T+A A 3100 HV Reference Power Amplifier

Selectable High Current and High Power operation, switchable stereo or mono configurations, 500 Wpc output, and more than 270 revisions to the A 3000 HV architecture

The T+A A 3100 HV builds on the A 3000 HV power amplifier after its ten-year production run, retaining the fundamental HV architecture while incorporating more than 270 engineering changes and refinements. Revised circuit boards, tighter-tolerance components, improved thermal management, a new transformer, and a selectable High Current mode extend the design well beyond a conventional model update.

The A 3100 HV can be used as a stereo amplifier or configured for mono operation, and it offers two distinctly different operating modes. High Current mode prioritizes elevated bias and an expanded class-A operating range, while High Power mode provides 300 Wpc into 8 ohms and 500 Wpc into 4 ohms for loudspeakers requiring greater output.

High Current or High Power

In High Current mode, the A 3100 HV reduces the output-stage supply voltage while substantially increasing its idle current. This allows the amplifier to operate in pure class-A up to approximately 75 W before transitioning into class-AB operation, with output extending to approximately 140 W.

High Power mode raises the operating voltage and delivers the amplifier’s maximum output: 300 Wpc into 8 ohms and 500 Wpc into 4 ohms, with peak output reaching 380 Wpc and 700 Wpc, respectively. The operating mode is selected using a switch on the rear panel.

Switchable Stereo and Mono Operation

The A 3100 HV can also be converted from stereo to mono operation, allowing one amplifier to be used for each loudspeaker. Instead of bridging its two channels, the amplifier connects the output stages in parallel. This approach increases current capability while retaining the load stability of the individual output stages. In mono mode, the A 3100 HV delivers 380 W into 8 ohms or 650 W into 4 ohms, with peak output reaching 430 W and 800 W.

Iso-Thermal Dual-Mono Construction

The internally isolated dual-mono amplifier boards use an optimized component layout designed to distribute heat predictably across both channels. Thermal-tracking diodes continuously monitor the bipolar output transistors and stabilize their operating points as the amplifier and surrounding room temperature change.

Voltage and current amplification take place on separate boards within physically isolated compartments. These stages are also galvanically isolated, reducing the interaction between the low-level voltage-amplification circuitry and the much larger currents being delivered to the loudspeakers.

Symmetrical Signal Architecture

The voltage-amplification stage uses a broadband, cross-coupled differential cascode circuit followed by a single-ended class-A large-signal stage. A fully symmetrical current amplifier combines MOSFET drivers with bipolar output transistors.

The circuit-board traces, output stages, and power-supply paths are arranged with mirrored symmetry. This layout allows opposing signal currents and their associated magnetic fields to compensate for one another rather than relying solely on additional filtering or shielding.

A Shielded 1,000 W Power Supply

The A 3100 HV is powered by a 1,000 W toroidal transformer that is hermetically sealed and enclosed within a magnetic shield. A 10 mm aluminum partition separates the transformer and high-current power circuitry from the voltage-amplification stages above.

Twelve low-inductance, low-ESR reservoir capacitors provide a total storage capacity of 120,000 µF. Their parallel arrangement reduces internal resistance and supports rapid current delivery during musical transients. A Power Link connection also allows the output stages to be powered by a compatible external T+A HV power supply, leaving the internal supply dedicated to the input and voltage-amplification circuitry.

Connections and System Integration

Balanced XLR and unbalanced RCA inputs are provided for each channel. Two independently switchable pairs of rhodium-plated brass speaker terminals support conventional wiring, bi-wiring, or two-zone operation. The A 3100 HV also includes H Link, a 5–20 V trigger input, a remote-control input, and a LAN connection for diagnostics and integration with compatible home-automation systems.

Features

• Switchable stereo and mono operation
• Selectable High Current and High Power modes
• Up to 75 W of pure class-A operation in High Current mode
• 300 Wpc into 8 ohms and 500 Wpc into 4 ohms in High Power mode
• Fully symmetrical dual-mono construction
• Physically and galvanically isolated voltage- and current-amplification stages
• Thermal-tracking diodes stabilize the output-transistor operating points
• Broadband cross-coupled differential cascode voltage-amplification stage
• Single-ended class-A large-signal stage
• MOSFET drivers and bipolar output transistors
• Hermetically sealed and magnetically shielded 1,000 W toroidal transformer
• 120,000 µF power-supply reservoir capacity
• Power Link connection for a compatible external T+A HV power supply
• Balanced XLR and unbalanced RCA inputs
• Two pairs of rhodium-plated brass speaker terminals
• Front-panel output meters with adjustable illumination and clipping indication
• H Link, LAN, remote-control, and 5–20 V trigger connections
• Made in Germany

Included Accessories

• Power cord
• H Link cable
• User manual

Specifications

Principle: Switchable stereo/mono power amplifier

Operating Modes: High Current and High Power

Amplifier Architecture: Fully symmetrical dual-mono

Analog Inputs: 1 pair balanced XLR, 1 pair unbalanced RCA

Speaker Outputs: 2 independently switchable pairs

Control Connections: H Link, LAN, RC input, 5–20 V trigger input

Output Power

Stereo (8 Ohms, 4 Ohms): 300 Wpc, 500 Wpc

Mono (8 Ohms, 4 Ohms): 380 Wpc, 650 Wpc

Peak Output Power

Stereo (8 Ohms, 4 Ohms): 380 Wpc, 700 Wpc

Mono (8 Ohms, 4 Ohms): 430 Wpc, 800 Wpc

High Current Mode Output: Up to 75 W pure class-A; up to 140 W class-AB

Slew Rate: 60 V/µs

Damping Factor (4 Ohms): >65

Input Sensitivity (25 V RMS Output): RCA 600 mV; XLR 1.2 V

Input Impedance: RCA 25 kohms; XLR 50 kohms

Gain: RCA 32.4 dB; XLR 26.5 dB

Power-Supply Reservoir Capacity: 120,000 µF

Mains: 110–120 V, 60 Hz

Maximum Power Consumption: 1,500 W

Standby Power Consumption: 0.5 W

Dimensions (HWD): 6.7" x 18.1" x 18.1" (17 x 46 x 46 cm)

Weight: 83.8 lb. (38 kg)