The MicroFrame™ Series Product Overview
The MF-1 is a single rack
unit Modular Frame that is designed to house two power supply modules, as well
as the amplifier modules, and operate them in a redundant configuration from a
common power transformer and power entry module. The IEC type power entry device
at the rear of the frame is a combination line filter, mains voltage selector
(120-240 volt 50/60 Hz operation) and power plug allowing for all international
power cords.
The MF-1C is the normal choice
for most customers. The MF-1C is a connectorized version of the module frame. Three types of output
connectors are available. 50 pin D-sub type, 50 pin Champ style, and 50 pin Elco
connectors are available. The new AES 50 pin wiring standard is also available.
Check with the sales department for pricing.
Audio interconnect may also be
left to the end user, as each user has their own preference. Provision is made
at the rear of the MF-1 for your choice of multi-pin connectors. A removable
flat rear panel allows easy punch and wiring of the multi-pin connectors of your
choice. 0.025" sq. posts are provided on the backplane for three ports at each
module position. PL-2 pre-connectorized wire assemblies are available. These
assemblies consist of a three position Molex® SL housing and pins attached to a
two foot length of Gepco #24 solid shielded pair, ready for your multi-pin
connector at the rear of the chassis. Alternately, wire wrap connections may be
made to the 0.025" posts and attached to the rear panel connectors of your
choice.
The MF-1 is finished with a high
quality black paint. The modules are held in place by the anti-vibration nylon
card guides and the edge card connector, forming a very secure arrangement
suitable for mobile environments.
The plug-in modules have attached
front panels that correspond to the module itself, and form a contiguous
attractive front view of the frame. The finish on the panels is the same black
paint with white silk screen graphics. Each module has a small extruded aluminum
handle that has a bright anodize finish, and provides an ideal location for
attaching labels as to the use of the module.
The LA-1 Line Amplifier
The
LA-1 is the first in
a series of very high performance audio amplifier and processing modules. It is
characterized as a one in, two out line/distribution amplifier with front panel
adjustable variable gain from +20 to -20 dB. Unity gain has a center detent
position on the potentiometer. The input to the amplifier is a common mode
filter that ensures very high RF rejection to common mode RF energy. The filter
in turn feeds an instrumentation amplifier with a gain of - 6 dB. Common mode
rejection of the instrumentation amplifier is approximately 100 dB to 3 kHz and
75 dB at 20 kHz. The variable gain stage follows and has active adjustment of
the amplification for the most optimum noise performance. A trim potentiometer
allows the detent position of the front panel gain potentiometer to be set
precisely at unity.
The module has a balanced output
section that utilizes a current boost integrated circuit, that in and of itself
is almost totally free from crossover distortion. However, when placed in the
feedback loop of a NE5532, it provides all of the very desirable qualities of
the NE5532 but with 300 mA of output current capability. This is essential for
driving long capacitive transmission lines. This high output current capability
allows 150 ohm true power matched transmission lines, for instance, to be driven
to +26 dBm or higher, with very low Total Harmonic Distortion. Each LA-1 has two
60 ohm outputs unless the module was ordered specifically with a 150 ohm output
impedance. The output stage gain is +6 dB. Input and output clip points, at
unity gain, are +26 dBu. The modules bandwidth is greater than 200 kHz for
excellent transient and square wave response (without overshoot or ringing).
This carefully compensated wide bandwidth also provides low phase shift at 20
kHz (-8.6°), while exhibiting outstanding RF immunity. On board fuses assure the
continued operation of the system in the highly unlikely event of a catastrophic
failure on an amplifier module.
A bicolored signal indicating LED
provides a green indication when a signal of a predetermined threshold is
present, and a flashing red/green indication when the module approaches overload
at the output. The threshold for the peak indication is factory set to trip at
+20 dBu, but may be set at any level from +16 to +26 dBu. The signal presence
threshold is adjustable from -10 dBu to +8 dBu, average, (-2 to +16 dBu peak)
and is factory set at -10 dBu (-2 dBu peak).
The MP-1 Microphone Preamplifier
The
MP-1 is the second in
the series of very high performance audio amplifier and signal processing
modules for the MicroFrame™. The MP-1 uses the same topology that is found in
the now highly regarded MP-4 microphone preamplifier from Benchmark. Benchmark
preamplifiers are used by Telarc Records, The Boston Symphony, Deutsche
Grammophon, National Public Radio, NBC's "Nightly News" with Tom Brokaw, among
many others.
The performance of the MP-1 is
state-of-the-art, and features; A gain range of 6 to 75 dB, (including 20 dB
pad) with an adjustable maximum gain limit trim, to limit the gain range when
using high sensitivity microphones. It has a noise floor that is within 1 dB of
the theoretical limit, a bandwidth greater than 200 kHz, THD @ 20 kHz = 0.0009%
(A = 40 dB), a maximum input level of +21 dBu, CMRR @ 2 kHz =100 dB, and @ 10
kHz = 65 dB. It has outstanding RF immunity due to it's common mode input
filter, and the dynamic range is greater than 120 dB. Transient Intermodulation
Distortion is virtually nonexistent, with the 1 kHz difference twin tone CCIF
curve flat to 70 kHz. All electrolytic capacitors are paralleled with large film
capacitors. The preamplifier is ultra transparent! Call for a copy of the review
of the MP-4 (formerly the MIA-4) by the late Hugh Ford of Studio Sound Magazine,
for further information.
In addition to having the
extraordinary performance of the MP-4, the MP-1 incorporates a switchable 70 Hz
low cut filter, and the bicolored signal presence and onset of overload
indicators found in the LA-1. The signal indicating LED can be strapped to
indicate either pre or post filter. The module also has the same balanced output
section found in the LA-1 described above.
The MX-1 Mix Amplifier Option
The
MX-1 is a sixteen
input mixing module that mounts in the rear of the MF-1 frame. Mix any or all of
the modules' outputs into the low noise MX-1. The balanced output is like that
of the LA-1 or the MP-1 with a high current (300 mA), buffered, 60 ohm drive
capability.
The PS-2 is the power
supply module for the MicroFrame™ Series. It provides a linearly regulated ±15
volts, at a maximum of 1.5 amps, to power the system. Linear regulators are used
to ensure ultra low noise amplifier operation. Two power supply modules are
needed for each MF-1. The module has combining diodes at the output to the
backplane allowing redundant regulator operation. The MF-1 uses a common power
transformer and power entry module to feed the two PS-2 power supply modules.
Individual voltage trim potentiometers are provided to allow for load balancing
between the two supply modules. The power supply regulator modules have
transformer secondary fuses to isolate them from the transformer, in the highly
unlikely event of a catastrophic failure in one of the modules.
Operation of the MicroFrame™
Series should be done with forced air cooling, as 80 watts of power may be
dissipated by the system. Operation without forced air is permitted for short
time periods, but regular operation in this manner is not recommended.
The PH-1 Phantom Power Supply
The PH-1 supplies the
+48 volts necessary for powering microphones from the MicroFrame™ through the
MP-1 microphone preamplifier. The active regulator circuitry provides an
extremely low noise source of power which ensures the maintenance of the MP-1s
outstanding noise performance.
The PS2000 External Power Supply
The PS2000 is
a small bipolar 15 volt power supply that is capable of powering the MicroFrame
with 16 MP-1 microphone preamplifiers. Two supplies may be used for redundancy
and are recommended. The +48 volt supply has a current rating of 0.2 A for full
operation with today's high current microphones. A shielded toroidal power
transformer is used for ultra low noise, both physical and electrical. The
PS2000s may be mounted in the the RM-1 accessory
rack mount frame.
Accessories
The EX-1 Extender Board
The
EX-1 is an
extender board for the MF-1 frame. This unit allows servicing of a module at the
frame rather than removing it to a test bench.
The BP-1 Blank Panel
BP-1 Blank
panels are available to fill any unused module positions providing a continuous
front panel for the MF-1.
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