Henry Engineering STEREOMIXER User Manual
HENRY ENGINEERING
STEREOMIXER
EIGHT INPUT STEREO MIXER
DESCRIPTION
STEREOMIXER is an eight-input, two-output stereo line level mixer/combiner for utility use. The
unit has balanced bridging inputs for eight audio sources (4 stereo pairs or 8 mono sources)
which can be mixed to two outputs in stereo or to one output in mono. A level control is
provided for each input. The output DC coupled circuitry provides excellent sonic performance.
INSTALLATION
All connections to the StereoMixer are made via plug-in connectors. Remove about 1/8” of
insulation, insert wires into the plug, and tighten the screws. Be sure that no bare wires are
exposed.
Audio inputs to the StereoMixer should be connected to the balanced input terminals labeled 1
thru 8. For unbalanced inputs, install a jumper between the (-) terminal and G (ground). All
inputs are bridging; it is not necessary to terminate the source unless required by the source
equipment.
Audio outputs from the StereoMixer are connected to the two outputs labeled L (Left) and
(Right). The output circuitry will drive any load of 600 ohms or higher. It is not necessary to
terminate the outputs. For unbalanced outputs, connect to the (+) and G terminals only. DO
NOT short the (-) terminal to ground.
OPERATION
The input levels to the StereoMixer should be between -10 and +8 dBm. Adjust each input
channel using the INPUT LEVEL controls. Unity gain is achieved with these controls set to 10
o'clock; with nominal input levels of +4 dBm the Input Level controls should be run near this
setting. It is recommended that input levels be initially set with a level indicator (VU meter,
scope, VOM) temporarily connected to the StereoMixer's output to monitor output levels. The
average output level should not exceed +8 dBm to ensure adequate headroom.
StereoMixer can operate in either stereo or mono, determined by the OUTPUT MODE switch.
In Stereo mode, the odd numbered inputs are mixed to the Left output; the even numbered
outputs are mixed to the Right output. In Mono mode, ALL inputs are mixed to the Left output.
(The right output is not used in mono mode.)
SPECIFICATIONS
INPUTS -10 to +8 dBm; balanced 20K or unbalanced 10K
GAIN 10 dB maximum
OUTPUTS +4 dBm nominal, +26 dBm max; 600 ohms or higher, 4X
FREQ RESP DC to 20 kHz, +/- 0.25 Db
NOISE 80 dB below +4 dBm output
CROSSTALK 75 dB below +4 dBm output, typ. @ 1 kHz
DISTORTION .008% IM/THD
503 Key Vista Drive
Sierra Madre, CA 91024
tel: 626.355.3656
fax: 626.355.0077
website: www.henryeng.com
5
4
3
2
1
INPUTS
J1
+
1
1L
-
2
GND
1R
GND
3
+
4
-
5
C2
.001uF
6
D D
J2
+
1
2L
-
2
GND
3
+
4
2R
-
GND
5
6
C C
C6
.001uF
RP1A10K DIP
RP1B10K DIP
C1
.001uF
RP1E10K DIP
RP1F10K DIP
C5
.001uF
116
215
RP4A
6.34K DIP
512
611
RP4E
6.34K DIP
116
512
-15V
U1A
-
2
3
1
+
NE5532
8 4
+15V
5K VAR
-15V
U2A
-
2
3
1
+
NE5532
8 4
+15V +15V
5K VAR
R2
R8
RP4B
6.34K DIP
2
1 16
1 3
611
RP4F
6.34K DIP
2
2 15
1 3
RP3A
10K DIP
RP3B
10K DIP
C4
.001uF
C8
.001uF
RP1C10K DIP
RP1D10K DIP
C3
.001uF
RP1G10K DIP
RP1H10K DIP
C7
.001uF
314
413
RP4C
6.34K DIP
710
89
RP4G
6.34K DIP
314
710
-15V
U1B
-
6
5
7
+
NE5532
8 4
+15V
5K VAR
-15V
6
5
7
+
NE5532
U2B
-
8 4
5K VAR
R3
R9
413
RP4D
6.34K DIP
5 12
2
1 3
89
RP4H
6.34K DIP
2
6 11
1 3
RP3E
10K DIP
RP3F
10K DIP
SW1
R5
24.9K
2
1
3
413
215
3L
GND
3R
GND
215
J3
+
1
-
2
3
+
4
-
5
C10
.001uF
RP2A10K DIP
1 16
2 15
RP2B10K DIP
C9
.001uF
RP5A
6.34K DIP
116
-15V
U3A
-
2
3
1
+
NE5532
8 4
+15V
5K VAR
6
R13
RP5B
6.34K DIP
2
3 14
1 3
RP3C
10K DIP
C12
.001uF
RP2C10K DIP
3 14
4 13
RP2D10K DIP
C11
.001uF
RP5C
6.34K DIP
314
-15V
U3B
-
6
5
7
+
NE5532
8 4
+15V
5K VAR
R12
RP5D
6.34K DIP
RP3G
2
7 10
10K DIP
1 3
89
2
3
6
5
2
3
C17 30pF
R1 24.9K
-15V
-
1
+
NE5532
8 4
+15V
R6 10K
R7 10K
-15V
-
7
+
NE5532
+15V
8 4
C18 30pF
R11 24.9K
-15V
-
1
+
NE5532
8 4
+15V
R15 10K
U5A
U5B
U6A
R4 47, 5%
R10 47, 5%
R14 47, 5%
OUTPUTS
J5
+
1
LEFT
-
2
GND
3
+
4
RIGHT
-
5
GND
6
B B
611
2
3
PRI
E9
-15V
-
+
8 4
SPW-061
1
2
3
4
+15V
T1
U4A
1
NE5532
5K VAR
5
SEC
6
7
8
1N4004
J4
+
1
4L
-
2
GND
3
+
4
4R
-
5
GND
6
AC BLK
AC
E1
E2
E4
A A
GROUND TIE
C14
.001uF
115V: 250 ma; 230V: 125ma
WHT
.001uF
F1
C13
5 12
6 11
RP2E10K DIP
RP2F10K DIP
RP5E
6.34K DIP
E7
115V
E8
230V
512
E6
E5
R18
D4
RP5F
6.34K DIP
4 13
2
1 3
1N4004
1N4004
RP3D
10K DIP
D2
D3
D1
1N4004
LED1
LED
C16
.001uF
R20
3.9K, 5%
C20
330uF 25V
+
+
BIPOLAR POWER SUPPLY
5
4
RP2G10K DIP
7 10
8 9
RP2H10K DIP
C15
.001uF
Q1 LM7815
3
IN
C19
330uF 25V
Q2 LM7915
2 3
IN OUT
RP5G
6.34K DIP
OUT
GND
2
GND
1
710
1
3
-15V
U4B
-
6
5
7
+
NE5532
8 4
+15V
5K VAR
TP2
1
C22
.1uF
C21
.1uF
C24
.1uF
C23
.1uF
1
TP3
R17
RP5H
6.34K DIP
2
8 9
1 3
+15V
1
-15V
RP3H
10K DIP
TP1
R16 10K
-15V
-
6
+
5
8 4
+15V
U6B
7
NE5532
R19 47, 5%
NOTE: UNLESS OTHERWISE SPECIFIED
1. ALL RESISTORS ARE 1/4W, 1%.
HENRY ENGINEERING
503 Key Vista Drive
Sierra Madre, CA 91024 USA
telephone - (626) 355-3656
Title
SCHEMATIC: STEREOMIXER
Size Document Number Rev
B
3600 A
2
Date: Sheet
FAX (626) 355-0077
1
of
11Friday, February 21, 2003
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