The Formula DAC is the first in the aqua’s production to show a proprietary D/A conversion system, that we name Optologic. The signals sent to the resistor ladders are generated by a proprietary digital circuit, implemented inside an FPGA (Field Programmable Gate Array). Formula has a sign-magnitude converter structure, and this requires not two but four 24 bit resistors banks, each one made of very low tolerance discrete resistors.
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The Aqua HiFi Formula xHD DAC represents a comprehensive approach to high-resolution audio conversion. At its core lies Optologic, a proprietary D/A architecture utilizing discrete resistor ladder technology with four 24-bit resistor banks and sign-magnitude converter topology. Galvanic and magnetic isolation between the FPGA and R2R converter ensures complete digital-analog separation, yielding a pristine ground plane and perfect symmetry between counter-phase halves. Operating as a filter-less DAC, the Formula prioritizes native sample rate processing without upsampling compensation, favoring emotional authenticity over instrumental metrics. Its modular construction—with each resistor bank and circuit board independently mounted on connectors—enables future upgrades and technological evolution. The xHD update introduces a hybrid XMOS xCore 200 dual-core processor paired with optimized FPGA code, supporting playback up to 768kHz PCM and native DSD512. Fully-floating USB decoding with proprietary clock generation ensures bit-perfect transmission across Windows, macOS, and Linux platforms. Discrete BJT, Mosfet, and J-Fet circuitry powers both analog and digital supplies, while the signal path remains direct-coupled and capacitor-free. Premium passive components—tantalum, OS-CON, and double-metalized MKP capacitors—combined with ultra-low RF noise design deliver the refined tonal contrast and musicality that define Aqua's acoustic philosophy.
