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MicroFrame Amplifier Modules LA-1

Product Overview Photo: 
LA-1

The LA-1 is a one-in, two-out line/distribution amplifier with front panel variable gain adjustments from -20 to +20 dB. A center detent is supplied for unity gain. A bi-colored signal indicating LED furnishes a green indication when a signal of a predetermined threshold is present (usually just below the house reference level) and a flashing red-green indication when the module approaches overload at the output. The input to the amplifier uses a common mode filter to ensure very high rejection of common mode RF energy. The module has a balanced output section that uses a new current boost integrated circuit, which is almost totally free from crossover distortion. Each LA-1 has two 60 ohm outputs (150 ohm also available). On board fuses assure the continued operation of the system in the highly unlikely event of a catastrophic failure of an amplifier module.

Price: $199.00

Features
  • Superb RF immunity
  • 300 mA high current output
  • I/O clip point = +26 dBu
  • Peak threshold adj. from +16 to +26 dBu
  • Bandwidth = 200 kHz, 20 kHz Ø = -8.6°
  • THD = 0.0009% @ 2 kHz
  • CMRR > 100 dB to 3 kHz, 75 dB @ 20 kHz


THD+N and Phase vs. Freq

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).