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D-28 (ES9038Pro)

 DAC + Discrete transistors Headphone amplifier & Preamplifier
With XLR & RCA analog inputs
built in Sabre ES9038Pro

USB / HDMI support DXD,up to DSD Native 512APCM 32Bit /384KHz
Heavy power supply by total of 10 groups of double stage PSU
1500 mW @ 100 ohm
(per channel) Pure class A output
9500mW @ 25 ohm (per channel) with H / L gain ,
drive the 80DB -115DB sensitivity headphone
easy
User can change the digital parameter settings on front plate

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Summarize Use Manual Specs Shipping Cost

The Windows necessary install the driver for USB connect ,click to download the driver
Amanero combo 384

Price:  ( Exclude shipping cost, Please send your address, name to audio-gd@vip.163.com  get the quote. )

D-28.28 Standard version :               USD699  (ES9028Pro)
D-28.38 Standard version :               USD780  (ES9038Pro)
D-28.38 Full upgrade version:           USD850 (ES9038Pro,Femtosecond Accusilicon upgrade the stock clock and Femtosecond Crystek *2 upgrade on USB interface)


Custom order RCA replace ACSS output , price +USD5 . After upgraded user can connect two different RCA amps in same time .C
The free mini remote without warranty .

 
The metal remote controller price USD45 .


Accusilicon clocks and Crystek clocks in the full upgrade version :

       


Summarize
Fully balanced non-feedback design built by discrete transistors
Total of 10-groups of  PSU are used to purify the power supply
Total of 7-groups of PSU combined into double stages PSU for digital parts
The ES9038Pro built in DA parts power supply separately by two groups ultra low noise transistor serve PSU
The analog amp power supply by discrete linear PSUs
Four channels could be digitally controlled within 100 steps relay-based volume control built by tolerance 0.05% resistors for  avoid channel imbalance

Large R-core transformers and Hi-end grade parts
High / Low gain design for drive the 80-115DB sensitivity headphones
User can change the digital parameter settings on front plate
4 digital inputs:   USB / Optical / Coaxial RCA / I2S 
2 analog inputs:  XLR / RCA (The RCA input can be converted to balanced output natively without extra converter   )
DAC output:   XLR / RCA / ACSS  
Headphone output : 4 pin XLR / 1/4" (6.3MM) SE 
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Modification guide on headphone jack for 4-pin balanced headphone output.
  
modification guide

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Detail of the Current Conveyor (ACSS) Technology

Simple and short signal path 
    
   The D-28 applies the newest ESS high-end Sabre32 D/Achip . ES9038Pro can support up to 32Bit/768KHz input . 
       The ACSS circuit naturally works in current mode , it can transfer the ES9038Pro current signal to the output and implement the I/V conversion in current mode in one ACSS amp . And this ACSS amp only have one current gain stage , the ES9038Pro output signal only go through one stage which is very short signal path .

        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 non-feedback can't do well in test measurements but can offer better sound quality .Here is a conflict of the classic circuits.
        But the ACSS design opens a new field, it can offer a least coloration to the sound which is more neutral with very low distortion and high linearity. So it can retain the dynamics, detail and neutral without being bright or harsh.
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Zero Distortion Diamond Rhombus output stages:
         The D-28 has 4 groups of Zero distortion diamond rhombus output stage for the balance output .  Every  part  has been tactfully design , can achieve zero distortion state without any adjust
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         The output stages have  built in  4 pairs of  15W transistors  to offer strong drive capability .
         The D-28 has the large pure class A output power (1500mW at 100 ohm, max 9500mW at 25 ohm) , drive most headphones to listen music not to exceed the pure class A area.
         The balance drive mode kills  the noise and distortion ,improves the sound stage, background and the transparency.
         The D28 built in amps can be an excellent decent headphone amps and preamps .

             
Heavy power supplies :
         The D-28 uses a R-core transformer and  total of 10 groups of  PSU to power supplies  for all digital and analog circuits.
         There are 7 groups PSU combined into double stages PSU , power supplies to the digital parts separately .
         The ES9038Pro built in DA parts had very sensitivity to the power noise and ripple . The D-28 had designed two groups transistor serve PSU to power supply the Left and Right channel DA parts separately ,compare to the ultra PSU chips, the serve PSU can improve over 15DB on THD and dynamic, boost the ES9038Pro to work with full performance . The Left and Right DA parts power supply separately almost can avoid the channel crossing, makes the sound stage more deeper and wider .

         The D-28 analog amps power supply by 2 groups high speed linear discrete transistor PSU . That is a bit complex design than the normal PSU chips but they can make the sound quality has better dynamic and detail but still sound like analog that is worth to apply .
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 The I/V conversion volume control without sound degradation:
           The D-28  applies the I/V conversion volume control, the volume control is just a variable passive I/V conversion being placed at the ACSS amplifier output, where the output is in current mode  and not voltage mode . I/V conversion changes the volume level from the current (I) signal to the voltage (V) signal. (Like R-2R D/A chips output passive I/V conversion) It can keep the signal frequency band flat while not losing any detail. It does not degrade the sound quality at any  volume level. In front of the volume control, there are four groups of zero distortion diamond rhombus  non-feedback output stages that offer very low and flat distortion output.
            The D-28  applies four channels could be digitally controlled within 100 steps relay-based volume control built by tolerance 0.05% resistors for  avoid channel imbalance
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 Shield:

           The D-28 has  built in Multi-ply shield boards, to separate the  transformer, power supply, digital parts and analog  parts to  avoid the different parts interfering with each other. Even the power input IEC socket is wrapped in a copper shield .
          


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