Theta Showcases Citadel Power Amplifier

Monaural 400-Watt, Fully Balanced, Zero-Feedback Amp Delivers No-Compromise Performance For Two-Channel And Home Theatre Systems

1-Oct-01

Theta Digital, long acclaimed America's leader in digital technology, showcased the new Citadel Power Amplifier at CEDIA EXPO 2001.The Citadel is a monaural power amplifier, created to satisfy the needs of the most revealing two-channel music reproduction systems, as well as home theatre environments demanding abundant power to effortlessly recreate the vast spectrum of movie soundtracks. A no-compromise amplifier in every sense of the word, the Citadel offers all the advantages -- and then some -- of the knowledge, research and dedication Team Theta brought to developing the legendary Dreadnaught Amplifier.Possessing a nominal power rating of 400 watts into 8 ohms, the Citadel's power supply is an exercise in delivering massive brute power with absolute integrity. Sonically, this is expressed as a new level of veracity and intimacy in the experience of music, and also movie sound performance that no commercial theatre can hope to rival.The core of the Citadel is fully balanced differential, zero-feedback circuitry, and zealously selected, solid-state devices. Theta engineers scrutinized the selection of component parts in each and every stage for the finest possible performance. Custom-made capacitors, Vishay precision resistors, copper buss bars, 12-gauge Litz/Teflon wires, a custom-made, high pressure contact, Delrin/Rhodium-plated output connector, and more combine to make the Citadel an unprecedented technical statement.The Citadel's fully balanced design, created by the use of two mirror-imaged signal paths, results in the rejection of common mode noise -- discontinuities picked up in the course of amplification. Other means of dealing with noise are crude by comparison in that they leave artifacts in the signal, phase anomalies that degrade spatial information, and inter-modulation distortion, which make timbres sound wrong. These parameters are not quantified in measurements on the ""spec sheets"" typically available.While most power amplifiers use global feedback in large proportions, and exhibit the common byproducts of global feedback, such as smearing of the image or harshness and glare at upper-midrange levels, the Citadel contains no global feedback at all. The result is a very clean, pure, fast circuit from input to output.The Citadel's output stage employs a high current, kilowatt power transformer that feeds a unique dual-choke, capacitive filtering system. This technique is rarely applied, because of the huge choke size necessary to avoid impeding high current demands. Citadel's filtering system employs two massive chokes almost as large as the power transformer. These are fed from an ultra-fast/soft-recovery, 35-amp full-bridge rectifier. This filtering system results in high current power supply lines more than 800 percent cleaner than conventional supplies. The sonic result of such super clean supply lines to output transistors has not previously been achieved at high power levels.The Citadel's seamless housing, devoid of traditional fasteners on the top, front and sides, provides a stable operating environment, and delivers a strong aesthetic statement. The power supply resides in the base, isolated from the amplifier module above. Additional features that distinguish the Citadel include:- Custom-made polypropylene capacitors - Ultra-fast/soft recovery bridge rectifiers for regulated and high current supplies- Gold-plated RCA and XLR input connectors - Rear panel LED indicators for fuses and thermal overload - Rear panel jacks for remote control of Mute/Standby and Input Selection - A slot for future upgrade expansion - Separate AC lines for analog power and possible future digital circuits - RS-232 connections for computer controls and status information - Control tower buttons for Mute/Standby and Input Selection; LED indicators for Mute/Standby, Input Selection and Thermal Overload The Citadel Power Amplifier is available now for a suggested price of $7,900 each.For additional information about Theta Digital, visit www.thetadigital.com.

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