Master 9 (2019 Edition) Balanced CAST Design

Pure Class A output (9W @ 40 ohms),

Preamp & Headphone Amplifier.

Connects to the CAST input of KRELL amplifiers:

Master 9 is compatible with the CAST input of KRELL amplifiers.

All that is needed is a pair of signal cables to connect one end of Master 9 to the CAST input of the KRELL amplifier and the other end to the CAST input of the KRELL amplifier.

The output pins of Master 9 are defined as follows.

Pin 1, GND

Pin 2, Hot

Pin 3, Cold

Pin 4, GND

If the customer expects to connect the CAST input of the Krell amplifier, he can specify when placing the order, and we will increase the output signal to match the KRELL amplifier.

Overview.

True balanced all-transistor feedback-free CAST current transfer circuit,

Six pairs of precisely paired 150 W high power tubes (up to 1800 W total) act as output stages and voltage regulators for high power pure Class A output

3 high performance R-bulls with a total power of 135 W Over 55,000 UF of audio filter capacitors,

9 groups of regulated power supply use,

100-level four-channel digital control relay I/V conversion volume controller to avoid channel imbalance and sound quality degradation.

Super exponential wide response volume control, with a variety of high and low sensitivity headphones or speakers are easy to adjust
16, 25, 31DB three kinds of gain, drive a variety of sensitivity headphones as easy as a hand

Hi-end level components, precise pairing tube, OCC line

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

Preamp output : XLR / RCA / CAST

Headphone output : 4 core XLR X1 / 3 core XLR X2 / Single ended X1

Impedance matching:

There are many different brands of DACs in the world, with different designs and potentially very different output impedances. To prevent the sound quality from being affected by the different output impedances of different DACs, in Master 9, we designed four expensive single-pole pure Class A Wollman FET buffers on the input side, through which all input signals pass, so that the output impedance is constant and not affected by the high or low output impedance of external sources.

The FET buffers operate in a pure Class A state, and they have an extremely short signal flow that ensures that the sound is not colored and does not produce dryness and harshness.

Core:

Master 9 is a truly balanced design preamp, applying 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).

Master 9 may seem complex, but it is actually the simplest design in the world, with many devices used for power processing. The simple and short signal processing channels result in a dramatic improvement in sound quality and minimal coloration.

Master 9 applies 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 transistor amplifier with no feedback at all. Many audiophiles know that a negative feedback design provides better test metrics, but a feedback-free design provides better listening. This is a contradiction between traditional circuits. But the CAST circuit has opened up a new era by providing extremely low tone coloration, extremely neutral and natural sound with very low distortion and excellent linearity. So she can reproduce the dynamics and details without feeling rough and dry.

All signal gain stages work in current transfer mode, and all transistors work in Class A state.

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

All components of the Master 9's balanced four channels are precisely paired and mounted.

Powerful pure Class A output stage:

The Master 9 is designed with four diamond-shaped output stages that serve 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 a pure Class A state. The pure Class A output stage has more drive power than the specification and is no worse than a Class AB design with twice the power. It goes without saying that the pure Class A design is the best sounding design in the world. The balanced driver makes the output power than the same conditions of the unbalanced driver to increase the output power by 4 times, even if the high resistance or low resistance headphones are driven well. Balanced driver can be noise and distortion in the headphones to offset, so that the sound field more quiet, clearer details.

Power supply:

Three separate transformers supply power to the audio and control circuits.

Master 9 uses eight groups of high-performance all-transistor regulators to power 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 avoid power interference into the audio circuitry, providing a clean and fast power supply to the circuitry.

Master 9 uses a separate linear regulated power supply to separate the power supply for the display and control sections to avoid interference with the audio circuitry and degrade the sound quality.

Input/Output:

The Master 9 accepts XLR and RCA inputs as well as CAST current transfer inputs. Outputs XLR, RCA and CAST signals. Even with RCA input, Master 9 will convert to CAST signal and then amplify and output a truly balanced XLR and CAST signal.

Master 9 can output RCA, XLR and CAST signals simultaneously in preamp mode without switching, and in headphone mode to balanced and unbalanced headphones.

The Master 9 inputs use the idle shield method. Unused inputs are shorted and disconnected from ground, so that even if more inputs are connected, the sound quality will not be affected.

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

Volume control:

Master 9's volume control is different from other technologies. Traditional volume control is to place a volume control potentiometer at the input of the amplifier to attenuate the signal, but the quality of the potentiometer directly affects the sound quality, low quality potentiometers cause loss of detail and channel imbalance, even with high quality potentiometers will also cause loss of detail. No matter what quality potentiometer is used, the signal-to-noise ratio will be degraded.

However, in Master 9, we use an I/V conversion type of volume control, where the volume control is like a variable passive I/V converter mounted to the output of the CAST amplifier, where it works with a current signal instead of a voltage signal, (like the passive I/V converter output from the R-2R DAC chip), which gives The frequency response is very straight and no detail is lost. Following the power controller are four diamond-shaped, feedback-free buffer amplifiers that provide extremely low output impedance.

Mark Levinson understands the advantages of volume control in the current region, so in their top preamps, they use a significant number of devices to convert the voltage signal into a current signal for volume control, and then back into a voltage signal. The Master 9 is supposed to work in the current signal region without conversion, getting a higher degree of fax.

The quality of the volume control has a serious impact on the performance and sound quality of a truly balanced amplifier. It must ensure precise control of the signals of the four channels. If the + and - signals of the balanced signal are not guaranteed to be accurate, the balanced output will have severe distortion and make the sound quality and performance even worse than a normal single-ended output amplifier, wasting the design and high cost of a truly balanced amplifier.

The Master 9 uses a four-channel, digitally-controlled relay-type volume control, which controls the volume by switching high-precision DALE resistors, eliminating channel imbalances and inaccuracies in the balance signal + and -, achieving the best sound quality and performance. It is easy to adjust. When the user adjusts the volume, different relays switch the resistors, so the output may have a slight relay switching sound, once you stop adjusting the volume, the switching sound will disappear.

Super exponential wide response volume control :

Corresponds to normal knob type volume range

Lsolation:

The Master 9 completely isolates the left and right amplifiers, power supply regulator and transformer.

The Master 9 uses a heavy, all-aluminum chassis to prevent eddy currents from being conducted through the chassis and affecting the sound quality.

Even the power input IEC socket is shielded with a copper shield box.

Components:

The Master 9's balanced four-channel system is precisely matched with all components.

Please note:

1, If the customer does not have a good DAC or good audio source, only intend to connect the PC sound card or cell phone audio output use, this product is not suitable for you.

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

3, Due to the restrictions of the courier company, the metal remote control needs to install two AAA i.e. No.7 batteries for use by yourself.

The function of shielding idle input (this function can be canceled by yourself).

This machine is designed with idle input short circuit shielding function in order to avoid interference between signal sources when connecting different sources.

This design is also used in many Hi End brand products.

Working principle: If there is no idle input short circuit function, suppose 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 to mix into the selected signal, although this is very weak but will also lead to the deterioration of the sound quality. This is very weak but can lead to deterioration of the sound quality.

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

In the following cases, users need not shield the idle input function, you can open the machine, the corresponding channel short-circuit plug to dial out and need to dial out the two channels at the same time.

1, the same external signal source is not only connected to the analog input of the machine, but also connected to other amplifiers.

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

Function description.

HP/PRE switch :

Selects Master 9 from the headphone output (H is displayed) or the preamp output (PRE is displayed).

Gain switch :

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

H gear: 25DB gain, suitable for 80-100DB or less headphone use.

S gear: 31DB gain, suitable for the use of 80-100DB low sensitivity headphones when the source only 2-3V @ XLR or 0.7-1.5V @ RCA low output level or according to their personal preferences to set (only RCA and XLR effective).

We use new gain control technology, when switching between different gains, there is no line switch, relay or amplifier parameters are changed, so in H and L different gain, the sound quality is exactly the same, the user only need to choose the appropriate mode to make the volume control more convenient for personal adjustment preferences can be.

Selector Switch :

Selects Master 9 inputs 1-5.

Volume knob :

Selects the volume of Master 9.

Debug switch :

Press to set the menu.

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

Press "Gain" and the flashing display will be changed, 0 means the function is stopped, 1 means the function is effective.

The first display is the remote control function setting, mainly for the remote control volume function, when set to 0, the volume will change one grade when the remote control is pressed. When set to 1, the volume will increase or decrease continuously when the remote control button is pressed continuously. If the machine is easily disturbed by other devices, please set this function to 0.

The second bit is the auto-dark screen setting, when set to 0, the display will be bright after power on. When set to 1, the display will automatically turn off after about 10 seconds without operation, leaving only one LED to show that the machine is powered on.

The third bit is the volume memory function setting, set to 0, the volume does not use the memory function. When set to 1, the volume has a memory function, even if the machine is turned off and then switched on and off again, the volume will remain the same as when it was last turned off.