Crown Power Line Four Stereo Amplifier Instruction Manual

Section 1: General Information

The Crown Power Line Four is a single or dual channel, high output power amplifier, designed for audio enthusiasts. This manual provides comprehensive details on its features, operation, and technical specifications to ensure user satisfaction and proper usage. It also includes information on the Crown warranty.

Key Features:

• 165 watts per channel minimum RMS into 8 ohms (20Hz-20KHz).
• 330 watts minimum RMS bridged into 16 ohms (20Hz-20KHz).
• Extremely low harmonic and intermodulation distortion, and low noise.
• Amber "on/off" lamp indicates power status.
• Crown IOC™ (Input/Output Comparator) and Frequency Analyzing Display LEDs.
• Detented Input Level controls for precise adjustment.
• Four-second mute/delay circuit to prevent turn-on thumps.
• Low Frequency Interrupt circuit for protection against DC output.
• Thermal circuit for automatic standby mode during overheating.
• Multi-Mode™ circuitry for optimum performance across different listening levels (Class A, A+B, AB+B).
• Protection against shorted, low impedance loads, input overload, and high frequency overload.
• Front panel output monitor jack for headphone use.
• Conventional unbalanced pin jacks for input signal.

Service Policies:

Servicing should only be performed by qualified technicians. For service, return the unit to the factory in original packaging. Contact Crown International Customer Services Department for authorization before returning the unit. Crown will pay shipping costs within the U.S. for warranty service upon receiving shipping receipts.

Glossary of Terms: A comprehensive glossary of audio-related terms is provided, including definitions for A-B Test, AGC, Attenuation, Balanced Input, Balun, Bandpass Filter, Biamp, Butterworth Filter, Capture Ratio, Ceramic Filter, Channel, Channel Separation, Clipping, Corner Frequency, Cross Modulation, Crossover Frequency, Crossover Network, Crosstalk, Damping, Damping Factor, Decibel, Decoder, De-emphasis, Distortion, Dynamic Range, EAROM, Equalization, Feedback, Flutter, Frequency Response, Gain, Headroom, Hertz, High Pass/Low Pass Filter, IF, Image Response, Input Sensitivity, IOC™, LED, Limiter, Load, LSI, Mixer, Monitoring Amplifier, Multipath Delay, Music Power, Muting Circuit, Pre-emphasis, PLL, Polar Curve, Quartz Crystal, Rotor, SAW Filter, Selectivity, Sensitivity, Signal, Signal-To-Noise-Ratio, Superheterodyne, Synthesizer, Triamp, Varactor, and Wow.

Section 2: Specifications and Performance

2.1 General Specifications

• Hum and Noise: 112dB below rated output (20Hz-20KHz).
• Phase Response: +0, -15 degrees 10-20KHz at 1 watt.
• Input Impedance: 30K ohm, ±20%.
• Amplifier Output Protection: Short, mismatch, and open circuit proof.
• Overall Protection: AC line fused, thermal switch, controlled slewing rate voltage amplifiers, input overload protection.
• Low Frequency Interrupt: Activates at DC outputs > 10V or low frequency outputs > 10V at 2Hz.
• Turn-on Delay: Four second delay.
• DC Output Offset: 10 millivolts or less (adjustable).
• Power Supply: 1 kilowatt transformer, massive computer-grade filter capacitors, two regulated supplies.
• Power Requirements: 50-400Hz AC, selectable taps for 100, 120, 200, 220, 240V ±10%. Idle: 40 watts; Max output: 560 watts.
• Heat Sinking: Massive black-anodized heat sinks integrated with chassis.
• Chassis: All aluminum construction.
• Controls: Pushbutton on/off, independent input level controls, rear panel Stereo/Mono switch.
• Display: Three-pair LED Frequency Analyzing Display, two red IOC™ LEDs, one amber Power LED.
• Connectors: AC Line (2-wire male), Input (pin jacks, unbalanced), Output (color-coded dual binding posts), Output Monitor (1/4" stereo phone jack).
• Dimensions: 19" (48.3cm) standard rack mount, 7" (17.8cm) high, 10.125" (25.7cm) deep.
• Weight: Approximately 55 pounds (24.9kg) net.
• Finish: Brushed or satinized aluminum front panel, or black polyester vinyl coated aluminum front panel.

2.2 Stereo Specifications

• Output Power: 165 watts/channel (8 ohms), 265 watts/channel (4 ohms) RMS at 0.05% THD (20Hz-20KHz).
• Frequency Response: ±0.1dB 10-20KHz at 1 watt into 8 ohms; +0dB, -1.5dB 10Hz-100KHz.
• 1KHz Power: 180 watts RMS/channel into 8 ohms at 0.1% THD.
• Harmonic Distortion: < 0.001% (20Hz-800Hz), increasing to 0.025% at 20KHz (165W RMS/ch into 8 ohms).
• I.M. Distortion: < 0.05% (0.01W-0.25W), < 0.01% (0.25W-165W) into 8 ohms/channel.
• Slewing Rate: 16 volts/microsecond.
• Damping Factor: > 400 (DC-400Hz into 8 ohms).
• Output Impedance: < 7 milliohms in series with < 3 microhenries.
• Load Impedance: Rated for 4 and 8 ohm usage.
• Voltage Gain: 20.6 ±2% or 26.3 ±0.3dB.
• Input Sensitivity: 1.76 volts ±2% for 165 watts into 8 ohms.
• Output Signal: Unbalanced, dual channel.

2.3 Monaural Specifications

• Output Power: 330 watts RMS (16 ohm load), 530 watts RMS (8 ohm load) at 0.05% THD (20Hz-20KHz).
• Frequency Response: ±0.15dB 10-20KHz at 1 watt into 16 ohms; +0dB, -1dB 10-60KHz at 1 watt into 16 ohms.
• 1KHz Power: 360 watts RMS into 16 ohms at 0.1% THD.
• Harmonic Distortion: < 0.001% (20Hz-800Hz), increasing to 0.025% at 20KHz (330W into 16 ohms).
• I.M. Distortion: < 0.05% (0.01W-0.25W), < 0.01% (0.25W-330W) into 16 ohms/channel.
• Slewing Rate: 32 volts/microsecond.
• Damping Factor: > 400 (DC-400Hz into 16 ohms).
• Output Impedance: < 15 milliohms in series with < 6 microhenries.
• Load Impedance: Rated for 8 and 16 ohm usage.
• Voltage Gain: 41.2 ±2% or 32.3 ±0.2dB.
• Input Sensitivity: 1.76 volts for 330 watts into 16 ohms.
• Output Signal: Balanced, single channel.

Performance Graphs: The manual includes graphs illustrating Nominal Power Efficiency (Fig. 2.1), Nominal Frequency Response (Fig. 2.2), Nominal Phase Response (Fig. 2.3), Typical Damping Factor (Fig. 2.4), Typical Crosstalk (Fig. 2.5), Low Frequency Interrupt Action (Fig. 2.6), Typical Output Impedance (Fig. 2.7), Nominal Noise Spectrum (Fig. 2.8), and Nominal Output Phase Angle (Fig. 2.9).

Section 3: Installation and Operation

3.1 Unpacking

Inspect the unit for any damage incurred during transit. Notify the transportation company immediately if damage is found. Save the original carton and packing materials for potential future transport or shipping.

Return the warranty registration card within ten days to receive the Crown Care Card.

3.2 Accessories Supplied

The Power Line Four includes: Instruction Manual, 4 mounting screws, 4 nylon washers, 2 fuses, 2 fuse holders, 2 banana plugs, 2 wire nuts, and 2 6' pin-pin cables.

3.3 Mounting

The Power Line Four can be mounted in a Crown walnut cabinet or a custom-designed cabinet. Standard 19" width spacing is recommended. Ensure adequate ventilation with approximately 1 3/4" clearance above and below the unit for hot air discharge.

3.4 Operating Precautions

1. Use care when making connections and selecting signal sources.
2. Do not parallel amplifier outputs.
3. Avoid driving devices that appear as low frequency shorts (e.g., < 3 ohms at DC) without a series isolating capacitor.
4. Do not short the ground lead of an output cable to the input signal ground.
5. Never remove the covers to avoid shock hazard or damage.
6. Operate the amplifier from AC mains within 10% of the selected voltage and at 50-60Hz.
7. Do not connect the output to a power supply, battery, or power mains.
8. Tampering with or unauthorized modifications to the circuitry will invalidate the warranty.

3.5 Controls and Adjustments

A. Power Switch/Indicator: Activates the unit and the amber power indicator. IOC™ indicators illuminate during the turn-on mute delay.

B. Input Level Controls: Detented controls with thirty-one positions for precise input signal adjustment.

C. Frequency Analyzing Display: Three LEDs (orange=high, green=mid, yellow=low) indicate the frequency range of the output signal.

D. IOC Indicators: Red LEDs indicate potential issues like excessive input signal or improper load impedance. They also serve as Stand-by indicators.

E. Output Monitor: 1/4" phone jack for accessing the stereo output signal.

3.6 Connecting Power

The unit uses a standard two-wire AC plug. For operation with different AC voltages (100, 120, 200, 220, 240 VAC), conversion should be performed by a qualified technician.

3.7 Connecting Input/Output Lines

All connections are made from the rear panel. Use standard pin jacks for inputs. Avoid undesirable signals, ground loops, and feedback. Ensure input signals are free of large sub-sonic frequencies. For loudspeaker connections, use appropriate speaker cables and ensure proper impedance matching. Figure 3.5 provides a nomograph for selecting fuse size based on speaker impedance and power.

Note on Ground Loops: Tie input and output cables together along their length and keep them away from power cords to prevent ground loops. Do not join amplifier input and output grounds externally.

Load Impedance: For stereo operation, use a minimum load impedance of 4 ohms per channel. For mono operation, the minimum load impedance is 8 ohms.

3.8 Mono Operation

To switch to mono mode, move the rear panel slide switch to "Mono". Use only the left channel input and level control. Unplug the input to the right channel and turn its level control fully counterclockwise. For mono output, use only one dual-pin banana plug connected to the red (+) terminals.

Caution: Ensure all equipment connected to the mono output lines is balanced and isolated from input grounds to prevent oscillation.

3.9 Protection Mechanisms

The Power Line Four features extensive internal protection circuitry including:

• Fast-acting limiter circuit for open, shorted, or mismatched speaker loads.
• Low Frequency Interrupt circuit to prevent accidental speaker damage from DC at the output.
• Thermal protection for each channel to prevent overheating.

3.10 Load Protection Methods

Common load protection methods include using fuses in series with the load. High-speed instrumentation fuses are recommended. Figure 3.7 is a nomograph for selecting fuse size. An alternative protection method involves a relay-controlled circuit with an overload indicator lamp, as shown in Figure 3.8.

Section 4: Technical Information

4.1 General Information

This section provides technical information regarding the electrical operation of the Power Line Four. It is not intended for service purposes; always refer servicing to Crown or a qualified service center.

4.2 Block Diagram Explanation

The block diagram (Fig. 4.1) illustrates the signal path through the amplifier. Key stages include:

• Input Stage: Receives unbalanced input signals via pin jacks.
• Main Amplifier: Establishes maximum gain, with a variable potentiometer for input level control. Features ultra-low noise and temperature-controlled bias compensation.
• IOC™ Circuitry: Detects non-linearity and illuminates the IOC™ LED. Includes a pulse stretching circuit for better visibility.
• Gated Switches: Control signal path based on activation of Delay, Thermal, or Low Frequency Interrupt circuits.
• Signal Translator and Last Voltage Amplifier: Form the voltage amplifier stage.
• Current Amplification (Multi-Mode™ Circuit): Operates as Class A at low levels, Class A+B at medium levels, and Class B at high levels for optimum performance and low distortion.
• Protection Circuitry: Monitors voltage and current at the output stage to limit bias servo voltage.

The output signal is processed by the Frequency Analyzing Display circuitry before reaching the output jacks. The unit utilizes MDP or banana jacks for output, with positive terminals used for bridged or mono operation. The power supply is a continuous-duty, full-wave capacitor input type with zener-regulated power supplies for the amplifiers and circuitry.