Introducing the new Formula xHD. The Optional R2R

Aqua conversion system believes that the most musical D / A conversion system is based on the circuitry generally referred to as "resistance ladder".

This technology has been replaced in the mass market by so-called sigma-delta converters.

The sigma-delta converter is an almost completely digital circuit and for this reason it can be embedded in silicon and produced inexpensively.

Instead, a quality resistor ladder DAC uses a circuit based on a set of high-precision discrete resistors: at least 2 resistor banks, one for each stereo channel.

The DAC Formula is the first in Aqua's production to feature a proprietary D / A conversion system, which we call Optologic.

The signals sent to the resistance ladders are generated by a proprietary digital circuit, implemented within a FPGA (Field Programmable Gate Array).

The formula has a sign-magnitude converter structure, and this requires not two, but four banks of 24-bit resistors, each consisting of very low tolerance discrete resistors.

To separate the digital section from the sensitive analog circuits, galvanic and magnetic isolations are implemented between the FPGA and the four branches of the R2R ladder converter.

This creates complete isolation of all digital circuits, including the clock, from the analog section, for a clean and quiet ground plane. It also plays the main role in the differential management of the R2R stairs, achieving a perfect symmetry between the halves of the push-pull phase. The result is the highest tonal contrast and naturalness.

The FORMULA, like the other Aqua models, is a DAC without a digital filter.

Our conviction is that despite the instrumental measures displayed by upsampling / upsampling DACs, they can rarely produce the same emotional and realistic results. Modularity

A third important aspect in Aqua production is the modularity of the various electronic circuits.

Aqua equipment is not short-lived products: as modular, they are open to future improvements and to follow the evolution of technology.

The formula is made up of a set of circuits, each developed on a separate, easily interchangeable printed circuit board.

As an example, each of the four resistor banks in the converter is separate and mounted on connectors.

The latest in digital and analog electronics.

As explained above, the DAC Formula does not use digital filters or any other compensation, relying instead on manic attention to each subcircuit.

The separate analog and digital power supplies are run exclusively through the extensive use of discrete BJT, Mosfet, J-Fet, and ultra-fast diodes.

The passive parts were selected not only for the best sonic result but also for their high quality, longevity and reliability. With the exception of six premium electrolytics, all other caps are Tantalum, Solid Polymer OS-CON, and Double Metalized MJP.

The signal path itself is directly coupled and completely free of capacitors.

The two output stages (one single ended, one transformer-coupled coupling) use discrete BJT and J-Fet with metal film resistors. All parts of the electronics show ultra-low RF noise.

An advanced ARM microcontroller manages the front panel user interface, IR remote command and communication port (serial, RS232 standard).

Digital to analog

Conversion type D / A conversion system Optional proprietary

Pure R2R ladder - FPGA (Field Programmable Gate Arrays) based without digital filter

Supported native sample rates

AQlink / I2S serial bus - PC USB audio: 44.1kHz at 768kHz PCM up to 24 bits

DSD64, DSD256

Supports DSD via DoP on all inputs

DAC architecture

Multibit sign Magnitude R2R ladder (upgradeable)

Asynchronous USB (high speed)

USB Audio Class 2 with type B connector

Digital receiver

PLL (loopback) technology phase lock) 128 or 256 FS internally selectable

AQlink (I2S bus)

LVCMOS level Oversampling

factor: 1x

Digital inputs

- RJ45 AQlink (I2S serial bus) - PCM 24 bit / 768kHz - DSD64, DSD256 via DoP

- Coaxial BNC (S / PDIF) 75 ohm - PCM 24 bit / 192kHz - DSD64 via DoP

- Coaxial RCA (S / PDIF) 75 ohms - PCM 24 bit / 192kHz - DSD64 via DoP

- AES / EBU balanced 110 ohms - PCM 24 bit / 192kHz - DSD64 via DoP

- USB port - PCM 24 bit / 768kHz - DSD64, DSD256 via DoP

Modular input:

- AES / EBU balanced 110 Ohm - 24 bit / 192kHz - DSD64

- Coaxial RCA (S / PDIF) 75 Ohm - 24 bit / 192kHz - DSD64

- AT&T (ST fiber) - 24 bit / 192kHz - DSD64

- Optical TOSLINK - 24 bit / 96kHz

Analog outputs

UNBAL 2 RCA 2.4 V RMS output

BALANCED (passive transformer balanced) 2 XLR outputs: 3.8V RMS

Output impedance

10 ohm RCA - 600 ohm XLR

Load impedance

10 kohm (min.) RCA - 600 ohm XLR

Frequency response

20Hz to 22kHz + 0.5dB / -0.5dB Phase

response

Linear phase

THD + N

<0.016% 1KHz -10dB

Main processor

STM-ARM microcontroller

Controls

9 buttons on the front panel, infrared remote control, isolated 9-pin RS-232 D-SUB connector

Front panel

Power, reversing phase, mute, input switch, remote sensor RC5

Power consumption: 100-115V / 220-240V; 50 or 60Hz - 58VA

Dimensions: (W x W x H) 450 x 370 x 100 mm

Weight: 9 kg

Front finish

Satin Alu Silver or Satin Black

Case finish

Nextel gray powder coated

Formula XHD brochure