Speaker System Design
Different speaker for different frequency ranges
In a perfect world, a single speaker would reproduce then entire audible frequency range from 20Hz to 20,000 Hz. With conventional drivers this is not possible. To maintain the output, for every halving of a given frequency a speaker must increase its excursion by two times. A speaker moving only 1 mm at 20,000 Hz would have to move 1km at 20 Hz to have the same output level!
To operate effectively, we have different speaker to operate in different frequency ranges. The audio bandwidth can be effective divided into three or four frequency ranges depending on your system configuration. Table 1
These frequency ranges are suggestions for conventional drivers in a close field situation (in a car). Let’s look at the different frequency ranges and the speakers that are optimized to reproduce them.
- 2,500 to 20,000Hz- This Frequency Range is covered by tweeters. Tweeters are typically dome type speakers that has a dome material that also serves function as the surround of the speaker. Tweeters are small drivers with an average size of 1” (25.4mm) in size. The wavelength size is very small. A 20,000 wavelength is only 0.7” (1.7cm).
- 400Hz to 2,500Hz - This frequency range is covered by midrange speakers. These speakers are generally cone type speakers that have a separate cone body and surround material. Midranges range in size from 3” in diameter up to 8” inches in diameter. Most common is size is 5 1/4” (135mm).
- 100Hz to 400 Hz- This frequency range is covered by midbass drivers. These speaker share the same features of midranges except they are typically larger is size and are designed for higher excursion. Typical size of midbass drivers are 6.5” to 10” in diameter. Most common size is 6.5”. NOTE: In some systems, a single driver can cover the range from 100Hz to 2,500Hz. Typically these drivers are 5.25” to 6.5” inches in diameter.
- 20Hz to 100Hz- This frequency range is covered by woofer drivers. These speakers share the same features of midbass and midranges except that the resonant frequency of the woofers are lower and the excursion capability of the woofers are higher. Typical size of the woofer ranges in size from 6” to 36”. Average size is 10” to 12” in diameter.
back 
topFrequency and Wavelength
Listed below is the audible frequency range and the wavelengths distances. These frequencies are displayed in 1/3 octave increments that coincide with the frequencies on an 1/3 octave real time analyzer.
Frequency | Wavelength | |||
in Hertz | feet | inches | meters | centimeters |
20 Hz | 56.6 ft. | 679.2 in. | 17.2 m | 1720.0 cm |
25 Hz | 45.28 ft. | 543.4 in. | 13.76 m | 1376.0 cm |
31.5 Hz | 35.94 ft. | 431.2 in. | 10.921 m | 1092.1 cm |
40 Hz | 28.3 ft. | 339.6 in. | 8.6 m | 860.0 cm |
50 Hz | 22.64 ft. | 271.7 in. | 6.88 m | 688.0 cm |
63 Hz | 17.97 ft. | 215.6 in. | 5.46 m | 546.0 cm |
80 Hz | 14.15 ft. | 169.8 in. | 4.3 m | 430.0 cm |
100 Hz | 11.32 ft. | 135.8 in. | 3.44 m | 344.0 cm |
125 Hz | 9.06 ft. | 108.7 in. | 2.752 m | 275.2 cm |
160 Hz | 7.08 ft. | 84.9 in. | 2.15 m | 215.0 cm |
200 Hz | 5.66 ft. | 67.9 in. | 1.72 m | 172.0 cm |
250 Hz | 4.53 ft. | 54.3 in. | 1.376 m | 137.6 cm |
315 Hz | 3.59 ft. | 43.1 in. | 1.092 m | 109.2 cm |
400 Hz | 2.83 ft. | 34.0 in. | 0.86 m | 86.0 cm |
500 Hz | 2.26 ft. | 27.2 in. | 0.688 m | 68.8 cm |
630 Hz | 1.8 ft. | 21.6 in. | 0.546 m | 54.6 cm |
800 Hz | 1.42 ft. | 17.0 in. | 0.43 m | 43.0 cm |
1000 Hz | 1.13 ft. | 13.6 in. | 0.344 m | 34.4 cm |
1250 Hz | 0.91 ft. | 10.9 in. | 0.275 m | 27.5 cm |
1600 Hz | 0.71 ft. | 8.5 in. | 0.215 m | 21.5 cm |
2000 Hz | 0.57 ft. | 6.8 in. | 0.172 m | 17.2 cm |
2500 Hz | 0.45 ft. | 5.4 in. | 0.138 m | 13.8 cm |
3150 Hz | 0.36 ft. | 4.3 in. | 0.109 m | 10.9 cm |
4000 Hz | 0.28 ft. | 3.4 in. | 0.086 m | 8.6 cm |
5000 Hz | 0.23 ft. | 2.7 in. | 0.069 m | 6.9 cm |
6300 Hz | 0.18 ft. | 2.2 in. | 0.055 m | 5.5 cm |
8000 Hz | 0.14 ft. | 1.7 in. | 0.043 m | 4.3 cm |
10000 Hz | 0.11 ft. | 1.4 in. | 0.034 m | 3.4 cm |
12500 Hz | 0.09 ft. | 1.1 in. | 0.028 m | 2.8 cm |
16000 Hz | 0.07 ft. | 0.8 in. | 0.022 m | 2.2 cm |
20000 Hz | 0.06 ft. | 0.7 in. | 0.017 m | 1.7 cm |
stereo
perception
