Figure 7.
18 dB/Octave Blank Crossover Card [JBL Model
51-5130]
Component values for various frequencies are listed in Table
3. Components should rest against the printed circuit board.
Leads should be soldered and cut flush.
T a b l e 4 .
J B L 12 d B / O c t a v e C r o s s o v e r C a r d
C o m p o n e n t V a l u e s
M o d e l
N u m b e r
C r o s s o v e r
F r e q u e n c y
( H z )
C a p a c i t o r s
C 1 - C 5 '
C
m
F)
J B L
P a r t
N u m b e r
R e s i s t o r s
R 1 - R 5 '
f k
n )
J B L
P a r t
N u m b e r
52-5121
250
.018
48481
24
35757
52-5122
500
.015
48480
15
35752
52-5123
800
.022
48482
6.2
35743
52-5124
1200
.0082
48947
11
35749
52-5125
5000
.0015
48927
15
35752
52-5127
7000
.0015
48927
1 1
35749
52-51 4 0
1
.018
48481
272
10255
1. Crossover characteristics of the 52-5140 are tailored specifically
for the 4343 and 4350 Studio Monitors.
2. R1' and R2' only. The value for R3; R4; and R5' is 22
kn,
J B L
part n u m b e r 10944.
T a b l e 5.
J B L 18 d B / O c t a v e C r o s s o v e r C a r d
C o m p o n e n t V a l u e s
C r o s s o v e r
J B L
J B L
M o d e l
F r e q u e n c y
C a p a c i t o r s
P a r t
R e s i s t o r s
P a r t
N u m b e r
( H z )
(MF)
N u m b e r
(kn)
N u m b e r
51-5132
500
C1 -.082
48489 R1 -5.1
11461
C2 -.22
48494 R2 -5.1
11461
C3 -.012
48479 R3 -5.1
11461
C4 -.033
48484 R4 -6.8
11604
C5 -.033
48484 R5 -2.7
12817
C6 -.033
48484 R6 -47
12260
51-5133
800
C1 -.056
48487 R1 -4.7
10074
C2 -.15
53068 R2 -4.7
10074
C3 -.0082 53052 R3 -4.7
10074
C4 -.012
48479 R4' -12
10077
C5 -.012
48479 R5' -4.7
10074
C6 -.012
48479 R6 -82
12598
1
ii or Pi i oti n
Whenever a midrange or high frequency driver is con-
nected directly to a power amplifier, a series capacitor is
r e c o m m e n d e d to attenuate unwanted low frequency "on-off"
switching transient signals which can damage the driver.
Specific capacitor values are given in Table 6.
T a b l e 6.
M a x i m u m V a l u e s
f o r L o w F r e q u e n c y A t t e n u a t i o n C a p a c i t o r s
( g i v e n in ^ F ]
Crossover Frequency
Driver Impedance
4 n 8 n 16 n
250 Hz to 500 Hz
150 80 40
500 Hz to 5 kHz
80 40 20
Above 5 kHz
8 5 2
T a b l e 7.
C a p a c i t o r s A v a i l a b l e F r o m J B L
The following 10% tolerance, non-polarized electrolytic
capacitors are suitable for driver protection and may be
ordered from a J B L professional products dealer or directly
from JBL.
J B L
For O p t i m u m Results At
Value
0
(F) Part Number
16 n
8 n
4 n
72
52938
275 Hz
550 Hz
1100 Hz
52
52939
400
750
1500
20
53881
1000
2000
4000
16.5
10358
1200
2500
5000
13.5
10359
1500
3000
6000
12
10434
1 700
3500
7000
8
10391
2500
5000
10000
7
57529
3000
6000
11000
6
10296
3500
7000
13000
4
41040
5000
10000
-
3
11937
7000
13000
-
The o p t i m u m value cited above assumes that the capacitor is active
at approximately one octave below the listed crossover frequency for
m i n i m u m acoustical interference with crossover region perfor-
mance. Smaller capacitor values may be required for additional pro-
tection in high-power reinforcement.
WARNING: This section of the manual contains service instructions for
use by qualified service personnel only.
Capacitor working voltages should be at least 50 V. Do not use polar-
ized electrolytic capacitors; paper or Mylar capacitors are acceptable.
A 50 W resistor having a value of two to three times the rated
impedance of the driver should also be connected across the driver
terminals to shunt the reactive c o m p o n e n t of the driver's impedance
below horn cutoff. These parts are available from' electronic parts
suppliers. A listing of capacitors that can be obtained f r o m J B L is
provided in Table 7. Note: Below the cutoff frequency of the capaci-
tor, the power amplifier will be unterminated. If the power amplifier has
an output transformer, a 20 W resistor equal to ten times the driver
impedance should be installed across the amplifier output terminals.
Содержание 5233
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