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Mains: 15" v 12"

Discussion in 'Live Sound [BG]' started by Thumper, Mar 12, 2013.


  1. Thumper

    Thumper

    Mar 22, 2000
    Syracuse Ut
    Thanks to the feedback here we are now looking at powered mains. Most of the threads I've read recommend 12s if using subs, and state that the vocals sound better through a 12. 15s if no sub, and they have slightly less focused vocals.

    Is this a generalization, or does it pertain to specifice speakers?
     
  2. I use QSC K12's and sometimes K10's for my tops. I can add a sub when needed.
     
  3. Already In Use

    Already In Use

    Jan 3, 2010
    I use 15 mains and 18 in subs. To me it all sounds great. We always get compliments on the sound quality.
     
  4. MLC_BassPlayer

    MLC_BassPlayer Supporting Member

    Feb 15, 2010
    Apex, NC
    When my band was looking for a new sound system , we received two independent recommendations, from two completely different sources. Interestingly, both quotes received were for the exact same Yamaha system. Powered 12s over powered 18s.
     
  5. craig.p

    craig.p

    Sep 28, 2008
    New Hampshire
    It is a generalization and a valid one.

    Sometimes budget-driven compromises have to be made. I think that's where 15s fit in, because they can be (gently) pressed into light low-end duty, though I've never been a fan of that because of the phase/delay issues that accompany identical but physically separated bass sources (vs. one centralized location). If that need isn't there, though, I see no justification for 15s.

    3-way 15s are another matter entirely. Then you've got a mid horn (or mid cone/cones, or mid horn-loaded cone/cones) to handle the mids, which is where the vocals are. Different animal altogether.
     
  6. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    All too true. I'm using the Carvin 1503 3-ways which meets this description. Not my first choice but they were available used-as-new and I do occasionally use them sans subwoofers...fair trade-off, IMO.

    These particular 15's have a huge wide "bump" centered around 350 hz. I wonder if this is a common problem?

    Riis
     
  7. Runnerman

    Runnerman Registered Bass Player Supporting Member

    Mar 14, 2011
    We use 2x15/6/1 Mackie powered combos and up to 2x18 B36 Cerwin Vega subs if needed.
    The Mackies are nice enough on their own soundwise to be honest. I'd go with 15's for flexibility when not using subs and get a 3 way combo rather than 2.

    (We can also add to that for outdoor stuff if needed with additional CV 18's and piezo horns.)
     
  8. Thumper

    Thumper

    Mar 22, 2000
    Syracuse Ut
    After a quick look 3 ways seem to add substantial weight and cost. Weight is the bigger drawback. This is a pretty good band and sounded fine with just 2 way passive JBLs. I did go listen to them a couple of times before I accepted the bass chair and never thought "gee, they need better speakers and a sub." Just saying....
     
  9. craig.p

    craig.p

    Sep 28, 2008
    New Hampshire
    Cab honk, most likely. Pop the 15s and see if all walls are lined, and with what. And if they're braced, too.
     
  10. Thumper

    Thumper

    Mar 22, 2000
    Syracuse Ut
    I didn't mean to sound condescending, this band manages volume well, all that goes into the mains in most venues is vocals and an acoustic Martin direct.
     
  11. Runnerman

    Runnerman Registered Bass Player Supporting Member

    Mar 14, 2011
    I didn't remotely take it that way. It's all good.
    Powered mains I think are going to be pretty heavy regardless but I def. see your point.
     
  12. modulusman

    modulusman Banned

    Jan 18, 2004
    montana
    Powered mains are not that much heavier than un powered. JBL PRX612m is 35 pounds The 3 way 635 weigh 60 pounds.
     
  13. Tuned

    Tuned

    Dec 6, 2007
    The main differences are that the dispersion of 12" speakers narrows at a higher frequency than 15"s, 1150Hz versus 830Hz, while the crossover point is generally 2kHz for 1" HF horns. This means for the octave under the crossover point the dispersion is less compromised for 12" speakers than 15"s, which is important for getting the vocals to a crowd evenly. Crossovers for 2" horn designs are often at 1Khz and can go as low as 500Hz, which is a much better match for a 15".

    It's not that 15" speakers are worse than 12" speakers, it's that 15" speakers should use 2" horns, but most don't.
     
  14. 12" mains and a 18" sub works well for me. Yorkville E-12's and 801. Great combination. I have always had better luck with 12's than 15's but that's not to say that one is better.
     
  15. Thumper

    Thumper

    Mar 22, 2000
    Syracuse Ut
    Thanks for the input. Went and listened to some today but only with a Cd, will get the lead vocalist to go sing thru them.

    Generally found powered EV 15s had best bass, prx JBL 15s best if not a little shrill highs and K12 best mid and best to my ear overall (nice bass as well) no K10 to try
     
  16. Tuned

    Tuned

    Dec 6, 2007
    It's important to test with an EQ. You need to know how much EQ is needed to get an even response, and how they sound once they're EQ'ed as best you can. Some speakers have issues an EQ can't fix (i.e. cheap Peaveys), some need quite a bit of EQ but sound good once they're dialed in (i.e. JBL PRX series), very few need little EQ at all (Yorkville NX25 and NX55).

    It depends how crafty you are with an EQ. If you're not handy with EQ's, the NX55 is your daddy. No sound shaping EQ required at all. Ring'em out and you're done. Can't say the same for other Yorkville speakers though.
     
  17. TimmyP

    TimmyP

    Nov 4, 2003
    Indianapolis, IN
    I've mixed on the QSC 153 and was pretty happy.

    A friend just got the new Yamaha two-way as his baby system and is very impressed by both the fidelity and the output capability.
     
  18. TomB

    TomB Supporting Member

    Aug 24, 2007
    Vermont
    I've just bought & started working with a pair of Big-E 4x6's for mains (passive). They're a little spendy but IMO provide a whole other world of sound & power compared to conventional 2 & 3-way designs, regardless of driver size. Do a TB search to find out more if interested. I'm very happy with them, and I've tried a lot of systems over 40 years. ...just one more data point for your research, anyway!
     

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