Step 2: Choosing The Best Speaker, Amplifier And Enclosure For Your Project
Plan, Canvas And Gather Information:
Be sure to plan everything before you buy your wood, speaker, amplifier and everything. Also consider the space that is limited on where you are going place your boombox. Try to research first before you buy everything. After researching, write it doen on your blueprints
Before you buy a pair of speakers, try to research on different brands that are reliable and have been known for producing speakers with excellent quality, brands like Dayton, Tangband, Focal, Seas, Fostex and Crown (only found in the Philippines). I chose the brand of Crown since it was known for cheap speakers with excellent sound quality, I also had great experiences with it. Try to buy speakers that can exceed 80W of audio power. Do not be fooled by the maximum wattage of the speakers, it all depends on the audio quality.
Also try to find speakers that can reach a wide range of frequency response. For woofers, a frequency response of 60Hz - 6kHz are good to start with and a frequency response of 200Hz - 20kHz for fullrange speakers are recommended. The wider the better! Mine has a two way crossover design so both speakers combined should reach 45Hz - 20kHz (without a frequency gap)
Remember that the human ear can only hear 20Hz - 20kHz of audio frequencies so don't get excited if you find speakers can go above or below the audible frequencies, it would be a great impracticality.
You can easily judge a speaker by its appearance, the magnet size, the cone's material, the size of the rubber surround, the wieght, the size and the beauty of its design.
The first time I found my speakers in the store, I easily goty excited to buy one, when I found the over sized magnets and the wide rubber surround design with a thick polypropylene cone, I told myself that I should buy these someday. When I checked the specs and its price, I was extremely impressed, everything exceeded my expectations.
Its better to make your own amplifier, I built an amplifier with a TDA8569 (2x40W BTL) amplifier chip and connected to a TDA1524 tone control circuit (Bass, Treble, Volume and Balance Knob). Chip amplifiers are definitely more energy efficient than MOSFET amplifiers. You can choose to make one or to buy one, if you are experienced in making amplifiers I suggest to make one, the TDA1554 (2x22W), TDA7394 (2x30) and TDA8560 (2x40W) sounds terrific and also try the TDA1524 tone control chip. If you don't know how to make circuits you can try to find a ready made car amplifier. Making one is cheaper than buying a ready made.
If your amplifier and speakers are good but your enclosure is poorly designed, the sound quality will greatly be affected. There are two commonly used speaker enclosures, one is the ported and one is the sealed. Try the method of bracing, bracing is the of additional support structure added inside the speaker enclosure's edges, in this way vibrations can be eliminated outside the enclosure thus giving a better audio experience.
The sealed enclosure is perfect for small enclosures, it self-dampens the sound given off. The pros is that this enclosure can be used for small and compact enclosures, and gives of a smooth and damp sound while the cons is that this design will require a 100% airtight enclosure for it to be effective. The ported enclosure is only ideal for large speakers (+ 6.5 inch") with large enclosures.
You can use a ported enclosure and just plug a thick foam into the port for it to be a closed enclosure although air could still escape.