PA for outdoor gig

TwoNotesSolo

Student Of The Blues
Not sure to post this here or in the gig section

Our band got a gig for an outdoors part for a homeowner association. it's in one of the community park, about 200 people expected. We're debating what kind of PA to rent for the day (the cost of course comes out of our profit). We have mics but but that's about it. we usually play inside venues (bars) that have their own PA,. so the band doesn't own one.
I figured we should get a 1000W PA with min 12 input mixer, and a couple of monitor wedges.
Our drummer swears his uncle (who is a professional musician) told him there was no need to mic the drums and that guitar amps were enough.

I find that hard to believe, except maybe for a patio gig at a bar. We are not expected to play super loud, we're just the background music.

anyone has experience with outdoors gigs? we are not buying, just renting for the day.

the band has 3 guitars, 2 singers, bass, drums, harmonica. we have no dedicated sound guy.

One advantage of the PA is that it's probably easier to adjust overall volume and balance instruments, but if can do without it's money in our pocket.
 

Jalapeno

Student Of The Blues
First off, if it were my band the homeowner association would be paying for the PA rental. End of story.

If you are just background music and you have to pay for the PA then just get a PA for the vocals. That should be enough. If you really want to get into the whole sound engineering thing I'd suggest getting advice from the people you'll be renting the PA system from. They know their equipment.

I had a lot of experience doing sound at outdoor gigs and they were easier for me than indoor gigs because you don't have room acoustics to contend with. A lot of times we just took a 4 channel mixer for the vocals and two 500 watt JBL EONS so the crowd could hear the singers.

I think putting your guitar amps on stands is important because down low the highs will be absorbed.

Just my $0.02

Have fun!

Eric
 

CaptainMoto

Blues Voyager
Is this helpful?

Selecting and setting up a PA system for a live performance can be an overwhelming process. There are the microphones on stage, the mixing console at front of house, the power amps and the speakers. Everything needs to be specifically calibrated otherwise you run the risk of damaging the equipment, or worse, having to cancel the show and refund everyone’s money.

With all of that being sad, selecting the proper PA is actually much simpler than it seems (Vintage King offers several pre-assembled PA packages), and deciding what is right for you starts with just a few questions. Whether you’re in a band looking to supply your own system for shows, an engineer looking to rent and operate PA systems for events, or even a venue manager looking to upgrade your rig, continue reading below to discover how to choose a PA and set it up.

Selecting the Right PA
Let’s start with the basics. There are three components to every PA system:

  • An input transducer (microphones or line-level output from an instrument)
  • Amplifiers (both preamps in the console and power amps in the speakers)
  • An output transducer (speakers or headphones)
That can range from simple DJ setup with two turntables and a microphone, to a full blown stadium spectacle with line arrays and time-aligned fill speakers.

To select the perfect PA for your event, you need to know a few details about the gig. You don’t want to show up to a coffee house with a semi truck full of line array speakers, or worse, show up to the arena gig without one.

Obviously, larger spaces require more powerful PA systems to fill the venue with sound, but to determine exactly how powerful, you need to know four things.

1. How far is it from the speakers to the back of the room?
The further you are from the speakers, the quieter signal becomes. In smaller venues this likely won’t be an issue, as the level difference from the stage to the back of the room will barely be noticeable. But, as you get into larger venues, the level decrease becomes more apparent. While every venue is different, here’s are some approximate dimensions to get you in the ballpark:

  • Coffee shop, restaurant, bar: 5~10 m (16~32 ft)
  • Club, auditorium, house of worship, small outdoor festival: 10~30 m (32~96 ft)
  • Concert hall, stadium, arena, large outdoor festival: 30 m+ (96 ft+)
Once you know the distance from the loudspeaker to the farthest listener, you can determine exactly how much signal loss you’re going to incur at the back of the venue.

Every time you double your distance from the speakers, the SPL will decrease by 6dB. For example, if you’re standing 1 meter (~3ft) away from a speaker pumping out 110dB SPL the signal will decrease as follows:

  • 1m (~3 ft): 110 dB SPL
  • 2m (~6.5 ft): 104 dB SPL
  • 4m (~13 ft): 98 dB SPL
  • 8m (~26 ft): 92 dB SPL
  • 16m (~52 ft): 86 dB SPL
  • 32m (~105 ft): 80 dB SPL
  • 64m (~210 ft): 74 dB SPL
  • 128 (~420 ft): 68 dB SPL
So, even though they may be plenty loud in the front row, those in the back can easily talk over the music. That’s when fill speakers come into play, which are additional speakers strategically placed to keep the SPL level consistent throughout the venue.

2. How loud does it need to be?
The general rule of thumb here is the heavier the music, the louder it should be. Genres like folk, jazz and classical typically range from 80-95dB SPL, while genres like pop, hip-hop and rock are typically around 95-110 dB SPL.

After determining the desired volume (be sure to check local noise ordinances!), you can select appropriate speakers for the gig. Make sure you find something with a maximum SPL capability high enough to meet your needs!

*Author’s Note: Because loudspeakers are tested in anechoic chambers, the technical specs don’t account for room reflections. If you’re mixing indoors you’ll typically see a 6dB SPL increase throughout the venue, which can be really handy when trying to squeeze a little more volume out on an undersized PA.

3. What's the sensitivity rating of your speakers?
All speakers have a listed sensitivity rating, which essentially measures how efficiently a speaker converts wattage from power amps into SPL.

Smaller PA speakers have lower sensitivity, meaning they operate less efficiently than larger PA speakers. Speaker sensitivity is calculated by sending a speaker 1 watt of power and measuring the SPL from 1 meter away. Professional PA speakers can range anywhere from 95 to 110 dB SPL/Watt/meter, meaning a single watt of power can produce anywhere from 95 to 100 dB SPL, depending on the speaker.

Now that you know the technical specs on your PA speakers, there’s only one more question before selecting the right power amps for the gig.

4. How much headroom do you need on your power amps?
Live music can have transient peaks as high as 25 dB above the average level, which can cause power amps to peak and create distortion. There are two options for dealing with this. 1. Use a limiter on your master output and prevent signals from peaking above a certain point. 2. Provide enough headroom on your power amps that the peaks won’t cause clipping.

That’s much easier said than done. To add 3 dB of headroom you need to double the amount of power you’re supplying to the speakers. That means if a 1000 watt amp allows you 3 dB of headroom, you need a 2000 watt amp for 6 dB of headroom.

While more is almost always better, you can get by with as little as 3-6dB of headroom in most cases. However, it would still be wise to include a limiter just to be safe.

Calculations
Now that you’ve answered all four questions about the gig, it’s time to do the math and determine exactly how much power you’ll need to fill the venue. But hey, you’re an audio engineer, not a mathematician, just use a calculator!

As you can see, power requirements can quickly skyrocket. Here’s a quick reference guide for common shows:

  • Coffee shop, restaurant, bar: ~250 W
  • Small/medium club, auditorium, house of worship, outdoor festival: ~250-1500 W
  • Medium/large club, auditorium, house of worship, outdoor festival: ~1500-3000 W
  • Large concert hall, outdoor festival: 4000-15,000 W
  • Stadium, arena: 15,000 W+
Author’s Note: Some major production companies tour with as much as 400,000 watts of power!

Pairing Speakers + Power Amps
Most permanent or large installations use passive PA systems, meaning the speakers require external power amps. This allows you to fine-tune the system and dial in the perfect amount of power for every venue. To find the right power amps for your system, check the tech specs of your speakers for the following stats:

  • Nominal Impedance
  • Continuous/RMS/Program Power Capacity
Impedance is a form of electrical resistance, measured in Ohms. Most speakers are designed to operate at 4, 8, or 16 Ohms—as are most power amps. This information can be found in the tech specs.

It’s important that you match the impedance rating of your speakers to the impedance rating of your power amps. If your speakers' impedance is too low for the amp, the amp will send more power than the speaker can handle, and can damage your equipment. If your speakers' impedance is too high for the amp, it won’t send enough power to the speaker, and the system will sound weak.

Power Capacity is essentially a measurement of how much wattage a speaker can continuously handle. This number should not be confused with Peak Power Capacity, which is a measurement of the most power a speaker can handle in a given instant. If you try to continuously supply a speaker with the peak power wattage, it will wear out very quickly.

As a general rule of thumb, you want an amp that can supply 2-4 times the continuous power capacity, which allows for 3-6dB of headroom for peaks. This should be sufficient headroom for any genre as long as you have a limiter on your master output. If that’s not possible, you may want to supply more power to account for larger signal peaks.

Setting Up a PA System
After selecting the speakers and power amps for the gig, it’s time to put it all together! Although every PA system is different depending the particular equipment being used, here’s a basic overview of PA signal flow:

  • Instruments and microphones connect to the stage box/snake on stage.
  • Signals are split and identical copies are sent to front of house and monitor world.
  • Signals are processed on the console, and sent out the console outputs.
  • Each output is processed by an EQ, and in the case of front of house, most likely a limiter.
  • Depending on the system, signals may be run through a speaker distribution system to disperse the main left and right outputs to a variety of speakers.
  • After distribution, signals are routed to their respective power amps.
  • Power amps are connected to their respective speakers.
Calculator:
https://geoffthegreygeek.com/calculator-amp-speaker-spl/
 
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TwoNotesSolo

Student Of The Blues
Thanks Eric, I had you in mind when I posted as I know you have extensive outdoors gigging experience.

First off, I wasn't the one negotiating this gig and I had suggested the HOA rents the PA but they don't know anything about it, "last year's band had their own equipment" and "then we'd need to take it out of the agreed fee". So in the end it's probably easier for us to choose what we need. This is our first gig of this type and we're hoping it will open new similar opportunities or small festivals.

Glad to see you agree we can probably do without a full PA. Our singer has a small PA wee use during practice, not sure if it's powerful enough.
Good tip on raising the amps. Should I do the same on my bass amp? (I have a Fender Rumble v3 500W, but without an extra cab it's more like 250W)

We're going to go check out the park this week (gotta find power) and set up with the equipment we have and give it a try. Its won't be the same without a crowd milling around but we'll see...
 

straightblues

Blues Junior
I have done a ton of these type gigs. I would recommend that you just use your normal setup. Without a sound guy who really knows how to mix stuff, and about 15 mics (6 or 8 for the drums), you will just make a mess of it. Just use your normal setup with everyone's normal amps. You guys should be used to mixing yourself so everyone is heard. The loudest thing will be the drums and you can set the overall volume based on the drums. Don't mic anything except for the vocals, and MAYBE the kick drum. You may want to consider a couple of powered speakers for the vocals if they aren't loud enough through your practice rig.

When you set up on the stage, set up like you always do which is typically close together. DO NOT spread out just because you have a bigger stage. If you spread out you won't be able to hear each other like normal.

In all of my gigs, I have never once been asked to turn up because I wasn't loud enough. It has never ever happened. Don't think you need to be super loud just because you are outside on a bigger stage.
 

Jalapeno

Student Of The Blues
I figured it was a first time booking. Sometimes you do what you got to do but also sometimes he who blinks first loses :)

As for bass amps, the low frequencies carry so a stand is optional. If you've ever come up from a distance to a band playing outside or even in a bar you'll always hear the bass and kick drum before you hear any guitars, vocals or keys. Personally I used a 100w bass amp and always put it on a stand because I didn't like bending over to use the controls and therefore putting my backside out towards the audience :) Anything more than 250w is mostly headroom when you are just background music. IMO. Bass frequencies carry well.

Of course if you were playing a concert you'd need to make sure of the clarity of the music and vocals but for background music its more important that the party goers can have conversations. If people want to dance (providing you play that kind of material) you can turn up a little for the dancers. Like straightblues said we were never asked to turn up though we were asked to turn it down on a couple of occasions.

I think I've relayed this story on here before so I'll keep it short. We were booked to play a 30 year class reunion and the "promoter" said the class of '84 loved to rock out. He wanted us to bring our complete sound systems including a Marshall stack and Ampeg 8x10. Me and the drummer tried to explain to him that at a class reunion people wanted to talk and catch up. He insisted that the class of '84 were rockers and wanted it loud. We obliged. During the reunion (an outdoor summer gig with a covered table and bench area) No one was within 40 yards of the band. The next day we, the band, got ripped a new one on Facebook for being WAY TOO LOUD. The @rsewipe promoter threw us under the bus saying he'd never book us again to the people on Facebook. Lesson learned, background music is not a concert :)

Eric
 

D. R. Miller

Good News Blues
We play outside gigs quite often but also have our own PA equipment. I use two Behringer 12" 1000W speakers for the mains and two or three floor monitors (Harbinger 750W). We mic or run direct all instruments and amps, have a mic on the kick drum and one overhead mic on drum set. I normally mix ourselves from the stage. So far results have been decent for most people in the audience who I ask for suggestions after a couple songs and make adjustments as needed.
 
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