Master-3A (50W pure Class A)

90W per channel @ 8 ohms, 360W @ 2 ohms max output

True balanced CAST power amplifier

CAST and XLR balanced inputs

Ultra-linear, fully feedback-free output line with linear fax technology

Built-in power supply soft-start circuit.

Please note:

This is a 50W pure Class A amplifier and will operate at approximately 50 degrees, please do not place in poorly ventilated cabinets.

The maximum output of this amplifier is 90W at 8 ohms and 360W per channel at 2 ohms. This is in consideration of the fact that the average home user usually uses speakers below 88DB in a small room of about 20 square feet, while in a large room of about 40 square feet, the speakers are usually above 88DB. Such an environment and speaker configuration, the average power of 1W per channel can already meet the requirements of daily listening, even at high volumes, the average power of 5W per channel, can already make 88DB to produce sound pressure close to 100DB, and the machine also has 18 times the power margin, pure Class A design than the same or more powerful than some Class A or AB class to show a more powerful driving ability, to cope with sudden large dynamic The pure Class A design is also more powerful than some Class A or Class AB units of the same or higher power.

Overview:

The fully negative feedback-free CAST circuit gain stage operates in a pure Class A state, with no OPA or coupling capacitors used in the signal path,

Completely feedback-free output stage using linear fax technology, avoiding switching distortion and providing excellent linearity, resulting in performance as good as a pure Class A amplifier without the high heat of a pure Class A amplifier.

2 inputs: XLR / ACSS, even with XLR input, the signal is amplified by the CAST amplifier,

Uses 24 ON Semiconductor high power transistors. 50W X2 (8 ohms) pure Class A output, and 90W X2 (8 ohms), 360W X2 (2 ohms) maximum output

Two high quality ring bulbs, two R bulbs for a total of 1600W and 140,000 UF filter capacitors for independent power supply to the gain and output stages,

Four pure Class A parallel regulated power supplies,

All high quality audio components are used, including DALE resistors, WIMA, NOVER (UK brand) capacitors and audio input and output sockets as per our requirements, gold plated RA power sockets,

All components of the four balanced channels are precisely paired and mounted

Completely feedback-free output lines using linear facsimile technology.

Completely feedback-free output lines using linear fax technology:

After years of experience, we have designed a linear fax technology circuit that can be used in the output stage to achieve stable and reduced distortion without the need to apply loop feedback, giving the amplifier unparalleled ultra-linear performance.

In many conventional amplifier designs, the distortion level of the output varies considerably with the output power, and at the same power output, the distortion level varies considerably across the frequency range, especially in the high and low bands.

The following graph shows the distortion curve of a brand-name mono post-amp, the blue line shows the distortion rate at 8 ohms and 20 watts.

The following charts show the spectral range of various common instruments. The spectrum covers the range from 20Hz to 4KHz.

The different distortion levels must affect how the instrument sounds when played back. For example, if a piano is played back with a large difference in distortion between the different bands, the lower band may sound like a piano of brand A, the middle band like a piano of brand B and the upper band like a piano of brand C. The whole performance may sound like a mixture of several different piano brands cut together.

The main purpose of negative feedback techniques is to reduce distortion.

Some people believe that while negative feedback reduces distortion, it also makes the sound unnatural.

Although negative feedback designs have a low distortion rate when tested with static loads, once an inductive load such as a real loudspeaker is connected, the electrical potential of the loudspeaker operation is fed back into the amplifier input from the feedback loop and the resulting distortion is significantly increased and has a significant impact on the sound quality. A completely feedback-free design avoids this disadvantage completely.

Negative feedback techniques reduce distortion, but distortion increases as the output power increases. This makes it easy for some of the larger dynamics to fly off the speakers during listening and come crashing down on you with a sense of dissonance.

Distortion is usually higher and less controllable in designs without feedback. This is especially true for output stages operating at high currents.

The gain amplifier in this unit is a completely feedback-free amplifier using CAST technology, which, due to its technical advantages, allows for very low distortion.

The output stage uses Rexchip's linear fax technology completely feedback-free technology.

The whole machine is working in a completely negative feedback-free state. However, as you can see from the graph below, the distortion level at 20Hz to 5KHz stays fairly flat and straight, ensuring a consistent sound when various instruments are played.

The distortion in the higher frequency range from 5KHz drops dramatically and is even lower than that of an amplifier that relies on negative feedback, fully demonstrating that Rexchip's Linear Fax technology has brought the amplifier's linearity to the highest level.

The distortion level of this unit is almost indistinguishable from small to large output power, and in terms of listening, both large and small signals sound consistent and clear and round, with a very stable soundstage. The soundstage is very stable, and there is certainly no chance of the sound becoming rough and unpleasant at high volumes and high outputs.

The distortion level of this unit is almost indistinguishable from small to large output power, and the sound field is very stable with a consistent, clear and round sound regardless of the size of the signal. The soundstage is very stable, and there is no roughness or pounding when the volume and output are high.

　
How to connect a preamp with RCA outputs:

The Master 3 is a true balanced design amplifier, so even when connecting an unbalanced preamp with only RCA outputs, it is possible to convert to balanced outputs within the amplifier without any additional design, and the sonic improvement over some bridge amplifiers that are not true balanced designs is noticeable.

When connecting an unbalanced preamp, the best way to connect it is to use the signal cable connection as shown below. Changing to RCA inputs on the Master 3, or using RCA-XLR adaptor sockets will introduce more noise.