AMS 1081 User manual

© 2000 AMS Neve plc own the copyright of all
information and drawings contained in this manual which
are not to be copied or reproduced by any means or
disclosed in part or whole to any third party without
written permission.
As part of our policy of continual product improvement,
we reserve the right to alter specifications without notice
but with due regard to all current legislation.
Disclaimer: The information in this manual has been
carefully checked and is believed to be accurate at the
time of publication. However, no responsibilty is taken by
us for inaccuracies, errors or omissions nor any liability
assumed for any loss or damage resulting either directly or
indirectly from use of the information contained within it.
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User Guide
527-230
Issue 3
1081 Channel Amplifier
Including 3U and 7U Rack Options

Contents
Introduction 1
Installation 1
Dimensions 2
Power Requirements 3
Phantom Power 4
Output Level Control 4
Amplifier Controls 5
EMI Filter Components 6
Rear Panel Views 7
Connector Details 8
Connector Details Continued 9
Specifications 10
Service Information 11
1081 Recall Sheet - Horizontal Module 12
1081 Recall Sheet - Vertical Module 13
User Guide Issue 3 Page i
1081 Channel Amplifier

Introduction
The 1081 channel amplifier was first produced in 1972 to provide the mic/line-amp and EQ
sections in Neve consoles such as the 8048. A look through the credits on today’s top selling CDs
will reveal that these vintage consoles are still widely used to great effect and that the 1081 module
has become a hugely popular design classic. This is why AMS Neve have resumed production of the
1081, using the original components and construction methods.
Installation
The 1081 is available as a stand-alone module, or in a choice of two housings that provide power
supply, phantom power switching for each module and connectors for balanced inputs (mic and
line) and outputs:
The 3U rack houses two modules mounted horizontally in a 19” rack-mounting unit. The rear panel
has XLRs for transformer balanced I/O and a 25-way ‘D’-type connector for solo and spare switch
contacts and unbalanced outputs plus an IEC connector for mains power.
The 7U rack houses 8 modules vertically in a 19” rack-mounting unit. The rear panel has XLRs for
transformer balanced I/O and a 25-way ‘D’-type connector for solo and spare switch contacts and
unbalanced outputs plus an IEC connector for mains power.
User Guide Issue 3 Page 1
1081 Channel Amplifier Introduction
PHANTOM
CH1
CH2
+48V
+24V
MAINS
1
2
OUTPUT
NEVE
AMS
56 · 150
47
82
18 27 OFF
8·2
KHz
12
270
Hz
56
303
39 ·
10 0
0
81
33
OFF
Hz
680
1000
820
270
330
1200
OFF
220
3·9
5 ·6
4 ·7
8 ·2
6 ·8
1 ·8
3 ·3
2 ·7
2 ·2
3 ·3
KHz
1·5
4 ·7
OFF
MIC
15
10
68
·
20
30
OFF
LINE
10
40
50
60
+10
10
0
80
dB
70 20
Hi
Q
Hi
Q
EQ
SOLO
PH
470
390
560
56 · 150
47
82
18 27 OFF
8·2
KHz
12
270
Hz
56
303
39 ·
10 0
0
81
33
OFF
Hz
680
1000
820
270
330
1200
OFF
220
3·9
5 ·6
4 ·7
8 ·2
6 ·8
1 ·8
3 ·3
2 ·7
2 ·2
3 ·3
KHz
1·5
4 ·7
OFF
MIC
15
10
68
·
20
30
OFF
LINE
10
40
50
60
+10
10
0
80
dB
70 20
Hi
Q
Hi
Q
EQ
SOLO
PH
470
390
560
CH8
CH7
CH2
CH1
CH4
CH3
CH6
CH5
NEVE
AMS
+48V
+24V
MAINS
1
2
3
4
5
6
7
8
PHANTOM OUTPUT
56 · 56 · 56 · 56 · 56 · 56 · 56 · 56 · 150 150 150 150 150 150 150 150
47 47 47 47 47 47 47 47
Hz Hz Hz Hz Hz Hz Hz Hz
82 82 82 82 82 82 82 82
18 18 18 18 18 18 18 18
27 27 27 27 27 27 27 27
OFF OFF OFF OFF OFF OFF OFF OFF
8·28·28·28·28·28·28·28·2
KHz KHz KHz KHz KHz KHz KHz KHz
12 12 12 12 12 12 12 12
270 270 270 270 270 270 270 270
Hz Hz Hz Hz Hz Hz Hz HzHz Hz Hz Hz Hz Hz Hz Hz
56 56 56 56 56 56 56 56
333333330000000033333333
39 · 39 · 39 · 39 · 39 · 39 · 39 · 39 ·
111111110000000000000000
00000000
8888888811111111
33 33 33 33 33 33 33 33
OFF OFF OFF OFF OFF OFF OFF OFF
55555555
88888888
2222222200000000
Hz Hz Hz Hz Hz Hz Hz Hz
66666666 8888888800000000
11111111000000000000000000000000
1111111122222222
777777770000000022222222
6666666600000000
44444444 7777777700000000
33333333 9999999900000000
333333333333333300000000
0000000000000000
OFF OFF OFF OFF OFF OFF OFF OFF
000000002222222222222222
3·9 3·9 3·9 3·9 3·9 3·9 3·9 3·9
5 ·6 5 ·6 5 ·6 5 ·6 5 ·6 5 ·6 5 ·6 5 ·6
4 ·7 4 ·7 4 ·7 4 ·7 4 ·7 4 ·7 4 ·7 4 ·7
8 ·2 8 ·2 8 ·2 8 ·2 8 ·2 8 ·2 8 ·2 8 ·2
6 ·8 6 ·8 6 ·8 6 ·8 6 ·8 6 ·8 6 ·8 6 ·8
1 ·8 1 ·8 1 ·8 1 ·8 1 ·8 1 ·8 1 ·8 1 ·8
3 ·3 3 ·3 3 ·3 3 ·3 3 ·3 3 ·3 3 ·3 3 ·3
KHzKHzKHzKHzKHzKHzKHzKHz
2 ·7 2 ·7 2 ·7 2 ·7 2 ·7 2 ·7 2 ·7 2 ·7
2 ·2 2 ·2 2 ·2 2 ·2 2 ·2 2 ·2 2 ·2 2 ·2
3 ·3 3 ·3 3 ·3 3 ·3 3 ·3 3 ·3 3 ·3 3 ·3
KHz KHz KHz KHz KHz KHz KHz KHz
1·51·51·51·51·51·51·51·5
4 ·7 4 ·7 4 ·7 4 ·7 4 ·7 4 ·7 4 ·7 4 ·7
OFF OFF OFF OFF OFF OFF OFF OFF
MIC MIC MIC MIC MIC MIC MIC MIC
15 15 15 15 15 15 15 15
10 10 10 10 10 10 10 10
68
· 68 · 68 · 68 · 68 · 68 · 68 · 68 ·
20 20 20 20 20 20 20 20
30 30 30 30 30 30 30 30
OFF OFF OFF OFF OFF OFF OFF OFF
LINE LINE LINE LINE LINE LINE LINE LINE
10 10 10 10 10 10 10 10
40 40 40 40 40 40 40 40
50 50 50 50 50 50 50 50
60 60 60 60 60 60 60 60
+10+10+10+10+10+10+10+10
10 10 10 10 10 10 10 10
00000000
80 80 80 80 80 80 80 80
dB dB dB dB dB dB dB dB
70 70 70 70 70 70 70 70
20 20 20 20 20 20 20 20
HiQHiQHiQHiQHiQHiQHiQHiQ
HiQ HiQ HiQ HiQ HiQ HiQ HiQ HiQ
EQ EQ EQ EQ EQ EQ EQ EQ
SOLO SOLO SOLO SOLO SOLO SOLO SOLO SOLO
PH PH PH PH PH PH PH PH

Dimensions
Stand-alone Module
Dimensions: Front panel 45mm x 305 mm (1.8 inches x 12 inches).
Approx 300mm (12 inches) deep behind the front panel.
Approx. Weight: 3kg (6.6 lbs)
Rack Data
19" Rack Mounting U Depth
mm (inches)
Height
mm (inches)
Approx. Weight
kg (lbs)
2 Module Version 3 400 134 (5¼) 17 (37) *
8 Module Version 7 400 311 (12¼) 46 (101) *
* Fully populated rack
The 7U unit is heavy (over 20kg) and should be handled by two persons.
User Guide Issue 3 Page 2
1081 Channel Amplifier Dimensions

Power Requirements
3U 7U
Rated Voltage 100-230V AC 100-230V AC
Rated Frequency 50-60 Hz 50-60Hz
Rated Current 0.5A Max 0.8A Max
Surge Current (In Rush) Cold
Surge Current (In Rush) Hot
31.0A
33.0A
31.0A
33.0A
Earth Leakage Current Approx 1.2mA Approx 1.3mA
Warning for High Earth Leakage
Current Required
NO NO
Primary Protection Fuse:
Operating Voltage 100-230V AC 100-230V AC
Fuse Rating and Type T1.6A H 250V
20mm x 5mm CERAMIC
T1.6A H 250V
20mm x 5mm CERAMIC
Location IEC Mains connector IEC Mains connector
Secondary Protection Fuse:
Output Voltage 24V DC 24V DC
Fuse Rating and Type T 1.0A L 250V
20mm x 5mm GLASS
T 2.0A L 250V
20mm x 5mm GLASS
Location F1 on SZN825-058 F1 on SZN825A058
Output Voltage 48V DC 48V DC
Fuse Rating and Type T 500mA L 250V
20mm x 5mm GLASS
T 500mA L 250V
20mm x 5mm GLASS
Location F2 on SZN825-058 F2 on SZN825A058
Stand-alone 1081 Module
Power 192mA at 24V DC. Negative Earth
Mains Supply (rack units)
The power supply unit is a universal input type therefore no mains operating voltage setting is
required.
The mains switch on the front panel of the 3U and 7U rack units is non-illuminating.
The CH (chassis) and 0V Link should be connected or instability may result.
User Guide Issue 3 Page 3
1081 Channel Amplifier Power Requirements

Mains Fuse (rack units)
The mains fuse is located in the IEC mains input connector on the rear of the 3U and 7U rack units.
Secondary Protection Fuses (rack units)
Secondary protection fuses for the 24V and 48V supplies are located behind the front panel on the
power supply filter PCB SZN825-058 in both 3U and 7U rack units.
DC Power Supply Indicators (rack units)
The red LED on the front panel of both 3U and 7U rack units indicates +24V power healthy when
illuminated.
The green LED on the front panel of both 3U and 7U rack units indicates +48V power healthy when
illuminated.
Phantom Power
Phantom power can be supplied to each module by pressing the phantom power switch on the front
panel of the 3U or 7U rack. The LED in the switch will illuminate confirming that phantom power is
supplied.
Output Level Control
Each channel has an independent Output Level Control. The control is post-input, post-EQ and
pre-output. This control allows the input and EQ to operate at a higher level and then for the signal
to be returned to a normal operating level at the output.
When the Output Control is fully clockwise the output gain is unity. The output is 10dB down with
the control in the mid-position.
User Guide Issue 3 Page 4
1081 Channel Amplifier Phantom Power

Amplifier Controls
H.F. Controls: 5 switched frequencies, shelving or peaking curve, continuously
variable 18dB cut or boost.
H.F. Presence: 10 switched frequencies with continuously variable 18dB cut or
boost, high or low Q selection.
L.F. Presence: 10 switched frequencies with continuously variable 18dB cut or
boost, high or low Q selection.
L.F. Controls: 5 switched frequencies, shelving or peaking curve, continuously
variable 18dB cut or boost.
H.P. Filter: 5 switched frequencies with slope of 18dB per octave.
L.P. Filter: 5 switched frequencies with slope of 18dB per octave.
PH Button: Gives 180° phase change at the balanced output.
EQ Button: Selects equalisation in or out of circuit.
SOLO Button: Selects channel unbalanced output and closing switch contact.
Spare Button: Switches external device as required.
User Guide Issue 3 Page 5
1081 Channel Amplifier Amplifier Controls
56·150
47
82
1827 OFF
8·2
KHz
12
270
Hz
56
303
39·
10 0
0
81
33
OFF
Hz
680
1000
820
270
330
1200
OFF
220
3·9
5·6
4·7
8·2
6·8
1·8
3·3
2·7
2·2
3·3 KHz
1·5
4·7
OFF
MIC
15
10
68
·
20
30 OFF
LINE
10
40
50
60
+10
10
0
80
dB
70 20
Hi
Q
Hi
Q
EQ
SOLO
PH
470
390 560
56·150
47
Hz
82
18
27 OFF
8·2
KHz
12
270
HzHz
56
30339·
10 0
0
81
33
OFF
5
820
Hz
680
1000
12
702
60 470 390
330
00 OFF
022
3·9
5·6
4·7
8·2
6·8
1·8
3·3
KHz
2·7
2·2
3·3
KHz
1·5
4·7
OFF
MIC
15
10
68
·
20
30
OFF
LINE
10
40
50
60
+10
10
0
80
dB
70 20
HiQ HiQ
EQ SOLO
PH

EMI Filter Components
Jumpers may be fitted on the SUN870-081 I/O boards to allow the EMI filtering (three terminal
capacitors and common mode inductors) to be ‘removed’ from the signal path. This may be
desirable for those seeking sonic purity. However it must be noted that the immunity of the product
to external RF fields could suffer, and if this is the case then the jumper links should be removed.
The individual 1081 modules are offered for inclusion in the customers own housings. As such no
claim is being made regarding the immunity of these units. This will be principally governed by the
type of cabling, connectors and enclosure used. The use of screened cables and connectors is
recommended for all connections. Tests have shown that no problems with emissions as defined in
EMC standards should be present with these units.
User Guide Issue 3 Page 6
1081 Channel Amplifier EMI Filter Components

Rear Panel Views
User Guide Issue 3 Page 7
1081 Channel Amplifier Rear Panel Views
AC MAINS I/P
CH 0V AUXILARY
MIC 1 LINE 1 O/P 1
MIC 2 LINE 2 O/P 2
CH 0V
AC MAINS I/P
O/P 8
LINE 8
O/P 6O/P 7 O/P 5
LINE 6LINE 7 LINE 5
O/P 3O/P 4 O/P 2
LINE 3LINE 4 LINE 2
O/P 1
LINE 1
AUXILARY 7-8 AUXILARY 5-6 AUXILARY 3-4 AUXILARY 1-2
MIC 8 MIC 7 MIC 6 MIC 5 MIC 4 MIC 3 MIC 2 MIC 1

Connector Details
User Guide Issue 3 Page 8
1081 Channel Amplifier Connector Details
1081 Stand-alone
Wiring to 18 way Free Plug
A
B
C
D
E
F
H
J
K
L
M
N
P
R
S
T
U
V
0V
0V
Hi
Lo
Spare Switch Contact
0V
Hi
Lo
Link
Solo Switch Contact
Unbalanced O/P
Hi
Lo
BAL O/P
Solo O/P (unbalanced)
+24V at 192mA
Solo
Spare
Mic I/P
Line I/P
0dBu
-10dBu
0dBu
0dBu
-10dBu
Technical
Earth Link

Connector Details Continued
User Guide Issue 3 Page 9
1081 Channel Amplifier Connector Details Continued
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
-10dBu
NC
NC
NC
NC
Chassis Earth
Chassis Earth
Chassis Earth
Unbalanced 0V
Solo 1
Spare 1
Spare 2
Solo 2
Unbalanced O/P
CH 1
Chassis Earth
Solo O/P (unbalanced) CH 1
Solo Switch Contacts CH1
Spare Switch Contacts CH1
-10dBu
-10dBu
Unbalanced 0V
Unbalanced O/P
Chassis Earth
Solo O/P (unbalanced)
Solo Switch Contacts
Spare Switch Contacts
-10dBu
CH
2
CH
2
CH
2
CH
2
Rear of 1081 2 Module (3U) and 8 Module (7U) Racks
25 way D Auxiliary and XLR Wiring
25 way D-Type
Wiring View
12
3
12
3
XLR
Wiring View
Hi
Lo
Mic/Line I/P (Balanced)
Plug
O/P (Balanced)
Socket
Hi
Lo
For the 8 Module Rack :
CH1 is CH1, CH 3, CH 5 or CH
7
CH2isCH2,CH4,CH6orCH
8

Specifications
Microphone Input: Zin 300 or 1200 ohms switched,
gain +80 to +10 dB in 5dB steps.
Line Input: Zin 10k ohms bridging, gain +20 to -15dB in 5dB steps.
Both inputs are balanced and earth-free.
Outputs: Max +26dB into 600 ohms. Zout 75 ohms ±5% @ 1kHz,
balanced and earth-free. An unbalanced output 8dB below
the level of the balanced output is also provided.
Distortion: Not more than 0.07% for +20dBm output from 50Hz to 15kHz.
Frequency Response: ±0.5dB from 20Hz to 20kHz. -3dB at 7Hz and 35kHz.
Noise: Output noise better than -42dBm from Zin 1200 ohms and
-80dB input, giving an equivalent noise of -125dBm referred to
600 ohms input impedance fed from 100 ohms. Output noise
better than - 80dBm at all line input levels.
User Guide Issue 3 Page 10
1081 Channel Amplifier Specifications

Service Information
Schematic Drawing index
PL31081- Channel Amplifier Horizontal and Vertical module versions:
PL31081-C Channel Amplifier
PL10306-C Dual Voltage Follower
PL10312-C Channel Amplifier Motherboard
PL10338-C High Gain Amplifier
PL10340-C Output Amplifier
PL20046 Sensitivity Switch
PL20047 Treble Switch Assembly
PL20048/4 Upper Presence Switch Assembly
PL20048/5 Lower Presence Switch Assembly
PL20049 LP/HP Filter Switch Assembly
PL20050 Bass Switch Assembly
AM3631 - 3U Rack:
AM3631 2 CH 1081 Mainframe Assembly Detail
SZN825-058 PSU Filter PCB
SSN818-036 0V Stud Filter PCB
SUN870-081 2CH I/P O/P Backplane
SYN824-128 2 Switch Phantom Power PCB
NN3726 Chassis Cable Assy
AM3630 - 7U Rack:
AM3630 8 CH 1081 Mainframe Assembly Detail
SZN825A058 PSU Filter PCB
Same as the 3U Rack
User Guide Issue 3 Page 11
1081 Channel Amplifier Service Information

1081 Recall Sheet - Horizontal Module
User Guide Issue 3 Page 12
1081 Channel Amplifier 1081 Recall Sheet - Horizontal Module

1081 Recall Sheet - Vertical Module
User Guide Issue 3 Page 13
1081 Channel Amplifier 1081 Recall Sheet - Vertical Module