Hybrid single-ended digital input.
Dear Colleagues. I propose to discuss the next development. Description for Figure 20 DAC chip PCM1794A switched to mono , for greater impact current and to improve linearity. Digital input transformer, in addition to its normal function also performs the function of the level shifter . On this solution has been sought in the Eurasian Patent Office . Directly from the DAC chip RSM1794A served arising variable (sound) current ( + - 5 mA at 0 dB) for R- trimmer 470 ohm . The effluent will create a variable AC voltage sound on the left and the right end of the trimmer P1. Instead , you can set the trimmer resistance wire clamp . In the absence of such required denomination created paralleling . With this technical solution does not require precise selection of load resistors . The differential signal is applied to a typical differential amplifier tubes. Differential pair perfect means of suppressing ripple and harmonics. For example , the reaction rate of the supply voltage for the differential pair (PSSR) is 62 dB. For example, when a differential scope 7 volts at a frequency of 1 kHz harmonic distortion was 0.04 %, the third harmonic will be 0.0035 %. Differential pair suppresses the even harmonic distortion at 26dB . To create an offset and zero point for L5 and L6 lamps used controlled current generator . To reduce the harmonic distortion created by the standard differential cascade scheme supplemented unique dynamic load consisting of transistors T3 and T4 lamps L1 and L2 . Dynamic load T3 and T4 lamps L1 and L2 between a covered feedback that increased linearity repeater and extended dynamic range of the repeater . Dynamic resistance at a gain of the current mirror transistors will be about 1000 4mOm . In addition further improves linearity repeater power generators on lamps A2 and A3. In grid lamps instituted antiphase signals. In fact, in this case, the repeater is implemented Loftin - White. To improve linearity and increase the dynamic range analog power ICs - PCM1794A be increased to 8 volts. Read more about it here and here http://dddac.com/dddac1794_design.htmlо diyAudio - View Profile: Lil Knight
gain stage is 29 . This allows you to connect to a variety of output devices , for example - tsirklotrony two stroke output stage , single-ended output stages tubes and transistors . In general, the diverse range of applications . For noise suppression on digital , grid lamps L1 and L2 connected via an additional filter . AC output voltage level is determined by the trimmer P1. Zeroing scheme works as follows. Assume that the output drivers has become a positive voltage . The output voltage of the comparator increases. The voltage across the resistor R11 will be less. As a result, at the source voltage of the FET T31 is also reduced. Accordingly, the current of the generator is reduced , thereby reducing the DC voltage at the output. Consequently , the output will again be set to zero potential. Dignity scheme - single-stage differential amplifier , the absence of dynamic distortions , the minimum phase shift , the shortest path and thus the maximum correct ( reliable ) sound. Besides external DAC - driver with differential output with galvanic coupling will probably represent the top level . The volume control is set at the input differential stage . This tract can hear the real "voice" of the DAC. Especially this "voice" appears on disks with high resolution. Also noticeable saturation musical palette overtones. (High frequency component ) If possible , it is desirable that the use of the output stages operating in Class A. Applied chips - PCM1794A x 2 generator SIT5001, receiver WM8804. Four low-noise regulator 8 volts. Four low-noise stabilizer 3.3 volts . DDDAC 1794 NOS DAC - Non Oversampling DAC with PCM1794 - no digital filter - modular design DIY DAC for high resolution audio 192/24 192kHz 24bit