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PA Power requirements

Discussion in 'Band Management [BG]' started by rabid_granny, Feb 23, 2004.


  1. I read the rule of thumb for power requirements for a PA system is 2 watts per person. But given that you don't run an amp at 10, you shouldn't run a PA (I'm thinking a powered mixer) at 10 either.

    So should you amend the rule of thumb to say:

    2 watts x # people / 0.7 = Wattage

    The 0.7 is assuming you run the mixer at 70%.
     
  2. So a 5 piece band needs 7 watts??????

    I'd say that formula's a little off.

    70 watts? 700 watts? 7 kilowatts?? Uh, what style of music?? What size is the room or is this outdoors?
     
  3. Phat Ham

    Phat Ham

    Feb 13, 2000
    DC
    I think he means 2 watts per person in the audience. i.e. 50 people in the audience = 100 watt PA. Still doesn't add up if you ask me.
     
  4. What if the gear was a drumkit, 2 50w guitar amps, my 200w bass amp and one vocalist? I'm not looking at insanely loud, modern volume levels but something more balanced. What would you recommend for a set-up like this?
     
  5. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    The PA my rock band rents for club shows, all instruments through the PA as well as 4 monitor mixes, is around 20,000 watts total, the system is crossed over two-way. There's no way any mathematical formula can work, IMO.
     
  6. Passinwind

    Passinwind I Know Nothing Supporting Member

    I read the rule of thumb for power requirements for a PA system is 2 watts per person.

    Ten watts per audience member is a more widely quoted one, albeit still barely useful.

    What if the gear was a drumkit, 2 50w guitar amps, my 200w bass amp and one vocalist?

    Using what speakers, in what venue, playing what style of music?

    What would you recommend for a set-up like this?

    Like what? Just the one vocalist through the PA enough to get on top of the instruments? Everything miked equally? With subs or without?

    There's a lot to consider before anyone can answer your question, eh? I can give you some links to very precise answers, but what are the questions again? :cool:
     
  7. Oh, I was just blueskying and was thinking of a stand-alone PA for a vocalist. No monitors, no instrument miking. Just a system that could make vocals audible over that volume range. Keeping it real simple - like back in the day when you could hear a concert without earplugs.

    Decent Yorkville and Peavey powered mixers and speakers are in our local buysell paper all the time. Just wondering what would be a good fit, volume wise.

    Would a keyboard amp be a better solution?
     
  8. Passinwind

    Passinwind I Know Nothing Supporting Member

    If I were in your situation, I'd look at one or two powered speakers: Mackie, FBT, PAS, etc., a little Behringer or Mackie mixer, and a basic EQ. You could use the powered speaks for monitors for bigger gigs.

    If you want to go really basic, a 300 watt Peavey/Yamaha/Yorkville powered unit and two 12' + horn speakers will probably do just what you want. I used to gig with that sort of setup, and still would happily enough, if I didn't already own way too much PA gear, and if people didn't expect me to use it. Most keyboard amps are a little lo-fi on vocals for my taste, but I've seen people make it work.

    I have to say, I rarely play, mix, or attend shows that require earplugs, either on stage or in the audience. And the sound quality is way better than it was in the 70s, I think. Like I could really remember though...
    [​IMG]

    luck,

    Charlie Escher
     
  9. No monitors? I think not. A small active cab for vocalist will save many a gig. A toster-sized box with 5" woofer is enough, If your overall volume is low.
     
  10. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    Thousand watts.


    Next? Next, please!
     
  11. In my experience with small to above average sized clubs, a 2500 to 4000 watt PA is sufficient for moderate volume with healthy low end. If you start to push the FOH levels too much, three things start to happen:

    1) Provided that stage volume is low (which lends to better FOH sound) the PA begins to saturate the venue with SPL, uch that the stage mix is washed out, musos cannot hear themselves as well.

    2) Audience cannot have a conversation without screaming in one another's ear.

    3) Club owners / waitstaff gets annoyed with the pounding.

    Loud is a thing of the past. A full healthy mix... that draws people away from their 5.1 channel, subwoofer - equipped home systems ... is the hot setup. ;)
     
  12. Passinwind

    Passinwind I Know Nothing Supporting Member

    Loud is a thing of the past. A full healthy mix... that draws people away from their 5.1 channel, subwoofer - equipped home systems ... is the hot setup.

    Amen to that. Still, none of us know rabid granny's musical style or venue size, so I'm sticking by my bottom line for one or two monitors or FOH speakers that'll get one vocalist over his lineup, just enough to be heard in a practice or coffehouse type scene.
     
  13. The music style would be rock and the venue would be small...I was think if we wanted to throw a house party or move up and play a small hall/pub.

    The big thing for me is reasonable volume levels. I've participated in a couple "too loud" threads and "earplugs good - tinnitus bad" threads. Passinwind, you recommended a 300 watt powered + 2 12" speakers. I'll use that as a yardstick (plus a monitor). I've seen some 150 watt powered mixers and was wondering if they would be adequate.
     
  14. Passinwind

    Passinwind I Know Nothing Supporting Member

    Passinwind, you recommended a 300 watt powered + 2 12" speakers. I'll use that as a yardstick (plus a monitor). I've seen some 150 watt powered mixers and was wondering if they would be adequate.

    300 is really minimalistic, but that's the least I'd consider worth spending any money on. You could use that power for monitors in a slightly more upscale setup, at least. More is definitely better though, when it comes to power. It can equate to clarity, not volume, given the right operator.

    If you want to go really bare bones, you could get two small wedges with pole mount ports for use at FOH. Then you'd have monitor wedges for bigger gigs.
     
  15. As you can tell from the previous posts, there isn't a definite rule to go by. Here goes with my experience:

    Many years ago I bought a small PA, just a 4 input, 150 watt head with a couple of 12 inch 2 way speakers. Worked well for practices, and I've used it or loaned it out for use in gigs. One night I listened to another band, just running their lead vocalist through this setup (no monitors), and the vocals were loud. Loud as in shrill, uncomfortably so. But for smaller coffee-house type gigs, where the volume could be turned down, it would work great, even without a monitor (though a single 5 inch hot spot would be nice).

    Fast forward to my current PA setup which I've been using for the last couple of years, running sound for a 6 piece party band. A pair of 15 inch, 3 way main speakers each getting 150 watts; two pairs of monitors, each monitor speaker getting 75 watts. Five vocal mics, plus acoustic guitar, sometimes a little lead guitar or bass, occassionally cymbals or hihats in the mix. Typical crowds of 100 to 200 people. The volume is good, not overpowering, but acceptable. Yet I'm completely out of headroom. That's why tomorrow the brown truck should be delivering MORE POWER. Each main speaker will now get 350 watts, each monitor speaker will get 150 watts. Should be much better. Total system power will be 1300 watts.

    It would be tempting to say "buy as much PA as you can afford" but there are other factors. PA gear costs money. This stuff is very heavy, I can no longer set up by myself (I can't lift a 100 lb speaker and set it on top of a speaker stand by myself without getting a hernia). The gear completely fills the back of a pickup as it is--what next, buy a van or a trailer? And electrical power is sometimes a problem, there's nothing like tripping a breaker in the middle of a gig. Furthermore, it takes a couple of hours to set up as it is, add more stuff, the time factor increases. And the more stuff there is, the more likely something will be lost/broken/stolen.

    PS these watts are real RMS. Not "program" or "peak" -- those inflated ratings are useless.
     
  16. Ryan L.

    Ryan L. Moderator Staff Member Supporting Member

    Aug 7, 2000
    West Fargo, ND
    For bigger clubs and outdoor events, we use 4 2X18 cabs and 4 2X15+horn cabs. Cut that in half for smaller venues. We are running about 12,000 watts to the mains for bigger stuff, and again, half for smaller stuff. This does not include our monitor setup, and I am not exactly sure what we have for power in that rack, but we run 5 15+horn monitors onstage, so each band member has his own monitor.

    EDIT: My bad, I should have said 10,000 watts, not 12. I added wrong. :oops:
     


  17. That's a big PA. Arena size, in fact. Most clubs wouldn't be able to supply enough electricity to power this big a system...I'm jealous. :D
     
  18. Ryan L.

    Ryan L. Moderator Staff Member Supporting Member

    Aug 7, 2000
    West Fargo, ND
    We have our own 220 box, it gets to be a pain sometimes when the club isn't wired for it and we have to tap in to their circuit breaker box, but most of the places we play have 220 power right to the stage, so all we have to do is plug it in.
     
  19. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    I don't follow your math, r_g, but concert sound companies typically go with from about 5 to 15 watts per audience member, depending on how much loudness and headroom their client wants and can afford. Your needs might not be that high.
     
  20. Pete

    Pete

    Jan 3, 2004
    Seattle, WA
    Please don't skimp on PA. You'll find that the average band with a PV xr200 and 2 SP2's really don't cut it. Get out and listen to some bands in your genre.

    If you want a vocals only PA with some simplicity here ya go (take notes): 2 mackie 1530's, Allen & Heath 16:2 Mixwiz, 2 SRM450's. Add subs if need be.

    Band thru PA: EV SX500+ (2), EV SB180's (2/4), QSC 3002(tops), 3402 (subs), 2x 2402 (monitors). EV EliminatorI monitors (4x). FOH board: A&H GL2200 (or Yamaha 01v, my fave). 31band eq's for every mix, good crossover, buch of DBX comps. Nothing should be behringer if possible. OK, any questions? That's a rig, substitute with other stuff if need be but DON'T settle for less.

    pete
    ]
    it isn't a question of wattage, it' a question of clean. Clean power, clean headroom, clean sound. You're only as good as the source, so sell you f-ing squire!!