Gustard H20 Full Balanced Headphone Amp PreAmplifier HIFI EXQUIS XLR Class A Dual LM49720 Balanced Output

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  • The post-stage amplifier circuit uses its own application for many years to separate the sub-line, each channel 2 pairs of power chip, a total of 8 power chip
  • Each channel uses two independent amplifying units to form a symmetrical output line, which outputs both single-ended and balanced;
  • The front class consists of a separate 4-way amplifier circuit, using two LM49720 dual op amp;
  • Have a separate pre-stage output, can be connected to active speakers or pure after the class;
  • The use of matrix relay volume, effective to ensure that 4-way volume unanimous;
  • Native full-balanced architecture, from input to volume control to before and after zoom, without any conversion, complete four-way architecture;
  • Equipped with third gear gain (high middle low), amp and line (XLR) at the same time
  • There are three inputs: RCA * 1, XLR * 2
  • The left and right channels each adopt a custom 50W audio ring transformer, completely independent of each other without interference;
  • All aluminum chassis, full silver and all black colors available;
  • Machine size: width 330 * deep 260 * high 65MM (without protruding parts);
  • Packaging size: length 420 * wide 360 ​​* high 175MM;
  • Package weight: 6.5KG;
  • International voltage AC100V-240V (manual adjustment);
  • XLR interface definition: US standard 
  • Frequency response: 20-80kHz /-0.1dB
  • Signal to noise ratio:> 120dB
  • Channel crosstalk: -120dB @ 1kHz
  • THD + N: <0.0005% @ 6000mW into 32Ω LOAD
  • IMD: <0.0005% @ 6000mW into 32Ω LOAD
  • Maximum distortion output power 6000mW into 32Ω LOAD
  • Maximum output power 12000mW @ 32Ω (when THD = 1%)
• Headphone power:
  • 64Ω 5360mW
  • 150Ω 2680mW
  • 300Ω 1340mW
  • 600Ω 670mW
• Analog input:
  • RCA standard input group, input sensitivity typical value: 2Vrms; input impedance 47kΩ
  • XLR balanced input two groups, input sensitivity typical: 6Vrms; input impedance 2.4kΩ
• Front Analog Output (XLR):
  • Three-core balance x2
  • four-core balance x1
  • Output impedance 200Ω
  • Frequency response: 20-80kHz /-0.1dB
  • Signal to noise ratio:> 122dB
  • Channel crosstalk: -130dB @ 1kHz
  • THD + N: <0.0004%
  • IMD: <0.0004%




Line input: RCA * 1, XLR * 2
Line output: XLR * 1 (front output)

Ampere output: 6.35 single-ended high resistance * 1,
                         6.35 single-ended low resistance * 1
                         Three-core balance * 1 (2),
                         four-core balance * 1

There are pre-class output, can be used as an independent pre-class active monitoring or pure after the class.aeProduct.getSubject()
After the amplifier circuit with its own use for many years the whole division of a class line. The discrete devices only need to consider their own performance alone, so just for a device, less a lot of application restrictions, it can give full play to the performance of a single component. Because unlike integrated circuits that are integrated in the chip can not be separated and changed, the use of discrete devices is more flexible, you can freely adjust the parameters of each level, to achieve the best working condition. But also because it is more developable, and for the distortion of the part is also relatively controllable, can give different circuit architecture to bring more variable sound style.
The disadvantage of discrete devices is that the distribution parameters of great impact on the design and debugging becomes very difficult, need to have some technical experience and a long debugging process. In terms of consistency is also relatively weak, so the material needs to be very elegant.
Each channel using two pairs of 8 pairs of power chip, to ensure adequate driving force and control.

Front op amp with two straight LM49720 dual op amp, composed of 4-channel circuit.

2 imported transformers, left and right channels each one, do not interfere with each other (prototype is made of cattle, bulk has been imported cattle).

The main filter uses Nikon nichicon audio capacitor KG gold tune

Pre-regulator circuit.
Semi - intelligent control circuit.

Using matrix relay volume, to ensure that the 4-way volume to an unvoiced.

Frequency response

THD + N 1W (into 33R) 22KBW
Signal to noise ratio



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Gustard H20 Full Balanced Headphone Amp PreAmplifier HIFI EXQUIS XLR Class A Dual LM49720 Balanced Output

Gustard H20 Full Balanced Headphone Amp PreAmplifier HIFI EXQUIS XLR Class A Dual LM49720 Balanced Output