Monday, March 26, 2012

Rockna Wavequest dac























































€3000

The limitations of the classic 16 bit/44.1k are well known for some time now. Except for the NON-OS DACs, all other solutions tried to overcome the major disadvantage of the redbook format: the higher the frequency of the sound, the smaller becomes the number of samples which describes it.

The notions of upsampling or oversampling came into place, with more or less successful implementation. Upsampling to 192K is trivial on the current level of technology. 384k is found from time to time, and barely you can find a machine to upsample to 768k.

Inside WQ we are pushing the limit to a whopping 1,5 Mhz sample rate! You might ask, what kind of DAC supports this high sample rate? The fastest R2R chip to this day(PCM1704) accepts rates up to 16x(768k) - this is why after some consideration we choosed to use nothing less but discrete R2R DAC modules, which can work up to 3 Mhz.

The interpolation engine we designed is quite flexible; you can select lower interpolation factors (8x, 4x) or it can by bypassed, transforming the dac into a non-os one.

How about a volume control? Is it available as a feature? Of course. Made entirely in digital domain, the volume control is carefully engineered to achieve a 256 step accuracy. The WQ DAC low-impedance output can drive directly a power amplifier, skipping the preamp from the audio chain. The volume control can be bypassed by setting it's attenuation to 0 dB, and that's a valuable feature for anyone which intends to use a preamp in the system.

How about a direct connection to a computer? Is the WQ DAC equipped with such a link? The answer is yes. We have installed a convenient USB input for direct streaming your files into the dac. This transparent bit-perfect interface allows high-resolution files up to 192k/24 bit to be transmitted directly. To avoid computer's operation system tampering with the sound, special USB drivers are available.

TECHNICAL CHARACTERISTICS (for firmware 1.3 - subject of some changes in future versions):

INPUTS (all 24 bit) :
COAXIAL S/PDIF : 44.1-192K
AES/EBU : 44.1-192K
OPTICAL : 44.1-96K
USB : 44.1-192K
I2S : 44.1-384K
I2S compatible devices: ROCKNA WQT, PS Audio PWT

DIGITAL PROCESSOR :

MEMORY BASED ADPLL : 0.3 ps jitter (fixed mode setting)
ADPLL loop corner frequency : 0.5 Hz
DIGITAL FILTER : 2x-32x (max. 1.536 Mhz output rate), can be bypassed for NOS operation
DIGITAL FILTE TYPE : polyphase sin x/x interpolation , 4000 taps
DIGITAL FILTER STOPBAND ATT : -145 dB
DIGITAL FILTER PASSBAND RIPPLE : 0.5 udB max.
INTERNAL PRECISION : 63 bit
DITHER : 4 bit, gaussian ultrasonic
VOLUME CONTROL : custom multiplier array 256 steps

OUTPUT :

THD+N, 0 dB : 0.006%
DYNAMIC RANGE : 125 dB (A-weighted)
S/N RATIO : 140 dB (A-weighted)
IMPEDANCE : 5 ohm
MAX. OUTPUT : +/- 5 Vpp

USER INTERFACE:

APLHANUMERIC DISPLAY, 16 character (dimmer available)
MENU ENTRIES : VOLUME, INPUT SELECT, PHASE, INTERPOLATION RATIO, ADPLL TYPE, DITHER
REMOTE CONTROL WITH ALL FUNCTIONS

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