ATI Technologies M1000 Operating And Maintenance Manual
M1000
DUAL MICROPHONE AMPLIFIER
OPERATING AND MAINTENANCE MANUAL
© Copyright 1997-2005, Audio Technologies Incorporated - Printed in USA
Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax 856-719-9903 | www.
audio.com
DESCRIPTION
This section is strictly written to boost the designer’s ego by letting him tell you of
some of the clever things we have done inside the MicroAmp. It may be skipped
by anyone having anything better to do.
For many years engineers (ourselves included) have been using operational
amplifier ICs in audio circuitry. These ICs, developed primarily for the
instrumentation market, had many shortcomings when used in high quality audio
applications. The lack of audio related specifications, crossover distortion, high
noise for low source impedances, limited output capability and limited gain
bandwidth product forced many compromises when used in high gain audio
systems. High ratio input transformers, output boost stages and multiple stage
designs were all used to compensate for op amp deficiencies and in turn added
additional response and distortion problems of their own.
Walter Jung in a definitive series of articles' analyzed and defined slew rate
induced distortion mechanisms, tested many commonly available ICs and
correlated various distortion tests with subjective (listening) criteria. A very
significant result of his efforts was the identification of an IC originally developed
for the European professional audio market which has almost ideal
characteristics for audio use and in particular provides a high rate capability of 13
volts /microsecond, virtually eliminating slew induced Transient Intermodulation
Distortion. By contrast the old standard 741-op amp has a slew rate of only
.6V/microsecond.
This op amp is now available from several U.S. Manufacturers in single and dual
versions and forms the basis for our MicroAmp designs. This chip incorporates a
low noise input stage designed for excellent noise performance even with low
source impedances thus eliminating the necessity for touchy 1:20 input step up
transformers in the M1000. High output capable of driving 600 ohm loads directly
to +22dBm with total freedom from crossover distortion, high inherent linearity,
100 dB open loop gain and 50Mhz gain bandwidth product make this an ideal
device for highest quality audio. The absence of Transient Intermodulation
Distortion may be detected in the smooth effortless high frequency output
capability, the absence of the harsh, raspy sound typical of IC amplifiers driven to
full output at high frequencies and the freedom from increasing harmonic
distortion vs. frequency. As used in the MicroAmp a minimum of 40 dB of loop
gain is available for 100:1 distortion reduction even at 20 kHz.
The high output swing capability allows the amplifier to use a simple, low
distortion, flat response 1:1 output transformer. ATI provides three models of
each MicroAmp; Transformer outputs (with faraday interwinding shields) for high
RF field environments, a balanced differential output stage version (bridge circuit)
for low RF environments where balanced output lines are required for hum
rejection in long runs and the minor performance degradations of an output
Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax 856-719-9903 | www.
audio.com
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