Stereo Power Amplifier (1995)
The Quad 707 can deliver 120W per channel into an 8 ohm load and 250W into 4 ohms. It uses a current dumping output circuit, a Quad invention which eliminates many of the problems associated with transistor amplifiers and is covered by patents in several countries.
In a current dumping amplifier there is in effect both a low power very high quality amplifier, and a high power, heavy duty amplifier. The low power amplifier controls the loudspeakers at all times, calling on the high power amplifier to provide most of the muscle.
The low power amplifier is so arranged, it carries an error signal, that provided the larger power transistors (the current dumpers) get within the target area of the required output current it will fill in the remainder accurately and completely. The reproduced quality is solely dependent on the small amplifier which because of it's low power can be made very good indeed.
Problems of crossover distortion, quiescent current adjustment, thermal tracking and transistor matching all disappear. There are no internal adjustments or alignments and the choice of power transistor types is less restrictive.
Power output: 120 watts per channel into 8Ω (stereo), 240W into 4Ω (mono)
Frequency response: 20Hz to 30kHz
Total harmonic distortion: 0.01%
Input sensitivity: 0.5V
Signal to noise ratio: 105dB
Speaker load impedance: 4Ω (minimum)
Dimensions: 321 x 140 x 235mm
Finish: carbon or nextel front panel
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