Parasound A 23 Technically Speaking, Audio Trigger Sensitivity Adjustment, Bare Speaker Wire Ends

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15TECHNICALLY SPEAKING

Audio Trigger Sensitivity Adjustment

The Audio Sensitivity Control sets the threshold of the audio trigger signal. You can adjust this level from a maximum sensitivity of 50 mV (fully counterclockwise) to a minimum sensitivity of 200 mV (fully clockwise). If you set this control to 50 mV, the A 23 might be falsely triggered on by non-musical or noisy signals that can appear in the system, such as when you switch preamp inputs at high volume levels. If you set this control to 200 mV, the A 23 might not turn on during quiet musical passages. The detented position (click stop) at 12 o’clock corresponds to 100 mV. It’s a good starting point and will be suitable for most systems.

Balanced and Unbalanced Lines

Recording and broadcast studios use balanced connections exclusively because of their inherent ability to reject noise and hum, thus assuring the best sound. Certain high quality preamplifiers and surround controllers built for residential use utilize balanced connections with XLR jacks for the same reasons. All Parasound Halo series power amplifiers have balanced inputs with XLR jacks so you can take full advantage of their inherent noise reduction capability and superior sound quality.

Unbalanced connections with RCA jacks are found on all home audio equipment. RCA jacks and two- conductor wires are less costly than the additional circuitry, higher priced XLR connectors and three- conductor wiring required for balanced connections.

In an unbalanced line, the positive audio signal appears at the center pin of the RCA jack and the negative signal on the outer shield wire, which also functions as the ground connection. Unbalanced interconnect cables are vulnerable to hum from an AC line, or other noise, such as RF (Radio Frequency), which can be reproduced through your loudspeakers. Since the unbalanced line’s ground also carries the audio signal, there is no way for the connected amplifier or preamplifier to distinguish between the audio signals you want and unwanted noise emanating from external sources.

Balanced lines are superior because they utilize separate conductors for audio and ground: two inner conductors carry the positive and negative audio signal, and a third outer wire connects the grounds and also shields the two signal conductors. When the positive and negative signals appear at the component receiving the signal they are equal, but 180 degrees out of phase with each other with respect to ground. To send and receive balanced signals requires special differential circuitry.

A differential input circuit amplifies only the difference between the positive and negative signals. For example, when a 1 Volt signal arrives at a balanced input stage, the differential input “sees” a positive 1 Volt minus a negative 1 Volt, or 2 Volts total. External hum and noise that somehow gets into a

balanced line is common to both its positive and negative conductors with respect to ground. Therefore, it is canceled or rejected by the differential input circuit.

This phenomenon of rejecting noise signals common to both positive and negative conductors is called common mode rejection. Differential inputs are specified according to how well they reject signals common to both conductors. This is measured in dB and is called the common mode rejection ratio or CMRR.

Bare Speaker Wire Ends

If you plan to use connections with bare wire ends, use a wire stripper to remove just enough insulation to expose a 1/2” (13mm) length of bare wire. You can insert the stripped wire into the hole that goes sideways through the terminal's metal post. Before inserting the wire, twist its bare strands to prevent any of the strands from making contact across the two speaker terminals. If you have a soldering iron, you can “tin” (apply a small amount of molten solder) to each stripped bare wire to prevent it from unraveling, fraying and oxidizing.

Bridged Mono Operation

In normal operation, the left and right amplifier channels each amplify both the positive and negative halves of the musical signal. In bridged mono operation, the A 23’s entire left channel drives only the positive half of the musical signal and its entire right channel drives only the negative half of the musical signal. This doubles its voltage swing.

This doubled voltage swing enables the A 23 to deliver double its 150 watts per channel 4 power, or 300 watts, into a single 8 speaker.

The audible benefit of this higher power is increased dynamic range, or headroom, so that musical peaks can be reproduced with less distortion. Considering that musical peaks and crescendos require 10-100 times as much power as average listening levels, this added headroom is a substantial advantage for unrestrained, undistorted listening, even if your average listening level is moderate.

Bridging allows an amplifier to deliver more power into a single speaker because in this mode, the load appears to the amplifier as only half of its rated impedance. Thus, the single 8 speaker appears as a 4 load and a 4 speaker appears as only a 2 load.

The A 23 is not capable of driving 2 for extended periods because it will draw more current and generate more heat than it can dissipate. We strongly recommend against using speakers rated at less than 8 when bridging.

Remember that mono bridging requires a separate A 23 for each speaker. You can’t simultaneously drive two speakers in stereo and one speaker mono bridged.

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Contents Amplifier Parasound Staff Unpacking Your a Thank YOUCongratulations and Thank You for Choosing Parasound Keeping Records for Future ReferenceTable of Contents AmplifierPlacement Guidelines for Your a Rack Mounting Your Parasound aWhat You’ll Need Before ConnectingLeft and Right Balanced Input Jacks To ConnectLeft and Right Unbalanced Inputs Loop Out Connector Speaker Terminals Connecting Speakers to the aSpeaker Wire Length and Gauge thickness Correct Speaker Polarity is ImportantConfiguring the a 23 for Bridged Mono Operation IMPORTANT! Before Trying Bridged MonoManual and Automatic Turn ON-OFF Options Connecting an Active Audio Source for Automatic On-OffTurn Off Delay in the Audio Mode Manual On-Off from the Front PanelAutomatic ON-OFF Connecting the a 23 to Trigger Another Component Understanding the Indicators on the a Connecting the AC Power Cord AC Power ConnectionsAC Voltage Selection Switch Maintaining Your a Troubleshooting Guide Trouble Probable Cause RemedyServicing Your a If All Else Fails -Call Us for HelpTechnically Speaking Audio Trigger Sensitivity AdjustmentBare Speaker Wire Ends Balanced and Unbalanced LinesChoosing Brands of Interconnect Cables and Speaker Wire Loop Out JacksLevel Controls Parasound a 23 Design Overview Total Protection Output StageClass A-A/B Operation Relay ProtectionParasound a 23 Specifications Parasound Products, Inc Battery Street, San Francisco, CA

A 23 specifications

The Parasound A 23 is a highly acclaimed power amplifier recognized for its performance and versatility in high-fidelity audio systems. Designed for both audiophiles and casual listeners, it offers robust sound quality, making it a popular choice in the world of home theater and music reproduction.

One of the standout features of the Parasound A 23 is its power output. The amplifier is rated at 125 watts per channel into 8 ohms, and it can deliver 200 watts per channel into 4 ohms. This substantial power allows it to drive a wide range of speakers effectively, from more sensitive models to those requiring additional power. The A 23’s high current capability ensures that musical dynamics are accurately reproduced, resulting in a responsive and engaging listening experience.

Built using a Class AB topology, the A 23 balances efficiency and sound quality. Class AB amplifiers like this one maintain low distortion levels while delivering the warmth associated with tube amplifiers. The careful engineering provides a natural sound, ensuring that vocals and acoustic instruments are rendered faithfully. The dual-mono design minimizes crosstalk and maximizes separation between channels, enhancing stereo imaging.

Another characteristic of the Parasound A 23 is its versatile connectivity. It features both balanced XLR and unbalanced RCA inputs, allowing you to integrate it seamlessly into various audio setups. The design includes a high-quality power supply with a large toroidal transformer, which contributes to the amp's stability and reliability. The robust build quality is evident in its all-steel chassis, ensuring durability and performance in any environment.

The A 23 also incorporates several advanced technologies, such as a soft-start circuit that prolongs component life and increases reliability. The amplifier is equipped with reliable thermal protection circuitry, preventing overheating and ensuring long-term operation without issues.

In conclusion, the Parasound A 23 is a powerful and versatile amplifier that delivers outstanding audio performance. Its blend of high power output, Class AB design, dual-mono architecture, and solid construction make it an ideal choice for those looking to elevate their audio experience, whether in a home theater system or a dedicated listening room. With its combination of features and durability, the A 23 stands out among amplifiers in its class.