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I still don't understand needing an 18 in a PA

Discussion in 'Amps and Cabs [BG]' started by plowboy, May 9, 2006.


  1. plowboy

    plowboy

    Apr 24, 2006
    I am really wanting to find a small bass cab that will also serve second duty as a bi-amped sub on a 420 Watt PA (with no drums). I will run full-range speakers off one 210 watt amp, and run the sub off the other. Now if the best bass sound in the world comes from these tiny cabs with tens and twelves, then why would a person ever need a huge eighteen inch sub on the PA to reproduce the same tone? Am I wrong here, or is the 18" sub only needed for the kick drum? It seems the PA sub should be the same cab as the bass amp, which would mean tens or twelves.
     
  2. Trevorus

    Trevorus

    Oct 18, 2002
    Urbana, IL
    Kick drum, and to carry the bass throughout the room. In big places, or outside, they really are useful.
     
  3. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    True, if you want the sound in the PA to be the same as the stage amp. By and large that notion hasn't existed in the pro-touring genre for at least 20 years, and is rare today even in the semi-pro ranks.
     
  4. Exactly, it's there to put the kick in your chest where it belongs.
     
  5. Eric Moesle

    Eric Moesle

    Sep 21, 2001
    Columbus OH
    You need to have bass fill an entire large room and carry farther, not just fill a smaller stage and not carry as far. Therefore, 18's exist for mains, and 10's exist for closer monitoring.
     
  6. Who said 10's and 12's were the best for bass amps? 15's and 18's still are used by many!
     
  7. elros

    elros

    Apr 24, 2004
    Norway
    Proprietor, Helland Musikk Teknologi
    Bigger speakers for larger areas (and longer distances). You won't be able to appreciate the lows of a 18" up close, but farther away (in the audience area) it will be heard and felt well. The bass amp 10" speakers won't be that good at a distance, but on stage they'll do great. That is my limited experience.
    I once used a 2x15 cab on my bass rig, and we found that we didn't need to put the bass throught the PA at all. This was in a church with roughly 400 seats.
    BTW: my favourite PA leeasing co. uses Turbosound rigs with 21" subs. Soudns fantastic.
     
  8. a 2you will chew up 10 ro 4 10 will not reproduce lows even close to what an 18 can or 15. While they all may have a similar freq range, lets say 40-1500. The 18 will have a lot more towards the 40 and the 10's will have a lot more towards the 100. A 10 can theoretically go as low as an 18, but is not as efficient. you chew up more watts (and EQ) trying to get that last octave out of the speakers. OTOH, bagend with their ELF has made 12" subs that go very low. Like 20 hz. they have 10s that hit 34. That have 18's that do 10 hz. In a TINY box.
     
  9. What if you tune your bass like Jauqoo?
    Or you got 9 string bass with a strange tuning, so you might need an eighteen inch speaker, just to make your low string sound appropriately.
     
  10. high mileage

    high mileage

    Apr 17, 2006
    Rockford IL
    18" subs take a lot of power. I'm talking more than your total 420w per driver. With a high-powered PA rig and 15" vs 18" subs, you will definately hear a difference. The main difference is in the amount of thump the kick drum produces, but it's a big difference.

    I have used an 18" cab with a former bass rig, and it wasn't what I was looking for. Cabinets on stage and mains are two different deals.
     
  11. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    You're kidding right ?
     
  12. Bill, since you have much experience with loudspeaker design can you clarify your stance on this issue for me?

    Yes it would replicate the sound better but also these 10's and 12's have mic, guitar, drums going throught the same speakers as well. Do you feel this woudl affect it at all?

    Granted speaker design/efficiency has a lot to do with affecting this equation....personally I just like 15s because I feel it fills up a large room better than 10s. For a PAs job to that, do you have an opinion one way or another on the size affecting this? Thanks
     
  13. plowboy

    plowboy

    Apr 24, 2006
    I said: "will run full-range speakers off one 210 watt amp, and run the sub off the other."

    He said: "You're kidding right ?"


    No, not kidding at all. We do acoustic bluegrass. Does that make sense now? I'm wanting top notch tone, but not much extra volume. The PA is to bring everthing together. For example, the vocals are a little soft with a manolin, banjo, and guitar banging together. Also, a modest 420 watt PA can give a lot of extra kick in those larger situations where just the acoustic instruments get lost in the space. I used to play guitar over a Boogie sitting on top of two 4x12 cabs. Been there and done that. I'm never going back to those kinds of volumes, or lugging that kind of stuff around. At my old age, if it can't fit in a mini-van, then it's staying home.
     
  14. plowboy

    plowboy

    Apr 24, 2006
    "True, if you want the sound in the PA to be the same as the stage amp. By and large that notion hasn't existed in the pro-touring genre for at least 20 years, and is rare today even in the semi-pro ranks."


    YES!, I agree with Unatratnag. That comment was loaded with cryptic but densely loaded information. I would love to hear him expound on that more.
     
  15. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Go to a concert and listen to what's being put out by the PA system. 95% of the time you'll hear a low frequency content from the subs that bass amps on stage are simply incapable of creating, while the sound you hear from the kick drum is so far from what the drum sounds like acoustically that it's not the same instrument. 40 years ago the PA's job was to amplify the sound as it existed on stage to high enough levels to be heard in the audience. Today the PA creates a sound in the audience that doesn't exist on stage at all.
     
  16. billfitzmaurice:
    "Today the PA creates a sound in the audience that doesn't exist on stage at all"

    With this said, I'm kinda wondering if there is really any point in investing in a large-projection, BASS frequency-heavy amp rig, or if it would be smarter (and cheaper) just to get a smaller, easily transportable amp that you like the sound of, and let the FOH mains do the job of projecting both the overall volume and specifically the lower-frequency volume to the audience (???)
     
  17. plowboy

    plowboy

    Apr 24, 2006
    "With this said, I'm kinda wondering if there is really any point in investing in a large-projection, BASS frequency-heavy amp rig, or if it would be smarter (and cheaper) just to get a smaller, easily transportable amp that you like the sound of, and let the FOH mains do the job of projecting both the overall volume and specifically the lower-frequency volume to the audience (???)"


    If I allow myself to clear thoughts in a row, then this also is my inescapable conclusion...and oh by the way, it's simpler.
     
  18. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    That depends on a couple of things. One, do you have a PA that will do the job? As far as the average garage band is concerned the answer is no. Two, do you want the same sound on stage that the audience hears? Very few bass cabs are up to the job, but they do exist.
     
  19. CraigV

    CraigV

    Jan 8, 2002

    A bass cabinet has to reproduce the entire range of sound of a bass guitar, which is for all intents and purposes a full-range instrument. The PA subs only handle from 20-100Hz or so, but must do so to the extent ncessary to fill a possibly large space.

    Typically the bass amp would only be used as the bassist's instrument monitor on stage if sufficient PA support is available. This is good as stage volume should be kept to a minimum, and the amount of stage volume needed to fill an arena would make the rest of the mix terrible as stage amps would bleed into vocal and other mics.
     
  20. wwittman

    wwittman

    Apr 21, 2004
    Westchester, NY
    The "best bass sound in the world" comes from bass cabs with 15's or 18's.


    You're starting from an inaccurate preconception.
     

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