Specifications

DECIBEL - dB
Examples of fixed dB relations:
For voltage and current:
dB Amplification
0 dB 1 time
1 dB 1,1 times
3 db 1,4 times
6 dB 2 times (double)
10 dB 3,16 times
20 dB 10 times
The amplification increases logarithmic.
For power:
dB Amplification
0 dB 1 time
3 dB 2 times
6 dB 4 times
10 dB 10 times
20 dB 100 times
An attentuation of -6 dB is a half for voltage and
current and a quarter when talking about power.
CONNECTING RESISTORS
4 Ω
6 Ω
8 Ω
12 Ω
R tot = 4 + 6 + 8 + 12 = 30 Ω
IN PARALLEL:
When connecting in parallel the total resistance
always becomes lower, it is always lower than the
lowest resistor value in the connection.
Formula:1 = 1 + 1 + 1 + 1
R R1 R2 R3 R4
1 = 1 + 1 + 1 + 1
R4 4 8 8
CONNECTION OF CAPACITORS
4 Ω 8 Ω8 Ω
4 Ω
R = 1,33 Ω
Capacitors acts in the opposite way as resistors when
connected in series or parallel.
IN PARALLEL:
The total capacitance when connecting capacitors
in parallel is the sum of each capacitor.
C tot = C1 + C2 + C3 + C4 etc.
10 µF
50 µF
50 µF
100 µF
C tot = 10 + 50 + 50 + 100 = 210 µF
When connecting only two resistors in parallel you
can use the formula below.
R1 x R2 4 x 8
R1 + R2 4 + 8
R =
Ex.
32
12
= = 2,66Ω
Formula: 1 = 1 + 1 + 1 + 1
C C1 C2 C3 C4
100 µF
50 µF
50 µF
10 µF
1 = 1 + 1 + 1 + 1
C 10 50 50 100
C= 6,66 µF
1 µF = 0,000001 Farad (10
-6
)
1 nF = 0,000000001 Farad (10
-9
)
1 pF = 0,000000000001 Farad (10
-12
)
dB is a unit used to describe a realation. It´s used to
describe an amplification as well as an attentuation.
At an attentuation a minus sign is put before the
figure.
An amplification is the relation between the input and
the output signal. In can be valid for voltage, current
or power.
When used for power amplification you must
remember that current x voltage = power. This means
that the relation becomes larger, see the table below.
The formualas below is valid when connecting
resistors and inductances in series or in parallel.
It can also be used for speakers.
IN SERIES:
The total resistance is equal to the sum of all
resistors in the connection.
R tot = R1 + R2 + R3 + R4 etc.
When connecting only two capacitors you can use
the same formula as in the example with two
resistors connected in parallel above.
3
IN SERIES:
When connecting capacitors in series you calculate
in the same way as for resistors connected in parallel.
DLS SOUND HANDBOOK - FORMULAS AND FACTS