23
DISTRIBUTION AMPLIFIER/ZONE MIXER/MIC SPLITTER DA-410.
FREQUENCY
5% RESISTORS
1% RESISTORS
10 kHz
4,7 k
Ω
4,87 k
Ω
12,5 kHz
3,9 k
Ω
3,83 k
Ω
16 kHz
3 k
Ω
3,01 k
Ω
20 kHz
2,4 k
Ω
2,43 k
Ω
If you don't find the resistances for low frequencies, since they are very big, you could
change the capacitors C2 and C3 to 33 NF, and divide the resistor value of the table by 10.
This could only be made between frequencies in the range of 25 Hz and 2 kHz, since the RF
and RF' resistors could never be less than 2 k
Ω
.
As in the gain calculation, for more accurate results, It is advisable the use of 1% film
resistors.
BANDWIDTH CALCULATION (Q)
The Q is the filter bandwidth. So that the Q is the filter centre frequency
divided by the difference of the higher and lower frequency, which the
amplitude response is three dB down from the filter centre frequency.
The next picture shows a filter with different Q at the same frequency and gain. How
you could see a high value of Q indicates a small bandwidth and a low value of Q a big
bandwidth.
F = 1 kHz.
Q=0,5
Q=1,0
Q=2,5
Q=5
There are two resistors in the equaliser card labelled RQ and RQ,' those configure the
bandwidth (Q) of the equalisation point. These two resistors should be equal RQ = RQ.'
The next table shows the resistor that you should use for bandwidths (Q) from 0.1 to 10.
The maximum value allowed for the RQ and RQ' resistors are 150 k
Ω
corresponding to Q=15.
If you want an intermediate bandwidth, you are able to calculate an intermediate value:
