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Frequency response difference between typical bass cab and typical PA cab

Discussion in 'Amps and Cabs [BG]' started by superbassman2000, Apr 5, 2006.

  1. Hello all!

    So i am kinda looking at cabs right now, and i have been also reading about that DIY cab link in the harmony-central bass section (http://www.core-sound.com//bottom-article.html), and the guy picked a home audio speaker for its frequency response. anyways, that got me thinking about PA cabs, and so i have also checked out those...

    so http://www.diyaudio.com/forums/showthread/t-32205.html says that the low E is at 41 hz.
    Do i need a cab that goes right down to 40 hz? i saw this one PA cab i like thats starts at 50 hz...what would happen if i played an open E on that cab? would it blow up? kill my cat? burn my school down? make the universe implode?!??!?!
    anyways, i can't seem to find any frequency ranges for bass cabs, so i don't have anything to compare anything off of.

    oh, and i usually don't turn my amp up past 75% if that helps at all

    Thanks for the help folks!
  2. CamMcIntyre


    Jun 6, 2000
    If i remember correctly-many of our favorite classic amps have a roll off that starts before 50hz. I haven't checked this number but i'm thinking the old Ampeg SVT Rig [8X10+tube head] had a roll off around 60 hz.

    I know this isn't quite the answer that you're looking for, but i always that bass cabs were "voiced" differently. I don't know the specifics. For an experiment, plug your CD player/Ipod/Boombox into your bass amp & cab. Play the music-hear how it sounds? If your experience is the same as mine-not nearly what you would expect. Now do the same thing with a PA cab/speaker. Much more pleasant sounding IME. However, with some tweaking the bass cab sounds fine.

    take it easy.
  3. It would make sense for a CD player to sound good through a PA cab as opposed to a bass cab- PA is voiced for just about every instrument whereas the voicing on a bass cab is much more focused on freqs that we hit. That said, most bass cabs have a rolloff at above 40 Hz, so a PA cab with a roloff higher than 40 is fine. Just make sure you try it before you buy it.
  4. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    Some PA cabs provide a curve, so you can see where they actually roll off.
  5. here is the frequency curce for the cab i am looking at


    i see i cut off the left side, it says db spl
  6. That cab does look a tad bass weak, but try it out yourself and see.
  7. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    That curve is typical of what you'll get from the average 2x10plus tweeter, it's OK, nothing to get really excited about.
  8. is there a website that has different frequency response curves like that one?
  9. since i don't really know exactly what i am reading in that graphic, does that mean that with the volume setting at one setting (say, 50%), the E string won't ring out as loud as say, an A?
    or maybe since the line is lower at 40 hz, will the frequency be too much for the cab to handle and it will distort?
  10. ESP-LTD


    Sep 9, 2001
    It could very well mean those 2 things.
  11. Most likely thats a 1 watt test of efficency- its not farting out but its not as loud where the line goes down.
  12. Long story short, there are many frequencies that come from your bass when you hit your Low E. ~40hz is the fundamental, but it's the harmonics that form the complete sound. Some people agree that the fundamental isn't necessary and in many cases is undesired. Not *that* many people actually know what a fundamental that low sounds like. The point is though that you don't need a cabinet that produces a 40hz fundamental to hear your low E. Some of the BEST sounding low B sounds I've heard (low B is just under 31hz fundamental) have come from recordings or cabinets where the rolloff is well into the 60hz range.

    Also, even if your cabinet responds that low, it takes a LOT of power to generate the same perceived volume at that low a frequency as at a higher frequency. This is why most bassists in loud bands end up cranking the mids up to "cut through". It's still definitely a Low E, no mistaking that, but it cuts through because the harmonics are emphasized.
  13. There is not much fundamental output in a bass guitar because the strings are not long enough. So you can get away with rolling off freq. response below 60 hertz.
  14. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    True, but with enough EQ boost, and speakers that will do the job, a much more fundamental based tone is possible. That's what you hear at large concerts. If you want to get that same type of tone without massive PA your typical bass cab just isn't going to hack it.
  15. this post makes be feel better :)

    thanks for all the help everyone!

    i was looking at these cabs -> http://northernsound.net/Sales/speakers/community/DnD.html and the 12" speaker is the one that caught my attention...that is the one with the frequency graph i i put up before. I just was wondering how that cab (a full range cab) would compare to a standard bass cab (maybe not a full range cab). I don't exactly set my tone to "reggae tone" with full bass, but but don't want to hurt the cab if it can't take a bass :)
  16. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    You get what you pay for. It's a cheap PA cab that will work about the same as a cheap bass cabinet in the same price range.
  17. ok, thats what i kind of figured :)
  18. seamonkey


    Aug 6, 2004
    The difference is, is that you can actually find measurements of PA cabinets. There aren't any for Bass cabinets.

    Take a look at the graphs, and walk into a store with your head and try out the different PA cabinets. You'll soon recognize how the graphs match up to the sound of a bass in general. Don't forget the EQ can go a long way. If you have to crank the Bass control up to get decent bass sound out, it's probably not usable for bass. You can skip other cabinets that have similar roll offs on their graphs.
  19. My spectral analysis says otherwise.

    Depending on the instrument, the 2nd harmonic is at least equal to, and often slightly stronger than the fundamental.

    In a live (indoor) situation, the fundamental mostly contributes mud. The 2nd and higher harmonics are more audible, and the mids cut through in the live mix. Most rooms and clubs suck for bass unless specifically treated.

    Outdoors is another matter. The lack of fundamental makes the bass sound like a loud ukelele. No thanks.

    If you want a big fundamental, you have to move the air. That means a large radiating plane and drivers sufficient to reach down that low.

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