Power amplifiers stereo — Gryphon Audio Hyperion

The Hyperion is a power amplifier from the Danish firm Gryphon Audio, offered in stereo and mono versions. Gryphon presents it as the successor to its Mephisto amplifier, combining technology from the Apex with new engineering. The stereo version is designed and manufactured in Denmark, with Tom Møller responsible for the electronics.

Key specs that matter

The stereo unit delivers 2 x 180 W into 8 ohm, 2 x 360 W into 4 ohm and 2 x 720 W into 2 ohm at 115 V or 230 V mains. Output impedance is 0.025 ohm, and the -3 dB bandwidth covers 0.3 Hz to 330 kHz. Gain is +31 dB with a 1.07 Vrms input level, and the balanced input impedance is 20 kohm. Unweighted noise across 20 Hz to 20 kHz is below -80 dBV, and A-weighted noise is below -83 dBV. Idle consumption is 206 W on the low bias setting, 470 W on mid and 715 W on high, and standby draw is under 0.5 W. The chassis measures 59.4 x 33 x 65.4 cm and weighs 126 kg net.

Engineering and use context

Operation is Class A in a pure dual mono configuration with zero global negative feedback. The output stage holds 40 bipolar transistors rated for very high current, backed by a 500,000 uF capacitor bank and two separate custom 1,500 VA toroidal transformers in individually decoupled left and right castings. The signal first meets an extremely low capacitance Class A J-FET buffer, then balanced dual differential Class A input circuitry and a fast symmetrical Class A voltage amplifying stage. All voltage amplifying stages draw from a fully regulated low-noise supply, and digital and analog circuits each have a separate linear supply. DC servo coupling gives a frequency-independent damping factor. Zn foil capacitors, which Gryphon says have a loss factor ten times lower than metallized PP film types, decouple the local supplies, and circuit boards have four layers with copper traces as thick as 105 um. Internal wiring is Gryphon silver.

Pairing

Inputs are true balanced via gold-plated Neutrik XLR connectors, and outputs use custom gold-plated Gryphon binding posts. Bias can be set automatically through the Green Bias link or chosen manually. A 12 V link handles remote power, an AC polarity indicator is fitted, two C19 inlets take the mains and new firmware is installed from a USB stick. The mono version gives 200 W into 8 ohm per unit.

Alternatives

Gryphon's heavier Apex Stereo steps up to a larger output stage and power supply.