EsotericA-03usedEsoteric A-03 Class A Amplifier Excellent ConditionI have an Esoteric A-03 Amplifier for sale. Class A output 50 Watts @ 8 omhs / 100 Watts @ 4 omhs. This amp is in excellent condition and I have rated it as 8 but should be a 9. I am the 2nd own...4000.00

Esoteric A-03 Class A Amplifier Excellent Condition [Expired]

no longer for sale

I have an Esoteric A-03 Amplifier for sale.  Class A output 50 Watts @ 8 omhs / 100 Watts @ 4 omhs.  This amp is in excellent condition and I have rated it as 8 but should be a 9.  I am the 2nd owner and purchased from an Esoteric Dealer; original owner (purchased in 2014) traded it in on another amp.  I have the factory boxes (double boxed) with power cord. 

Now in for review is a class-A stereo amplifier from Esoteric, the A-03 ($14,000 USD). It measures 17.5"W x 8.6"H x 17"D and weighs about 70 pounds. My first impression of the A-03 was of how attractive it is. The photos I’d seen of it had not done it justice -- this amplifier is stunning. The front faceplate is natural aluminum subjected to a combination of blast and short-scratch finishing. It’s 20mm thick, with Esoteric engraved on it. An indention below the logo houses the Power and Warm-Up buttons, each backlit by a blue light. Press Warm-Up and the amp readies itself to play by using less power than if you were to just turn it on and leave it on. In Warm-Up mode, the total power consumption is 220W, or about 45% less than full throttle. Once the Warm-Up button is pressed, it blinks a few times, and the amp reaches its optimal operating temperature.

The symmetrically placed heatsinks on the A-03’s sides are processed from black Alumite, a liquid compound that is an excellent casting agent. Poured into a mold, Alumite solidifies in three minutes, to a consistency very much like manufactured plastic. The little ridges on the sinks increase their surface area, which means they can dissipate more heat. Great effort went into making the chassis of the A-03 as inert as possible; however, when I rapped a knuckle on the amp’s top plate, I did hear a slight resonance.

The input and output connections on the A-03’s rear panel are far enough apart to permit easy connections. The amp has one pair of speaker binding posts per channel; these are WBT-0710Cu terminals, whose conductor cores of pure copper are gold-plated for high conductivity and low resistance. The input connections are the standard balanced XLR and Esoteric’s own RCA terminals. In the top right corner is a selector for choosing between RCA and XLR input, and just below that is a switch to select between BTL (bridge-tied load, or mono configuration) and Stereo. The A-03 is claimed to output a minimum of 50Wpc into 8 ohms, 100Wpc into 4 ohms, or 200W into 8 ohms in BTL.

Audiophiles read a specification like "50Wpc" and immediately assume that it refers to a low-power amplifier. However, while that is the A-03’s official power-output spec, I’m told that, in reality, its maximum useful output into 8 ohms is more like 77Wpc. The A-03 has large, independent toroidal transformers, one per channel. According to Esoteric, this enhances the amp’s ability to "supply current to each channel’s speakers, while preventing interference between channels. By using an independent transformer and power circuit for the voltage amplifier stage, which drives the current amplifier stage, the effect of variations of 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 delicacy of expression within the music."

But why class-A, a very inefficient way of converting AC power into sound? Because the output devices of a class-A amp are always switched on, the unused energy is converted into heat and expelled into the listening room. Sure enough, the A-03 ran hot -- after an extended listening session, its heatsinks were hot enough to burn the skin. But while such inefficiency can heat a room while raising your electrical bill, the benefits in sound quality make up for it -- class-A amps are generally low in distortion and high in linearity, which means they sound cleaner and more natural to many people’s ears. The A-03’s signal/noise ratio of 117dB is impressive, and supports Esoteric’s claim that the A-03 has great sound. But did it?

Esoteric’s Website:

Rated output power      

STEREO 50W+50W (8ohms) 100W+100W (4ohms)

BTL         200W (8ohms)

Maximum useful output power STEREO 77W+77W (8ohms) 127W+127W (4ohms)

Frequency response       5Hz to 100kHz (1W, 8ohms. +0/-1.2dB)

Signal-to-noise ratio more than 117dB

Total harmonic distortion 0.009% (1kHz, rated output, 8ohms)

Minimum allowable speaker impedance 4ohms

Input sensitivity (rated output)  RCA (STEREO)    0.76Vrms (50W, 8ohms)

XLR (STEREO)     1.56Vrms (50W, 8ohms)

RCA (BTL)            1.62Vrms (200W, 8ohms)

XLR (BTL)             2.35Vrms (200W, 8ohms)

Input impedance RCA 150kohms  XLR 320kohms

Input terminal   RCA ×1 XLR ×1

Output terminal                Speaker terminal              Screw type (WBT-0710Cu) ×1

Ground terminal               Large screw terminal

General Power supply     AC 230V 50Hz  AC 120V 60Hz AC 220V 60Hz

Power consumption       400W

External dimensions (W×H×D)    445×220×430 mm (17 1/2×8 5/8×17)

Weight 38kg (84lb)

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