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Old 11th June 2014, 11:28 PM   #1
FinBot is offline FinBot  Australia
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Default Art Car Sound System - A unique challenge

Hello Brains-Trust!

We are looking for your input or suggestions on an interesting project.

In Melbourne Australia, we are building an 'Art Car', and want to build the best quality sound we can for it.

We play dance music.

We have some limitations, and some interesting characteristics:
  • The vehicle moves around, well it's a vehicle after all!
  • People need to be able to stand/dance on the subs.
  • The top end housings cant be too big, around the size of a Mackie or RCF compact self powered speaker.
  • It needs to serve around 300 people, so 120db upwards would be great, the more the better.
  • It needs to be water resistant as it is outdoors.
  • Our max Generator power is 6KVA

I would love to have two 50 degree two way unity/synergy type horns up top, but I fear the sub will have to carry too much of the spectrum, or worse we will end up with a big hole in the mid bass.

The tapped horns in the 3D sketch are not to scale. The image is to sell the idea to the crew...


BUDGET: We will find the money that's not a big issue, we want to focus on optimal audiophile class sound for now.
Attached Images
File Type: jpg Long Artcar.jpg (97.0 KB, 232 views)
File Type: jpg 10432322_10152465830480818_672758841_n.jpg (14.9 KB, 231 views)

Last edited by FinBot; 17th June 2014 at 12:32 AM.
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Old 16th June 2014, 11:36 PM   #2
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I like the sound of this, what is it being used for? Personally I'm interested in battery powered portable sound

A few points to note, having helped with street parties in Sydney (a few Reclaim the Lanes events drawing 500-1000 people) and building my own compact portable system:

If you want the cart to be stable enough for people to dance on, you'll need to get the wheels wide apart but narrow enough to move up footpath ramps if need be (maybe 700mm) and possibly make the base as such the subs sit "cradled" close to axle level, or use low profile wheels to keep COG low - good quality solid castor wheels worked for big heavy rigs, inflatable wheels suffer a bit with weight.
Getting the tops high is ideal, but may affect balance of the cart - again needing wide wheelbase
Requirement for "compact" tops may rule out synergy horns, both for size and weight. Perhaps look at a bunch of 10"+horn tops, maybe with neo drivers if you can budget for them
Also think about how you approach bass - is chasing anything lower than 50hz practical, for outdoors? Probably not.

Will it be pushed or powered? Make sure you account for handles or the like and ensure there's enough space to move around the carts to control them

For reference, this was a "brute force" approach using PA gear on hand. Would definitely do it differently if you're starting from scratch...
Click the image to open in full size.
5KVA generator in the DJ console, heavy amp rack, 2x 18" subs and a 15"+horn top per cart. Took 6-8 people to move, and didn't like hills or rough surfaces!

"audiophile" requirement is a bit leap, as is the big budget... there are a heap of compromises in making a rolling rig, don't get caught up in pure sound and worry more about practical issues. Greatest sounding system is no good if it can't be moved, or worse you run out of money 3/4 through!

Throwing around ideas... a pair of 15" tapped horns per cart, and 2x 10"+horn on poles, could be a good middle ground between loud and lightweight. SS15 or the like for bass, and basic reflex design for top. Class D amps, of course.

Anyway I'm interested in seeing this project progress... ensure you post updates
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Old 17th June 2014, 12:30 AM   #3
FinBot is offline FinBot  Australia
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Cheers bitSmasher!

This feedback is invaluable.

The ArtCar is to be used at festivals. The chassis has been made by an F1 engineer and taken out successfully a few times. The rubber tires help with suspension quite well.


TAPPED HORNS
At this stage we are looking at using two tapped horns per side due to the efficiency gains.

I've succumb to the reality that we don't have the space or the power to reproduce below 40hz to any noticeable volume.

This is the driver we are currently considering:
FaitalPRO | LF Loudspeakers | 15HP1060

It is noted that the driver is treated to be outdoor resistant, water specifically. (it also comes with a warning it contains carcinogenic chemicals....hmmm)

We are about to start modelling and get an idea about how far up they are going to reach. Looking at models so far, 40hz to 200hz looks realistic. As the Freq rises the TH's start ringing so the bandwidth is limited, the trade-off of the TH.


TOP END
With the tapped horn we need to fill in over 200hz. As bitSmasher pointed out a Unit/Synergy horn would thus need to be large. The Pictures above denote our initial ideal horn, the Danley SM60, but it is going to be fairly impossible to reproduce one successfully at home due to the unique drivers and method of tapping the mids.

A direct radiator seems the most practical, but I am a bit of a fancy pants, and want to build something both impressive and challenging. The easy way out for me is just not appealing....
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Old 17th June 2014, 12:31 AM   #4
FinBot is offline FinBot  Australia
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GENERATOR:

bitSmasher, what generator was used? I am looking for one of similar power.
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Old 17th June 2014, 02:21 AM   #5
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" ... (it also comes with a warning it contains carcinogenic chemicals....hmmm) ..."

That would be lead.
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Old 23rd June 2014, 01:09 AM   #6
dangus is offline dangus  Canada
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If the car engine is running most of the time, it might be feasible to use 12v amps. I'd use a high-output alternator, possibly more than one if there's mounting room.
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Old 23rd June 2014, 01:24 AM   #7
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Quote:
Originally Posted by FinBot View Post
GENERATOR:

bitSmasher, what generator was used? I am looking for one of similar power.
Honda EU - I think it's a 5KVA beast but all the amps are old Class A/B in that rig so everything's heavy and inefficient
If you're starting from scratch, best to use efficient/light switching amps and a smaller generator - the EU2000 are compact and light
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Old 25th June 2014, 04:04 PM   #8
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Palm tree line array, anyone?
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Old 25th June 2014, 08:06 PM   #9
wg_ski is offline wg_ski  United States
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Quote:
Originally Posted by bitSmasher View Post
Honda EU - I think it's a 5KVA beast but all the amps are old Class A/B in that rig so everything's heavy and inefficient
If you're starting from scratch, best to use efficient/light switching amps and a smaller generator - the EU2000 are compact and light
Get a light switching amplifier and a voltage surge and you'll be buying a new amplifier. Use an iron transformer capable of 50 Hz (not just 60) and class H. They're efficient enough and more tolerant of the **** that happens. Not to mention serviceable if you do manage to blow it.
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Old 28th July 2014, 04:18 AM   #10
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Hey Wg-ski.

We have been looking at the IR series of class D's and plan to use proper regulation and protection.

Do you have any links to class H gear / info you might recommend for the project?

The main goals are high SQ, low weight and high efficiency.

Cheers all.
Dean
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Last edited by thunk303; 28th July 2014 at 04:42 AM.
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