Предусилители — CAAS Elysian Pre-amplifier II

The Elysian Pre-amplifier II, or EPre II, is a fully balanced line preamplifier in the Reference series from CAAS Audio. It follows the original Elysian Pre-amplifier and is built as a dual monaural design, with dedicated transformers and power supplies for the left channel, the right channel and the digital control section. The chassis is machined on a 5-axis CNC from a single piece of high-grade aluminium and is finished in silver or black anodising.

Key specs that matter

Inputs comprise three stereo pairs of balanced XLR and two pairs of RCA, and one pair each of XLR and RCA outputs is provided. Level runs from plus 6 dB to minus 64 dB with mute, in 0.5 dB steps. CAAS quotes a frequency response from 0.3 Hz to above 200 kHz at the minus 3 dB points, with DC coupling from input to output. Input impedance is 33 kohm and output impedance 60 ohm. THD is below 0.01 percent at 1 kHz with a 0 dB level and 2 V RMS. Apart from the audio sockets, the rear carries connections for the CAAS bus, which switches pre and power amplifiers on together.

Engineering and use context

CAAS calls its output buffer the True Zero Feedback stage, a parallel, ultra linear Class A circuit using bipolar transistors, which CAAS says reduces THD, IMD and TIM while giving the cable and load drive that passive preamplifiers lack. Volume uses the Switched Resistor Volume Control, a computer-controlled, relay-switched attenuator with 128 steps that can be run by remote. Six separate zero-feedback Class A modules make up the Switched Amplifier Modules scheme. In this approach gain is set only by emitter degeneration, with no global or local feedback loops. The input-to-output path carries no coupling capacitors. Three transformer supplies isolate the sections, and the Fastpower arrangement uses 12 discrete analogue and 7 digital regulated supplies. RWave refers to the use of RF and microwave layout and stability techniques with fast transistors and short signal paths, CSD is a balanced differential Class A topology meant to let zero feedback circuits run fast at low distortion, and NIDS is a DC servo that acts only at ultra-low subsonic frequencies. The attenuator uses precision metal film resistors rather than a potentiometer.

Pairing

CAAS builds the Elysian 100 as both mono-block and stereo power amplifiers, and these can be switched on with the preamplifier over the CAAS bus. With its balanced outputs and low output impedance, the EPre II can also drive power amplifiers from other makers over XLR or RCA, and the Elysian Audio Streamer from the same series can act as a source.

Alternatives

The original CAAS Elysian Pre-amplifier is the earlier Reference series line preamplifier that the EPre II replaced.