Page 1
Service Manual
Model: aMICTUBE
STEREO TUBE PREAMP
www.altoproaudio.com
Version: 1.1
Page 2
CONTENTS
1. Specification…………………………………………. 1
2. Block Diagram………………………….…………… 1
3. Schematic Diagram..…………………………..……. 3
4. Printed Circuit Board………………………………. 11
5. Wiring Diagram…………………………………..…. 1
6. Test Procedure………………………………….…… 2
7. Electrical Parts List………………………………… 11
8. Exploded Views………………………………..……. 1
9. Notes…………………………………………….……
Page 3
1.Specifications
Input
XLR Impedance 5K Ohm
1/4” High Z 1M Ohm
Connectors NeutrikTM Combo
Output
XLR Balanced 100 Ohm
1/4” Unbalanced 100 Ohm
Panel Controls
Tube Drive 0dB to +40dB
Gain 0dB to +30dB
Phase Reverse
20 dB Pad
+48V Phantom Power
Performance
THD+Noise <0.5%
Signal To Noise >90dB
Power Supply Rejection >98dB
Amplifier Type Dual Servo
Meter
8-Digit LED -24dBu to +18dBu
Physical
Weight 1.05Kg
Dimensions
131(W)X116(D)X44(H)mm(5.16”X4.57”X1.7”)
Chassis Steel
Panel Brushed Aluminum(? LTO® Style)
Power Supply
Type Linear,External
Input 18VAC
Power 14Watts
Transformer External Wall Mount
Page 4
2.Block Diagram
D
C
B
A
CH1 OUTPUT
213
4
321
213
4
213
221133
2
1
PHASE
3
4
CH2 OUTPUT
213
221133
2
1
PHASE
3
AC18V
Block Diagram
X1X2X3
U1(INA163)
+ PAD(20dB)
12345
POWER SUPPLY
VOLTAGE REGULATOR
+ PAD(20dB)
12345
PHANTOM
-15VDC
+12VDC
+15VDC
+48VDC
6
1 2 3 4
TUBE-12AX7
U2(INA163)
6
X1X2X3
CH1 MICROPHONE INPUT
D
C
CH2 MICROPHONE INPUT
B
A
Page 5
7654321
3.Schematic Diagram
8
C53
104P
R2
100R 1/4W
-15V
TR6
HR
LD9
GR
LD10
GR
LD11
GR
LD12
GR
LD13
GR
LD14
GR
LD15
YEL
LD16
RED
CN4
CON8
1
2
3
4
5
6
7
8
+48V
VCH1-IN
VCH1-OUT
GND
+12V
R120
10K0
VCH2-IN
VCH2-OUT
KT2
GT2
HT2
PT2
4
3
2
1
R121
10K0
R122
10R
HT1
5
TB1 TUBE-12AX7
D
C
PT1
6
GT1
7
KT1
8
9
HM
+15V
R50
+15V
312
U10E
-15V
DA204K
R38
47R 1/4W
C54
104P
47K5
R49
47K5
D5A
C6
103P
+15V
C51
104P
TR9
HR
1
2
3
(PHASE-CH2)
312
U9E
LM339
U11A
2068DD
R17 47K5
SW5A
PS-22E85L
P
SW3C
PS-42E85L
(PAD-CH2)
C55
104P
D8
DA204K
3
1
2
3
7
8
9
C52
104P
LD21
RED
-15V
C64
104P
C65
104P
R74
1K00
C63
1uF
+15V
R123
4K53
+15V
84
U11C
2068DD
-15V
LD22
RED
(PWR ON)
R94
110R
R95
100R
R96
200R
R97
402R
R98
806R
R99
1K58
R100
3K24
R101
6K34
R102
8K06
D7
DA204K
-15V
R72
1K00
C62
1uF
DA204K
1
2
LD17
GR
P
SW2C
PS-42E85L
(PAD-CH1)
LD18
GR
SW4A
PS-22E85L
(PHASE-CH1)
312
U8E
LM339
C59
104P
C56
104P
D6A
7
8
9
1
2
3
312
U7E
LM339
LD20
GR
LD19
GR
6
5
C60
104P
R18 47K5
C57
104P
7
U11B
2068DD
P
SW1B
PS-42E85L
(PHANTOM)
4
5
6
C66
10U
C67
10U
CN9-14
D
CN8-14
TR8
HR
C
R39
47K5
LM339
TR3
HR
R3
47K5
C1
103P
7
6
5
4
11
10
9
8
7
6
5
4
11
10
9
8
OUTPUT1 OUTPUT2
U7B
LM339
U7A
LM339
13
U7D
LM339
14
U7C
LM339
U8B
LM339
U8A
LM339
13
U8D
LM339
14
U8C
LM339
1
2
1
2
C50
104P
100R 1/4W
-15V+15V
R1
TR4
HR
LD1
GR
(-24)
LD2
GR
(-18)
LD3
GR
(-12)
LD4
GR
(-6)
LD5
GR
(0)
LD6
GR
(+6)
LD7
YEL
(+12)
LD8
RED
(+18)
R103
110R
R104
100R
R105
200R
R106
402R
R107
806R
R108
1K58
R109
3K24
R110
6K34
R111
8K06
+15V
+15V
R4
47K5
C2
103P
7
6
5
4
11
10
9
8
7
6
5
4
11
10
9
8
TR5
HR
U9B
LM339
U9A
LM339
U9D
LM339
U9C
LM339
U10B
LM339
U10A
LM339
U10D
LM339
U10C
LM339
1
2
13
14
1
2
13
14
(CH1 INPUT GAIN)
VR1 A20K
B
A
1 2 3 4 5 6 7 8
CN8-7 CN8-8
(CH2 INPUT GAIN)
VR2 A20K
CN9-8CN9-7
SW4B
PS-22E85L
( PHASE )
P
6
CN8-10
5
CN8-14
4
CN8-13
SW5B
PS-22E85L
( PHASE )
P
6
CN9-10
5
CN9-14
4
CN9-13
R82
100R
R81
100R
R65
100R
R67
100R
VR3B
C1K2P
VR3A
C1K2P
R64
100R
R25
100R
R66 100RVR4B C1K2P
R45 100RVR4A C1K2P
CN8-10
CN8-9
CN8-12
CN8-11
CN9-10
CN9-9
CN9-12
CN9-11
P
SW3D
PS-42E85L
SW3B
PS-42E85L
P
CN9-3
CN9-4
CN9-5
CN8-4
CN8-3
P
SW2D
PS-42E85L
SW2B
PS-42E85L
P
CN8-5
CN8-6CN9-6
10
11
12
4
5
6
R31
169R
R19
619R
R33
619R
10
R32
169R
R20
619R
R34
619R
11
12
4
5
6
PHANTOM ON (+48V)
PHANTOM OFF
SW1A
PS-42E85L
1
2
R5
47K5
SW1C
PS-42E85L
7
8
R6
47K5
3
9
CN8-1
CN9-1
B
+48V
P
+48V
+48V+15V
CN8-2
CN8-15
CN8-16
+48V-15V
CN9-2
CN9-15
CN9-16
Titel
ALTO Mobile : ALPHAMICtube FRONT PANEL BOARD
Size
A3
Date:
File:
7-Mar-2002
AMTUBEFP.Sch
CN8 HEADER 8X2
CN8-1 CN8-2
CN8-3 CN8-4
CN8-5
CN8-7
CN8-9
CN8-11
CN8-13
CN8-15
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
CN8-6
CN8-8
CN8-10
CN8-12
CN8-14
CN8-16
CN9 HEADER 8X2
CN9-1
CN9-3
CN9-5
CN9-7
CN9-9
CN9-11
CN9-13
CN9-15
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
CN9-2
CN9-4
CN9-6
CN9-8
CN9-10
CN9-12
CN9-14
CN9-16
ALPHAMICtube
Sheet
Drawn By:
RevisionModel No:
C.C.LIN
A
VER020307
11 of
Page 6
R42
1M00
7654321
8
PS: H2=MMSZ5242
14
CN1-12
CN1-11
14
CN2-12
CN2-11
R46
301K
R26
301K
R68
301K
R69
301K
CN1-10
CN1-9
R71
301R
CN2-10
CN2-9
9
10
6
5
R76
1M00
9
10
6
5
R84
301R
R80
1M00
R40
100R
R62
100R
R70
301R
R83
100R
TL074CD
R37
100R
R51
301R
TL074CD
TL074CD
C45
100P
U3B
TL074CD
C26
100P
U5B
U3C
U5C
C46
100P
C16
100P
R56
10K0
R86
R63
1K00
2
3
U4A
TL074CD
C48
0R
1
R61
10K0
6
5
U4B
TL074CD
8
0R
7
C47
R73R85
R55 10K0
7
CN1-10
CN1-14
CN1-13
CH1-OUT
+15V
-15V
+48V+15V
CH1-OUT
GND
CH2-OUT
CN1-2
CN1-15
CN1-16
+48V
+12V
CN5
7P-2.0
1
2
3
4
5
6
7
D
LOW BUMP
C
R53 10K0
R52
8
0R
7
C28
10K0
R60
9
10
U4C
TL074CD
R57
1K00
C29
0R
8
R54
10K0
13
12
U4D
TL074CD
CN2-10
CN2-14
CN2-13 CN2-15
CH2-OUT
14
+48V-15V
CN2-2
CN2-16
B
R59R58
CN1 HEADER 8X2
LOW BUMP
CN1-1 CN1-2
CN1-3 CN1-4
CN1-5
CN1-7
CN1-9
CN1-11
CN1-13
CN1-15
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
CN1-6
CN1-8
CN1-10
CN1-12
CN1-14
CN1-16
CN2 HEADER 8X2
CN2-1
CN2-3
CN2-5
CN2-7
CN2-9
CN2-11
CN2-13
CN2-15
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
CN2-2
CN2-4
CN2-6
CN2-8
CN2-10
CN2-12
CN2-14
CN2-16
A
R47
+15V
5
4
3
12
U6B
11
12
6
-15V
U1
INA163
1
14
10
CN2-8
3
R48
2K21
8
7
2K21
C22
C30
10U
104P
1
8
9
14
10
C31
104P
C23
10U
C40
0.47U
1M00
C24
C32
10U
104P
9
C33
C25
104P
10U
C42
0.47U
R36
51R1
1M00
CN3
+48V+12V
CON8
1
2
3
4
5
6
7
8
CH1-INPUT
R21
D
X2 X1
X3
S
SS
R
RS
T
TS
J1
COMB-XLR
47/63VZ
CH1-INX3
1
2
3
4
5
6
CH1-INX2
CH1-INT
CH1-INTS
169R 1/4W
CN1-5
CN1-3
CN1-1
R7
CN1-4
CN1-6
47/63VZ
R9 6K81
R10 6K81
C3
100/63V
C11
C12
20K0
R22
20K0
10R0
R28
10R0
R27
CH2-INPUT
R23
C
B
X2 X1
X3
S
SS
R
RS
T
TS
J2
COMB-XLR
C71
10U
C72
10U
C20
10U
C21
10U
CH2-INX3
1
2
3
4
5
6
CH2-INX2
CH2-INT
CH2-INTS
R8
169R 1/4W
CN2-5
CN2-3
CN2-1
CN2-4
CN2-6
47/63VZ
R11 6K81
R12 6K81
C4
100/63V
R13
C78
C58
104P
C61
104P
C35
104P
C36
104P
+15V
84
U6C
2068DD
-15V
+15V
411
U3E
TL074CD
-15V
C34
10U
C38
10U
C49
104P
C5
104P
+15V
411
U4E
TL074CD
-15V
47U
C9
104P
402R
C37
10U
C39
10U
R15
1M00
2
3
C68
104P
C69
104P
CN1-7
U6A
2068DD
+15V
411
U5E
TL074CD
-15V
CN1-8
R35
51R1
1
C13
47/63VZ
C14
20K0
20K0
C79
47U
10R0
10R0
R24
R29
R30
C10
104P
R14
402R
1M00
R16
6
5
ZD5
H2
ZD6
H2
C19
220P
ZD7
H2
ZD8
H2
C18
220P
CN2-7
ZD1
H2
ZD2
H2
ZD3
H2
ZD4
H2
5
4
+15V
11
6
-15V
U2
INA163
2068DD
C41
0.47U
R43
R77
R44
1M00
2
3
0.47U
R78
1M00
C44
0.47U
2
3
C43
13
12
0.47U
13
12
0.47U
0.47U
C17
C7
C15
U3D
TL074CD
R41
1M00
TL074CD
R75
1M00
U5D
TL074CD
R79
1M00
U5A
TL074CD
U3A
C8
104P
C27
104P
1
1
R0
0R
A
FrontPanel
AMtubeFP.sch
HR=MMBT3906LT1 / 2SA1036K(R)
1. H2 = Zener Diode MMSZ5242BT1NOTE:
2. LOW BUMP ON
3. LOW BUMP OFF
1 2 3 4 5 6 7 8
C9,C12,C39,C42=104P R21,R32=4K99 R73,R28=200K
C9,C39,R21,R66 =0R OMIT:C12,C42,R28,R32,R73,R77
Titel
ALTO Mobile : ALPHAMICtube MAIN BOARD
Size
Date:
File:
A3
ALPHAMICtube
7-Mar-2002
AMTUBEMN.Sch
Sheet
Drawn By:
RevisionModel No:
VER020225
11 of
C.C.LIN
Page 7
4321
C40
R67
47P
20K0
D
C76
47/50VNP
R25
20K0
R68
6K81
R77
9
10
U4C
TL074CD
C41
47P
20K0
13
12
TL074CD
2
C
CH1-OUT
3
TL074CD
CN4
7P-2.0
+48V
+15V
U4D
U4A
R79
20K0
C44
8
47/50VNP
C45
47/50VNP
R80
10K0
14
C46
47/50VNP
1
R86
100K
R87
100K
R90
100K
R37
100R
R40
100R
R41
100R
R45
51R1
R26
20K0
J3
BAL-MALE
1
3
2
4
C77
47/50VNP
R69
20K0
R70
6K81
R78
20K0
CH1-OUTPUT CH2-OUTPUT
9
10
13
12
J4
LJB0661
2
22
33
3
11
1
2
3
C42
47P
U5C
TL074CD
C43
47P
U5D
TL074CD
U5A
TL074CD
R81
20K0
C47
8
47/50VNP
C48
47/50VNP
R82
10K0
14
C49
47/50VNP
1
R88
100K
R89
100K
R91
100K
R42
100R
R43
100R
R44
100R
R46
51R1
BAL-MALE
1
3
2
4
2
22
33
3
11
1
J5
J6
LJB0661
D
C
1
2
3
4
5
6
7
+12V
B
-15V
CH2-OUT
D4
1N4004
D3
1N4004
C8
100/63V
R92
150R
C5
100/63V
C73
100/63V
C7
100/63V
R83
10K
TR7
TIP122
C17
100/63V
ZD9
1N5261B
(47V)
+48V
C68
M104P
C26
10U
C27
10U
C34
104P
C37
104P
+15V
411
U4E
TL074CD
-15V
C28
10U
C29
10U
C38
104P
C39
104P
411
U5E
TL074CD
B
-15V
J7
AC IN
(AC 18V)
D1
1N4004
U13
LM7815CT
C64
2200/25V
C66
47/25VZ
+15V
C69
M104P
U15
LM7812CT
C74
47/25VZ
+12V
C75
M104P
-15V
C70
M104P
Titel
ALTO Mobile : ALPHAMICtube REAR BOARD
Size
Date:
File:
A3
AMTUBEPU.Sch
ALPHAMICtube
7-Mar-2002
Sheet
Drawn By:
A
RevisionModel No:
VER020225
11 of
C.C.LIN
D2
1N4004
A
C65
1000/25V
C67
47/25VZ
U14
LM7915CT
1 2 3 4
Page 8
AMTUBEFP Top Layer
4.Printed Circuit Diagram
AMTUBEFP Bottom Layer
AMTUBEFP Top Solder Mask
AMTUBEFP Bottom Solder Mask
AMTUBEFP Top Scilkscreen
AMTUBEFP Drill Drawing
--------------------------------------------------------------------------NCDrill File Report For: AMTUBEFP.PCB 9-May-2002 16:26:29
---------------------------------------------------------------------------
Layer Pair : TopLayer to BottomLayer
ASCII File : NCDrillOutput.TXT
EIA File : NCDrillOutput.DRL
Tool Hole Size Hole Count Plated Tool Travel
--------------------------------------------------------------------------T1 24mil (0.6096mm) 72 29.54 Inch (750.27 mm)
T2 31mil (0.7874mm) 140 30.14 Inch (765.64 mm)
T3 39mil (0.9906mm) 28 14.01 Inch (355.84 mm)
T4 79mil (2.0066mm) 4 9.78 Inch (248.33 mm)
T5 83mil (2.1082mm) 9 6.04 Inch (153.35 mm)
T6 87mil (2.2098mm) 4 10.82 Inch (274.86 mm)
--------------------------------------------------------------------------Totals 257 100.33 Inch (2548.29 mm)
Total Processing Time : 00:00:00
Page 9
Page 10
AMTUBEMN Top Layer
AMTUBEMN Bottom Layer
AMTUBEMN Top Solder Mask
AMTUBEMN Bottom Solder Mask
Page 11
--------------------------------------------------------------------------NCDrill File Report For: AMTUBEMN.PCB 9-May-2002 18:22:27
---------------------------------------------------------------------------
AMTUBEMN Top Scilkscreen
AMTUBEMN Drill Drawing
Layer Pair : TopLayer to BottomLayer
ASCII File : NCDrillOutput.TXT
EIA File : NCDrillOutput.DRL
Tool Hole Size Hole Count Plated Tool Travel
--------------------------------------------------------------------------T1 24mil (0.6096mm) 58 26.73 Inch (678.84 mm)
T2 31mil (0.7874mm) 44 20.77 Inch (527.61 mm)
T3 35mil (0.889mm) 32 11.01 Inch (279.53 mm)
T4 39mil (0.9906mm) 15 13.68 Inch (347.41 mm)
T5 47mil (1.1938mm) 20 9.43 Inch (239.45 mm)
T6 138mil (3.5052mm) 2 8.74 Inch (221.92 mm)
T7 83mil (2.1082mm) 4 NPTH 6.86 Inch (174.24 mm)
T8 138mil (3.5052mm) 2 NPTH 15.44 Inch (392.11 mm)
--------------------------------------------------------------------------Totals 177 112.64 Inch (2861.12 mm)
Total Processing Time : 00:00:01
Page 12
Page 13
AMTUBEPU Top Layer
AMTUBEPU Bottom Layer
AMTUBEPU Top Solder Mask
AMTUBEPU Bottom Solder Mask
Page 14
AMTUBEPU Top Scilkscreen
AMTUBEPU Drill Drawing
--------------------------------------------------------------------------NCDrill File Report For: AMTUBEPU.PCB 9-Mar-2002 18:30:07
---------------------------------------------------------------------------
Layer Pair : TopLayer to BottomLayer
ASCII File : NCDrillOutput.TXT
EIA File : NCDrillOutput.DRL
Tool Hole Size Hole Count Plated Tool Travel
--------------------------------------------------------------------------T1 24mil (0.6096mm) 1 6.10 Inch (155.01 mm)
T2 28mil (0.7112mm) 14 10.41 Inch (264.49 mm)
T3 31mil (0.7874mm) 57 20.11 Inch (510.86 mm)
T4 39mil (0.9906mm) 29 14.11 Inch (358.42 mm)
T5 47mil (1.1938mm) 4 10.33 Inch (262.28 mm)
T6 59mil (1.4986mm) 12 12.09 Inch (307.05 mm)
T7 63mil (1.6002mm) 4 10.41 Inch (264.44 mm)
T8 110mil (2.794mm) 2 9.26 Inch (235.31 mm)
T9 126mil (3.2004mm) 1 9.77 Inch (248.28 mm)
T10 71mil (1.8034mm) 4 NPTH 10.90 Inch (276.85 mm)
--------------------------------------------------------------------------Totals 128 113.50 Inch (2883.01 mm)
Total Processing Time : 00:00:01
Page 15
Page 16
PCB:AMTUBEFP
Page 17
PCB:AMTUBEMN
Page 18
PCB:AMTUBEPU
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Test Procedures(aMICTUBE)
Required Equipment
Audio Precision System 2 with APWin software
100MHz oscilloscope connected to APS2 Analyzer Signal Monitor output (Ch. A and Ch. B)
Connection Mode
Use Audio Precision System 2 analog unbalanced (XLR) inputs/output
11.1
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Test Procedures for aMICTUBE
06/25/02 11:48:07
Amplitude response test
On PC:
-Load file:amictube_amplitude(APWin File menu / Open / Test)
Test Connections:
-Output A of Audio Precision System Two � CH1 input of the device under test.
-Output B of Audio Precision System Two � CH2 input of the device under test.
-CH1 output of the device under test � A input of Audio Precision System Two.
-CH2 output of the device under test � B input of Audio Precision System Two.
On the aMICTUBE:
-Set INPUT GAIN to zero.
-Set DRIVE to maximum.
Start the sweep (F9) and control the results (Page3 – Graph) in the following conditions:
SEKAKU
+25
+20
+15
+10
+5
d
+0
B
m
-5
-10
-15
-20
-25
-30
20 20k50 100 200 500 1k 2k 5k 10k
Hz
Colo r Line Style Thick Data Axis
Red Solid 1 Anlr.Level A Left
Magenta Solid 1 Anlr.Level A Left
11.2
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aMICTUBE-ALTO-230V-
Midprod NO
NO.
Quanity
Unit
Structure Needing Material Detail List
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8.Exploded Views
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