Mounting speakers on cars for political purposes

D

Daniel Postilnik

Junior
Jan 14, 2011
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San Francisco, CA
I've been getting an inordinate amount of calls in the Chicago area from various political offices wanting to mount PA systems on vehicles to create a "sound truck" to roll through a neighborhood and proclaim a message.

Apart from the fact that this is a really obnoxious campaigning tool and generally disruptive, I was wondering if any of you had experience safely setting up speakers on vehicles that are normally reserved for SOS setups. What size did you use, how did you provide power, how did you secure the speakers, etc. Assume there's no access to a generator.

Thanks!
 
Re: Mounting speakers on cars for political purposes

Big power inverter wired directly to the battery, everything else as usual.

I'd probably have them get a roof rack installed on the vehicle, then use some strut to make a frame to attach speaker rigging points to the roof rack.

That might work really well if using Community's R series- you wouldn't even need to take them off in the rain!
 
Re: Mounting speakers on cars for political purposes

Silas,

I actually have the R-series! They're great, but I haven't had a chance to rent them out much.

The problem is that the calls I'm getting are for one-off type rentals, the election is next week, or in any case too few weeks to convince someone to build something on their vehicle.

I get the power inverter part, but how would you do this if you couldn't make any modifications to the vehicle?
 
Re: Mounting speakers on cars for political purposes

Daniel Postilnik said:
Silas,

I actually have the R-series! They're great, but I haven't had a chance to rent them out much.

The problem is that the calls I'm getting are for one-off type rentals, the election is next week, or in any case too few weeks to convince someone to build something on their vehicle.

I get the power inverter part, but how would you do this if you couldn't make any modifications to the vehicle?
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Hello,

I thought THEY were asking you in regards to a vehicle mounted Sound System...what's there to "convince"? There are plenty of roof rack systems that do not damage or change the vehicle. Puchase a roof travel rack, add a platform or mounting device for the Speaker boxes/Drivers, and run a couple of cables to your Amplifer that's mounted/stationed inside the vehicle.

Cheers,
Hammer
 
Re: Mounting speakers on cars for political purposes

Charlie Zureki said:
Hello,

I thought THEY were asking you in regards to a vehicle mounted Sound System...what's there to "convince"? There are plenty of roof rack systems that do not damage or change the vehicle. Puchase a roof travel rack, add a platform or mounting device for the Speaker boxes/Drivers, and run a couple of cables to your Amplifer that's mounted/stationed inside the vehicle.

Cheers,
Hammer
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Exactly what Hammer said. Roof racks these days are 'hot swap' and might even be universal, clipping to the top of the door frames on each side of the vehicle. If it's strong enough to hold boats and bikes, I bet it can hold some speakers.

As far as the inverter, I don't think it would be hard to run a piece of 8/4 SO cord from the engine compartment back to the rear door of a van or an open window. I'd double-up the conductors of the SO cord to yield something like 100 amps of capacity, because 100 amps at 12V is only 10 amps at 120V, or only half a circuit. And, running the ground back to the battery would eliminate having to tech-screw a ground to the inside of the vehicle somewhere.
 
Re: Mounting speakers on cars for political purposes

They have the money, so make them pay for a good safe design. If they cry poor than here's something that I have done before.

I made several mini PA systems for the Avon 3 day walk for the sweep vans, They play music and saying encouraging things to the walkers. I did it 50's style with basic horns from Radio Shack. It's basically speech re-inforcement so the lower vocal frequencies never mattered and it was women on the mice mics. I made a basic center console that head a Shure mixer, small amp and inverter that ran to a 12volt lighter plug. The horns were a little under powered but we only wanted the audio to travel 40 feet or so. Any more would be overkill for the purpose. The small PA systems had to be taken out of the vans each night and re-installed by someone who barely knows how to turn on a computer.

Shure Mixer:
http://cgi.ebay.com/Shure-M267-4ch-...448?pt=LH_DefaultDomain_0&hash=item1c1a8e0598

Amp:
http://cgi.ebay.com/Stewart-Audio-C...761?pt=LH_DefaultDomain_0&hash=item2c51032989

Horns:
http://cgi.ebay.com/Radio-Shack-Hor...824?pt=LH_DefaultDomain_2&hash=item3f08640f08
 
Re: Mounting speakers on cars for political purposes

Why don't you just use a car audio amplifier? They have line in's so using them with a small battery powered mixer would be easy. Add a couple of efficient speakers and you are good to go.
 
Re: Mounting speakers on cars for political purposes

Chris Gruber said:
Why don't you just use a car audio amplifier? They have line in's so using them with a small battery powered mixer would be easy. Add a couple of efficient speakers and you are good to go.
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I hate car amplifiers. They are a huge pile of hyped-up fake ratings. The cost of a good car amplifier will be over $500, and there are very few multichannel units that can do more than 100 watts per channel at 4 ohms.

Also, since car amps are designed for 4 and 2 ohm loads, they will produce significantly less power at 8 ohms (ideally, half of 4 ohm power).

For $500 I'd buy a nice power inverter, and use it for other cool things when it isn't out on rental :) Both the power inverter and power amplifier are going to require the same direct-battery connection, unless you're talking really, really low-power applications.
 
Re: Mounting speakers on cars for political purposes

Silas Pradetto said:
I hate car amplifiers. They are a huge pile of hyped-up fake ratings. The cost of a good car amplifier will be over $500, and there are very few multichannel units that can do more than 100 watts per channel at 4 ohms.

Also, since car amps are designed for 4 and 2 ohm loads, they will produce significantly less power at 8 ohms (ideally, half of 4 ohm power).

For $500 I'd buy a nice power inverter, and use it for other cool things when it isn't out on rental :) Both the power inverter and power amplifier are going to require the same direct-battery connection, unless you're talking really, really low-power applications.
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How much power could you possibly need to announce a political message while driving through a neighborhood? Speech into so PA horns won't need 1000 watts of power.
 
Re: Mounting speakers on cars for political purposes

Bennett Prescott said:
Finally, a voice of reason! Just use a cheap plastic powered box, run it off a run of the mill inverter, you'll be fine.
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I did this with an EV sxa250 for two weeks several years ago. One week later the amplifier module on that speaker died (still under warranty) , and the 11 others have been without issue for many years. Obviously I can't say with certainty the inverter caused the problems, but I'd buy a very good inverter if I was going to do this again. This one was a premium unit from our equivalent to Sears (1000 'watts' I think) direct to the battery.

I've done similar things more recently with Community Wet series speakers and an old powered mixer - but this time it was powered off a small Honda generator. The Wet series have a bracket that let me safely mount them to a truck and trailer (no photos - sorry).
 
Re: Mounting speakers on cars for political purposes

Pat Latimer said:
You mean like this??

http://www.google.com/images?hl=en&...+mobile+with+speaker&gbv=2&aq=f&aqi=&aql=&oq=

bluesmobile_speaker_1974_dodge_monaco.jpg



Pat
Click to expand...

Exactly!
 
Re: Mounting speakers on cars for political purposes

Chris Gruber said:
How much power could you possibly need to announce a political message while driving through a neighborhood? Speech into so PA horns won't need 1000 watts of power.
Click to expand...

If I were a politician, I wouldn't want to be heard through a cheapo PA horn, because it might be seen as 'cheap'. I think at least some attempt at full range would be worth it.
 
Re: Mounting speakers on cars for political purposes

Silas Pradetto said:
If I were a politician, I wouldn't want to be heard through a cheapo PA horn, because it might be seen as 'cheap'. I think at least some attempt at full range would be worth it.
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Prior to my family having access to my truck, my dad had a roof rack for the top of our cars. It was a square wooden frame with 2 large suction cups in each corner. Then there were some nylon straps that would hook near the doors. The problem we found with it (and we've had this thing for years) is that as car styles changed the roofs got more and more curvy and it was hard to make the rack work on it. If you had a flat top SUV or something, that style of roof rack would probably be a good frame to build off of.

If I were doing it, a cheap 200W pawn shop car stereo amp and some efficient speakers would be my choice.

Re-elect Mayor Red Thomas. Progress is his middle name!
 
Re: Mounting speakers on cars for political purposes

I used some of these http://www.prolineracks.com/proline-gmr165-rain-gutter-racks.html ( something older actually) and some unistrut cross beams to bolt on 4 atlas APC 30 horns ran off of a inverter and a toa 120 watt paging amp - loud as hell.

In high school I Had a old 400 watt Majestic Car amp and a Radio shack battery DJ mixer and cd walkman I used to run some old sp-2's from the back of a pick-up during a foot ball game and for parades
 
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