200W Boombox (How to build)

This step by step guide will show you how to make your own boombox. So go forth and gather your tools to create your own awesome sounding boombox.....




Tools you may need:

• Drill
• Variety of drill bits
• Table saw (or a normal wood saw)
• Hack saw
• Selection of screwdrivers
• Wood and metal files
• Chisels 

Step 1: Parts List

Basic Info:

There are four main components to a boombox that determine how it performs:

• The amplifier
• The speakers
• The power source
• The housing

The amplifier I used was an unbranded 200W rms amplifier which was perfect for the deep bass notes at high volume. It was also conservative of battery life.  I used two speakers from maplin (UK), which were 6 1/2 inchs, 75W peak, mid to bass drivers. The boombox is powered by a 9AH sealed lead acid battery that is charged internally with a trickle charger. I used 18mm medium density fibre or MDF to construct the housing but would recommend a thicker material for yours, however the diamension will need changing.

Parts that you may require:

• An amplifier in the range of 150W~300W RMS
• 2x 6 1/2" 75W hi-quality speakers 6 ohms
• a sealed lead acid battery of about 9AH but the higher the capacity the better
• several large off-cuts of 3/4" MDF
• sheet aluminum to make the interface panel
• various screws
• heavy duty flight case handle
• 3.5mm headphone to RCA cable
• textured stone effect paint
• mains junction blocks
• switches
• wire

Comments

[nickmccullough]

looks and sounds pretty freakin sweet:D

[garren11]

http://www.instructables.com/id/Suitcase-Boom-Box/

Check out my suitcase boom box! and awesome boom box you made

[eXtremeSomething]

Cool! What does it sound any good ? Thats a big speaker, have you tried using a small car amp and sealing the case with sealent or tape? Sorry for the delay, been working on more instructables of my own :D

[liamjonze]

I was wondering if you could tell me what you used to build your boombox. A detailed list. I need all the help I can get and the more it can be spelled out, the better. Thanks so much.

[eXtremeSomething]

Hey thank you for you time and sorry I have only just got back to you. I don't think this is the best build for a beginner as it has some heavy duty componants such as the massive battery that is a huge fire risk if the schematic is not followed exactly.

Can I point you in the direction of this instructable, it is very well done and might be easier to follow: http://www.instructables.com/id/DIY-Portable-Boombox-Audiophile-Quality/

Thanks again for your interest and time.

[ihren]

Hey i have to say a great project, and thanks to you im building my own now, have almost all the components but i can not get the wiring around the dpdt rocker and the charger, because doesn't a charger need a 220 v input a the connections on the dpdt i dont understand how is the charger connected to the battery and where go the wires from the battery and charger?

[eXtremeSomething]

Hey, thanks for the comment. I have overhauled the instructable, sort of. I have Included a clearer schematic as well.

The charger is always connected to the high voltage in. The xbox power supply is also always connected to the mains. When running from the battery the 12 volt of the amplifier is connected to the + on the battery. When on battery, the charger's 12v output is disconnected from the battery. You should be able to work it out but fell free to comment again if you need help.

Be careful as these batteries dont like being shorted out :D

[gschoppe]

What is average power consumption of a 200W amp? I ask because the way I imagine it, a 200W amp draws 200W when running at maximum volume... that would mean that a 12V 200W amp would draw 16.67A at max... which would make a 12V 9Ah battery last about 32 minutes... which is a FAR cry from 14 hours

my only guess is either that 200W is being used as a volume measurement and does not equate to power requirements, or that the 14hour measurement requires the amp to be operating at a 7.71W input... which (making the huge assumption that power consumption is linear over volume) is about 3.86% of the unit's total possible volume.

I am assuming something is wrong with this math. Do you know where I went wrong?

[Yerboogieman]

Simply put, It's not always going to be putting out 200watts constantly. At low-mid volume it will probably be putting out less than 100 watts.

[pfred2]

At a Watt the speakers are probably putting out around 90 db. Probably the only way that amp is going to put out 200 Watts is if you set it on fire.

[eXtremeSomething]

Intuitive thinking, however I did state this is only the case when at a low volume. Also please note that I am using a 200W rms amp but only using 150W rms because of the 2, 75W speakers. The rms applies to the pure / constant waveform (i think) and the actual consumption when an iregular information signal ie music, could well be less.

As for the relationship between power and output voltage, as far as I can tell, I think it is exponential but there are lots of if and buts.

I think this explains it - eXtremeSomething

[karlpinturr]

I have no experience with car amplifiers - can you explain "short the remote of your amplifier to 12v", please?

[eXtremeSomething]

Certainly. Standard car amplifiers have 3 power connection, 12V+, 0V (or GND) and REM (or remote). When the cd player in your car is turned on it sends 12V to the amplifiers REM to switch the amplifier on from standby. See the attached image, (I do not own this image however).

It is used to save time as powering up from scratch takes takes about 4 seconds longer. I find it is simpler to just connect it the the 12V input so that they both get power at the same time. I do this as it uses some power in standby mode and it alo saves me a switch.

I hope this explains the situation, if not I will try to re-illiterate.

Thanks and good luck
.

[karlpinturr]

Ah - yes, that explains it fine. Thank you.