Homemade Boombox help, do I need a Port? - diyAudio
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Old 11th April 2011, 04:51 PM   #1
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Default Homemade Boombox help, do I need a Port?

I built this portable boombox for my daughters traveling softball tournaments.
I knew the box would be heavy, so I designed it around a Northern Tool heavy wagon capable of hauling 2200lbs.
There is a 15" Sub in it's own ported 5 cubic foot enclosure which is part of the big box.
Then the main area houses 2 - 6x9's, and 2 horns.
Inside are 2 amps. One 3000 watt for the sub, another 1500 watt for the other speakers. I have a car stereo with cd player mounted on the top of the unit, and the top opens on hinges and stays up with the help of some gas struts. Inside also houses 2 - Marine batteries, with a toggle to cut off power.
The box sounds just awesome, but here is my question...
When I open the lid, the base increases from where the 6x9's are, and comes out the top of the unit, making it sound better. Should I install a port in the front of the main area between the 6x9 speakers to allow more air to escape, increasing the sound? When the radio is really turned up, the top door vibrates, so I stick a piece of wood under the door to elevate it about a half inch, and it sounds great. The door does have rubber installed to help elliminate the vibrations, but when it's really turned up, like rock concert volume, it rattles where the piece of wood really helps.

This box ended up being to heavy to pull, so I installed a gear reduction motor underneath, welded a sprocket to the rear wheel, have a control module with a throttle, and 2 - 12ah batteries underneath to allow me to haul it around. there is also a key switch for off/forward/reverse.
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Old 13th April 2011, 01:18 AM   #2
Davejs is offline Davejs  United States
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Ok some things come to mind with this unit.
A. It does look cooler then anything just really to big.
B. How do you transport it to and from events and in what type of truck or van ramps or what?
C. If you can't pull it and the battery dies for the motor then what?
D. Will your daughter or the team be moving this?
E. Why do they need a boom box so big.
Finally if it needs more vent add it, I spent years moving equipment in bands and as a DJ. Sorry guy when it is hot out and your dog tired at the end of a long day the last thing you want to do is move/load something that big. Plus if the person or persons that need to help load unload are injured or missing before or after your stuck solo.
If I had to redesign it as a smaller unit use an Ipod or MP3 player.
Use the speakers you have skip the sub, in outdoor events it is hard to create the heavy bass without lots of power and more drivers. Another option is a briefcase suitcase size unit. Have a small charger/converter built in and smaller gel cell batteries. A provision to just plug into a car 12v outlet will go along way to keep it powered up.
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Old 13th April 2011, 01:39 PM   #3
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Hi Davejs,
A) I transport the unit in a covered trailer. The trailer has a built in ramp. The boombox with the wagon weighs a bit over 300 lbs. The wagon has 16" wheels. These traveling softball teams are pretty serious about the game, and the music. My box IS on the large size, but I've seen bigger. But none with a 15" sub.
B) I've never run out of juice on the batteries that pull the unit. Even when at a tournament where I have to go back and forth between fields. I've had the motor pull this thing for about 2-3 miles, and the batteries are still at 75-80%. I run 2 - 12 ah batteries in series (24v), and the motor is a gear reduction, so it travels my walking speed, but with plenty of power.
C) I go to all the games and tournaments, so I haul this around in the trailer. Almost every team has their own trailer. Each painted with the teams name, and houses smaller wagons to hold the teams supplies, (bags, balls, coolers). Every team has some sort of radio. I've seen some housed in large coolers.
D) The box needed to be big because of the 15" subwoofer. Since the games aren't inside a small room with nice acoustics, I needed a radio that could produce loud music outside like a concert. So I built the box with an internal ported box for the subwoofer. The sub needed 5 cubic feet, then the rest of the box had to house,
2 - amps
2 - marine batteries in parallel
electronics, high power fuses, switches, etc. And I needed the door big enough to get the batteries out to charge them.
E) There is also an input for an Ipod which we use all the time. This way anyone can play their music. A kid can move this thing. With the motor, you just steer it, and it drives by itself, and rides up the ramp into the trailer. With this subwoofer, you feel like you're in a concert. PLENTY of bass you can feel. This is a big deal to have a big bad radio for the team. Most of these tournaments last the weekend. You could have 4 games in a row, and need the power and volume to play all day.
By the way, even after moving this back and forth from field to field all day, I load the top of the unit up with a bat bag, chairs, cooler, bucket of balls, camera bag, etc.
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Old 13th April 2011, 06:06 PM   #4
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A shame you didn't see my Boominator thread (google it) before building that behemoth but it's never too late to make something that is much smaller, much lighter, and plays a lot louder for much longer.
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Old 13th April 2011, 07:02 PM   #5
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Nice box. I had to keep all my drivers on the front though. Most softball fields are back to back. With the speakers on the front only, the kids can hear the music in the outfield, but it's not that loud behind it, except for the bass from the sub. The deep impact from the sub, is what drains my batteries, but with two in parallel, I never run out of juice. During these tournaments, the other teams try to out-do your sound system. It just won't happen with this setup.
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Old 13th April 2011, 07:21 PM   #6
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I'm curious. Why have you used such large amplifiers? I'd bet you're running them nowhere near their claimed capability.

If you find the sound improves when you open the lid, adding a port may not give the same effect, as it only passes bass through, whereas the open lid will pass the midrange, too.

Chris
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Old 13th April 2011, 07:29 PM   #7
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The increased bass is coming from the 6x9's mounted to the front. The crossover is set to 250hz and up to the 6x9's (I believe)
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Old 3rd October 2011, 05:52 AM   #8
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Can you give me some specs on that motor your using, or where to buy one? I am building a similar boombox wagon and would love to have a motor on mine as well. Also, what do you think about adding solar panels or even a windmill?
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Old 7th October 2011, 07:43 AM   #9
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mcgyverism

I see lots of money in your future over this.

What was total cost?

What would you retail it for?
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Old 18th November 2011, 08:57 PM   #10
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Quote:
Originally Posted by honkama View Post
Can you give me some specs on that motor your using, or where to buy one? I am building a similar boombox wagon and would love to have a motor on mine as well. Also, what do you think about adding solar panels or even a windmill?
I ended up using a moped motor (24vdc) It's a gear reduction motor so it has more torc, and less speed. Then a moped motor controler. The controller has inputs for the battery, throttle, motor, and break if you want it. Also used is a throttle mounted to the handle bar of the wagon. I use 2 - 15ah 12vdc sealed lead acid batteries in series to give me 24 volts. They will pull the wagon for miles before they need to be charged. On the drive wheel I bought a 72 tooth #35 chain minibike sprocket. I welded this to the inside of the rim. Now since mopeds don't use a #35 chain, I bought another 11 tooth sprocket for the motor, and had to drill it out with a 11mm drill to fit the shaft of the motor.

As to solar power, I just recently added a 20 watt solar cell which fits on the side of the wagon for storage, and does a great job of charging the batteries in between games. The charger controller is mounted on the inside of the box.

Next I need to add a 4-farad Amplifier capacitor because when the box hits a big bass note, it really draws on the battery and the voices get muffled.

Total cost I estimate is about $2500-$3000.

With the motor pulling and pushing the wagon, (Yes there is a switch I installed for forward and reverse) it bent the back axelforward, so I had to buy some 1/8" angle iron and weld in braces on both sides of the rear axle, then paint it to match the wagon. The motor is also installed on a 1/4" steel plate that is welded underneath the wagon. It is on slotted holes so as the chain stretches, I can adjust the chain tension.
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