Decibels, Boomboxes, and consumer audio gear
Speakers are super important and very confusing.
Boomboxes, bluetooth speakers, and home stereo systems are generally not loud enough for protests outoodrs, especially where there is road noise. Systems that feel loud in a house are likely not going to be loud on the street.
This article will help you know
what to ask to borrow, rent, or buy for your demonastration.
What the Watt?
This paragraph is pretty technical, and you can skip it if you like. There are a few ways speakers are labelled for loudness. Sadly, most of the time, power ratings(measured in Watts) are entirely made-up for marketing/sales and not based on any actual measurements. A 2000 watt system from a low-end brand (like Pyle, ION, etc) is likely less loud than an 80 watt system from an honest brand(JBL, QSC, even Behringer). The real level of loudness is usually not listed on any low-end equipment, but the number is “maximum SPL (Sound pressure level) at 1 meter” this refers to how many decibels the unit can produce at a distance of 1 meter. 110db is a good minimum for a protest environment. Note that every 3 dB is “twice as loud” Another factor is that a 50 watt horn speaker is loud enough to hurt through earplugs, but a 50 watt subwoofer is not very loud at all. Loudness and watts are often not usefully related due to efficiency differnces, how much less power it takes to make higher pitch sounds, and how there is no accountability for honest labelling in the industry.
Portable Battery Powered PA Speakers
Battery powered speakers are often not loud enough for large actions, with some exceptions for higher-end systems.
These are a dream in terms of ease and flexibility, and can be operated with minimal traning and minimal setup time.
The loudest is the new Soundboks $1000 (122 dB SPL @ 1m)
If you wanna borrow one, it may be worth posting in this facebook group for SoundBoks Owners
Note that only the newer ones (SB3)have built-inmicrophone support, so for the older ones you will need a mixer and a cabel for the mixer which has an aux cable at the output end.
Another loud one is the $550 JBL Eon Compact One(113 dB SPL @ 1m) it is a little hard to use, it has a confusing interface.
Behinger also makes a few models which are very loud, asy to use, and popular
Samson makes a few, but they are not quite as loud.
Some low end units (Pyle, ION, etc- generally have flashing lights) are designed to look loud and often are not, but are better than megaphones and can work in a pinch.
Call local shops, some, including Guitar Center have rental programs.
Powered PA Speakers
Our general purpose choice, wall-powered, or active PA speakers are very commonly owned by musicians and venues. In COVID, these are left unused. If you ask around, you may be able to borrow them. They are self contained sound systems, needing only a sound source and power to operate. We recommend borrowing or renting these, as they can cost $500- $1500 each. The QSC 12.2 (132 dB SPL @ 1m) is an example of a model that is very loud and popular. Because they are self-contained, they are able to protect themselves against blowing out at improper volume levels. The frustrating thing is they are not battery powered so you need to plug them in to something. See power section.
Powered speakers can accept line level sound from a phone or a mixer, or you can plug a microphone directly into most units. They can be connected together for a louder system or one with more coverage.
Megaphones - Easy but crass
Most megaphones are very poor quality, sound awful, and are not as loud as speaker systems.
Having said thatt, they are very portable, easy to use, and photograph well.
Some “50 Watt” megaphones are louder, but the ratings are often dishonest.
Pyle’s more expesnive units $30+ are decent
We have heard better things about ThunderPower
but nice megaphones may not exist.
Public Address Horns - Advanced option
These are difficult to set up for non-technical people, but are very loud and use very little power.
Our choice for speech, Commercial PA horns, typically used for tornado warnings, stadium sound, and schoolyards have been useful for us.
- + For speech, they sound almost good.
- + They looks great in photos
- + They are lightweight and easy to mount
- + They use 90% less power than equally loud full-range speakers with more bass
- + They are cheap
- - For Music, they sound like 1940s folk recordings.
- - They require separate amplifiers making set up a little more work
Some larger horns require special 70 volt amplifiers. We have had great luck with the Pyle 16” 100w horn. We have never run it at full volume as it has been too loud, a good problem to have. It can run off 70v amplifiers or normal ones.
We have been using this 70 volt unit from ebay for pretty cheap ($70). Atlas Sound PA1001G but it needs a mixer to hook up to Mics. Here is An Example amplifier that has a mixer built in.
Here is a tutorial about 70 volt speakers.
Passive PA speakers with Power Amplifiers - Advanced Option
Passive speakers require a seperate amplifier and the loud professional models are easy to damage if used by inexperienced people. As such, they are hard to borrow. While they can be the loudest option, they should be operated by experienced people. They are more complex to set up, as the amplifier is separate and often large and heavy. We would recommend against buying them, as they add complexity. If you are operating these, be cautious with volume levels and especially bass levels to reduce the chances of damage.
Car Audio Gear - Advanced Option
Car audio gear is designed to run off of a car. So far so good!
Car audio amplifiers are great and very efficient. They are designed to turn line-level audio into speaker signals for any speakers, generally in the 2-8 ohm range. Some crafty group members have had great results hooking car audio amplifiers up to passive PA speakers strapped to their vehicle.
Speakers designed for cars generally are not that loud because the listener is very close. When they areloud, they emphasize bass. They do not come with cabinets, and speakers need enclosures to work. You can use any speaker on these amplifiers, as long as the impedience is right (usually 4 or 8 ohms)
Things also get tricky because car systems never have microphone inputs, meaning you need a mixer , but you can get usb-powered mixers for about $50.