Pick a Protest PA system for ~500 people
July 10, 2016 6:30 PM Subscribe
I'm sick of attending rallies and protests where the speakers are talking into an under powered megaphone and no one past the first row can hear. I'd like to purchase a nice, powerful, somewhat portable PA system to share with progressive groups in my city. I need your help since I know a fair amount about electronics but not much about audio.
The Washington Peace Center lends out a system they say is suitable for crowds up to 300 people - two 250 watt speakers and a 2x800 watt amp/mixer (more details in this doc). I'd like to be able to handle crowds of 500-600 in an outdoor setting so somewhat more powerful.
Rallies here are typically held outside at the state capitol building where there is some traffic noise and frequently helicopters. I've found that high power megaphones are fine for marching so I'm not looking for a completely mobile setup, although that would be a great bonus. It does need to be portable, weather proof enough that it can see the light of day and easy enough to set up that a novice can be trained in 10 minutes. I haven't looked in to the legal situation - there may be different permitting requirements for a larger generator powered system vs battery powered megaphones but for now let's assume a larger system is OK.
I'm not opposed to building my own cabinets or even soldering an amplifier but from my brief research it doesn't seem like there are great cost savings to be had by DIY, especially if you need something somewhat rugged.
I already have access to a Honda EU1000i generator but that may not be sufficient. I'd like to consider two or three price points, say sub $1k, $1-2k, $3k. If those price points aren't sensible then feel free to let me know. Help me hive mind!
The Washington Peace Center lends out a system they say is suitable for crowds up to 300 people - two 250 watt speakers and a 2x800 watt amp/mixer (more details in this doc). I'd like to be able to handle crowds of 500-600 in an outdoor setting so somewhat more powerful.
Rallies here are typically held outside at the state capitol building where there is some traffic noise and frequently helicopters. I've found that high power megaphones are fine for marching so I'm not looking for a completely mobile setup, although that would be a great bonus. It does need to be portable, weather proof enough that it can see the light of day and easy enough to set up that a novice can be trained in 10 minutes. I haven't looked in to the legal situation - there may be different permitting requirements for a larger generator powered system vs battery powered megaphones but for now let's assume a larger system is OK.
I'm not opposed to building my own cabinets or even soldering an amplifier but from my brief research it doesn't seem like there are great cost savings to be had by DIY, especially if you need something somewhat rugged.
I already have access to a Honda EU1000i generator but that may not be sufficient. I'd like to consider two or three price points, say sub $1k, $1-2k, $3k. If those price points aren't sensible then feel free to let me know. Help me hive mind!
Why don't you look at doing a live pod cast that people can listen to on their phones during the protest? The protestors with unlimited data can bring their small speakers for those who don't have unlimited data. It would allow you to cover more area without having to deal with permits or noise ordinances.
posted by myselfasme at 7:13 PM on July 10, 2016
posted by myselfasme at 7:13 PM on July 10, 2016
Do you have 110v power, or do you need a battery powered system?
posted by straw at 7:40 PM on July 10, 2016
posted by straw at 7:40 PM on July 10, 2016
$1,000 - 2,000 is definitely doable.
If all you want is to amplify speech to a crowd, I would suggest a daisy-chained array of 2 - 3 powered PA speakers (integrated amplifier and transducers in one cabinet), atop stands, pointing in an arc to 2 - 3 different sectors in the crowd. Locating the speakers all in the same spot rather than spacing them out (eg. in a concert situation) will greatly improve speech intelligibility. You put the speakers up on folding speaker stands, run an AC cord to each, run an XLR cable to the mic input of the first and 1/4 inch audio line cables from the first to the second, etc. No separate amplifier or mixer needed. I will send you a sketch via MeFi Mail if you wish.
Anchor makes speech-oriented powered speakers that would fit the bill ... They tend to be a little pricey ... Some even have rechargeable batteries. Avoid the ones with wireless mic and built-in receiver; the wireless feature is not that great.
QSC, JBL, Alto and others make musician-oriented powered PA speakers with a wider audio frequency range than the Anchors, and more competitively-priced. You can find them at Guitar Center and other music stores.
Avoid wireless mics unless you ABSOLUTELY MUST have one. The cheap (sub-$500) systems suck, and even the higher-priced ones are subject to radio interference and batteries running dead when you need them most. A wired Shure SM57 mic is the universal utility mic and is damn near indestructible. Get a good-quality ($30 min.) 25 ft+ XLR cable to go with it, and good ($10 ea) ~3 ft. 1/4 inch audio cables for daisy-chaining.
You can get "disposable" folding short-boom mic stands for $15 - 20 ... Probably DON'T want to buy a stand with a weighted base in case the crowd were to jump the stage looking for things to throw. :P
Ultimate Support makes some adequate speaker stands, but parts tend to stick or break-off after awhile. Perhaps you can find better ones.
Consider 2nd hand gear (eg. Craigslist.org) if you want to save money.
Be sure to familiarize yourself with the system first before the event by setting it up and tearing it down a few times before the event.
Good luck!
posted by ZenMasterThis at 7:46 PM on July 10, 2016 [6 favorites]
If all you want is to amplify speech to a crowd, I would suggest a daisy-chained array of 2 - 3 powered PA speakers (integrated amplifier and transducers in one cabinet), atop stands, pointing in an arc to 2 - 3 different sectors in the crowd. Locating the speakers all in the same spot rather than spacing them out (eg. in a concert situation) will greatly improve speech intelligibility. You put the speakers up on folding speaker stands, run an AC cord to each, run an XLR cable to the mic input of the first and 1/4 inch audio line cables from the first to the second, etc. No separate amplifier or mixer needed. I will send you a sketch via MeFi Mail if you wish.
Anchor makes speech-oriented powered speakers that would fit the bill ... They tend to be a little pricey ... Some even have rechargeable batteries. Avoid the ones with wireless mic and built-in receiver; the wireless feature is not that great.
QSC, JBL, Alto and others make musician-oriented powered PA speakers with a wider audio frequency range than the Anchors, and more competitively-priced. You can find them at Guitar Center and other music stores.
Avoid wireless mics unless you ABSOLUTELY MUST have one. The cheap (sub-$500) systems suck, and even the higher-priced ones are subject to radio interference and batteries running dead when you need them most. A wired Shure SM57 mic is the universal utility mic and is damn near indestructible. Get a good-quality ($30 min.) 25 ft+ XLR cable to go with it, and good ($10 ea) ~3 ft. 1/4 inch audio cables for daisy-chaining.
You can get "disposable" folding short-boom mic stands for $15 - 20 ... Probably DON'T want to buy a stand with a weighted base in case the crowd were to jump the stage looking for things to throw. :P
Ultimate Support makes some adequate speaker stands, but parts tend to stick or break-off after awhile. Perhaps you can find better ones.
Consider 2nd hand gear (eg. Craigslist.org) if you want to save money.
Be sure to familiarize yourself with the system first before the event by setting it up and tearing it down a few times before the event.
Good luck!
posted by ZenMasterThis at 7:46 PM on July 10, 2016 [6 favorites]
I'm not opposed to building my own cabinets or even soldering an amplifier but from my brief research it doesn't seem like there are great cost savings to be had by DIY, especially if you need something somewhat rugged.
Your research is entirely correct.
I'd like to be able to handle crowds of 500-600 in an outdoor setting so somewhat more powerful.
Part of your issue is you don't need "somewhat" more powerful, you need flat out more powerful, because sound waves are inverse-proportional, a variation of the inverse-square law - for every doubling of distance, the sound pressure (volume) of the sound is 1/4th the intensity.
So, basically, if the 2-speaker system you linked to can cover 300 people (which I think it could, barely), then you need 4 or 6 speakers to cover 500-600.
ZenMasterThis' idea about powered speakers is good, although 2 are not likely to be significantly more powerful than the system you can borrow. You'll want 4 or 6. (Also, these days, almost any powered speakers from QSC, JBL, Mackie, Electro-voice, or other companies aimed at the pro sound/musician market will use XLR cables in and out, no need for 1/4" cables. Many will also have some digital signal processing (DSP) built in that lets you change the tone & response of the speaker with specific tone & volume controls and/or presets. IOW, RTFM.)
Seconding ZMT to avoid wireless, although I'd go for a Shure SM58 over a 57.
Seconding ZMT that under $1k probably won't get you what you need, $1k-$2k should be totally possible, even buying new.
I already have access to a Honda EU1000i generator but that may not be sufficient.
If you go for new or relatively new powered speakers, they all have lightweight high-effeciency amps in them, powering 4-6 off that will be fine.
It does need to be portable, weather proof enough that it can see the light of day
Many current powered speakers are made of plastic, so they weigh about 35-40 pounds (very light for sound gear), and can certainly handle the sun and dirt of outside. If it rains, throw a garbage bag over them - seriously.
The A#1 thing that will help people be heard at rallies, regardless of what you wind up getting, is SPEAK INTO THE MIC. KISS THAT THING, PUT YOUR LIPS RIGHT UP ON IT. Remember that inverse-square law I mentioned above? Works the same for sound going into a sound system. Move that microphone just a couple of inches away from your mouth and suddenly you're a LOT quieter. Unless your voice is naturally loud enough that you could almost get away without any amplification, you'd better have that mic right up against your kisser if you want to be heard.
posted by soundguy99 at 10:37 PM on July 10, 2016 [4 favorites]
Your research is entirely correct.
I'd like to be able to handle crowds of 500-600 in an outdoor setting so somewhat more powerful.
Part of your issue is you don't need "somewhat" more powerful, you need flat out more powerful, because sound waves are inverse-proportional, a variation of the inverse-square law - for every doubling of distance, the sound pressure (volume) of the sound is 1/4th the intensity.
So, basically, if the 2-speaker system you linked to can cover 300 people (which I think it could, barely), then you need 4 or 6 speakers to cover 500-600.
ZenMasterThis' idea about powered speakers is good, although 2 are not likely to be significantly more powerful than the system you can borrow. You'll want 4 or 6. (Also, these days, almost any powered speakers from QSC, JBL, Mackie, Electro-voice, or other companies aimed at the pro sound/musician market will use XLR cables in and out, no need for 1/4" cables. Many will also have some digital signal processing (DSP) built in that lets you change the tone & response of the speaker with specific tone & volume controls and/or presets. IOW, RTFM.)
Seconding ZMT to avoid wireless, although I'd go for a Shure SM58 over a 57.
Seconding ZMT that under $1k probably won't get you what you need, $1k-$2k should be totally possible, even buying new.
I already have access to a Honda EU1000i generator but that may not be sufficient.
If you go for new or relatively new powered speakers, they all have lightweight high-effeciency amps in them, powering 4-6 off that will be fine.
It does need to be portable, weather proof enough that it can see the light of day
Many current powered speakers are made of plastic, so they weigh about 35-40 pounds (very light for sound gear), and can certainly handle the sun and dirt of outside. If it rains, throw a garbage bag over them - seriously.
The A#1 thing that will help people be heard at rallies, regardless of what you wind up getting, is SPEAK INTO THE MIC. KISS THAT THING, PUT YOUR LIPS RIGHT UP ON IT. Remember that inverse-square law I mentioned above? Works the same for sound going into a sound system. Move that microphone just a couple of inches away from your mouth and suddenly you're a LOT quieter. Unless your voice is naturally loud enough that you could almost get away without any amplification, you'd better have that mic right up against your kisser if you want to be heard.
posted by soundguy99 at 10:37 PM on July 10, 2016 [4 favorites]
Good advice, soundguy99! NB: My thought about 2 - 3 speakers was more about coverage (arranging them in an arc) rather than power.
Also, gah ... Yes, I meant meant SM58! :P
posted by ZenMasterThis at 5:28 AM on July 11, 2016 [1 favorite]
Also, gah ... Yes, I meant meant SM58! :P
posted by ZenMasterThis at 5:28 AM on July 11, 2016 [1 favorite]
Response by poster: Thank you for the good advice so far. Is the best setup to arrange them in a small arc in front of the microphone, as opposed to separated 20' to the left and right?
What wattage should I be looking at for the 4-6 powered PAs? Looks like around $2-300 per powered speaker? Is it better to go with more lower (250 watt?) powered speakers or fewer more powerful ones (500-1000?)? Guitar Center does have some 1k watt PAs for ~$500. Are wattage ratings at this level actually accurate or just marketing lies? No need for a mixer, just plug the mic straight in to one of the speakers and daisy chain the rest off of that? What is the current consumption of this sort of set up? I assume they all have class D amplifiers so fairly efficient? It would be awesome to be able to go with some sort of 12V battery bank rather than a generator. Probably 90 minutes of power would be a good target.
posted by ChrisHartley at 7:44 AM on July 11, 2016
What wattage should I be looking at for the 4-6 powered PAs? Looks like around $2-300 per powered speaker? Is it better to go with more lower (250 watt?) powered speakers or fewer more powerful ones (500-1000?)? Guitar Center does have some 1k watt PAs for ~$500. Are wattage ratings at this level actually accurate or just marketing lies? No need for a mixer, just plug the mic straight in to one of the speakers and daisy chain the rest off of that? What is the current consumption of this sort of set up? I assume they all have class D amplifiers so fairly efficient? It would be awesome to be able to go with some sort of 12V battery bank rather than a generator. Probably 90 minutes of power would be a good target.
posted by ChrisHartley at 7:44 AM on July 11, 2016
Yes in a small arced cluster ... Will Improve speech intelligibility ... Ideally in front, but off to one side is okay too. Just gotta keep the mic away from the speakers.
Check for "IEC" in the wattage ratings on the spec sheets to know whether they're "real" or not.
Don't necessarily need a mixer if you're only running one mic, but for EQ, feedback control and dynamics control you might want to consider something in the dbx DriveRack series ... eg. this one or this one.
Depending on what the jacks are on the back of your powered speakers you would go line-out from the first speaker to line-in on the second via either XLR or 1/4 inch.
Yes, these are all Class D or Class T these days ... Very efficient. I don't think doubling the power would buy you much for speech purposes (2x power increase = +3 dB ... barely perceptible).
Total energy-wise, a standard small 12 volt car battery is about 45 amp-hours (AH) or nominally 12 volts X 45 amp-hours = 540 Watt-hours. I'm guessing your speakers won't be running anywhere near their rated power on average, probably more like 10 - 50 Watts would be my S.W.A.G., so it should be good for 10+ hours.
If you can't find adequate speakers that run directly off 12 volts DC, buying an inverter to match will take some care. My guess is you should buy something rated close to the full combined power rating of your speakers to handle transient peaks without the inverter shutting-off. Also, you should probably spring for an inverter with sine wave output (more expensive); will probably be quieter electrically (won't throw so much noise into you speakers and could prolong the life of your speakers' electronics. See if you can borrow one first ... I believe AutoZone has a pretty liberal returns policy, especially if you upgrade with them (ask first).
The Class D/T amps in the speakers could present AC power factor issues w.r.t. the inverter, especially on turn-on. If you notice funky behavior, try a more expensive inverter.
posted by ZenMasterThis at 8:48 AM on July 11, 2016
Check for "IEC" in the wattage ratings on the spec sheets to know whether they're "real" or not.
Don't necessarily need a mixer if you're only running one mic, but for EQ, feedback control and dynamics control you might want to consider something in the dbx DriveRack series ... eg. this one or this one.
Depending on what the jacks are on the back of your powered speakers you would go line-out from the first speaker to line-in on the second via either XLR or 1/4 inch.
Yes, these are all Class D or Class T these days ... Very efficient. I don't think doubling the power would buy you much for speech purposes (2x power increase = +3 dB ... barely perceptible).
Total energy-wise, a standard small 12 volt car battery is about 45 amp-hours (AH) or nominally 12 volts X 45 amp-hours = 540 Watt-hours. I'm guessing your speakers won't be running anywhere near their rated power on average, probably more like 10 - 50 Watts would be my S.W.A.G., so it should be good for 10+ hours.
If you can't find adequate speakers that run directly off 12 volts DC, buying an inverter to match will take some care. My guess is you should buy something rated close to the full combined power rating of your speakers to handle transient peaks without the inverter shutting-off. Also, you should probably spring for an inverter with sine wave output (more expensive); will probably be quieter electrically (won't throw so much noise into you speakers and could prolong the life of your speakers' electronics. See if you can borrow one first ... I believe AutoZone has a pretty liberal returns policy, especially if you upgrade with them (ask first).
The Class D/T amps in the speakers could present AC power factor issues w.r.t. the inverter, especially on turn-on. If you notice funky behavior, try a more expensive inverter.
posted by ZenMasterThis at 8:48 AM on July 11, 2016
BTW, building on what soundguy99 said, yes, make sure speakers have their mouths basically ON the mic. However, this will highlight the mic's "proximity effect," so roll-off the low-end frequencies, say 250 Hz and below, 'cause they'll only add boominess and suck-up power without adding intelligibility.
I'm of two minds on mic switches (SM58 is available with and without a switch). I find they are always fumbly for people not used to them. On the other hand, there may be times when you want to be able to mute the mic without having to run to a volume control somewhere else.
posted by ZenMasterThis at 9:57 AM on July 11, 2016
I'm of two minds on mic switches (SM58 is available with and without a switch). I find they are always fumbly for people not used to them. On the other hand, there may be times when you want to be able to mute the mic without having to run to a volume control somewhere else.
posted by ZenMasterThis at 9:57 AM on July 11, 2016
Is the best setup to arrange them in a small arc in front of the microphone, as opposed to separated 20' to the left and right?
Depends on the location - people tend to absorb and diffuse sound rather well, so you want the speakers to be at least slightly above the heads of your audience. So if the people speaking are partway up a flight of stairs, with the audience down at the bottom, sure, set the speakers in an arc on the next step down from the presenters. If everyone's on the same level, you'll want the speakers on poles, in which case an arc in front of the presenters won't work, so you'd go with a separated setup.
Are wattage ratings at this level actually accurate or just marketing lies?
Mmmmm . . . . . maybe not "lies" so much as "best case measurements in the lab presented in the best possible light." As in, something listed as "1000 watts" turns out to be "1000 watts PEAK" when you dig a little deeper, which means it can handle an occasional burst of 1000 watts, but won't actually run 1K watts all day. Dig into the specs, and also look at max output level or "output sensitivity" expressed as db.
Is it better to go with more lower (250 watt?) powered speakers or fewer more powerful ones (500-1000?)?
Again, depends on the location and/or how quickly you want to set up and tear down and how many wires you want to run. If you're in a space 100' wide by 30' deep, you could do some low powered stuff spread out along the 100' width, if you're covering a space 30' wide by 100' deep better to have more powerful speakers set up relatively high to blast to the back of the area.
I mean, in general, if you have "too much" power you can always turn things down, yeah? If you don't have enough power you'll just blow up your speakers trying to push them beyond their limits.
No need for a mixer, just plug the mic straight in to one of the speakers and daisy chain the rest off of that?
Yup. At the very least there will be a "mic/line" switch or button that sets the input gain, and a volume knob, and again, many powered speakers have more controls or presets these days that let you tweak volume & tone.
While DriveRacks or other speaker processors have their place, I would not bother - too complex for your purposes.
What is the current consumption of this sort of set up?
Might say in the specs/manuals, might not. But yes, Class D or T, so fairly low. I've run 4 Crown xTi 4000 amps off a single 15-amp circuit full out all day, no problem. (Note that you can't really figure out current draw from wattage specs, since the wattage specs refer to the power handling of the speaker components.)
It would be awesome to be able to go with some sort of 12V battery bank rather than a generator.
Why? That Honda weighs less than 29 pounds, and has wheels, and yes it really will run for 8 hours on a tank of gas (which is less than a gallon.) A single car battery weighs like 40 pounds on average. The Honda wins, as far as I'm concerned.
(Heck, lots of buildings will have an electrical outlet or two on the outside - depending on the space, you could just run some extension cords.)
Check for "IEC" in the wattage ratings on the spec sheets to know whether they're "real" or not.
There are serious problems with the IEC "standards" (they're not really all that "standard"), and so few manufacturers of this type & level of gear use them anyway that I don't think it would be of much practical help.
One thing to consider is that you can almost certainly rent this gear for not too much money, if you want to give the whole idea a try, see what works and what doesn't, before plunking down $2K of your own cash. Independent music instrument stores, A/V rental companies, live production companies, event companies, are places to look for to rent this stuff, seat-of-the-pants guess would be a couple hundred bucks for a whole package (speakers, cables, stands, microphones) if you pick it up. You probably won't be able to get your hands on every possible model, but you can try a couple of different setups & speaker power ratings and see what works.
posted by soundguy99 at 5:23 PM on July 11, 2016 [1 favorite]
Depends on the location - people tend to absorb and diffuse sound rather well, so you want the speakers to be at least slightly above the heads of your audience. So if the people speaking are partway up a flight of stairs, with the audience down at the bottom, sure, set the speakers in an arc on the next step down from the presenters. If everyone's on the same level, you'll want the speakers on poles, in which case an arc in front of the presenters won't work, so you'd go with a separated setup.
Are wattage ratings at this level actually accurate or just marketing lies?
Mmmmm . . . . . maybe not "lies" so much as "best case measurements in the lab presented in the best possible light." As in, something listed as "1000 watts" turns out to be "1000 watts PEAK" when you dig a little deeper, which means it can handle an occasional burst of 1000 watts, but won't actually run 1K watts all day. Dig into the specs, and also look at max output level or "output sensitivity" expressed as db.
Is it better to go with more lower (250 watt?) powered speakers or fewer more powerful ones (500-1000?)?
Again, depends on the location and/or how quickly you want to set up and tear down and how many wires you want to run. If you're in a space 100' wide by 30' deep, you could do some low powered stuff spread out along the 100' width, if you're covering a space 30' wide by 100' deep better to have more powerful speakers set up relatively high to blast to the back of the area.
I mean, in general, if you have "too much" power you can always turn things down, yeah? If you don't have enough power you'll just blow up your speakers trying to push them beyond their limits.
No need for a mixer, just plug the mic straight in to one of the speakers and daisy chain the rest off of that?
Yup. At the very least there will be a "mic/line" switch or button that sets the input gain, and a volume knob, and again, many powered speakers have more controls or presets these days that let you tweak volume & tone.
While DriveRacks or other speaker processors have their place, I would not bother - too complex for your purposes.
What is the current consumption of this sort of set up?
Might say in the specs/manuals, might not. But yes, Class D or T, so fairly low. I've run 4 Crown xTi 4000 amps off a single 15-amp circuit full out all day, no problem. (Note that you can't really figure out current draw from wattage specs, since the wattage specs refer to the power handling of the speaker components.)
It would be awesome to be able to go with some sort of 12V battery bank rather than a generator.
Why? That Honda weighs less than 29 pounds, and has wheels, and yes it really will run for 8 hours on a tank of gas (which is less than a gallon.) A single car battery weighs like 40 pounds on average. The Honda wins, as far as I'm concerned.
(Heck, lots of buildings will have an electrical outlet or two on the outside - depending on the space, you could just run some extension cords.)
Check for "IEC" in the wattage ratings on the spec sheets to know whether they're "real" or not.
There are serious problems with the IEC "standards" (they're not really all that "standard"), and so few manufacturers of this type & level of gear use them anyway that I don't think it would be of much practical help.
One thing to consider is that you can almost certainly rent this gear for not too much money, if you want to give the whole idea a try, see what works and what doesn't, before plunking down $2K of your own cash. Independent music instrument stores, A/V rental companies, live production companies, event companies, are places to look for to rent this stuff, seat-of-the-pants guess would be a couple hundred bucks for a whole package (speakers, cables, stands, microphones) if you pick it up. You probably won't be able to get your hands on every possible model, but you can try a couple of different setups & speaker power ratings and see what works.
posted by soundguy99 at 5:23 PM on July 11, 2016 [1 favorite]
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