Henry Engineering USDA 2X4 User Manual
TM
U.S.D.A. 2X4
UTILITY SUMMING & DISTRIBUTION AMPLIFIER
DESCRIPTION
USDA 2X4 is a 2-in/4-out audio distribution amplifier that has the unique ability to combine as
well as "split" audio signals for distribution. The unit has two inputs (one stereo pair) and four
outputs (two stereo pairs). USDA 2X4 can be used as a 1X4 or 2X4 DA and can combine a
stereo input to a mono output(s) without degrading the separation of the stereo source signal.
All inputs are 20K bridging balanced; each output can drive a 600 ohm load to +26 dBm. An
output level adjustment is provided for each output channel. Overall gain is adjustable from -12
to +14 dB. Nominal input levels between -10 and +8 dBm are recommended. All USDA 2X4
circuitry is active and direct-coupled.
INSTALLATION
All audio connections are via the plug-in euroblocks. Remove about 1/8” of insulation, insert
wires into the plug, and tighten the screws. Be sure that no bare wiring is exposed.
Connect input signals to the USDA inputs, labeled "1" and "2". For unbalanced inputs, install a
jumper between the - input and GND. Single (mono) inputs may be fed to all 4 output channels
by connecting both 1 and 2 inputs in parallel. Connect output loads to USDA outputs, labeled 1
through 4. For unbalanced loads, connect to the + and GND terminals only. (Do not
the - terminal to ground.) It is not necessary to terminate unused outputs.
OPERATION
The signal fed to input 1 will appear at outputs 1 and 3. The signal fed to input 2 will appear at
outputs 2 and 4. Hence, outputs 1 and 2 are a Left/Right stereo pair, as are 3 and 4. Each
stereo output pair has a STEREO-MONO SWITCH. If the switch is in the "S" position, a stereo
input will produce a stereo output. If the switch is in the "M" position, that output will be
combined to monaural. The two stereo outputs operate independently; switching one output
pair to MONO has no effect on the other pair, and does not degrade the separation of the stereo
input signal. Each output has a gain adjustment for setting output level. A maximum of +8dBm
(average) is recommended. Input levels should be between -10 and +8 dBm. For input levels
outside of this range, consult the factory.
HENRY ENGINEERING
503 Key Vista Drive
Sierra Madre, CA 91024
Tel: 626.355.3656
Fax: 626.355.0077
www.henryeng.com
connect
SPECIFICATIONS
Input impedance 20K ohms balanced; 10K ohms unbalanced
Input levels -10 dBm to +8 dBm nominal
Gain -6 db to +15 db
S/N ratio 100 dB, ref +4 dBm output w/ unity gain
Output source Z 100 ohms balanced; 50 ohms unbalanced
Output load 600 ohms or more per output, X4
Output level +24 dBm max
Specifications subject to change without notice. P/N 3310 Rev. 6/04.
J3
OUTPUTS
LEFT
+
3
1
RIGHT
GND
3
-
+
4
GND
4
5
6
of
11Monday, November 03, 2003
-
2
1
1
503 Key Vista Drive
Sierra Madre, CA 91024 USA
telephone - (626) 355-3656
1. ALL RESISTORS ARE 1/4W, 1%.
R27 47
2
25K, POT
R39
1 3
-
RP2F
2.2K DIP
6 11
2
RP2E
2.2K DIP
1
-15V
2
5 12
+
3
U4A
+15V
NE5532
RP2G
8 4
2.2K DIP
7 10
RP2H
8 9
2.2K DIP
R29 47
2
U4B
-15V
-
6
7
1
3
+
5
NE5532
+15V
8 4
R40
1 3
RP3F
2.2K DIP
6 11
25K, POT
C22 .001uF
2
R34 47
C23 100pF
-15V
-
2
RP3E
2.2K DIP
5 12
R36 47
U5A
NE5532
1
+15V
+
RP3G
8 4
3
RP3H
2.2K DIP
7 10
2.2K DIP
8 9
C24 .001uF
-15V
-
6
7
+
5
NOTE: UNLESS OTHERWISE SPECIFIED
U5B
NE5532
+15V
8 4
HENRY ENGINEERING
FAX (626) 355-0077
3310 A
SCHEMATIC: USDA 2X4
B
Title
Size Document Number Rev
Date: Sheet
2
SW2
RP1G
2.2K DIP
7 10
RP1H
2.2K DIP
8 9
C19
C17
C15
C8
C7
GND
.1uF
.1uF
.1uF
.1uF
.1uF
TP1
2
1
C20
.1uF
C18
.1uF
C16
.1uF
C10
.1uF
C9
.1uF
Q2 LM7915
IN OUT
2 3
1
-15V
TP3
GND
3
1
LEFT
+
-
1
1
2
J2
OUTPUTS
3
R13 47
2
R37
1 3
215
RP2B
2.2K DIP
C1 100pF C21 100pF
25K, POT
-
1
-15V
2
U2A
+15V
+
3
+
GND
3
4
NE5532
RP2C
8 4
2.2K DIP
RIGHT
-
2
5
RP2D
3 14
GND
6
2.2K DIP
4 13
C6 .001uF
R15 47
-15V
-
6
7
U2B
+
5
NE5532
+15V
8 4
2
1 3
R38
215
RP3B
2.2K DIP
C13 100pF
25K, POT
R20 47
-15V
-
2
+15V
1
TP2
R22 47
-15V
-
6
U3B
NE5532
7
+15V
+
8 4
5
1
OUT
IN
Q1 LM7815
U3A
NE5532
1
C14 .001uF
+15V
+
RP3C
8 4
3
RP3D
2.2K DIP
3 14
2.2K DIP
4 13
3
+
LED
C12
330uF 25V
D2
1N4004
D1
1N4004
D4
1N4004
SECPRI
5
687
RP2A
2.2K DIP
1 16
4
RP1B
2.2K DIP
2 15
RP1C
2.2K DIP
3 14
7
-15V
-
6
+15V
+
5
116
U1B
8 4
RP1A
NE5532
2.2K DIP
2
SW1
1
3
RP1E
2.2K DIP
5 12
RP3A
2.2K DIP
1 16
RP1F
2.2K DIP
6 11
1
-15V
-
2
+15V
+
3
413
U1A
8 4
RP1D
NE5532
2.2K DIP
R41
LED1
3.9K, 5%
1
E6
R1 4.99K
5
R3 4.99K
C3
.001uF
C2
.001uF
R6 4.99K
R7 4.99K
C5
.001uF
C4
.001uF
230V
E7
342
D3
115V
+
C11
330uF 25V
4
1N4004
T1
SPW-061
E9
BIPOLAR POWER SUPPLY
E8
5
1
J1
++-
1
INPUTS
LEFT
D D
2
3
GND
4
5
-
2
RIGHT
6
GND
BLK
E1
AC
F1
115V: 250 ma; 230V: 125ma
WHT
E2
AC
E4
C25
.01uF
E5
GROUND TIE
C C
B B
A A
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