KELVYN SHAW

High End Audio Design

The X5 is a high end headphone amplifier designed with quality in mind. It benefits from having a 100% discrete signal path with the addition of DC servo circuitry to eliminate any capacitors in the signal path. It is pure Class A biased with zero global feedback. Signal amplification is provided by a High Definition Amplifier Module that is fully discrete and specially designed for high quality audio applications. There is an internal over rated dual rail power supply with the benefit of discrete ultra low noise regulators to provide clean power to the amplifier. Quality has taken first priority in every aspect of the design. Choice of components has been carefully scrutinized and chosen based on performance and not compromised to reduce cost. It is a true no expense spared design.


The Internal Power Supply

The power supply consist of a low noise transformer which has been highly over rated at 15VA to provide a massive amount of reserve power for the amplifier and to reduce the output impedance of the power supply. The transformer is followed by two full wave rectifiers made from discrete ultra fast diodes for clean rectification and further improved with the addition of a snubber capacitor with each diode to minimise any switching noise. There are ample amounts of pre regulation and post regulation reservoir capacitance. Mundorf audio grade power electrolytics for pre regulator and Panasonic FM series ultra low impeadance for post regulation.


Ultra Low Noise Voltage Regulators

Having a clean power supply voltage is important, as any noise or imperfections from the power supply will undoubtedly reduce the quality of the whole amplifier. It’s like trying to wash your car with dirty water, only ever leaving your car as clean as the water being used to wash it. The regulator is totally discrete with a unique circuit topology giving it a fast transient response, excellent regulation and very low noise. The regulator offers a substantial improvement over the common 3 pin regulator IC’s found in typical power supply circuits.


HDAM

The High Definition Amplifier Module is responsible for all the small signal voltage gain in the amplifier. It takes the place of the common operation amplifier IC that is found in the majority of other inferior amplifiers. The module is totally discrete and constructed with only the highest quality audio grade transistors and resistors.

 

 

 

 

 

 

 

The no compromise circuitry has far superior sonic performance which leaves its rival counterpart, the IC, somewhat lacking in audio performance. The HDAM is ultra low noise and has excellent low distortion down to 0.0002%.


Output Driver

The output driver circuit is what is known as a Diamond Buffer and is responsible for all the current amplification to drive the headphones. It is totally discrete and uses audio grade bipolar power transistors on the output stage. It is a pure Class A biased output driver to eliminate any crossover distortion. The output transistors are mounted on large heatsinks for good thermal stability.


DC Servo

The entire audio signal path from input to output passes through no capacitors. Capacitors in the signal path usually serve as DC blocking capacitors and have a downside of being responsible for a lot of audio distortion. With the absence of these capacitors less signal distortion is achieved. To allow the amplifier to run without these capacitors a DC servo circuit is added to eliminate any DC offset voltage output from the amplifier and protect the headphones.


Output Connections

The entire audio signal path from input to output passes through no capacitors. Capacitors in the signal path usually serve as DC blocking capacitors and have a downside of being responsible for a lot of audio distortion. With the absence of these capacitors less signal distortion is achieved. To allow the amplifier to run without these capacitors a DC servo circuit is added to eliminate any DC offset voltage output from the amplifier and protect the headphones.


Quality Signal Routings

A pair of input connections are provided for the amplifier input signal. A pair of output connections are provided that are switchable from being a looped output or a preamp output. With a looped output the input connections are directly connected to the output connections as well as the internal amplifier. This is useful for example if you want your CD output going into the headphone amplifier and then looped back out to go to your power amplifier. When switched to preamp then the output connections are connected to the amplifier output for use as a preamp. There is a gain switch which controls the gain of the HDAM module. The gain setting is chosen to suit the impedance of your headphones..




X5 Specifications
Total Harmonic Distortion: <0.001%
Channel Separation: >110dB @ 1KHz
Dynamic Range: >120dB
Signal to Noise Ratio: >98dB @ 50mW into 30 ohm
Frequency Response: 7Hz – 20KHz (-0.1dB)
  2Hz - 50KHz (-1dB)
  0.8Hz – 90KHz (-3dB)
  0.5Hz – 160KHz (-6dB)
Maximum Output Power: 250mWrms into 300 ohm
  500mWrms into 30 ohm
Gain Settings: Low 0dB
  Mid 5dB
  High 10dB
Input Impedance: 47K ohm
Headphone Output Impedance: 5 ohm
Pre-amp Output Impedance: 50 ohm
Power Consumption: 15W maximum
Weight: 1.9Kg
Dimensions: 173mm Width
  65mm Height
  235mm Depth

Construction Details

 

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