dbx 3BX Service Manual

Tests the power supply and DC voltages for proper operation and stability.

Calibrates the RMS detection circuitry for accurate signal level sensing.

Adjusts the Voltage Controlled Amplifier (VCA) levels for unity gain across frequencies.

Measures and minimizes second harmonic distortion from the VCA circuits.

Ensures consistent level matching across different frequency bands and input changes.

Measures the output noise floor with inputs shorted to ensure low noise performance.

Verifies the dynamic range achievable by sweeping the transition level control.

Calibrates the LED display indicators for accurate visual feedback of signal levels.

Sets reference input and output levels for accurate dynamic range expansion.

Tests the output level's response to various input levels and frequencies.

Measures the unit's frequency response across the audio spectrum.

Tests the unit's remote control functionality using a simulator.

Determines the maximum undistorted output level before clipping occurs.

Verifies the sequential operation and accuracy of the LED display indicators.

Checks the output clamping behavior when the unit is powered on.

Analyzes the unit's transient response to tone bursts.

Final assembly, waxing of trim pots, and burn-in procedure.

Verifies power, remote LEDs, and the main LED display function.

Checks VCA level settings and distortion characteristics.

Confirms the relative input and output level settings.

Tests the unit's response to varying input levels.

Evaluates transient response using tone bursts.

Measures the output noise floor.

Checks the output clamping mechanism.

Verifies the operation of the LED display indicators.

Tests the unit's clipping characteristics.