Henry Engineering MICROMIXER User manual

MICROMIXER
FOUR INPUT STEREO MIXER
HENRY ENGINEERING
503 Key Vista Drive
Sierra Madre, CA 91024
tel: [phone]
fax: [phone]
website: www.henryeng.com
DESCRIPTION
MICROMIXER is a four-input, two-output stereo mixer/combiner for utility use. The unit has
balanced bridging inputs for four audio sources (two stereo pairs) which can be mixed to two
outputs (one stereo pair). A level control is provided for each input. Selectable 'assign'
switching permits any input to be fed to either or both outputs. DC coupled circuitry provides
excellent sonic performance.
INSTALLATION
All connections to the MicroMixer are made via plug-in connectors. Remove about 1/8” of
insulaton, insert wires into the plug, and tighten the screws. Be sure that no bare wires are
exposed.
Audio inputs to the MicroMixer should be connected to the balanced input terminals labeled 1, 2,
3, and 4. 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 MicroMixer are connected to the two outputs labeled L (Left) and
R (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 MicroMixer 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 MicroMixer's output to monitor output levels. The
average output level should not exceed +8 dBm to ensure adequate headroom.
Each output channel (L & R) has four ASSIGN switches that determine which of the four input
signals are fed to that output. Select the input sources desired by switching the appropriate
channels ON (down). For example, if inputs 1 and 3 should be fed to the LEFT output, set Left
output assign switches 1 and 3 ON, with 2 and 4 OFF.
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
DISTORTION .008% IM/THD

5 5
4 4
3 3
2 2
1 1
D D C C B B A A
RIGHT
AC
LEFT
+
GND
GROUND TIE
1. ALL RESISTORS ARE 1/4W, 1%.
-
GND
2
WHT
NOTE: UNLESS OTHERWISE SPECIFIED
INPUTS
115V
LEFT
+
+
RIGHT
-
+
GND
OUTPUTS
GND
-
+
LEFT
-
-
RIGHT
BIPOLAR POWER SUPPLY
4 1
INPUTS
SEC
-
230V
PRI
+
AC
B
GND
BLK
GND
3
3510 A SCHEMATIC: MICROMIXER
HENRY ENGINEERING
503 Key Vista Drive
Sierra Madre, CA 91024 USA telephone - [phone] FAX [phone]
11Wednesday, December 10, 2003
Title Size Document Number Rev Date: Sheet of
+15V
-15V
+15V
-15V
-15V
+15V +15V +15V
-15V+15V -15V
-15V
+15V
-15V
-15V
-15V+15V
+15V
R26 7.50K
RP1F 4.7K DIP
6 11
+ -
U2B
NE5532
5 6
7
8 4
C15 .1uF
+
C12
330uF 25V
RP2A
4.7K DIP
116
RP1G 4.7K DIP
7 10
C14 .1uF
+ -
U3A
NE5532
3 2
1
8 4
J2
1 2 3 4 5 6
RP3H 4.7K DIP
89
C18 .1uF
RP2E 4.7K DIP
512
E8
R25 47, 5%
R38
5K POT
1 3
2
E1
RP3A 4.7K DIP
116
Q2 LM7915
2 3
1
IN OUT
GND
+ -
U2A
NE5532
3 2
1
8 4
C6
.001uF
D3
1N4004
R36
5K POT
1 3
2
C20 .1uF
C21 .001uF
R27 1.00K
+
C11
330uF 25V
R29 47, 5%
TP3
1
RP1C 4.7K DIP
3 14
C16 .1uF
TP2
1
C23 .01uF
C5
.001uF
+ -
U4A
NE5532
3 2
1
8 4
RP2F
4.7K DIP
611
C8
.001uF
C2
.001uF
E9
E2
RP3G 4.7K DIP
710
RP2G 4.7K DIP
710
C17 .1uF
RP3B 4.7K DIP
215
C7
.001uF LED1
LED
J1
1 2 3 4 5 6
R32 1.00K
RP1B 4.7K DIP
2 15
R33 7.50K
C1
.001uF
TP1
1
RP1H 4.7K DIP
8 9
J3
1 2 3 4 5 6
RP2B 4.7K DIP
215
E4
C4
.001uF
RP3E 4.7K DIP
512
RP1E 4.7K DIP
5 12
RP1A 4.7K DIP
1 16
RP2H
4.7K DIP
89
C13 .1uF
+ -
U1B
NE5532
5 6
7
8 4
R35
5K POT
1 3
2
SW2
SW DIP-4
1 2 3 4
8 7 6 5
C19 .1uF
RP3D 4.7K DIP
413
C22 .001uF
+ -
U4B
NE5532
5 6
7
8 4
C9 100pF
R37
5K POT
1 3
2
E5
R34 47, 5%
D2
1N4004
SW1
SW DIP-4
1 2 3 4
8 7 6 5
RP2C 4.7K DIP
314
E6F1
115V: 250 ma; 230V: 125ma
RP3F 4.7K DIP
611
RP2D
4.7K DIP
413
T1
SPW-061
1 3 4 2
5 6 8 7
C10 100pF R28 1.00K
RP3C 4.7K DIP
314
D4
1N4004
R39 3.9K, 5%
+ -
U1A
NE5532
3 2
1
8 4
C3
.001uF
R30 47, 5%
Q1 LM7815
3
2
1
IN
GND
OUT
RP1D 4.7K DIP
4 13
D1
1N4004
R31 1.00K
E7
+ -
U3B
NE5532
5 6
7
8 4