DESCRIPTION |
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Reduced in July 2023. Was: €2.000. Solid-state stereo amplifier. Extensive cosmetic alterations, internal structural changes, and new circuit designs make it quite different from the No.27 and No.27.5 models that preceded it. The No.331 is a dual-mono design with completely independent power supplies, voltage, and current gain-stages packaged in one compact chassis; two toroidal transformers (801 VA), one for each channel, oriented to cancel stray magnetic fields; a soft-clipping circuit to reduce the subjective effects of amplifier overload and clipping; and all voltage gain-stages independently regulated. The design of the '331's signal circuitry is based on the No.33 Reference amplifier. It features a balanced signal path and three voltage gain-stages. An important aspect of the design was the implementation of a new sliding-bias output-stage topology which Madrigal calls "Adaptive Biasing." An amplifier with Great clarity, transparency, power and super control. Specifications: Rated output power, 20Hz–20kHz, with no more than 0.5% THD (FTC): 100Wpc minimum continuous into 8 ohms (20dBW); 200Wpc minimum continuous into 4 ohms (20dBW); 400Wpc continuous into 2 ohms (20dBW). Peak output voltage at rated line voltage: 48V into 8 ohms. Frequency response: 20Hz–20kHz ±1dB. S/N ratio (main output): <–80dB (ref. 1W). Input impedance: 100k ohms balanced, 50k ohms single-ended. Voltage gain: 26.8dB. Input sensitivity (for 2.8V output): 130mV. Input sensitivity (for full output): 1.3V. Output impedance: !x0.05 ohms, 20Hz–20kHz. Damping factor: >800, 20Hz–20kHz into 8 ohms. (2) Inputs: 1 x balanced (XLR) and 1 x unbalanced (RCA). Two pairs of speaker binding posts. Remarks: a) No original packaging; b) three dents on the top of the right heat sink and one mark on the top of the left rear heat sink. |
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