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140w 2 Channel current dumping amplifier
The 909 Stereo power amplifier incorporates Quad’s patented current dumping technology and is one of the finest audio amplifiers available today. The current dumping technique eliminates many of the problems associated with transistor amplifiers giving a consistent and predictable performance without a need for the fine tuning adjustments on the production line. In current dumping amplifiers there is a very high quality low power output amplifier and a very high power output amplifier whose performance is not critical. This high power output amplifier controls the loudspeaker at all times and provides the current or ‘muscle’ to generate the sound. The low power output amplifier is arranged to generate a signal that compensates for errors between the input signal and the signal fed to the loudspeakers. The result is that the quality and accuracy of the output signal depends only upon the performance of the low power amplifier. In the 909 this low power output amplifier has been engineered to the highest standards. The problems of crossover distortion; quiescent current adjustment; thermal tracking and transistor matching all disappear. If such a thing as a perfect amplifier were to exist, then the 909 would be very close to that perfection.

909 & 2905 Review TAS Part 1 (see 99 Series Overview for Part 2 of this review.)
Documents
909 Stereo Instruction manual (833.6kb)
909 Schematic (633.0kb)
Quad 909 Service Data (443.4kb)
 
Photos (view all)
909 (classique) (257.0kb)
909 Front (16.0kb)
909 Front three-quarter view (black) (84.9kb)
909 Front (2) (69.7kb)
909 Front (black) (75.8kb)
909 Rear (21.9kb)
909 Rear; large (96.8kb)
909; Internal bottom view (264.7kb)
909; Internal view (272.3kb)
 
Reviews
909 Review; Hi-Fi World August 2003 (757.4kb)
909 Review; What Hi-Fi Nov 2002 (117.6kb)
Review 99 and 909 Absolute Sound 2011 (312.7kb)
909 & 2905 Review TAS Part 1 (link)
Review 99 and 909 AVguide.com June 2010 (link)
Stereo Times August 2002 (link)
 
Internet Links
909 Stereo Official Site (link)
 

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