Technics stereo power amplifier SE-R1 sets a new high performance standard for amplifiers.
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The main amplifier layout separates the left and right channel signal paths completely, all the way back to the secondary winding on the power transformer, to prevent mutual interference and also achieve an ideal weight balance. This design gives optimal stereo separation, and also allows the two channels to be laid out in ‘mirror image’, giving equal signal-path lengths for each channel. The best power supply for delicate circuitry such as the clock generator in the new amplifiers is one entirely isolated from any noise or fluctuations in the mains supply.
Technics has extensive experience in circuits using battery isolation, having used them to create ultra-low-noise pre-amplifier stages in past analogue amplifiers. The accurate reproduction of everything from dynamic and powerful sounds to the low-level signals expressing delicate nuances requires a special power supply in an amplifier. It needs to be both powerful and low-noise, as well as capable of responding instantly to a continuously changing audio signal without any voltage fluctuation. The power supply circuit of an ordinary amp consists of a large-capacity power transformer and a rectifier circuit.
After examining ways to achieve ideal voltage and current waveforms, Technics decided to use a choke-input rectification, plus a discrete stabilised power supply circuit. These technologies incorporated in the power supply circuit enable the amp to drive the speakers powerfully under any conditions. The impedance of a speaker is not constant: it varies according to frequency, thus altering the loading on an amplifier and therefore potentially the sound. Technics is able to measure an amplifier's frequency amplitude-phase characteristics with speakers connected, and has developed a speaker impedance adaptive optimisation algorithm using digital signal processing to achieve ideal impulse response.
Correction processing based on the new algorithm achieves a flat frequency response for both amplitude and phase, not possible in conventional amps, and delivering a sound with rich spatial expression. In the speaker-driving section of the amplifier, Technics has employed a high-speed GaN (gallium nitride) FET driver device with super-low resistance. This enables the construction of a high-power amp using a single push-pull configuration, allowing the length of the large current carrying signal path to be shortened, and resulting in outstanding linearity regardless of the sound level. ■
