A Cheap Acoustic Measurement System

It simply blows my mind how many people build speakers without even trying to work with the real frequency response and impedance of the drivers they buy in the boxes they build. The tools to do so are easily available, and while learning to use them can take some time, I feel it is completely worth it. I would not even bother to build a speaker system if I didn't have a measurement system to work with. It would be an exercise in futility - the odds against coming up with the best system using the parts you have would be exceedingly slim, or else you'd have to devote so much time to the project that you wouldn't get to do much listening (which is supposed to be the whole point!).

Okay, ranting over - here is what you need:

And that's about it. Using SW, your computer generates a signal on the left and right output channels. One gets looped back to an input channel. The other one drives your audio system, whatever particular device you're wanting to test. Then you use your mic to pick up the sound generated by the speaker you're testing, and that gets recorded by the other input channel on your computer. Then the data recorded from the mic is compared to the data recorded from the output of the computer. Then lots of mathematical things go on and you can process your data in all sorts of useful ways in order to better tune your speakers. I would urge anyone contemplating getting into serious speaker building to try this type of approach before spending more money on fancy equipment and / or software. What if you build one set of speakers and never touch the stuff again? At least you haven't dumped hundreds or thousands of dollars on the greatest software out there. Even if you build speakers for the rest of your life, using a setup like this for a while will really let you / make you learn a lot, and you'll be better informed if / when you decide to get some more advanced equipment.

Copyright 1999-2004, John H Sheerin

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