The HE series products had the longest term of design and test in audio-gd history . Even though audio-gd had release the regenerative power supply products since 2006, and Mr. Kingwa had publish the article in the magazine explain the technology detail . The HE series products had finished the design in the New Year of 2014 , we were plan to release them in the date of audio-gd 10 anniversary , but for got the best sound quality and performance, we have even 3 times change the full design for made the compare, and compare different power frequency and voltage, create the longest design term record. The HE series products have better detail and dynamic reproduce ,blacker backstage ,better focus and larger sound stage , but the sound is better analog . The right saddle must is set on the right horse ,if you had not enough good system units, and had not enough cable match experiences, don't waste the money on HE series products. Please note the HE series products are upgrade from Master series, even though the price had a big rate increased but the sound quality had not same rate improved.Audio-gd products had design and test based on the AP SYS-2722 (The top-drawer professional equipment in world) Built in regenerative power supply Uses four R-core transformers (In total 295W ) and more than 95,000uf audio grade NOVER capacitors are used to ensure ample and smooth power delivery. 15 groups discrete class A PSUs power supply for the regenerative drivers and the digital / analog audio signal parts.Fully balanced class A Non- feedback ACSS analog design built by discrete analog stages without any OPA or coupling caps in the signal path.Especial design DSP software for the PCM1704 for avoid jitter and digital noise Built in 8 Pieces PCM1704UK design working with parallel connect and balance state.The SPDIF inputs have applied special interfaces for processing data, allowing the highest sound quality for the different SPDIF inputs. IN1: BNC input, up to 24bit / 96KHz support . (Best for the high grade disc transports connect) IN2: AES input, up to 24bit / 192KHz support . (Best for long distance signal transmit) IN3, RCA coaxial input, up to 24bit / 192KHz support . (Common coaxial input ) IN4, optical input , up to 24bit / 96KHz support . IN5 , RJ45-I2S input ,up to 32bit / 192KHz support . IN6 , HDMI-I2S input ,up to 32bit / 192KHz support . 3 outputs: XLR / RCA / ACSS Static storage mode control software for avoid disturb sound quality , the MCU output once control data and save in the perform parts ,then stop output data until users next operation. Please note: We are design the HE-7 only put the point on high sound quality reproduce , we have not design the mute design in it as our low end products, because we have consider any mute design cause the sound quality degrade . If the SPDIF sources ( only with some few disc player models) have design the SPDIF output signal switch on while playback and switch off while stop, the switch noise will reproduce by the HE-7, the issue is had a click sound while the source switch . Fortunately most sources had not switch the SPDIF output signal and always had output signal while power on . The HE-7 had the no compromise design, it may can't compatible with all TV, game box, low range disc player, ect.
Detail of the Current Conveyor TechnologyWhat's the regenerative power supply : While audio is life , the Power supply is water , Pure water create the wonderful life ,clean power supply reproduce the beautiful sound . The regenerative power supply like a proprietary electric generator built in the unit. It can block most disturb from the power line , supply the ultra clean power supply for the audio amps , reproduce the most neutral and analog sound like audio signal for the system and the users. In the regenerative power supply design, the AC power through the regenerative input transformer , conversion to DC power ,through the class A PSUs power supply for the regenerative wave generator and driver stages . A balance regenerative regular wave generator produce the ultra low distortion 50Hz wave ,through the balance gain amps and the strong output stages , drive the regenerative transformers produce the clean AC power supply feed to the separate class A PSUs power supply for the L and R channel preamps . The class A parallel connection PSU has very high input impedance to avoid disturb through the PSU from affecting the signal parts and low output impedance with very fast speed and high linear, it is a very clean power supply. Audio-gd on the regenerative power supply design points : 1, Through analyzed the AP SYS-2722 ,do a lot practises ,test and listen , full analog design of the regular wave generator have much lower distortion than the digital generator. 2, Digital drive stages have higher efficiency , but full analog drive stages have much better analog sound like . 3, 400Hz regenerative wave have higher efficiency , 50Hz regenerative wave had much far away the human ears sensitivity area than the 400Hz, boost the sound have much better analog sound like. ACSS: The HE-7 is a real fully balanced discrete design. Applies the 8 Pieces Expensive high-end grade PCM1704UK which can support up to 24Bit/192KHz through SPDIF input and 32 Bit / 192KHz through I2S input . Similar to other PCM1704UK designs , we applied Non-feedback ACSS analog stages. The 8 pcs PCM1704UK feed to the ACSS analog stages without any OPAs and couple caps so it can avoid sound coloration . The ACSS is a non-feedback technology made with fully discrete amplifiers. Most people know the global feedback design can offer better specs in test measurements, and classic non-feedback can't do well in test measurements but can offer better sound for the human's ears. Here is a conflict of the classic circuits. But the ACSS opens a new field, it can offer a least coloration sound which is more neutral with very low distortion and high linearity. So it can retain the dynamics, detail and neutral sound but not sound bright or harsh.Output buffer: The output buffers are Non-feedback. For low impedance, we applied the dual FET buffer output stage which is quite less colored than most conventional circuits.DSP-1 processor: HE-7 has built in DSP processor, which is a Two-channel Digital Interpolation Filter and data in-phase processor for digital audio. This Device offers advanced features for high-performance digital signal processing (DSP) applications up to 250-MHz. Data and Master-clock in-phase processing are without jitters. So HE-7 can offer a clear and focused soundstage, apart from accurate and neutral reproduction of the recorded disc/music. The Stopband Attenuation up to -130DB, enough clean the digital noise , avoid the digital noise degrade on the back stage and make the sound like digital.
Filter Characteristics: Stopband Attenuation: -130DB. Passband: 0～0.4535Fs. Passband Ripple: within ±0.00001dB. Stopband Attenuation Characteristics（-130dB） Passband Characteristics（-130dB)
Power supply: HE-7 applies the excellent 8 pcs PCM1704UK and excellent analog output stages, but these are not the only keys of the best sound. The power supply is most important. Even applying the best DA chip and the best amp, if matched to a normal power supply, the total sound may still be average or sound musical, but can't be neutral and detailed. That is why it is easy to find hi-end grade gears maybe without the best chips or amp stages, but with plenteous dedicated DC supply circuits. The HE-7 had total 21 PSU groups are applied. Uses 19 groups of high-quality class A parallel connection PSU with dedicated DC supply double-stage PSU, which can offer very clear DC power for the DAC, producing a very black background and neutral sound characteristic. The double-stage PSU is very important for digital parts. Some designs may have very low jitter in theory, but if the power is supplied by a dirty or low-speed power supply, it will increase the jitter and pollute the data, and degrade the sound quality obviously. The class A parallel connection PSU has very high input impedance to avoid pulse through the PSU from affecting the DAC and low output impedance with very fast speed and high linearity, so it is a very clean power supply. In my experience, its sound is better than battery power supply, better human sound and neutral.Shield: HE-7 has complete separation of digital process, analog left, right amplifier channels, regenerative drivers and transformer, even the 230V / 120V power input lines had shield in the copper conduit. HE-7 uses heavyweight all-aluminum chassis to prevent the eddy current of transformers from interfering on circuit board. Components: Uses all audiophile grade components, including DALE resistors, WIMA caps, custom order NOVER (UK brand) caps, all audiophile grade input & output sockets (Neutrik ) and gold IEC socket. HE-7 all parts of four channels had exact match before install.Static storage mode control software: In most control softwares design, the MCU will continuously output data to the perform parts , the MCU had the very high speed, so the output data become high frequency impulses disturb the audio signal circuits make the sound worst . This product had applied static storage mode control software , the MCU output once control data and save in the perform parts while just power on and users operate ,then stop output data until users next operation. This design make the sound quality improve on the clear and transparency .
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