Specifications
37
SOME USEFUL TABLES
Speaker sens- 88 91 dB 95 dB 100 dB 105 dB 110 dB 115 dB 120 db 125 dB
itivity in dB 95 98 dB 102 dB 107 dB 112 dB 117 dB 122 dB 127 dB
98 101 dB 105 dB 110 dB 115 dB 120 dB 125 dB 130 dB
TABLE 1:
Shows the relation between power increase and
SPL measured 1 mtr in front of the speaker at
three different speaker sensitivities.
Input power (W) 1 2 3 4 5 10 15 20 50 100 200 500 1k 2k 5k
A speaker with a sensitivity of 88 dB gives a SPL of 88 dB with an input of 1 Watt. If the input power is
increased to 2 Watts the SPL will be 91 dB etc. Duoble power will increase the SPL with 3 dB.
TABLE 2:
Shows how the inner resistance (impedance) of a coil changes in relation to the frequency.
Frequency in Hz
25 50 75 100 120 200 400 800 1k 1,2k 2k 4k 8k 10k 12k
mH
0,05 1,3 2,5 3,1 3,8
0,1 1,3 2,5 5,0 6,3 7,5
0,2 1,3 1,5 2,5 5,0 10,0 12,6 15,1
0,3 1,5 1,9 2,3 3,8 7,5 15,1 18,8 22,6
0,5 1,3 2,5 3,1 3,8 6,3 12,6 25,1 31,4 37,7
1 1,3 2,5 5,0 6,3 7,5 12,6 25,1 50,2 62,8 75,4
2 1,2 1,5 2,5 5,0 10,0 12,6 15,1 25,1 50,2 100,0
3 1,4 1,9 2,3 3,8 7,5 15,1 18,8 22,6 37,7 62,8
5 1,6 2,4 3,1 3,8 6,3 12,6 25,1 31,4 37,7 62,8
10 1,6 3,1 4,7 6,3 7,5 12,6 25,1 50,2 62,8 75,4
20 3,1 6,3 9,4 12,6 15,1 25,1 50,2
For example a coil with 10 mH inductance, often used as lowpass filter for subwoofers, has an inner
resistance (impedance) of 1,6 ohms at 25 Hz increasing to 6,3 ohms at 100 Hz, and 62,8 ohms at 1 kHz.
TABLE 3:
Shows how the inner resistance (impedance) of a capacitor changes in relation to the frequency.
12108643218007006005004003002001208060
ยตFkHz kHz kHz kHz kHz kHz kHz kHz Hz Hz Hz Hz Hz Hz Hz Hz Hz Hz
0,22 60 72 90 120
0,33 40 48 60 80 120
0,47 28 34 42 56 85 113
0,68 19 23 29 39 58 78 117
1 13162027405380
2,26 7 9 121824367290100120
3,3 4 5 6 8 12 16 24 48 60 69 80 96
4,7 3 4 6 8 11 17 34 42 48 56 68 85
6,8 2 3 4 6 8 12 23 29 33 39 47 58 78
10 2 3 4 5 8 1620232732405380
22 2 4 7 9 10 12 15 18 24 36 60
33 2 5 6 7 8 10121624406080
47 3456781116284256
68 3456812203939
100 3458131927
150 33591318
220 246912
330 2468
SPL in dB
Resistance in ohm
Resistance in ohm