SPEC Corporation RSA-777EX Amplifier


“A compact amplifier designed to sound more like tubes”

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SPEC Corporation of Japan do things differently. They challenge the accepted norms of the industry and push the boundaries of what is possible with existing technology through extensive research and design.

SPEC Corporation was founded by Mr. Shirokazu Yazaka, a former chief engineer at TEAC and Pioneer, to achieve one goal: to deliver tube sound using semiconductor technology.

Make no mistake, the owners of SPEC Corporation love, and have owned, some of the best tube amplifiers ever made, and they have taken that sound and brought it up to date in producing their range of “Real-Sound Amplifiers”.

The RSA-777EX is the entry level model in the range but still utilises the same technology adopted across all models. The principles of using natural products to positively effect sound reproduction are also seen here.

The wooden side panels and insulators create acoustic instrument-like sound.

Like a musical instrument maker SPEC carefully select materials, select the appropriate mechanism of connecting the timber with the metal chassis, and combine different types of wood. An amplifier which has a high gain is sensitive to rigidity and vibration, the use of a wooden structure provides suitable vibrational dampening properties.

The violin-like shaped wooden panel of the RSA-777EX is a structure created by sandwiching maple with spruce. Spruce dampens the vibration of chassis suitably and resonates with a music signal like a violin. Spruce is often used in the manufacture of high quality string instruments and is used to great effect here as well.

The 3-dimensional form ensures that only Maple supports the main body. This design is fundamental in controlling resonance and damping and brings out the beautiful sound of music. This example of Japanese craftsmanship originates in the historic town of Hida-Takayama, known for its skilled wood-work and craftsmen.

The technology driving the sound.

The basic technologies of the RSA-777EX are an ‘Audio class switching power supply’ and ‘Class D technology’ – but forget everything you think you know about these technologies because this is very different.

For the RSA-777EX SPEC utilised “HIBIKI-ICHI” capacitors in the ‘Audio class switching power supply’.

“HIBIKI-ICHI” was developed with the goal of rapid response and natural tone in collaboration with world renowned capacitor manufacturer Nichicon. The “HIBIKI-ICHI” brings out even more texture for a more musical sound.

SPEC further improved the Class D technology by using some newly adopted and rarely found parts. Class D technology is extremely sensitive so SPEC compared many alternatives to find parts optimal in their pursuit of “Real Sound”.

This newly improved Class D brings you all of the musical information, so you can hear all the subtleties in the recorded material. By means of these improvements, the RSA-777EX is able to reproduce higher musical resolution and more natural tonal characteristics and you will notice it is very close to live sound.

SPEC amplifiers create very little heat.

Class D amplification controls output voltage by switching the duration of MOSFET’s. Because the output device is only a switch, the power stage generates very little heat. There are zero ventilation holes on SPEC amplifiers. As a result of this they can apply real wood for resonance control.


The RSA-777EX has an exclusive amplifier circuit that is designed for headphones. The power supply and volume control device are in common with the main amplifier. You can hear the realistic sound through your headphones in the same manner as same as main amplifier. This construction method creates a pure, realistic output to drive your headphones.

Volume control technology.

Controlling amplitude is very important factor reproducing sound. A device of inferior quality will negatively impact sound quality. SPEC has adopted the electronic volume control device carefully utilising a completely analogue circuit. The sound level is determined by a resistance ratio.

The mechanical volume knob located on the front panel only generates the control command – the audio signal doesn’t go through it. This is important for reproducing minute signal stably. Conventional volume sometimes make the sound dull. By this system, the sound quality doesn’t vary depending upon the volume device itself. Additionally, you can enjoy great sound even if at small volume levels.

If you require remote control this is available a a separate device in the RSR-1 (£785.00) which connects to the rear of the RSA-777EX as a receiver for the remote device.

The SPEC RSA-777EX is an analogue amplifier.

SPEC believe that it is a myth to say Class D is a digital amplification. SPEC has adopted ‘Pulse Width Modulation’ (PWM) in their design. This PWM converts signal amplitude to duration switching through analogue processing. Therefore this system doesn’t digitise the audio signal.

This they believe creates a type of analogue amplifier because magnitude resolution is infinite – the same as in an analogue amplifier. In the past, some audio manufacturers adopted delta sigma modulation for CLASS D, this is quite simply 1bit digital modulation – Class D with PWM contributes to create a beautiful acoustical sound.


Maximum output 100 W × 2 (4Ω), 75 W × 2 (6Ω), 50 W × 2 (8Ω)
Frequency response 10 Hz – 30 kHz ±1dB (6Ω, 1W)
Harmonic distortion ratio 0.02% (at 1 kHz, 80% output)
Input sensitivity, gain 300 mVrms, 37.3 dB (at MAX volume, 6Ω, 1kHz, unbalanced input)
Line input terminals XLR input : 1

RCA inputs : 3

Speaker terminals 1
Power voltage 240V AC, 50Hz
Electrical consumption With no signal : 18 W, during maximum output : 180 W (8 Ω, 100 Hz)
External dimensions 350 mm (width) × 95 mm (height) × 375 mm (depth)
Weight 7.0 kg