Quad 909 Power Amplifier – Black

Peter Walker founded the Acoustical Manufacturing Co. in 1936, and since then all Quad products have displayed originality in design,. Here we have a 909 power amplifier that is in very good condition with just a couple of minor blemishes – please see photographs. It comes supplied professionally packaged, with manual, interconnect & mains cables plus our standard 3 month warranty.
Quad says….
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 Quad 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 Quad 909 would be very close to that perfection.
Specifications:
Maximum Power Output: 140 WRMS – 8 ohms(0.5% THD); 250 WRMS – 4 ohms(0.5% THD)
Maximum Output Current: 11 Amps peak each channel
Total Harmonic Distortion: ‹0.02% (140 watts, 8 ohms; 20 Hz to 20 kHz)
Input Sensitivity (phono ): 775 mV
Output Impedance: 1.5uH parallel with 0.05 ohms
DC offset voltage: less than 10 mV
Frequency Response: 13 Hz to 40 kHz (+0dB/-1dB)
Signal-to-noise ratio (70W): 108dB (20 Hz to 20 kHz)
Dimensions: 321 (W) x 240 (D) x 140 (H) mm

From What Hi-Fi?….
“This classic power amp design is a class performer that’ll work superbly in a wide range of systems.
Even-handed sonic delivery with strong dynamics and fine resolution.”