DIY Speakers: You can do it! Seriously...
If you're like me, the thought of building your own speakers may sound daunting. After all I came into this whole Value HiFi thing with next to zero knowledge of electronics and carpentry. But where there is a will, there is always a way - and I had a lot of will.
Ask yourself, "What do I want?"
- To build the best speakers in the world? That's not going to happen.
- To learn a new skill so you can build better speakers in the future? Definitely the right starting point.
Why Build Your Own Speakers?
1) Learn a new skill
2) Enjoy your own work
3) Show off to your friends
4) Troubleshoot faults yourself
5) Good value for money
6) Use the parts of your choice
What About Speaker Kits?
This is a good option as you don't need to select and source the parts. However, they are quite overpriced, you won't be able to customise your parts, and you won't learn much about crossover and cabinet design.
The Master once said, "Who builds a tower without first taking stock of what materials are available? If he starts building the foundation and finds out he doesn't have enough to finish it, others will mock him."
The more planning you do, the less mistakes you will make. You're almost guaranteed to make mistakes your first time around, but without planning you could end up with an unusable product.
Bigger speakers are harder to build - more wood, more bracing, harder to align panels, more sanding, more painting, more dampening material. Try starting smaller.
FULLRANGE, 2 WAY, 3 WAY...
Generally you want your speakers to cover low to high frequencies.
- tweeter = high
- midrange = medium
- woofer = low
Full range - the most simple build is one full-range driver per cabinet. A crossover to divide the input signal into lower and higher frequencies is not required. While simple to build, you probably won't get good sound unless you buy expensive drivers. You will also not learn about crossovers.
2 way - this comprises of one woofer and one tweeter and a crossover for each speaker cabinet.
3 way or more - this comprises of at least a woofer, midrange, and tweeter, a more complex crossover, and a speaker cabinet to accommodate for the woofer and midrange.
Try a 2 way system for the best balance between cost and ease of building.
This is generally the order from most to least.
WHERE TO BUY?
Americans are fortunate to have lots of choices such as Parts Express (link to the left). They will sell everything you need to build your speakers. In Australia, you will have very limited choices, and somewhat inflated prices. In this case, look around, Google is your friend!
Step by Step
1) Pick your drivers
- impedance: choose either two 4 or 8 ohm drivers
- size: woofers for bookshelf speakers range from 4 to 8 inches, tweeters are generally about 2-3 inches diameter in total.
- power: the drivers should be fairly evenly matched
- sensitiviy (dB): look for a mid to high 90s and above.
- frequency range: low bass is about 40Hz and high treble about 20kHz. You want there to be a good overlap between the two drivers.
(see right for a guide).
2) Determine Enclosure Size
Take note of the woofer's equivalent volume (VAS), resonance frequency (Fs), total Q (QTS), and cone diameter.
Go HERE and plug in the figures. For QTC use .707.
TO BE CONTINUED
Reading a Frequency Response Graph
The left image is for the woofer, the red line is the frequency response. Notice that at about 60Hz it rises above 80dB and doesn't drop below again until about 8000Hz. The tweeter graph on the right shows that it hits 80dB at about 900Hz. There is a good overlap between the woofer and tweeter, from 900Hz to 8000Hz.
click above to enlarge
3) Choosing a crossver frequency
For the drivers above I have chosen a crossover point of 2900Hz. A 2 way speaker means that both the woofer and tweeter will need to cover the midrange (low = 250-500, med = 500-2000, high = 2000 to 4000). I chose 2900Hz so that the tweeter will not need to very too hard, and can focus on the higher end of the upper midrange.