A-03 Class A Stereo Amplifier

    The Overview

    As you have never experienced it before, the vivid colors of live music!

    The grandeur of a Stradivarius; the clarity of a Steinway. The original master tapes record each and every part of the music’s essence, ranging from the fine flavor of individual sounds, or the beauty of a symphony when those sounds are richly blended, to the ambience of the concert hall and the enthusiasm of the audience.

    ESOTERIC’s Master Sound Works concept pursues the vivid reproduction of these elements. Born of ESOTERIC’s years of experience in the development of state-of-the-art technology, this is our latest evolution in sound quality: the Class A Stereo Power Amplifier A-03. An elegant figure with enormous potential ----its beautiful presence and exceptional output heralds the cutting edge of audio amplification.

    In the A-03, you encounter vivid sounds of unprecedented intensity, bringing you an even more intimate relationship with your music.

The Features

Stand-out drivability for clearly reproducing even the most subtle nuances of music

 A power amplifier that emits high-quality output is the source for reproducing a musical experience featuring beautiful resonance swelling within the reverberation of crashing waves and vitality. Esoteric’s A-02 stereo power amplifier continuously balances maximum drive power and natural timbre regardless of the size and efficiency of loudspeaker selection. This way, the A-02 can portray in full the dynamism and delicacy inscribed in the original master recordings.

Following the L/R dual mono concept to maximize the purity of music

 The A-03's superior channel separation, stable orientation, and depth of sound, will make you feel as though separate monaural amplifiers were used for each channel. This model employs dedicated dual mono technology that established Esoteric's reputation for high-end design implementation. Equipped with independent power sections featuring dedicated toroidal transformers for the left and right channels, this amplifier also boasts enhanced mechanical strength and rigidity. Separate dedicated compartments for the power transformer, the power circuits and the voltage and current amplifier stages, all help to prevent electrical interference between components.

Rapid, generous power supply from separate high-capacity toroidal transformers


 Dramatic transitions between sounds, each of which is injected with life by the A-03's power supply capacity, directly arouse musical emotion. The power section of the current amplifier stage---which drives the speakers---features independent, large volume toroidal transformers, mounted on the left and right channels. This enhances the amplifier's ability to supply current to each channel's speakers, while preventing interference between the channels. By using an independent transformer and power circuit for the voltage amplifier stage, which drives the current amplifier stage, the effect of variations in the voltage is suppressed and the current amplifier receives a stable power supply. Separating each circuit block into power circuits and providing independent transformers reduces cross channel interference and enables both robustness and a delicacy of expression within the music.

Pure "Class A" amplifier circuits to follow every motion of the recorded material.

 The performance capability to beautifully reproduce an outstanding musical climax, or a nuance of simple acoustic delicacy, is one of the most important core qualities in an audio amplifier. A pure class A implementation with low distortion and high linearity is used for the amplifier circuit. This design always ensures an idling current that can output a minimum of 50 watts RMS with an 8 ohm load. This, provides excellent responsiveness for sudden bursts of high volume demand, as well as high purity of expression. Large transistors with a current supply ability of 17 amps. for continuous output, and 34 amps. for sudden bursts of high output, are used for the current amplifier stage. Five of these transistors are mounted in a parallel push-pull configuration for each channel, driving all speakers without compromise.

Usable as a monaural power amplifier with bridged ("BTL"), connection

 By using this product as a monaural power amplifier in bridged (BTL), mode, a minimum output of 200 watts at 8 ohms can be achieved.

Obsessive use of high grade components everywhere


 We have gone to extremes to use the highest quality components to maintain signal clairity and minimize transmission loss. For connection terminals, the amplifier uses the XLR input terminal---which is highly reliable and provides excellent contact---along with ESOTERIC's original RCA input terminal. In addition, the WBT nextgen; WBT-0710Cu speaker terminals have conductor cores of pure copper with gold plating to achieve high conductivity and low resistance. On top of this, we have used ultra high grade components such as an electrolytic capacitor and a high frequency/low impedance transistor. These components were selected based on property examination and trial listening. It is an Esoteric requirement that all critical components undergo exhaustive listening tests before any final section is made.

A highly rigid structure to prevent circuit interference and suppress resonance

 The A-03 features a highly rigid body construction that surpasses a great number of power amplifiers. The amplifier's mass of about 38 kg (84 lbs.) presages excellent musical purity protected by thick steel. The internal circuit components are separated into dedicated inner compartments for each circuit, partitioned by 2 mm steel walls. Combined with a 5 mm steel bottom chassis, interference between circuits is prevented and the adverse effects of resonance caused by internal and external vibrations are minimized. Also, the unique chilled steel pinpoint feet provide a very strong four-point support system for the heavyweight housing.

Now equipped with warm-up mode


This function enables the device to be warmed up to play audio, while reducing electric power consumption (As compared to normal operation). At warm-up mode: power consumption of 220 watts (a reduction of about 45%) is achieved.

The Specs

Speaker Outputs
Rated output power STEREO 200 W + 200 W (8 Ω)
400 W + 400 W (4 Ω)
BTL BTL 800 W (8 Ω)
Maximum output power STEREO 250 W + 250 W (8 Ω) (JEITA)
500 W + 500 W (4 Ω) (JEITA)
BTL 1,000 W (8 Ω) (JEITA)
Frequency response 5 Hz ~ 100 kHz (1 W, 8 Ω, ±1 dB)
Signal-to-noise ratio (S/N) 117 dB or more (JEITA)
Total harmonic distortion 0.009 %
(1 kHz, 8 Ω, Rated output power)
Minimum required impedance STEREO 4 Ω / BTL 4 Ω
Gain 28 dB
Analog audio inputs
Jacks RCA jacks 1 stereo
XLR jacks 1 stereo
Input impedance RCA 150 kΩ / XLR 320 kΩ
Power supply AC 230V 50Hz
AC 120V 60Hz
AC 220V 60Hz
Power consumption 550 W
External dimensions (W x H x D) 445 x 220 x 430 mm
(17 1/2" x 8 5/8" x 16 15/16" )
(including protrusions)
Weight 41.2 kg (91.5 lb)
- Design and specifications are subject to change without notice.
- This product is available in three different power supply variations shown in the chart above. Make sure that the voltage shown on the rear panel matches the AC line voltage in your area.
- The shape of the AC inlet and plug of the supplied power cord depends on the voltage rating and destination country.