Benchmark MPS 400, MPS 420 microphone preamplifier Instruction Manual 24 Pages
Benchmark MPS 400, MPS 420 microphone preamplifier Instruction Manual
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The MPS-400 and MPS-420 Microphone Input Preamplifier Systems were designed to achieve the highest performance available in microphone pre-amplification. The MPS-400 and MPS-420 are ideal for the recordist that wants to maximize performance for analog or digital recorders using the superior microphone technologies that are emerging. With the MPS-400 and MPS-420 at or close to the microphone, additional performance benefits are realized as opposed to long mic cable runs to a console or recorder.
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MPS-400 and MPS-420 Instruction Manual
Contents
MPS-400 and MPS-420 Instruction Manual .................................................................................................... 1
Contents ............................................................................................................................................................... 1
1.0 General .......................................................................................................................................................... 1
1.1 MPS-400 Description ..................................................................................................................... 1
1.2 MPS-420 Description ..................................................................................................................... 1
2.0 Unpacking .................................................................................................................................................... 2
2.1 Equipment List................................................................................................................................ 2
3.0 Specifications................................................................................................................................................ 2
3.1 MPS-400 Specifications .................................................................................................................. 2
3.1.1 MP-4 Microphone Preamplifier ................................................................................... 2
3.2 MPS-420 Specifications .................................................................................................................. 3
3.2.1 MP-4 Microphone Preamplifier ................................................................................... 3
3.2.2 DOM-3 Differential Output Mixer ............................................................................... 4
3.2.3 HPA-1 Stereo Headphone Amplifier .......................................................................... 4
3.3 PS-10B Power Supply Specifications ........................................................................................... 5
4.0 Installation .................................................................................................................................................... 5
4.1 Introduction..................................................................................................................................... 5
4.2 Mechanical....................................................................................................................................... 5
4.3 Wiring .............................................................................................................................................. 5
4.3.1 Power Supply Connections ........................................................................................... 6
4.3.2 Audio Connections ........................................................................................................ 7
5.0 Operation ...................................................................................................................................................... 8
5.1 General Operation .......................................................................................................................... 9
5.1.1 Location Recording and Magnetic Fields ................................................................... 9
5.1.2 Phantom Power “Warm Up” ........................................................................................ 9
5.1.3 Panning of a 3rd Microphone ....................................................................................... 9
5.1.4 Setting Levels .................................................................................................................. 9
5.2 Discussion of Noise and Microphone Performance .................................................................. 10
5.2.1 Noise Primer ................................................................................................................... 10
5.2.2 Electro-Voice RE-20 Microphone ................................................................................. 10
5.2.3 Sennheiser MKH-40-P48 ............................................................................................... 11
5.2.4 Miscellaneous .................................................................................................................. 12
5.3 MPS-400 and MPS-420 Preamplifier Operation ......................................................................... 12
5.3.1 General ............................................................................................................................. 13
5.3.3 Differential Converter .................................................................................................... 13
5.3.2 Input Stage....................................................................................................................... 13
5.3.4 Output Stage ................................................................................................................... 14
5.3.5 Measurement Curves ..................................................................................................... 15
5.4 MPS-420 Additional Features ....................................................................................................... 17
5.4.1 DOM-3 Operation........................................................................................................... 17
5.4.1.1 DOM-3 Balanced or Single Ended Outputs................................................ 17
5.4.1.2 DOM-3 Terminations and Output Amplitude ........................................... 18
5.4.2 HPA-1 Operation............................................................................................................ 18
6.0 Servicing ....................................................................................................................................................... 20
6.1 Soldering Technique ...................................................................................................................... 20
6.2 HPA-1 Troubleshooting ................................................................................................................ 21
Contents
MPS-400 and MPS-420 Instruction Manual .................................................................................................... 1
Contents ............................................................................................................................................................... 1
1.0 General .......................................................................................................................................................... 1
1.1 MPS-400 Description ..................................................................................................................... 1
1.2 MPS-420 Description ..................................................................................................................... 1
2.0 Unpacking .................................................................................................................................................... 2
2.1 Equipment List................................................................................................................................ 2
3.0 Specifications................................................................................................................................................ 2
3.1 MPS-400 Specifications .................................................................................................................. 2
3.1.1 MP-4 Microphone Preamplifier ................................................................................... 2
3.2 MPS-420 Specifications .................................................................................................................. 3
3.2.1 MP-4 Microphone Preamplifier ................................................................................... 3
3.2.2 DOM-3 Differential Output Mixer ............................................................................... 4
3.2.3 HPA-1 Stereo Headphone Amplifier .......................................................................... 4
3.3 PS-10B Power Supply Specifications ........................................................................................... 5
4.0 Installation .................................................................................................................................................... 5
4.1 Introduction..................................................................................................................................... 5
4.2 Mechanical....................................................................................................................................... 5
4.3 Wiring .............................................................................................................................................. 5
4.3.1 Power Supply Connections ........................................................................................... 6
4.3.2 Audio Connections ........................................................................................................ 7
5.0 Operation ...................................................................................................................................................... 8
5.1 General Operation .......................................................................................................................... 9
5.1.1 Location Recording and Magnetic Fields ................................................................... 9
5.1.2 Phantom Power “Warm Up” ........................................................................................ 9
5.1.3 Panning of a 3rd Microphone ....................................................................................... 9
5.1.4 Setting Levels .................................................................................................................. 9
5.2 Discussion of Noise and Microphone Performance .................................................................. 10
5.2.1 Noise Primer ................................................................................................................... 10
5.2.2 Electro-Voice RE-20 Microphone ................................................................................. 10
5.2.3 Sennheiser MKH-40-P48 ............................................................................................... 11
5.2.4 Miscellaneous .................................................................................................................. 12
5.3 MPS-400 and MPS-420 Preamplifier Operation ......................................................................... 12
5.3.1 General ............................................................................................................................. 13
5.3.3 Differential Converter .................................................................................................... 13
5.3.2 Input Stage....................................................................................................................... 13
5.3.4 Output Stage ................................................................................................................... 14
5.3.5 Measurement Curves ..................................................................................................... 15
5.4 MPS-420 Additional Features ....................................................................................................... 17
5.4.1 DOM-3 Operation........................................................................................................... 17
5.4.1.1 DOM-3 Balanced or Single Ended Outputs................................................ 17
5.4.1.2 DOM-3 Terminations and Output Amplitude ........................................... 18
5.4.2 HPA-1 Operation............................................................................................................ 18
6.0 Servicing ....................................................................................................................................................... 20
6.1 Soldering Technique ...................................................................................................................... 20
6.2 HPA-1 Troubleshooting ................................................................................................................ 21
1
1.0 General
This manual contains all information necessary to install and operate the MPS-400 and MPS-
420 Microphone Preamplifier Systems.
The MPS-400 and MPS-420 systems were designed to achieve the highest performance
available in microphone pre-amplification. The MPS-400 and MPS-420 are ideal for the
recordist that wants to maximize performance for analog or digital recorders using the
superior microphone technologies that are emerging. With the MPS-400 and MPS-420 at or
close to the microphone, additional performance benefits are realized as opposed to long mic
cable runs to a console or recorder. By immediately raising the microphone signal amplitude
to the nominal system reference amplitude, minimum interference is allowed to enter the
system from power lines, SCR stage lighting, etc. Longer lines may also be driven from the
standpoint of system response. The line level output of the MPS-400 and MPS-420 systems
may be used with an existing mic input at a console by using an attenuator at the console
input, such as the LMA-1.
In addition to it’s obvious use as a microphone preamplifier, the MPS-400 and MPS-420 may
be used anywhere amplification of 20 dB or more is needed and minimum noise is desired.
One application which is finding increased acceptance is using the system to bring up low
telco levels without adversely effecting the noise floor. In fact with the overall amplification
range of -2 to +70 dB and input clip point equal to the output clip point minus the
amplification, the MPS-400 and MPS-420 become universal gain blocks with performance that
is nearly perfect.
The following is a brief description of each system.
1.1 MPS-400 Description
The MPS-400 Microphone Input Preamplifier System consists of four MP-4 Microphone
Preamplifier Cards installed in a 19" wide rack mount chassis. The chassis is fabricated of high
quality extruded aluminum with Lexan® front and rear panels. System height is one rack unit
(1RU = 1.75").
Controls for all four channels are located on the front panel. Each channel has a variable gain
control, 20 dB attenuator switch and a +48 V phantom power switch.
The rear panel contains eight XLR type connectors for audio inputs and outputs for all four
channels. A locking four pin XLR type receptacle is also provided for the external power
supply connection.
1.2 MPS-420 Description
The MPS-420 Microphone Input Preamplifier System consists of four MP-4 Microphone
Preamplifier Cards, two DOM-3 Differential Output Mixer units and one HPA-1 Stereo
Headphone Amplifier (Monitor) installed in a 19" wide rack mount chassis. The chassis is
fabricated from high quality extruded aluminum with Lexan® front and rear panels. System
height is one rack unit (1RU = 1.75").
1.0 General
This manual contains all information necessary to install and operate the MPS-400 and MPS-
420 Microphone Preamplifier Systems.
The MPS-400 and MPS-420 systems were designed to achieve the highest performance
available in microphone pre-amplification. The MPS-400 and MPS-420 are ideal for the
recordist that wants to maximize performance for analog or digital recorders using the
superior microphone technologies that are emerging. With the MPS-400 and MPS-420 at or
close to the microphone, additional performance benefits are realized as opposed to long mic
cable runs to a console or recorder. By immediately raising the microphone signal amplitude
to the nominal system reference amplitude, minimum interference is allowed to enter the
system from power lines, SCR stage lighting, etc. Longer lines may also be driven from the
standpoint of system response. The line level output of the MPS-400 and MPS-420 systems
may be used with an existing mic input at a console by using an attenuator at the console
input, such as the LMA-1.
In addition to it’s obvious use as a microphone preamplifier, the MPS-400 and MPS-420 may
be used anywhere amplification of 20 dB or more is needed and minimum noise is desired.
One application which is finding increased acceptance is using the system to bring up low
telco levels without adversely effecting the noise floor. In fact with the overall amplification
range of -2 to +70 dB and input clip point equal to the output clip point minus the
amplification, the MPS-400 and MPS-420 become universal gain blocks with performance that
is nearly perfect.
The following is a brief description of each system.
1.1 MPS-400 Description
The MPS-400 Microphone Input Preamplifier System consists of four MP-4 Microphone
Preamplifier Cards installed in a 19" wide rack mount chassis. The chassis is fabricated of high
quality extruded aluminum with Lexan® front and rear panels. System height is one rack unit
(1RU = 1.75").
Controls for all four channels are located on the front panel. Each channel has a variable gain
control, 20 dB attenuator switch and a +48 V phantom power switch.
The rear panel contains eight XLR type connectors for audio inputs and outputs for all four
channels. A locking four pin XLR type receptacle is also provided for the external power
supply connection.
1.2 MPS-420 Description
The MPS-420 Microphone Input Preamplifier System consists of four MP-4 Microphone
Preamplifier Cards, two DOM-3 Differential Output Mixer units and one HPA-1 Stereo
Headphone Amplifier (Monitor) installed in a 19" wide rack mount chassis. The chassis is
fabricated from high quality extruded aluminum with Lexan® front and rear panels. System
height is one rack unit (1RU = 1.75").
2
Controls for all four channels and the Monitor are located on the front panel. Each channel has
a variable gain control, 20 dB attenuator switch and a phantom power switch. The Monitor
controls include a TRS jack for headphones and a gain control.
The rear panel contains eight XLR type connectors for audio inputs and outputs for all four
channels. Two additional XLR type connectors are provided for Left and Right mixed outputs.
A locking four pin XLR type receptacle is also provided for the external power supply
connection.
2.0 Unpacking
Care has been taken during packing the MPS-400, MPS-420 system to assure it will withstand
normal shipping conditions. Examine the equipment carefully as it is unpacked. If the
shipping carton appears to have been damaged during shipment check the equipment and
notify the carrier and Benchmark immediately if there are signs of damage.
2.1 Equipment List
The following is a list of equipment and accessories provided with the MPS-400 or MPS-420
system. Check the list to assure all items have been received.
Qty. Item
1 MPS-400 Microphone Input Preamplifier Unit
or
MPS-420 Microphone Input Preamplifier Unit
1 PS-10B Power Supply (multiple systems can use the PS-102PH or PS-202PH)
2 Rack Adapters with attaching screws (4).
4 #10-32 Rack Mounting Screws with plastic washers
4 Rubber Feet for desk top use.
1 Installation Manual
3.0 Specifications
The following is a list of specifications for the MPS-400 and MPS-420 Microphone Input
Amplifier System.
3.1 MPS-400 Specifications
The MPS-400 Microphone Input Preamplifier System consists of four MP-4 Microphone
Preamplifier Cards designed to perform to the following specifications.
3.1.1 MP-4 Microphone Preamplifier
GAIN RANGE: Continuously adjustable from +18 to +70 dB. With the use of the 20 dB pad
the overall gain range is -2 to +70 dB.
Controls for all four channels and the Monitor are located on the front panel. Each channel has
a variable gain control, 20 dB attenuator switch and a phantom power switch. The Monitor
controls include a TRS jack for headphones and a gain control.
The rear panel contains eight XLR type connectors for audio inputs and outputs for all four
channels. Two additional XLR type connectors are provided for Left and Right mixed outputs.
A locking four pin XLR type receptacle is also provided for the external power supply
connection.
2.0 Unpacking
Care has been taken during packing the MPS-400, MPS-420 system to assure it will withstand
normal shipping conditions. Examine the equipment carefully as it is unpacked. If the
shipping carton appears to have been damaged during shipment check the equipment and
notify the carrier and Benchmark immediately if there are signs of damage.
2.1 Equipment List
The following is a list of equipment and accessories provided with the MPS-400 or MPS-420
system. Check the list to assure all items have been received.
Qty. Item
1 MPS-400 Microphone Input Preamplifier Unit
or
MPS-420 Microphone Input Preamplifier Unit
1 PS-10B Power Supply (multiple systems can use the PS-102PH or PS-202PH)
2 Rack Adapters with attaching screws (4).
4 #10-32 Rack Mounting Screws with plastic washers
4 Rubber Feet for desk top use.
1 Installation Manual
3.0 Specifications
The following is a list of specifications for the MPS-400 and MPS-420 Microphone Input
Amplifier System.
3.1 MPS-400 Specifications
The MPS-400 Microphone Input Preamplifier System consists of four MP-4 Microphone
Preamplifier Cards designed to perform to the following specifications.
3.1.1 MP-4 Microphone Preamplifier
GAIN RANGE: Continuously adjustable from +18 to +70 dB. With the use of the 20 dB pad
the overall gain range is -2 to +70 dB.
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Key Features
- Continuously adjustable gain
- High Frequency response
- Low noise floor
- R.F. protection
- Differential output mixer
- Stereo headphone amplifier
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Frequently Answers and Questions
What is the gain range of the MPS-400 and MPS-420?
The gain range is continuously adjustable from +18 to +70 dB. With the use of the 20 dB pad, the overall gain range is -2 to +70 dB.
What is the maximum output level of the MPS-400 and MPS-420?
The maximum output level is +27 dBu for balanced outputs and +21 dBu for unbalanced outputs.
What is the recommended load impedance for the MPS-400 and MPS-420?
The recommended load impedance is 2 kΩ or greater. Using a 600 Ω load is possible but not recommended as it reduces performance.
How can I prevent magnetic fields from affecting the noise floor of the preamplifier?
Locate the preamplifier system away from equipment that has power transformers, particularly power amplifiers. Listening to the output of the system without microphones, but with the pads engaged, under full gain will allow you to determine the presence of any magnetic field pickup. The location of the equipment packages in an equipment rack may have to be re-adjusted to isolate the preamplifier system from such fields.
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