USB Ultra DAC Orpheus

Ultra USB Dac Orpheus

When we decided to design D/A converter sounding as LP, we chose AD1852.This DAC chip has incredible analog sound, without the typical digital sound. One of the big problems of digital converters is that they can’t play all kinds of music. Some of them play jazz and rock very well, other -female vocals and classic music. We were able to create a DAC that plays phenomenally all kinds of music. The bass is dense and thumping without distortions.  The middles are clear and focused. Regarding its construction, the D/A converter is distinguished by the use of output transformers as an analog filter and battery power supply. The USB section is made with XMOS chip in asynchronous mode powered with separate ultra low noise power supply. In our DAC we use only high quality and expensive components with low manufacture tolerance. Low cost components give negative effect to sound quality and lead to frequent defects. All components are hand soldered on the PCB. After assembled, the DAC passes quality check and a week sound test before sale.

The output transformers

In this DAC we chosen output transformers from Sowter 3575 or LL 1545A from Lundahl.  Why output transformers? Why not OP –AMPs as analog filter. The otput transformers are perfect impedance equalizer, allowing the DAC to works with wide range of output loads (600ohm to 10Kohm). A large number of manufacturers use op-amps in output stage. But they consist many transistors and capacitors which imports frequency, inter-modulation distortions and phase shift (180deg phase shift). This problems degrade sound quality (bad and unfocused sound stage, sand treble and uncontrollable bass). The transformers are connected in differential mode to DAC outputs without ground point, reducing noises in output stage. When we use transformers we we reduce phase distortion (under 2 deg) and improving the bandwidth (10Hz-70kHz). Sowter 3575 optional is produced with OCC wire for clean and fast bass.




Power supply

Powering digital sources is very important, because interference and noise from poor power supply can be added to the music signal. We use separate ultra low noise LDO linear stabilizer for the digital and the analog parts. We use LT3080 discrete implementation and LT1086. The USB section is powered with separate power supply realized with LT1963.All stages in the dac are powered with battery 12V/2,2Ah. When we use battery, the power supply is with zero noises and inter-modulation frequency distortions. When the power supply is implemented with battery ( LI-Ion or  lead acid) ,the music is clean , balanced and without  hums. The sound stage is very deep and focused. Just listen!!!!

                                                    Technical data

  • Frequency response: +/- 0.25 dB 15 Hz to 60 kHz
  • Distortion at 50 Hz (Source 40 ohms):0.05% at +20 dBu
  • Output level:2,1V
  • Digital format: I2S 24bit/192kHz (PCM)
  • Analog outputs: 1RCA
  • Digital outputs: 1RCA asynchronous mode
  • Digital input: 1 RCA SPDIF;1 USB B asynchronous 32bit /384kHz
  • Phase shift: under 2 degrees
  • Dimensions: 230 mm X 280 mm X 80mm
  • Warranty: 5 years





© Ratzov Tsenkov - Audio Design