Parasound A 21 manual AC Present Indication, On, Off and Fault/Protection Status Indicators

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UNDERSTANDING THE INDICATORS ON THE A 21

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A&B AC Present Indication

When the A 21 is plugged into a live AC outlet, a soft blue halo glows behind its On-Offbutton and its red “P” Badge glows faintly. These indicate that the unit is plugged into a live AC outlet, even when it is turned off.

BOn, Off and Fault/Protection Status Indicators

Whenever the A 21 is turned on, the soft blue glow behind its On-Off button will change to red for about five seconds as its internal circuits stabilize. Then the red glow is replaced by a brighter blue glow to indicate normal operation. If the glow remains red after turn on or while the amp is playing, it indicates activation of the A 21’s protection circuits and no sound will be heard from the speaker. The A 21 protects itself from external conditions such as excessive heat, load impedance that is too low, or a short-circuited speaker connection or wire. After you correct the fault, the A 21 will resume operation. If the A 21 remains “in protection” after it has cooled down and you’ve confirmed there are no external faults, it could indicate an internal problem. Please contact Parasound’s Technical Service Department.

C&D Left and Right Channel Status Indicators

C&D

C&D

E

These are two small round indicators in the center of the recess in the front panel. The indicator on the left displays the status of the left channel and the indicator on the right displays the status of the right channel.

Both Illuminated

When both channels are operating normally, these both glow blue.

No Illumination:

When the A 21 is turned off, these indicators are off.

High-Temp Indicator

This indicator is near the right side of the panel recess. It will glow red if either channel overheats. The On-Off button will also glow red if the A 21 overheats.

FGain Control Knobs

These adjust the gain (level) of the A 21. We recommend that you rotate the Left and Right Gain controls to their maximum clockwise positions, marked THX Reference. Refer to Gain Controls in Technically Speaking for more information about these adjustments.

GGround Switch

The Ground switch can assist in reducing audible hum caused by ground loops in your

system. This switch should be in its Normal (down) position. If you hear hum you can move it to its Lift (up) position to eliminate it. Refer to the Technically Speaking section for more information about ground loops.

A

A 2

B C DE

F F

G

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Contents Amplifier Parasound Staff Unpacking Your a Congratulations and Thank You for Choosing ParasoundKeeping Records for Future Reference Amplifier Rack Mounting Your Parasound a Placement Guidelines for Your aBalanced XLR Jacks and Their Pin Configuration Before ConnectingLeft and Right Balanced Input Jacks What You’ll NeedInterconnect Cables and Their Color Codes Left and Right Unbalanced InputsLoop Out Connector Speaker Terminals Speaker Wire Length and Gauge thicknessCorrect Speaker Polarity is Important IMPORTANT! Before Trying Bridged Mono Configuring the a 21 for Bridged Mono OperationTurn Off Delay in the Audio Mode Connecting an Active Audio Source for Automatic On-OffManual On-Off from the Front Panel Mm sub-mini plug Connecting the a 21 to Trigger Another Component Left and Right Channel Status Indicators On, Off and Fault/Protection Status IndicatorsHigh-Temp Indicator Ground Switch120 V or 220 V 240 V Operation AC Power ConnectionsMaintaining Your a Main Power FuseTrouble Probable Cause Remedy Troubleshooting GuideServicing Your a Procedure for Returning Your a 21 to Parasound for ServiceIf All Else Fails -Call Us for Help Important Notice Shipping the aBare Speaker Wire Ends Audio Trigger Sensitivity AdjustmentTechnically Speaking Balanced and Unbalanced LinesGround Loops Eliminating Hum and Buzz Choosing Interconnect Cables and Speaker WireLoop Out Jacks Gain ControlsParasound a 21 Design Overview Output Stage Driver StageClass A-A/B Operation Total Protection DC ServosParasound a 21 Specifications Parasound Products, Inc Battery Street, San Francisco, CA

A 21 specifications

The Parasound A 21 is a high-performance power amplifier renowned for its exceptional audio quality and build integrity. It is designed to meet the demands of audiophiles and music enthusiasts, aiming to deliver an unparalleled listening experience. This amplifier stands out with a robust power output, delivering 250 watts per channel into 8 ohms and 400 watts into 4 ohms, providing ample power to drive a wide range of loudspeakers.

One of the key features of the Parasound A 21 is its ultra-linear Class AB amplification. This technology allows the amplifier to achieve high power without compromising on sound quality. The Class AB design is known for its low distortion and high efficiency, making it capable of reproducing dynamic music with clarity and precision. The A 21 also incorporates a toroidal transformer, which helps in producing clean power and minimizes electrical interference, ensuring that the sound remains unaffected by fluctuating power conditions.

The build quality of the A 21 is exceptional, with a sturdy chassis designed to minimize vibrations and enhance performance. The amplifier is housed in a sleek, attractive enclosure that not only looks elegant but also provides adequate heat dissipation. This is a crucial aspect, as it ensures the amplifier operates efficiently without overheating during extended listening sessions.

In terms of connectivity, the Parasound A 21 features balanced XLR and unbalanced RCA inputs, allowing users to integrate it seamlessly into various audio systems. The amplifier also has a 12V trigger input, enabling remote operation which can be a significant convenience for users with complex audio setups.

The A 21 is built with high-quality components, including high-current power supply capacitors and output transistors, further enhancing its reliability and performance. Its sound signature is characterized by an expansive soundstage, detailed mids, and deep, controlled bass, making it suitable for a diverse range of music genres.

For those seeking an amplifier that combines power, precision, and aesthetic appeal, the Parasound A 21 is a standout choice. It delivers an impressive blend of technological advancements and user-friendly features, ensuring that audiophiles can enjoy their favorite music as it was meant to be heard. Overall, the A 21 exemplifies Parasound’s commitment to excellence and remains a trusted option in high-fidelity audio systems.
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