According to Yee, “Our digital EQ is something akin to RIAA on LPs, though it starts at 40Hz and ends at 4kHz, rising at 6dB/octave. The boost at 4kHz is 40dB, where the curve ends. The analog de-emphasis looks very much like a phono preamp doing the exact complement to the digital EQ. The digital EQ is implemented in FPGA (Field Programmable Gate Arrays) in order to be an exact complement to the analog de-emphasis. This means that the higher frequency range is represented by numbers 100 times bigger when going through the DAC and the DAC appears to be 100 times more accurate.”
The MYDAC II employs a 24-bit DAC so that Yee’s design can support his EQ scheme. “For 24-bit audio, the MYDAC II ‘throws away’ eight bits of resolution in the bass and gives them to the high frequencies via noise shaping. For 16-bit audio, there is no reduction in resolution in the bass.” The patent on Yee’s new digital methodology, called MODR (Musically Optimized Digital Reconstruction), is currently pending.
Besides being used in the MODR process, FPGAs are also used in the MYDAC II for all internal signal processing and timing. Musical Surroundings claims that FPGA remove “another jitter source.” The heart of the MYDAC II is a Texas Instruments TI PCM1798 delta/sigma chip. Low distortion op-amps from TI are used in the MYDAC II’s output filter. This is the first time that Yee has used integrated op-amps in one of his designs, but they were “a high-quality affordable implementation to introduce this new technology.”
MYDAC II Sound
With this new whizz-bang digital technology does the MYDAC II sound different from all other DACs? Yes and no. At first listen the MYDAC II seems like many other good DACs—clean, dynamic, and harmonically well balanced, but further listening reveals its special sonic characteristics. Unlike many otherwise excellent DACs the MYDAC II sounds less “hard” without sounding mushy or soft. Details are every bit as clean and clear as through more conventional designs yet they lack that sometimes overly aggressive leading edge.
The MYDAC II also excels at preserving inner detail and low-level information. On Andy Statman’s brilliant, recently released album Superstring Theory, the MYDAC II preserves the gutty texture and the upper harmonics of Statman’s Kimble mandolin as well as the trailing edges of Jim Whitney’s stand-up acoustic bass. On one particular tune, “French Press,” it’s easy to hear that Statman’s mandolin was being routed through a less than pristine preamp because of the MYDAC II’s excellent retention of inner detail. Like the late Glenn Gould, Statman “vocalizes” while he plays. His humming, although at extremely low levels, is easy to follow through the MYDAC II.
Listening to my own live concert recordings through the MYDAC II, I was impressed by its ability to preserve and illuminate the sounds of the concert hall—not merely the sounds on stage, but also the peripheral sounds from offstage and in the audience. Instead of offering a “velvety black,” monolithic, and artificial-sounding background, the MYDAC II preserved the room’s myriad low-level sonic cues so that the entire space seemed to “breathe” in a more realistic manner.