The Raysonic CD-128 has single ended RCA and balanced XLR outputs. All outputs buffered by tubes and subjectively I'm quite pleased with the sound.
Unfortunately I have not been able to source the schematics, however as far as I've been able to tell it uses one set of OPA-2604 for buffering/filtering the DAC (PCM 1732M) and a second set of OPA-2604 for generating the balanced signals.
As mentioned, all six outputs are buffered by 6922EH tubes. The PSU for the tubes are marked 90v on the PCB (probably AC). Full wave rectified and with a single 220uF/220v capacitor. Tracing the tube section it seems that the XLR outputs are buffered with a simple cathode follower (one tube each XLR). The RCA output seem to be bufferd with a "white cathode follower".
I would appreciate if anybody can provide feedback on any of the following:
1 - Does anyone know where I could source service manual / schematic for this player?
2 - At this low voltage (estimated 50v/tube on the white follower) does these buffers serve a purpose or are they to be considered "effect box"?
3 - Are some tubes more suited for low voltage operation than others. The player come with EH tubes, but I also have NOS 6922 from GE and various NOW Phillips PCC and ECC-88 (of 3 various getter design)
Unfortunately I have not been able to source the schematics, however as far as I've been able to tell it uses one set of OPA-2604 for buffering/filtering the DAC (PCM 1732M) and a second set of OPA-2604 for generating the balanced signals.
As mentioned, all six outputs are buffered by 6922EH tubes. The PSU for the tubes are marked 90v on the PCB (probably AC). Full wave rectified and with a single 220uF/220v capacitor. Tracing the tube section it seems that the XLR outputs are buffered with a simple cathode follower (one tube each XLR). The RCA output seem to be bufferd with a "white cathode follower".
I would appreciate if anybody can provide feedback on any of the following:
1 - Does anyone know where I could source service manual / schematic for this player?
2 - At this low voltage (estimated 50v/tube on the white follower) does these buffers serve a purpose or are they to be considered "effect box"?
3 - Are some tubes more suited for low voltage operation than others. The player come with EH tubes, but I also have NOS 6922 from GE and various NOW Phillips PCC and ECC-88 (of 3 various getter design)