Stereo Power Amplifier SE-R1

Jitter is a major cause of distortion in digital systems, and is caused by mis-timing in the master clocks used in digital-to-analog conversion. To eliminate the degradation of sound caused by jitter, Technics has developed an original jitter reduction circuit, comprising a clock generator in the noise-shaping system to reduce jitter in the low-frequency range and a high-precision sample rate converter for suppressing jitter in the high-frequency range. Thus it reduces jitter in an ideal way over the entire frequency range.

This works with a newly-developed and original high-precision PWM (Pulse Width Modulation) conversion circuit, optimizing the noise-shaping speed, the degree and requantization number, and the PWM gradation, in order to convert high-resolution signals to PWM without causing any damage to the dynamic range. These new technologies enable new Technics digital amplifier designs to reproduce the natural and delicate nuances of music.

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.

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 optimization 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.

Some systems use a digital link between source component and pre-amplifier, keeping the digital signal pure as long as possible: Technics Digital Link goes further. It has eliminated the volume control function from the pre-amplifier, and instead transmits the volume control information, together with the audio signal, directly to the power amplifier in digital form. The power amp's jitter reduction circuit reduces any effect of jitter in signal transmission, then performs the volume control immediately before the PWM converter. This new sound transmission interface, Technics Digital Link, supports audio signals and also eradicates inter-channel effects by transmitting the left and right channel signals separately. Technics Digital Link has achieved an ideal amplifier configuration, minimizing any degradation between the pre-amplifier and the power amp, and resulting in superb stereo separation and reproduction of even the most subtle signals. The result is a more detailed and dynamic sound.

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 stabilized power supply circuit. These technologies incorporated in the power supply circuit enable the amp to drive the speakers powerfully under any conditions.

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 analog amplifiers.

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 length of the signal path is kept as short as possible to improve the signal to noise ratio, reduce potential sources of distortion and interference, and give the most direct communication of the music.

To support heavy parts and components and lower the center of gravity for improved stability, the inner chassis of the SE-R1 is made of 3-mm-thick plate, but the amplifier uses a huge, and very heavy, mains transformer: to support this better and reduce vibration, columns of die-cast aluminium are arranged at appropriate intervals between the bottom inner chassis and outer chassis. The external casing is made of a 7-mm-thick aluminium plate to resist the effect of electromagnetic noise.

Large, newly designed speaker terminals enable the connection of thick cables, and even the screws are high precision to ensure they remain tight, giving a firm and reliable cable connection. The insulators are cast iron for high rigidity and an excellent damping effect: this reduces both susceptibility to vibration, and the transmission of any vibration to external devices.