Advanced Monitoring Circuit; Power Monitoring; Temperature Monitoring; Mechanical Construction - CH A1.5 User Manual

Two-channel power amplifier

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1.2 Advanced monitoring circuit

Each power amplifier board is equipped with a DSP that monitors the instantaneous output voltage and current delivered to the

loudspeaker. Both values are sampled at around 100 kHz, ensuring peak values are properly detected. DSP monitoring has

several purposes: to give the user a feedback on the peak power delivered to the loudspeakers and to detect and act in case of a

malfunction such as a short-circuit or amplifier damage.

The DSPs also monitor the temperature of both the power transistors and the heatsinks. If the temperature gets excessive, the A1.5

will protect itself by turning itself off.

The A1.5 power amplifier is assembled from high-quality aluminum and steel elements with no visible screws on the front, top and

side panels. The front panel, base, side panels and top cover are machined from aluminum. The power supply is based on a fully

shielded 1'700 VA toroidal transformer and ultra low ESR rectifying capacitors sitting in the central position of the unit. The area

where the air flows to cool down the amplifier is hermetically sealed from the rest of the A1.5, ensuring the electronic circuitry is

protected from gradually gathering dust. Pin assembly of all chassis elements provides smooth joints between elements while

screws every 6cm ensures protection against electromagnetic interference. First class mechanical and chemical surface treatments

provide the luxury finish of the A1.5.

Four steel feet support the unit. Each foot ends with a elastomer ring to sit on delicate surfaces but is also equipped with a height

adjustable steel spike to fine tune the positioning of the unit. Horizontal adjustment is done with the provided screwdriver through

the four adjustment shafts accessible from the top of the unit. In addition to providing convenient horizontal adjustment from the

top of the unit, the shafts also serve as vibration evacuation channels for stacked units.

Special shaft covers (stacking covers) are provided to interface with the spikes of a stack of units. Any vibration from the upper

unit is transmitted by the shaft cover to the shaft of the lower unit and from there to the lower unit's feet or spikes, forming a

privileged path for vibrations evacuation. Support discs are provided and should be placed between the spike of the bottom unit

and the piece of furniture holding the equipment.

The A1.5 benefits from a fully modular architecture. It features separated sections for power rails, analog and digital power

supplies, front panel, signal routing and central host processor, monaural analog input boards and single channel amplification

boards. This modular architecture combined with the USB plug for firmware update allows for easy servicing and upgrade should

one section become faulty or obsolete.

The slot-in boards section consists of a vertically mounted backplane board with optional boards plugged into it. Optional boards

provide audio functionality and connectivity to other equipment.

A1.5 User Manual

Rev 1.0

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