Master 19

True balanced CAST design

Pure Class A output (9W @ 40 ohms)

Preamp & Headphone Amplifier,

Two-position volume characteristic control, direct drive for 80DB headphones without gain boost.

Mini Remote Control:

Please note:

1, If the customer does not have a good DAC or good audio source and only intends to connect to a PC sound card or mobile phone audio output, this is not the right unit for you.

2, In order to get the best performance from this unit, customers need to connect a balanced good audio source and balanced good headphones.

3, Due to the limitations of the courier company, the mini remote control does not have batteries installed, customers need to purchase their own CR2025 batteries to install. The metal remote control needs to be installed with two AAA or No.7 batteries.

Connection to the CAST input of KRELL amplifiers:

The Master 19 is compatible with the CAST input of KRELL amplifiers.

All that is required is a pair of signal cables to connect one end of the Master 19 to the CAST input of the KRELL amplifier and the other end to the CAST input of the KRELL amplifier.

The output pins of the Master 19 are defined as follows.

Pin 1, GND -----> Pin 1 and 4 (KRELL)

Pin 2, Hot -----> Pin 2 (KRELL)

Pin 3, Cold -----> Pin 3 (KRELL)

KRELL amplifiers have a lower gain compared to Rexroth's Master series. If the customer expects to connect to the CAST input of a Krell amplifier, they can specify this when placing their order and we will increase the output signal to match the KRELL amplifier.

Overview:

Truly balanced all-transistor feedback-free CAST current transfer circuit

Four pairs of precisely paired 150 W high power tubes (up to 1200 W total) act as output stages and voltage regulators for high power pure class A output

Two high performance R bulbs with a total power of 100 W. Over 35,000 UF of audio filter capacitors

4 pure Class A power supplies.

100-level, four-channel, digitally controlled relay I/V switchable volume control to avoid channel imbalance and sound degradation

Super exponential wide response volume control, easy to adjust with a variety of high and low sensitivity headphones or speakers

16, 25DB gain, easy to drive a variety of sensitivity headphones

Hi-end grade components, precision matched tubes, OCC cables

5 preamp inputs: XLR X2 / RCA X2 / CAST X1

Preamp outputs : XLR / RCA / CAST

Headphone output : 4 pole XLR X1 / Single ended X1

Core:

The Master 19 is a truly balanced design preamp that uses the latest CAST technology to advance the sound quality of the XLR input to be as good as CAST, with an all-transistor design (the OPA op-amp is a DC servo circuit).

The Master 19 may look complex, but it is in fact the simplest design in the world, with many of the components used for power processing. The simple and short signal processing channels result in a dramatic improvement in sound quality with very little colouration.

The Master 19 uses a single stage CAST amplifier circuit with extremely low distortion and is mounted directly on the motherboard for better sound quality. It is a full Class A preamp and uses a Class A power supply.

The CAST circuit is a transistorised amplifier with no feedback at all. Many audiophiles know that a negative feedback design provides better test specs, but a feedback-free design provides better listening. This is a contradiction between traditional circuits. But the CAST circuit breaks new ground by offering extremely low tone coloration, a very neutral and natural sound with very low distortion and excellent linearity. As a result, it reproduces dynamics and detail without sounding rough and dry.

All signal gain stages operate in current transfer mode and all transistors operate in Class A condition.

To drive the headphones and amplifiers, the output buffers use four pairs of high power 150W operating in pure Class A to achieve ultra low distortion and an output impedance of just 1 ohm.

All components of the Master 19's balanced four channels are precisely matched for installation.

Powerful Class A-only output stage:

The Master 19 is designed with four diamond-shaped output stages that act as balanced drive outputs, each precisely paired to eliminate the need for further human adjustment.

The four diamond output stages use four pairs of 150W transistors and operate in pure Class A condition. The pure Class A output stage has more power than a Class AB design with twice the power and it goes without saying that the pure Class A design is the best sounding design in the world. Balanced drivers increase the output power by four times compared to unbalanced drivers in the same condition, driving even high or low resistance headphones well. Balanced drivers cancel out noise and distortion in the headphones, resulting in a quieter soundstage and clearer detail.

Power supply:

Two separate transformers supply power to the left and right channel circuits respectively.

The Master 19 uses four pure Class A all-transistor regulators to supply the audio circuitry.

The Class A parallel regulated power supply has a very high input impedance and a very low output impedance, effectively isolating the audio circuitry from the power supply to prevent power interference from entering the audio circuitry, providing a clean and fast power supply to the circuitry.

The Master 19 uses a separate linear regulated power supply for the display and control sections to avoid interference with the audio circuitry and degradation of the sound quality.

Input/Output:

In addition to accepting XLR and RCA inputs, the Master 19 can also accept CAST current transfer inputs. Outputs XLR, RCA and CAST signals. Even with the RCA input, the Master 19 will convert to CAST and then amplify and output a truly balanced XLR and CAST signal.

The Master 19 can output RCA, XLR and CAST signals simultaneously in preamp mode without switching, and in headphone mode to balanced and unbalanced headphones.

The Master 19 inputs use the idle shield method. Unused inputs are short-circuited and disconnected from ground, so that even if more inputs are connected, the sound quality is not compromised.

CAST input / output is compatible with KRELL CAST products and SATRI products.

Volume control:

The Master 19's volume control is a departure from other technologies. Conventional volume control involves placing a volume control potentiometer at the input of the amplifier to attenuate the signal, but the quality of the potentiometer has a direct impact on the sound quality, as low quality potentiometers cause loss of detail and channel imbalance, even with high quality potentiometers. Even with high quality potentiometers, the signal-to-noise ratio will deteriorate regardless of the quality of the potentiometer used.

The Master 19, on the other hand, already operates in the current region without the need for conversion, giving a higher degree of fax.

The Master 19 uses a four-channel, digitally controlled, relay-based volume control, which is controlled by switching a high-precision DALE resistor, eliminating channel imbalances and inaccuracies in the + and - of the balanced signal, and achieving the best possible sound quality and performance. The volume control is easily adjustable with a wide range of high and low sensitivity headphones or loudspeakers. As the user adjusts the volume, different relays switch the resistors so that the output may have a slight relay switching sound, which will disappear once the volume is stopped.

Components:

All audio-grade components are used, including Toshiba transistors, WIMA capacitors, custom-made NOVER (British brand) capacitors and audio-grade input and output sockets to our specifications.

Function to shield idle inputs:

The unit is designed with a short-circuit shielding function for idle inputs to avoid interference between sources when connecting different sources.

How it works: Without the idle input short circuit function, when input 4 and input 5 are connected to two different external DACs, when the user selects either input 5 or input 4, the unselected input signal will be emitted across the line and mixed into the selected signal, although this is very weak, it will lead to a deterioration of the sound quality.

When the idle input short-circuit function is available, when the user selects either input 5 or input 4, the unselected input will be short-circuited and no signal will be emitted across the line to interfere with the selected signal, so the sound quality is not affected.

In the following cases, the user needs to open the machine without blocking the idle input function and remove the short-circuiting plug for the corresponding channel and both channels at the same time.

1. The same external source is connected not only to the analogue input of the unit, but also to another amplifier.

2. The same external signal source is connected to different inputs of the unit at the same time.

Features:

OUT switch :

Selects Master 19 from the headphone output (display H) or the preamp output (display P).

Gain switch :

L: 16DB gain, suitable for headphones above 100DB or for preamp use.

H: 25DB gain, suitable for headphones up to 80-100DB.

With our new gain control technology, there are no in-line switches, relays or amplifier parameters to be changed when switching between gains, so the sound quality is exactly the same at different gains between H and L. The user only needs to select the appropriate mode to make the volume control more convenient for personal adjustment.

Input switch :

Selects Master 19 Inputs 1-5.

Volume knob :

Selects the Master 19 volume.

Setting the hidden function mode :

Press the "Input" switch to input 5, adjust the volume to 0 and turn the volume knob down to enter the settings menu.

Press the "Input" button and the three displays will flash in turn, the flashing display means that the setting can be changed.

Press "Gain" and the flashing display will be changed, with 0 for the function to stop and 1 for the function to take effect.

The first display is the remote control function setting, mainly for the remote control volume function, when set to 0, the volume changes by one stop when the remote control is pressed. When set to 1, the volume will increase or decrease continuously when the remote button is pressed continuously. If the machine is susceptible to interference from other devices, please set this function to 0.

The second position is the automatic screen darkening setting. When set to 0, the display will light up when the machine is switched on. When set to 1, the display will automatically switch off after about 10 seconds of no operation, leaving only one LED to show that the machine is powered on.

The third position is the volume memory setting, when set to 0, the volume does not use the memory function. When set to 1, the volume has a memory function and will remain at the volume level of the last time the machine was switched off, even if the machine is switched off and then switched on again.