Power amplifiers stereo — Analog Domain The Apollo

The Apollo belongs to the DX9 line made by Analog Domain Audio GmbH, which also includes the Athene, Artemis, Calysto and Isis amplifiers. It is a stereo power amplifier housed in the brand's M4 chassis, and the maker positions it as especially suited to powering the LF or subwoofer channel when a split, multi-amplifier arrangement is used.

Key specs that matter

Analog Domain rates the Apollo at 4,000 W into 8 ohm and 8,000 W into 4 ohm as peak power, and states that it is 2 ohm stable while the minimum rated load is 4 ohm. Peak output voltage reaches 179 V AC (plus or minus 253 V peak to peak), with current peaking at 120 A. The output stage uses 100 audio-grade power transistors with a combined peak current capacity of 720 A. Input sensitivity is 1.55 V RMS into an input impedance of 10 kohm, and voltage gain is switch-selectable between +41 dB and +26 dB. The frequency range spans 1 Hz to 100 kHz, while full-power bandwidth is 5 Hz to 25 kHz. THD+N is below -92 dB (0.0025 percent), output noise stays under 50 uV RMS, dynamic range exceeds 126 dB linear or 132 dB A-weighted, while damping exceeds a factor of 1000.

Engineering and use context

All Analog Domain amplifiers use fully symmetrical bridged configurations with hand-matched transistors kept within their linear operating regions. The signal path is built exclusively from discrete components in proprietary circuits, and the company avoids operational amplifiers on the grounds that they limit dynamic range. Driving signals and control functions in the power stages are handled by the in-house DX901 hybrid chip with DXDrive technology, which went through nine design iterations. Energy comes from custom toroidal mains transformers designed in-house, backed by long-life capacitors for filtering and storage. The chassis is machined from solid aluminium blocks and is virtually airtight once assembled. Protection covers mains over- and under-voltage, overheating, input overdrive, output short circuit, DC at the output and excessive HF or RF, and a soft-start circuit limits current at power-up. The unit is factory set for 230 or 115 V mains, draws 200 W at idle and under 20 W in standby, and pulls less than 16 A at 230 V. It measures 440 x 298 x 545 mm and weighs about 85 kg, or 115 kg packed.

Pairing

Both XLR balanced and RCA unbalanced inputs are fitted, and 12 V trigger input and output on 3.5 mm jacks allow switching together with other components.

Alternatives

The Analog Domain Artemis is a lower-powered stereo model from the same DX9 range, able to share a stack with the Apollo.