SOWTER AUDIO TRANSFORMERS
ABOUT DECIBELS and dBu
dBu Ratio Voltage dBu Ratio Voltage
0 1.00 0.7746 0 1.000 0.7746
1 1.12 0.8691 -1 0.891 0.6904
2 1.26 0.9752 -2 0.794 0.6153
3 1.41 1.0941 -3 0.708 0.5484
4 1.58 1.2277 -4 0.631 0.4887
5 1.78 1.3774 -5 0.562 0.4356
6 2.00 1.5455 -6 0.500 0.3882
7 2.24 1.7341 -7 0.447 0.3460
8 2.51 1.9457 -8 0.398 0.3084
9 2.82 2.1831 -9 0.355 0.2748
10 3.16 2.4495 -10 0.316 0.2449
11 3.55 2.7484 -11 0.282 0.2183
12 3.98 3.0837 -12 0.251 0.1946
13 4.47 3.4600 -13 0.224 0.1734
14 5.01 3.8822 -14 0.200 0.1546
15 5.62 4.3559 -15 0.178 0.1377
16 6.31 4.8874 -16 0.159 0.1228
17 7.08 5.4837 -17 0.141 0.1094
18 7.94 6.1528 -18 0.126 0.0975
19 8.91 6.9036 -19 0.112 0.0869
20 10.00 7.7460 -20 0.100 0.0775
21 11.22 8.6911 -21 0.089 0.0690
22 12.59 9.7516 -22 0.079 0.0615
23 14.13 10.9415 -23 0.071 0.0548
24 15.85 12.2765 -24 0.063 0.0489
25 17.78 13.7745 -25 0.056 0.0436
26 19.95 15.4552 -26 0.050 0.0388
27 22.39 17.3411 -27 0.045 0.0346
28 25.12 19.4570 -28 0.040 0.0308
29 28.18 21.8311 -29 0.036 0.0275
30 31.62 24.4949 -30 0.032 0.0245
31 35.48 27.4837 -31 0.028 0.0218
32 39.81 30.8372 -32 0.025 0.0195
33 44.67 34.6000 -33 0.022 0.0173
34 50.12 38.8218 -34 0.020 0.0155
35 56.23 43.5588 -35 0.018 0.0138
36 63.10 48.8737 -36 0.016 0.0123
37 70.79 54.8372 -37 0.014 0.0109
38 79.43 61.5284 -38 0.013 0.0098
39 89.12 69.0360 -39 0.011 0.0087
40 100.00 77.4597 -40 0.010 0.0077

Conversion form Decibels to voltage and ratio

The table shows the ratio and voltage equivlent to a given level in dBu from +40 dBu to -40 dBu

dBu is a logrithmic voltage notation relative to 0.7746 Volts but not related to any impedance. dBm (the traditional unit 50 years ago) is relative to 1 mW into 600 ohms and is numerically equal to dBu.

dBV (rarely used) is relative to 1.0 Volts and like dBu, is not related to any impedance.

Comments and questions to support@sowter.co.uk

OTHER USEFUL INFORMATION

To convert max level at 50 Hz to 20 Hz subtract 7.96 dB

To convert an rms voltage to a peak voltage multiply by 1.414

To convert an rms voltage to a p-p voltage multiply by 2.828

To convert a dB value to a ratio in Excel: Ratio =POWER(10,dB/20)

To convert a ratio to a dB value in Excel: dB =20*LOG(ratio)