DAVE. Technology Presentation

Август 5, 2022

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DAVE. Technology Presentation

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2. WHY DAVE? DAVE is an acronym of Digital to Analogue Veritas in Extremis DAVE’s development was
3. TIME DOMAIN The primary purpose of a DAC is to reproduce the un-sampled continuous analogue waveform
4. DAVE WTA FILTERING DAVE has 164,000-tap WTA filter The WTA algorithm was subjectively optimised and improved
5. DAVE NOISE-SHAPER The noise-shaper takes the high-resolution 2048 FS data and converts to 5 bits It
6. ANALOGUE 20-element Pulse Array DAC Unique 2nd order analogue noise-shaper for output stage – this gives
7. MEASURED PERFORMANCE Maximum output voltage 6V RMS – the reference voltage dBA, measured using APx 555
8. FFT 2.5v RMS OUTPUT Blue 2.5v RMS, red no signal zero noise floor modulation. Noise floor
9. JITTER TEST No measurable jitter artefacts
10. TWO TONE 19/20kHZ TEST 1kHz is extraordinarily low at -152 dB I suspect that the APX555
11. 16bit -90.3dB 16 bit levels are perfectly reproduced Note how similar left/right channels are
12. 24bit -90.3dB No small-signal distortion Note how similar left/right channels are Extremely low noise
13. DAVE: CONCLUSION Most advanced DAC technology in the world! Redefines DAC measured performance In my view,
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WHY DAVE?
DAVE is an acronym of Digital to Analogue Veritas

in Extremis
DAVE’s development was centered upon a question: why was Hugo so musical?
Where was Hugo’s sound quality performance coming from in technical terms?
DAVE has an FPGA ten times the capacity of Hugo
This gave opportunities to further improve performance:
Improved time domain (transient timing accuracy)
Improved noise-shaper performance
DAVE has much more advanced analogue electronics

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TIME DOMAIN
The primary purpose of a DAC is to reproduce

the un-sampled continuous analogue waveform from sampled digital data
Conventional DACs do a poor job of reproducing the original continuous analogue signal, with timing errors on transients
Increasing tap-length of FIR filters gives better time domain accuracy in terms of timing of transients
The ear/brain is extremely sensitive to very small timing errors
Timing accuracy upsets the perception of the start and stopping of notes
It also degrades the ability to perceive instrument timbre and power
It degrades soundstage precision

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DAVE WTA FILTERING
DAVE has 164,000-tap WTA filter
The WTA algorithm

was subjectively optimised and improved to suit the longer tap lengths
WTA filtering is now up to 256 FS – no other DAC has ever FIR filtered at such a high rate
DAVE has massively parallel processing with 166 DSP cores
Further advanced filtering to 2048 FS
This means DAVE more accurately retrieves the original continuous analogue un-sampled signal

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DAVE NOISE-SHAPER
The noise-shaper takes the high-resolution 2048 FS data and

converts to 5 bits
It also creates the 20-element Pulse Array outputs, so is the heart of the DAC
Initially, Hugo-standard noise-shapers were employed
But increased FPGA capacity and 20-element operation allows better performance
Over 3 months of continuous listening tests and redesign pushing to improve sound stage depth perception – I (Rob) would not stop until performance would no longer increase
Constantly pushing for better sound stage depth-perception led to world’s most advanced and complex noise-shaper
It employs 17th order noise-shaping, with a total of 46 integrators; the design of the noise shaper alone would not fit into Hugo’s FPGA.

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ANALOGUE
20-element Pulse Array DAC
Unique 2nd order analogue noise-shaper for

output stage – this gives ultra-high HF linearity and no increase in distortion with difficult loads
Still employs single global feedback path with equivalent of simple 2 resistors and two polypropylene capacitors in direct signal path
Ultra-low-noise sub-milli-ohm power planes for Pulse Array element flip-flops
Digital DC servo
Headphone drive 6V and 0.5A RMS OP capability

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MEASURED PERFORMANCE
Maximum output voltage 6V RMS – the reference voltage

dBA, measured using APx 555
THD and noise at 5V RMS 1kHz -124 dBA A wt
THD and noise at 2.5V RMS 1kHz - 127 dBA A wt (-124 dBA into 33 ohms)
THD 1kHz 2.5V RMS 0.000015%
Dynamic Range at -60 dBFS 1kHz -127 dBA A wt
No measurable noise floor modulation, no anharmonic distortion
Analogue distortion characteristic – no distortion for small signals

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