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Turn yourself into a remarkable speaker demonstration.
To begin, just find a piece of heavy cardboard or corrugated carton about 14" x 20" and cut an opening in the center like the one above. Now you're ready! Grab a friend, your wife, your mother-in-law-anyone who can bear to hear you ramble on for the next 30 seconds. Hold the contraption you just made to your face so that your lips are against the opening and start talking.
Now, take it away quickly as you continue to talk.
Then hand it over and let the other person talk, with and without the cardboard.
If all went well, you probably noticed a coloration in voice quality whenever the cardboard was held up.
In essence, what you just did was to simulate the way every enclosure type of system is affected by the baffle board its speakers are mounted on.
You became the speaker and the cardboard be came the baffle.
As you spoke without the cardboard, the sound waves reached the listener normally. But when you spoke holding up the cardboard, some of the sound waves from your voice traveled along the surface of the cardboard until they reached the edges, the way they do on a conventional speaker. The sharp discontinuity caused an effect called "diffraction," which allows these waves to be heard too, but later than the original sound. This is what produces the unnatural coloration you heard.
But the Dahlquist DQ-10 overcomes this problem through an ingenious free-air mounting con figuration which has no large baffle surfaces to color the sound. At the same time we are able to reduce time-delay distortion, since all drivers are mounted in the correct acoustical plane.
The end result is sound that is so natural and open in quality that you will realize just how much coloration enclosure type speakers pro duce. Even if you don't want to go to the trouble of doing our little home demonstration, any Dahlquist Dealer will be happy to do it for you, using a DQ-10 instead.
The box-less speaker.
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(High Fidelity, 1976)
Also see:
Analog and Digital Systems (ADS)