are no good for anything else.

    There are many bassists using PA subwoofers in their stage rigs, but unless it's a huge stage the low end produced where the bassist is will be just as loud where the guitarist is. So the guitarist turns up, then the bassist can't hear so well so he turns up, then the guitarist can't hear so well so he turns up, then the drummer can't hear so he hits harder, etc etc.

    Standard PA cabinets can work fine for bass but only to maybe half their rated power. Beyond that their limited excursion becomes a problem.

    I always encourage bassists to keep their rigs reasonable and get them up and close to their torso. Don't think of it in terms of how much volume you can generate, think in terms of how large a ratio you can make of volume at your position versus your bandmates positions. I get a much higher ratio with a 4x10 on a stool 2' away than an 8x10 6' away. My bandmates and all sound techs appreciate it greatly.
  12. So wrong about sub bass not travelling. It travels a hell of a lot better than the rest.
  13. Dude.:scowl: The sky is blue with white clouds ok!
  14. iiipopes


    May 4, 2009
    Most PA mains are designed primarily for voice or broad range instruments, not bass. Therefore, most are designed to roll off below 50 or 60 Hz to limit driver excursion (and therefore warranty claims). Likewise, most subs are still designed for bass drum and not necessarily linear response needed for bass guitar.

    With the advances of technology for bass guitar cabs, I'd stick with a reputable company's cabs for bass guitar.

    For example, I have an SWR Triad (15, 10, tweeter) bass cab. It is full range, absolutely great for what I play. I have also used it to good effect as a PA cab. If it is PA-style response you want for bass, this is a good choice. With the array it has, including its good crossover and pad on the tweeter, you can tailor the cab for any bass guitar tone from old school to the most prog tone you desire.
  15. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Who the heck puts a 410 on a stool? Accident waiting to happen!
  16. BFunk

    BFunk Moderator Staff Member Supporting Member

    There is nothing wrong with using a PA system for a bass amp. You will need a three or four way system with a dedicated sub. I think what separates PA systems from bass cabs is that bass cabs are designed to make the bass sound good. PA systems are designed to make the mix sound good. The fact that the PA is not optimal for bass sound the best is ok since you are also hearing guitar, vox, drums, keys, etc.
  17. Tuned


    Dec 6, 2007
    10 years and counting, zero accidents
  18. Foz


    Jul 26, 2008
    Jax FL USA
    Playing bass through a mini-PA stack is a very nice experience. Its a way to get a rig that transcends all the flaws of traditional bass cabs [weak low lows, nonexistent highs, poor off-axis frequency response / dispersion, huge mid-range bumps and dips that yield a baked-in tonal profile that is difficult or impossible to subvert...].

    I used to do the mini-PA stack thing with an EAW 18" sub and various PA tops - and a pre-amp, and an active crossover and a PA amp. Worked great - and was a giant pain in the ass to lug around.

    I have found a better way to get similar results using Dave Green's [aka greenboy] fEARful bass cabs... essentially a PA top and a sub in one box with passive xover components so you don't have to bi-amp/tri-amp the stack. With this configuration you can use a simple Pre/PA amp rack or even a traditional head [with the advent of SMPS light weight high power bass heads you can get every last potential dB out of one of these high output cabs with a load out that is utterly trivial compared to all the crap I used to lug around].

    A step further, Dave now has newer designs out [fEARless f112 & f115 - and soon a f110 model]* that can sit on the floor as a wedge monitor when the PA is going to carry the room or you can stand em upright like a traditional cab when you carry the room with your rig. I don't have one of these units [yet] but its seems to me these close the circle of your question = mini-PA for small gigs / awesome floor monitor for full PA big gigs.



  19. Tuned


    Dec 6, 2007
    Travel might not be the best word, long story short bass cabinets cannot produce deep low end (40-80Hz) without also producing a lot of low mid overtones (120-250Hz). All of them. Same goes for bad subwoofers. It takes a dedicated design to do it properly, and then it's no good for anything else. Deep lows also pass through walls, ceilings, and floors much better than low mids.

    Long story short, if you're getting decent low end 6' from a bass rig, you're flooding the room with low mids, guaranteed. If you're getting them from 2' away, it's thanks to proximity effect and you're probably not flooding the room with anything.
  20. grisezd


    Oct 14, 2009
    I've got two cabinets, a 4x10 Madison (which I don't think I could lift onto a stool!) and a Carvin 15-whatever 3-way PA cab. I've played each separately and as a stack and felt that any of the setups sounded fine. What I've come to realize is that my stage tone matters less than being able to hear myself (and the bandmates hearing me) since the sound guy is going to make me sound any way he wants anyway. I'm starting to think of my rig as more of a monitor now. For shows with less PA support I'll worry more about it.
    I guess I'm agreeing with the OP.