Progressive Audio A 901 Integrated Amp

A901 Integrated Amplifier – Consistent Class-A architecture for uncompromising control

The A901 is a fully monoblock integrated amplifier that operates exclusively in pure Class A mode. With a continuous output power of 70 watts per channel, it offers a current delivery capability comparable to conventional Class A/B designs with significantly higher power ratings, in terms of dynamics and authority. The A901 drives even demanding loudspeakers with low efficiencies (down to 83 dB) or complex, low-impedance characteristics with precision and without loss of control.

Semiconductor technology and circuit design

Innovative silicon carbide semiconductors (SiC) are used in the signal path. Due to the extremely steep slope of their characteristic curves, these components ensure exceptionally fast signal processing, minimal switching compensation, and precise spatial separation.

The circuit design utilizes a fully symmetrical, feedback-free bridge output stage in a dual-mono configuration. The absence of overall negative feedback eliminates phase errors and time distortions, guaranteeing high signal purity across an extremely wide frequency range of 1 Hz to 1 MHz (+/- 0.1 dB).

Level setting and signal routing

For level adjustment, the A901 uses a relay-controlled volume control. This enables precise channel balance and fine-tuning in level-fixed steps of 0.75 dB.

The inputs include four high-level inputs, among them two balanced XLR connectors. Thanks to a specialized input circuit, the XLR interfaces can be used as additional unbalanced inputs without signal loss, if required, via an adapter.

On the output side, the amplifier offers dual speaker terminals per channel, facilitating direct connection for bi-wiring configurations. Operation is possible either via the front panel controls or the standard system remote control.

Technical data

Amplifier principle: Pure Class A, fully symmetrical, feedback-free bridge output stage

Design: Dual-mono, modular

Continuous power output: 70 watts (Class A)

Frequency range: 1 Hz to 1 MHz (+/- 0.1 dB)

Semiconductor assembly: Silicon carbide semiconductor (SiC)

Volume control: Relay-controlled in 0.75 dB steps

Inputs: 4 high-level inputs (2 × balanced XLR, 2 × unbalanced RCA; XLR can be used as RCA via adapter)

Outputs: Dual terminals per channel (4 pairs total, bi-wiring capable)

Housing finish: Black aluminum, front panel: high-gloss black acrylic

Operation: Controls on the front of the device, including remote control

Dimensions (W × H × D): 44 × 21 × 42 cm

Weight: 22 kg