Audio Note DAC Schematic

[iambeo]

Could anyone send me schematics to iambeo@libero.it ?

Thank you very much in advance!!

[Ken Newton]

Originally Posted by iambeo

Could anyone send me schematics to iambeo@libero.it ?

Thank you very much in advance!!

Is your interest in repairing a unit, or are you simply curious as to how AN DAC's function?

[iambeo]

Originally Posted by Ken Newton

Is your interest in repairing a unit, or are you simply curious as to how AN DAC's function?

Hi Ken,
actually I'm going to study all the aspects of DAC, my goal is to build my cd player based on AD1865, but listening to speak very well about Audionote DAC I'm curious to give a look to the schematics. Sorry for my English.
Thanks

Bruno

[Ken Newton]

While I don't have AN DAC schematics, I feel rather certain that they are relatively simple. The digital section appears common to all their DACs. It consists of an single RCA input to a AN S/PDIF interface transformer feeding a Cirrus CS8414/CS8416 digital input receiver. After clock and data recovery is performed by the Cirrus chip they are input to an AD1865 DAC chip, as you know. Famously, there is no digital interpolation filter utilized. Even the inter-channel delay, due to the the multiplexed nature of the serial data stream, is left uncorrected, resulting in an (IMHO, inconsequential) 11uS. arrival time difference. The AD1865 current outputs then are passively converted to voltage via AN tantalum resistors. No special steps appear to have been employed to reject incoming clock jitter beyond that provided by the Cirrus DIR chip. That's basically it.

Things get more interesting on the analog side, and vary among the AN line. All utilize vacuum tubes, but the lower range units typically feature capacitor coupled outputs while the upper range units typically feature step-up transformer interfacing within the I/V circuit in addition to single ended transformer coupled outputs. In my estimation/guess, the sound quality AN achieves in their DACs is primarily due to the use of R-2R DAC chip, no digital filter (NOS operation), tube analog stage, and particular passive component selection (i.e., tantalum resistors, black gate electrolytic capacitors, and large mu-metal slit-core single-ended transformers.