Watts's career and design history

Watts, Chord, community and miscellany

Answers on this topic

• What did Rob design before Hugo, and how did the WTA filter and pulse array come about?

Everything he said on this topic (233)

One-line summaries in our words, oldest first. Each link opens the original.

• 2014-04-16Watts compares QBD76's 16-element pulse array with Hugo's 4, says a replacement is in work, and recounts how QBD76 development reshaped the WTA filter to 18k taps. Head-Fi, Apr 2014
• 2014-04-27Watts explains why native DSD inside a DAC is a bad idea, recounting PDM1024 and pulse array history, and details Qute's DSD filter and Hugo's 140 dB decimation filter. Head-Fi, Apr 2014
• 2014-06-01Watts says 44.1 kHz came from a Philips versus Sony dispute that Sony won, citing Watkinson's The Art of Digital Audio, which he calls his digital audio bible. Head-Fi, Jun 2014
• 2014-06-09Watts recounts 1980s mains cable experiments that showed RF noise mattered, leading to a 12-stage RF mains filter, and explains RF-induced noise floor modulation, audible even at -200dB. Head-Fi, Jun 2014
• 2014-08-03Watts recounts moving from disliking digital in 1989 to the PDM1 and PDM 1024, then creating the pulse array DAC in 1995 to fix noise shaper resolution and jitter. article, Aug 2014
• 2014-10-14Watts says he has done his stint as a manufacturer and would not want to do it again. needs context Head-Fi, Oct 2014
• 2015-04-20Watts explains Hugo's discrete Class A output stage, his path from 1989 PDM DACs to the 16-element pulse array, its jitter immunity, time-domain reconstruction, and R2R's flaws. Head-Fi, Apr 2015
• 2015-10-03Watts criticizes uncritical acceptance in high-end audio, recounts leaving audio after DAC64 in 2001 for silicon work, and says Hugo's success led him back full time. Head-Fi, Oct 2015
• 2015-12-04Watts cites 27 years designing DACs and silicon chip experience, says no rival DAC has caught his attention, and that Dave sets new measurement standards. Head-Fi, Dec 2015
• 2015-12-30Watts says Dave is better than Mojo/Hugo, but Hugo was the first digital device that let him enjoy music rather than sound, despite being technically close to Qute. Head-Fi, Dec 2015
• 2016-01-09Watts says Mojo draws on ideas he began 30 years ago and that his background spans silicon chip design and high-end audio such as DAVE and Mojo. What Hi-Fi? 2:43
• 2016-01-09Watts says that ever since studying electronics he has wanted to go from microphone to loudspeaker. What Hi-Fi? 6:16
• 2016-01-25Watts says he would not design a DAC without his WTA filter, which he has used since 1999 with the DAC64. Head-Fi, Jan 2016
• 2016-01-29Watts says he had a non-audiophile engineer compare 190 dB and 200 dB noise shapers to convince a company he worked with; the engineer heard the difference easily. article, Jan 2016
• 2016-03-29Watts says DAC inconsistency and break-in 25 years ago led him to pulse array; Mojo units measure and sound alike, and brain break-in is now the biggest variable. Head-Fi, Mar 2016
• 2016-05-30Watts recalls using dither with multiple DSD256 noise shapers on the PDM1024 in 1992, says the pulse array made it unnecessary, and notes dither cannot be added to DSD directly. Head-Fi, May 2016
• 2016-06-18Watts recounts moving from word clocks and the DAC64's buffer to a DPLL perfected over six or seven years, and says word clocks would now be a backward step. Head-Fi, Jun 2016
• 2016-07-24Watts says studying sampling theory in the early 1980s showed him long tap lengths were needed to recover timing, which he knew mattered for perception, though he then hated digital. Hifistatement 0
• 2016-07-24Watts says late-1980s pulse density modulation DACs drew him into digital design, and that by the late 1990s FPGAs could run long filters; DAC64 was the first WTA product. Hifistatement 45
• 2016-07-24Watts says longer taps with normal filters on DAC64 changed the sound greatly, but refining the filter algorithm improved timing accuracy, leading to WTA and a tenfold improvement in sound. Hifistatement 1:39
• 2016-07-24Watts says Hugo's noise shaper reached around 200 dB, about a thousand times more resolving power than normal high-end noise shapers, and describes his silicon IP business, stopped weeks earlier. Hifistatement 58
• 2016-07-24Watts says nobody listens to noise shapers but he always has; FPGA size limited him, and to settle a client company's arguments he built 180 dB and 200 dB versions. Hifistatement 9:05
• 2016-07-24Watts says a non-audiophile engineer found the 200 dB noise shaper easily beat the 180 dB one considered perfect, reported this to his company, and the arguments stopped. Hifistatement 9:49
• 2016-09-04Watts recalls using multiple dithered noise shapers for DSD256 in the early 1990s, explains that his 1995 pulse array eliminates correlated jitter, and why discrete flip-flops beat on-chip shift registers. Head-Fi, Sep 2016
• 2016-09-05Watts says Head-Fi rules stop him criticizing an obviously Mola-Mola graphic, and notes he designed PWM chip DACs in 2002 but met fundamental limits on noise shaping and transients. Head-Fi, Sep 2016
• 2016-09-25Watts explains why DAVE uses his DPLL rather than the DAC64/QBD76 buffer, word clocks or an external master clock: PLLs add low-frequency jitter, causing FFT fringing and brightness. Head-Fi, Sep 2016
• 2017-01-09Watts says in the early 1980s he believed digital needed 16-bit sinc accuracy and a million taps, thought that impossible, and the M scaler shows his intuition was right. Head-Fi, Jan 2017
• 2017-02-10Watts says both tap count and algorithm matter; in the 1990s a non-aliasing filter became the first WTA, and a 256-tap WTA beat a 2048-tap conventional filter. Head-Fi, Feb 2017
• 2017-06-26Watts recounts his DAC history since 1988 and how Hugo, from 2012, made poor recordings musically involving, which he attributes to the ear's sensitivity to reconstruction timing errors. Head-Fi, Jun 2017
• 2017-07-04Watts says that was merely him as a teenager making boxes to put loudspeaker drive units in. needs context Head-Fi, Jul 2017
• 2017-07-04Watts recalls his first high-end system, his teacher's speakers with Decca ribbon tweeters, and says full-range Apogee ribbon speakers had the finest timbre variation he has heard. Head-Fi, Jul 2017
• 2017-08-22Watts identifies an early-1990s design of his, the DPA 200S with a thick-film hybrid Class A amplifier, but says no analog amplifier matches DAVE driving small speakers directly for depth. Head-Fi, Aug 2017
• 2017-10-13Watts says the filter algorithm hugely influences performance, and that around 1998 FPGAs could barely run an FIR filter; he needed three of them. miceblue425 20:34
• 2017-10-13Watts says doubling a Kaiser filter's tap length always improved bass, soundstage and timbre, but with no hope of more than a thousand taps he sought a better algorithm. miceblue425 21:21
• 2017-10-13Watts says his revised algorithm gave a tenfold improvement, a 256-tap WTA filter beating a 2000-tap Kaiser, yet going from 256 to 1000 WTA taps still helped. miceblue425 22:06
• 2017-10-13Watts says tap length is crucial and, with Moore's Law, tap counts rose: DAC64 1,000, QBD76 18,000, Hugo 26,000 and DAVE 164,000. miceblue425 22:51
• 2017-10-13Watts recalls buying his first digital recording, Telarc's 1812, in the 1980s: its treble first impressed, then sounded distorted, with a flat, mechanical soundstage. miceblue425 25:30
• 2017-10-13Watts recalls reading hearing physiology as a student and learning sampling theory, and realizing that LC filters, with no FIR filters available, could not recover transient timing. miceblue425 26:21
• 2017-10-13Watts says he calculated that a 16-bit-accurate sinc function for CD needs about 700,000 taps, roughly a million, when microprocessors were primitive; he recalls a 2K oil-rig monitor. miceblue425 27:06
• 2017-10-13Watts says a million taps was then impossible, with no FPGAs, DSPs or PCs, so he saw it as digital's fundamental flaw and long planned for a million-tap filter. miceblue425 28:00
• 2017-10-13Watts says a company paid millions for IP he patented, hired him for 3 years to transfer it, and its bright engineers insisted it could not affect sound. miceblue425 55:01
• 2017-10-20Watts recalls that early 1980s digital on vinyl sounded hard, bright and flat and 1984 CD awful, while he studied sampling theory and read about the physiology of hearing. Hifistatement 0
• 2017-10-20Watts says sampling theory needs an infinite-tap sinc filter, that limited tap length gets reconstructed timing wrong, and that he calculated getting on a million taps for guaranteed 16-bit performance. Hifistatement 44
• 2017-10-20Watts says a million-tap filter was impossible in the 1980s, so he thought digital would fail, since only a million taps reconstructs timing with guaranteed 16-bit accuracy. Hifistatement 1:28
• 2017-11-16Watts says he knew in the 1980s that a million taps would be needed to recover transients to 16-bit accuracy, then thought impossible. Head-Fi, Nov 2017
• 2017-12-05Watts recounts a project specified at 120 dB with 4 picoseconds of jitter, later changed to 15 picoseconds, which he met by changing the number of elements. RMAF 28:20
• 2017-12-05Watts says within a month he had a design giving 120 dB with 15 picoseconds of jitter, though he was annoyed the requirement was not stated at the start. RMAF 29:04
• 2017-12-05Watts says a PDM 256 DSD DAC, heard in 1989, was the first digital to sound warm and refined to him, though he doubted 256 pulses could reconstruct 20 kHz. RMAF 34:44
• 2017-12-05Watts says the explanation of noise shaping pushing noise out of band made no sense to him and is wrong, so he spent a lot of time understanding noise shapers. RMAF 35:33
• 2017-12-05Watts says DSD sounds fat as it cannot resolve small signals and has signal-dependent switching; his PDM DACs measured 95 to 100 dB and needed per-unit tweaking with capacitors. RMAF 39:52
• 2017-12-05Watts asks why he invented pulse array in 1995. RMAF 40:43
• 2017-12-05Watts says he invented pulse array to improve DSD's high-frequency and small-signal resolution while keeping single-resistor freedom from distortion, running at 2048 times rather than 64 times. RMAF 40:50
• 2017-12-09Watts says he has designed audio since the early 1980s, his first DAC (PDM/DSD 256) in 1989, the pulse array in 1995 and the first WTA filter in DAC 64 in 1999. article, Dec 2017
• 2017-12-09Watts says he has no other partners at present but has had several digital audio semiconductor clients in the past. article, Dec 2017
• 2017-12-09Watts says he built a matchbox radio at 12, and at 16 hearing his electronics lecturer's high-end system, including how good direct-cut LPs sounded, drew him into hi-fi. article, Dec 2017
• 2017-12-09Watts says the PDM 1024 DAC, using parallel chip noise shapers with different dithered data, sounded much better and showed fundamentally better performance was possible. article, Dec 2017
• 2017-12-15Watts says Philips Bitstream chips equal DSD256; his 1992 PDM1024 summed multiple PDM noise shapers, leading to pulse array in 1995 and WTA by 1999, neither patented. Head-Fi, Dec 2017
• 2017-12-16Watts says DAC64 split WTA and pulse array across FPGAs, and stresses the WTA algorithm, coefficient quantizing and internal truncation as more important than raw tap length. Head-Fi, Dec 2017
• 2018-01-11Watts says it is very different from NAD's (Qualcomm's DDFA) technology, which he invented, the key difference being a non-switching output. needs context Head-Fi, Jan 2018
• 2018-02-23Watts recounts experimenting with FPGA interpolation filters from 1999, hearing gains from 128 to 256 to 2048 taps in bass definition, imagery, separation and timbre. MajorHiFi 8:38
• 2018-02-23Watts says 16-bit sinc accuracy needs a million taps, impossible in the 1990s, so he used listening tests to optimize his algorithm to recover timing more efficiently. MajorHiFi 9:17
• 2018-02-23Watts recounts DAC64 using four FPGAs and about 15 watts for a thousand taps, then Hugo reaching 26,000 taps with a huge gain; both were 8FS filters. MajorHiFi 10:27
• 2018-02-23Watts recalls early digital recordings on vinyl in the early 1980s, such as the Telarc 1812, sounding glassy and flat, preferring Decca pressings while learning Whittaker-Shannon sampling theory. MajorHiFi 13:00
• 2018-02-23Watts says studying sinc functions and hearing physiology led him to conclude that without a sinc filter timing errors relative to 22 microseconds made digital sound bad, among other reasons. MajorHiFi 13:47
• 2018-02-23Watts recounts calculating in the 1980s that a 16-bit-accurate sinc function for CD needs a million taps, then impossible, making a million taps a lifetime goal. MajorHiFi 14:33
• 2018-03-31Watts says he is an independent consultant, not a Chord employee, working with Chord since 1996; increasing taps improved accuracy from 8 to 9 bits in 1999 to 16-bit today. article, Mar 2018
• 2018-04-04Watts says he began assembling electronics as a boy, building a matchbox radio for his paper round, and 40 years later designed the portable Hugo from the bottom up. article, Apr 2018
• 2018-04-04Watts says that in the 1980s sampling theory told him a 1,000,000-tap filter was needed to guarantee 16-bit performance, then inconceivable; today the M scaler has 1M taps. article, Apr 2018
• 2018-04-04Watts says he always wanted to be an electronics designer, and his high-end audio interest began at 16 when his teacher demoed a Sheffield Lab direct cut that sounded real. article, Apr 2018
• 2018-04-04Watts says 1980s design was arduous: his thick film hybrid audio op-amps (0.5 GHz gain-bandwidth) took months of hand calculation, work SPICE modeling now does in a day. article, Apr 2018
• 2018-04-04Watts says digital technologies have not made analog better apart from design tools and modeling, which make design easier and faster; the actual design has not changed much. article, Apr 2018
• 2018-04-04Watts says he never regretted starting a project, but several never reached production; he cancels designs he is not fully happy with, even ones that would beat competitors. article, Apr 2018
• 2018-07-18Watts recounts WTA development from 1980s sinc ideals, finding sinc closeness beat image rejection alone, and wonders whether Davina's alias-free decimation will change the importance of tap length. Head-Fi, Jul 2018
• 2018-07-21Watts calls WTA a unique windowing function applied to the sinc, and starts a tap-length history: DAC64 in 1999 had a thousand taps using three FPGAs and 15 watts. c w 14:48
• 2018-07-21Watts traces the million-tap goal to 1981 at Cardiff University, where he read hearing physiology on transients and learned that finite-tap filters leave errors under Shannon's theory. c w 16:17
• 2018-07-21Watts says he reasoned the errors would be in timing, and that reconstructing 16-bit audio to 16-bit accuracy needs roughly a million taps by back-of-envelope calculation. c w 17:04
• 2018-07-21Watts says a million taps was impossible in 1981, so he favored vinyl then; WTA listening tests followed, and the Xilinx A200T now gives 740 DSP cores at 12 watts. c w 17:48
• 2018-11-16Watts lists five unsolvable DSD flaws (jitter sensitivity, signal-correlated switching, poor small-signal resolution, amplitude-dependent delay, instability) that led him from PDM 256 to the pulse array in 1995. Head-Fi, Nov 2018
• 2018-12-12Watts thanks Nintronics, says he will explain the technology behind Chord products, and describes himself as an electronics design consultant who has designed silicon chips for large companies. Pursuit Perfect System 2:52
• 2018-12-12Watts says he invented the pulse array in 1995, using an FPGA plus discrete components for conversion, and that silicon DAC chips struggle to reach good measured performance. Pursuit Perfect System 14:00
• 2018-12-12Watts says from earlier cable design that purer copper, silver solder and plating purity sounded better, and attributes this to small-signal non-linearity from oxide layers and joints. Pursuit Perfect System 27:40
• 2018-12-13Watts says the algorithm strongly affects sound: his first WTA filter in 1999 used a thousand taps, the FPGA limit, versus 100 conventionally, and algorithm changes improved transients. Pursuit Perfect System 6:44
• 2018-12-13Watts says TT2 has 90,000 taps, then recounts studying electronics as a science degree and reading about the physiology of hearing in a nearby psychology lab. Pursuit Perfect System 10:56
• 2018-12-13Watts recounts concluding from Shannon theory and psychoacoustics that conventional filters create audible timing errors, and estimating that 16-bit CD performance needs nearly a million taps, impossible with 1980s processors. Pursuit Perfect System 11:42
• 2019-02-22Watts says he used DSD256-equivalent PDM DACs with 32 elements in the early 90s and invented pulse array to fix DSD's resolution, noise floor modulation and amplitude-dependent timing. Head-Fi, Feb 2019
• 2019-04-05Watts lists milestones in reducing the dominance effect: pulse array (1995), WTA with DAC64 (1999), Hugo (2014) and the M scaler (2016). Head-Fi, Apr 2019
• 2019-12-10Watts says DSD was a backward step for digital-to-analog conversion, and that he was rejecting DSD in 1995 when he created his Pulse Array DAC technology. Passion for Sound 6:13
• 2019-12-16Watts recalls that in 1989 Philips PDM chips sounded more musical, deeper and warmer than R2R, but he questioned how DSD256 could work with only 256 pulses. Passion for Sound 56
• 2019-12-16Watts says he doubted 256 pulses could encode 20 kHz at 120 dB, so PDM1024 summed four or eight randomized PDM DACs, improving depth and detail resolution. Passion for Sound 1:36
• 2019-12-16Watts says he wanted DSD's single-element benefit without signal-dependent switching, leading to the pulse array; Qutest has ten PWM elements arranged so one rises as another falls. Passion for Sound 3:58
• 2019-12-19Watts says transients matter for timbre, and that he learned this in the 1980s reading psychoacoustics textbooks at university, believing understanding hearing would make him a better designer. Passion for Sound 6:19
• 2019-12-19Watts says he was also studying Shannon sampling theory then, which showed that reconstructing the original sampled signal requires a sinc function. Passion for Sound 7:15
• 2019-12-19Watts says only a sinc function removes the error; in 1980 he calculated that 16-bit accurate reconstruction needs more than half a million, three quarters of a million, taps. Passion for Sound 10:57
• 2019-12-19Watts recalls that in 1980 there were no CDs, DSPs or FPGAs, only punch cards and an 8-bit microprocessor with 2K memory, making three quarters of a million taps impossible. Passion for Sound 11:25
• 2019-12-19Watts says early digital sounded bad half from interpolation filters and half from converter issues, and that the industry avoids sinc functions because it treats ringing as bad. Passion for Sound 12:09
• 2019-12-19Watts says required accuracy is found by making filters more sinc-like and listening; his first WTA filter, DAC64 in 1999, had 1,000 taps, the M Scaler one million. Passion for Sound 22:05
• 2020-06-25Watts says he is an independent design consultant, designing Chord's digital products since 1997, though semiconductor design dominated his work from about 2001 for 14 to 15 years. Part-Time Audiophile 3:56
• 2020-06-25Watts says his Chord work was a non-commercial side activity until Hugo, when Chord's business took off and he spent more time on high-end design. Part-Time Audiophile 4:40
• 2020-06-25Watts says semiconductor work aims at good enough rather than best performance, and silicon brings substrate noise and nonlinear resistors and capacitors that FPGA discrete DACs avoid. Part-Time Audiophile 4:58
• 2020-06-25Watts says silicon design is limited by cost, recalling a project nearly canceled for being five cents too expensive until a redesign and die shrink nine months later. Part-Time Audiophile 5:42
• 2020-06-25Watts says his Chord work went from a hobby to substantial royalties as product volumes grew, letting him focus all his activity on high-end audio. Part-Time Audiophile 6:57
• 2020-06-25Watts says Class D has innate noise floor modulation problems he has solved in his own feedback designs, but its PWM switching output stage harms transient reconstruction. Part-Time Audiophile 21:57
• 2020-12-19Watts says he worked with Zia of Tube Technology in the early 2000s, and that tubes sound good more easily but solid state can outperform them with more work. Head-Fi, Dec 2020
• 2021-04-06Watts recounts how Doug Sax's direct-cut discs and master tapes shaped his work on DACs, says live unamplified sound is his ideal, and doubts tape and vinyl. Head-Fi, Apr 2021
• 2021-04-20Watts says he was no prodigy, describing A levels in physics, math and chemistry, AS level electronics, and an electronics degree from 18. Head-Fi, Apr 2021
• 2022-02-08Watts says 14 years consulting for semiconductor firms taught right-first-time design; finished designs are frozen so a 2015 DAVE sounds like a 2022 one, and he avoids sales-driven upgrades. Head-Fi, Feb 2022
• 2022-02-09Watts declines to name consulting clients for confidentiality, repeats he has not started a DAVE replacement, and says likewise for Hugo 2, Qutest and TT2: no Hugo 3 next. Head-Fi, Feb 2022
• 2022-03-19Watts says he started design work at 20, over 40 years ago, used COVID for fundamental research, and that most designers voice a DAC rich and warm or sharp. MFG Audio Reviews 2:00
• 2022-03-19Watts says conventional DACs do not reach 140 dB, and that he invented the pulse array in 1995 to solve small signal non-linearity and eliminate noise floor modulation. MFG Audio Reviews 12:31
• 2022-03-19Watts says the WTA filter makes the best of limited processing, began in 1999 with DAC64 at a thousand taps, and explains what a tap is. MFG Audio Reviews 21:09
• 2022-03-22Watts says he began as a teenager building DIY designs he could afford from a paper round, later designing his own, starting with a matchbox radio. article, Mar 2022
• 2022-03-22Watts says his interest ignited at 16 when his electronics lecturer demonstrated his hi-fi with Sheffield Lab direct-cut vinyl, and he felt he was there. article, Mar 2022
• 2022-03-22Watts says his life might have been completely different without hearing that system, and recalls visiting Doug Sax of Sheffield Lab at the Mastering Lab. article, Mar 2022
• 2022-03-22Watts lists home-built loudspeakers, an AS-level project preamp and a turntable with a Hadcock tonearm, later a university power amp with his own compound Class A output stage. article, Mar 2022
• 2022-03-22Watts says the move was about ultimate performance: work on the Deltec PDM1024 showed serious problems in existing DACs, addressable only by his own FPGA design. article, Mar 2022
• 2022-04-16Watts says SPICE models non-linearities well below -200dB and parasitic LRC, and recalls months designing 1980s hybrid op-amps that SPICE would now do in a day. Head-Fi, Apr 2022
• 2022-05-14Watts says the phase-with-amplitude discovery dates from some years ago, and he will talk about the major discoveries he mentioned toward the end of this year or next. Head-Fi, May 2022
• 2022-08-19Watts says the story goes back to 1981, when the first digital recordings on vinyl sounded hard, brittle and flat, with poor instrument separation and focus. AVstore 1:09
• 2022-08-19Watts says that while studying electronics and sampling theory he also studied the physiology of hearing and psychoacoustics, which showed him the importance of transients. AVstore 1:37
• 2022-08-19Watts says a million taps would give 16-bit accuracy, calls this digital's major flaw, and says it was impossible in the early 1980s, when he programmed with punch tape. AVstore 3:56
• 2022-08-19Watts recalls the first PC around 1983 with 20 MHz processors and 64K of RAM, his own DACs from 1989 using others' chips, and moving to FPGAs around 1995. AVstore 4:46
• 2022-08-19Watts says he used FPGAs with off-board filters until 1999, when a Xilinx FPGA allowed 1,000 taps versus about 128 commercially, and he began developing the WTA filter. AVstore 5:30
• 2022-08-23Watts recalls designing around 1994 or 1995 at dpa digital with gate-level schematics on one-time-programmable Actel antifuse FPGAs, simulating on a 66MHz 486. Head-Fi, Aug 2022
• 2022-09-18Watts says he previously worked on DSP cores, having spent 15 years designing digital audio silicon for major chip manufacturers. The Source AV 33:51
• 2022-10-12Watts contrasts chip design, citing a ten million US dollar project to be canceled unless five cents were saved, with FPGAs' far greater computational resources. Upscale Audio 1:39
• 2023-02-04Watts introduces himself: keen on hi-fi as a teenager, he built preamps and power amps from kits, then studied electronics at university as a science. Dusty Audio 13:55
• 2023-02-04Watts says it makes no sense that such tiny errors are audible, but they are; critics say he invents the numbers; he spent 15 years designing silicon chip IP. Dusty Audio 25:22
• 2023-02-04Watts says a company paid him multi-million dollars to acquire and embed his IP, and he spent much time with its engineers, whom he calls more capable than himself. Dusty Audio 26:10
• 2023-02-04Watts says the chip company's engineers disputed his 200 dB noise shaper requirement, costly in gates, for two or three years, until he invited one to his house to listen. Dusty Audio 26:56
• 2023-02-04Watts says he set noise shapers to 180 dB and 200 dB; the engineer was surprised that the 190 to 200 dB difference was so big and easy to hear. Dusty Audio 27:40
• 2023-02-04Watts says the engineer's report ended the arguments, and when a tiny number seems implausible he confirms it with a blind listening test with his son. Dusty Audio 28:28
• 2023-02-04Watts says perfect reconstruction uses the infinite past and future; in the 1980s, knowing sampling theory and psychoacoustics, he identified timing reconstruction between samples as digital's fundamental problem. Dusty Audio 39:08
• 2023-02-04Watts says he worked out in the 1980s that reconstructing to 16-bit accuracy needs more than half a million taps, which then seemed impossible. Dusty Audio 39:52
• 2023-02-04Watts says 1990s FPGAs let him use 1000 taps against 128 in off-the-shelf filters, explains that taps measure processing, and says it sounded a lot better. Dusty Audio 40:34
• 2023-02-05Watts says his first FPGAs were simple Actel anti-fuse parts around 1990 or 1992, programmed by welding connections with a high voltage. Soundnews 16:39
• 2023-02-05Watts explains anti-fuse FPGAs needed a new chip for every change; from 1992 he used them for multiple dithered noise shapers summed in the analog domain. Soundnews 17:11
• 2023-02-05Watts says in 1995 anti-fuse FPGAs could run his noise shapers, when he created the pulse array and SPDIF receiver; in 1999, consulting for Chord, he adopted Xilinx FPGAs. Soundnews 18:09
• 2023-02-05Watts says that generation had enough processing power to do the interpolation filters as well. needs context Soundnews 18:49
• 2023-02-05Watts says from 1999 he did everything in the digital domain; his first DAC in 1989 used Philips chips, and he taught himself FPGAs and digital circuitry over that decade. Soundnews 18:57
• 2023-02-05Watts remarks on the DAC64 (the transcript's 'a 6 year-old' is an uncertain hearing). Soundnews 19:41
• 2023-02-05Watts says that was the first WTA filter. needs context Soundnews 19:45
• 2023-02-05Watts says from 1984 to 1989 DACs were all R2R DACs. Soundnews 20:12
• 2023-02-05Watts says R2R DACs sounded dreadful, flat and hard compared with more musical vinyl, until Philips launched Bitstream in 1988. Soundnews 20:24
• 2023-02-05Watts says Bitstream was effectively DSD256, a simple second-order noise shaper at 1 bit, 256 times, and was the first digital he heard sound musical and smooth. Soundnews 20:51
• 2023-02-05Watts says Bitstream's 256 one-bit pulses seemed too few for a 20 kHz waveform, so he modeled noise shapers and paralleled dithered noise shapers in early FPGAs. Soundnews 21:31
• 2023-02-05Watts says that work led to the pulse array; turning to R2R, its first fundamental problem is that the resistors can never be matched. Soundnews 22:19
• 2023-03-26Watts recalls studying sampling theory and, on his own, psychoacoustics in the 1980s, learning that transient timing is perceptually vital for pitch, timbre and soundstage. Eric's Hi-Fi 41
• 2023-03-26Watts says that in those days they did not have FPGAs. needs context Eric's Hi-Fi 43:08
• 2023-03-26Watts says he would have had a business partner who knew what he was doing and had some capital. needs context Eric's Hi-Fi 43:30
• 2023-03-26Watts says he ran the whole company himself, from design and manufacturing to sales and accounts, with no money; you must specialize in what you are good at. Eric's Hi-Fi 43:38
• 2023-03-26Watts says choosing A-level electronics over further maths sent him to Cardiff rather than Southampton University, which he imagines would have kept him in academia. Eric's Hi-Fi 44:23
• 2023-03-26Watts says meeting John Franks by chance in Vegas changed his path, as did another meeting that led to 14 years selling his IP to semiconductor companies. Eric's Hi-Fi 45:10
• 2023-03-26Watts says self-belief needs real abilities behind it; he and Chord are now successful, but he spent 20 or 30 years in poverty pursuing better sound. Eric's Hi-Fi 46:06
• 2023-03-28Watts describes himself as both an analog and a digital designer, doing FPGA design since the mid-1990s and selling IP to silicon companies for about six chip projects. The Headphone Show 1:37
• 2023-03-28Watts says he has designed about 50 DACs, worked with Chord just over 25 years while independent and owning his IP, and that femtosecond-clock claims are meaningless across DAC architectures. The Headphone Show 2:22
• 2023-03-28Watts says noise floor modulation causes grainy treble or reduced smoothness and timbre variation even below measurable levels; pulse array, invented in 1995, aimed to match DSD256 without its problems. The Headphone Show 44:50
• 2023-03-28Watts says that will not explain his DACs or interpolation filters; his work changed hugely in ten years, he left semiconductor companies in 2015, and owners enjoy music more. needs context The Headphone Show 54:58
• 2023-03-29Watts says he studied electronics, left university in 1984, set up his own business and has never worked for anybody but himself. microwirenews 20
• 2023-03-29Watts, now 62, says he has made more money than expected but is driven by doing new things, and is still discovering things that improve sound quality. microwirenews 5:06
• 2023-07-03Watts says powering the M Scaler after the source can break USB handshaking, so power the scaler or DAC first; he also reflects on reputation and CanJam Singapore. Head-Fi, Jul 2023
• 2023-10-01Watts explains that an FPGA can hold any digital circuit that fits, recounts his chip-consulting path (Verilog simulation, FPGA prototype, ASIC), and says FPGAs allow what chips cannot afford. The Source AV 4:47
• 2023-10-01Watts recalls a chip project at a company that had spent ten million US dollars developing it before presenting it to the board. The Source AV 5:36
• 2023-10-01Watts says the company would write off the 10 million unless the design could save five cents. needs context The Source AV 6:01
• 2023-10-01Watts says trimming the die cost nine months, mass-market chips are designed to minimum acceptable performance to cut cost, and with FPGAs he can do what he likes. The Source AV 6:15
• 2023-10-01Watts says depth is completely about accuracy, which reproduced audio lacks, and that at 16 he already wondered why reproduction sounded so flat. The Source AV 14:35
• 2023-10-01Watts says DAVE cannot fix a headphone's problems, so try another; asked by an Atlantic engineer about 'magic fairy dust', he said he had been grinding it out 40 years. The Source AV 22:11
• 2023-10-01Watts says long ago he designed a compression circuit whose variables could be set to create only second harmonic distortion and nothing else. The Source AV 31:41
• 2023-10-01Watts says output-stage bias must not drift with heat, notes he began as an analog designer, self-taught in digital, and says the DACs sound the same at switch-on and later. The Source AV 47:35
• 2024-03-20Watts says random RF noise harms all analog electronics; in the early 1980s his system sounded best at 2 am and sometimes bright and aggressive. MFG Audio Reviews 5:02
• 2024-03-20Watts recounts that solid-core mains cables sounded warmer, darker and smoother than stranded, puzzling given three 70 dB regulator stages and op-amps with 140 dB power supply rejection. MFG Audio Reviews 5:50
• 2024-03-20Watts explains that power supply rejection applied only in the audio band, so he concluded RF noise was changing the sound and began developing a complex RF mains filter. MFG Audio Reviews 6:40
• 2024-03-20Watts describes cascading ever-smaller LC filters from 100 kHz to hundreds of MHz; with the filter perfected, solid-core and stranded mains cables sounded identical, so the difference was RF. MFG Audio Reviews 7:30
• 2024-03-20Watts says he used linear regulators on the DAC64 expecting switchers to sound worse, but Hugo One needed internal switch mode supplies for efficiency, so he compared the two. MFG Audio Reviews 27:50
• 2024-03-20Watts says the modeling matched his 1980s mains filter, built by listening into a 12th-order design with hand-wound air-cored PTFE coils, agreeing with what he found subjectively. MFG Audio Reviews 35:41
• 2024-05-10Watts agrees and says that many years ago he used to design cables, so he knows. Reactcore 54
• 2024-05-16Watts says the project was also research on interpolation; Hugo M Scaler had sinc performance to 16-bit, a target he thought unreachable when he identified the flaw in the 1980s. ConvinceMeAudio 7:44
• 2024-07-12Watts says psychoacoustics is vital; studying electronics from 1979, he read psychoacoustics on his own because his halls of residence were next to the psychology library. HIFICLUB 3:28
• 2024-07-12Watts says what we hear is the brain's illusion built from ear data, and he studied its mechanisms to prepare for becoming an audio designer. HIFICLUB 4:16
• 2024-07-12Watts says in the 1980s digital recordings on vinyl sounded terrible next to pre-1970s Decca recordings, which made him wonder why digital was so bad. HIFICLUB 7:24
• 2024-07-12Watts says any interpolation filter that is not a sinc loses transient timing, his 1980s realization that digital would always be flawed. HIFICLUB 9:04
• 2024-07-12Watts says in the 1980s he calculated that 16-bit timing accuracy needs nearly a million taps for a 16 times oversampled filter, the key to the Hugo M Scaler. HIFICLUB 9:54
• 2024-07-12Watts describes programming with paper tape and says a million taps was then impossible, so he concluded digital would always sound bad until DSPs and FPGAs arrived. HIFICLUB 10:47
• 2024-07-12Watts says his son's blind descriptions nearly always match his own for errors at minus 350 dB, then starts a story about consulting on digital power amplifiers for semiconductor firms. HIFICLUB 21:57
• 2024-07-12Watts says the client's engineers argued that errors below the threshold of audibility do not matter when he insisted designs must be done a certain way because it sounded better. HIFICLUB 22:44
• 2024-07-12Watts says the pulse array, which he invented in 1995, solves all three major issues unlike PWM, n-bit delta-sigma or R2R, and no one else appears to have copied it. HIFICLUB 44:59
• 2024-08-01Watts restates the question about FPGA versus chip DACs, calls it complicated, and says he has designed DACs since 1989, used FPGAs since 1995, and worked with semiconductor companies. Audiophilesdoteu 3
• 2024-08-01Watts says he has designed silicon chips and sold his IP to semiconductor firms; an FPGA lets you do exactly what you want at low cost, while a custom chip costs millions and needs volume. Audiophilesdoteu 47
• 2024-09-29Watts says the right-first-time approach comes partly from designing with major semiconductor companies, where a mask set costs a million dollars. The Source AV 11:52
• 2024-09-29Watts says that when he left university his fellow students went into defense, but he chose music and audio as his passion. The Source AV 22:49
• 2025-01-13Watts compares feed-forward correction (about 20dB) with his second-order analog noise shaper (90dB), showing TT2 into 8 ohms, and links crossover distortion to amplitude-dependent transient delay. Head-Fi, Jan 2025
• 2025-02-17Watts says he spent 14 years consulting for semiconductor companies on digital amplifiers with patented feedback, and that substrate noise from digital sections corrupts a chip's analog section. audio-2G 1:20
• 2025-05-12Watts lists tap counts: DAC64 1,000 (1999), QBD 18 thousand, Hugo 26 thousand (2013), DAVE 164 thousand, Hugo M Scaler 1 million; more taps and WTA improvements each improved sound. Audiophile Junkie 13:35
• 2026-03-17Watts says he has worked on it since 1980, about 40 years. needs context ecoustics 28
• 2026-03-17Watts says it began with wondering why recordings he heard ('vinyl recordings on digital', as transcribed) sounded so awful next to pre-Dolby Decca recordings, and whether digital could be improved. ecoustics 45
• 2026-03-17Watts says early digital sounded hard, bright, flat and not musical, blocking emotional involvement; he studied sampling theory and knew transient timing governs perceived timbre, pitch and location. ecoustics 1:16
• 2026-03-17Watts says he was right that reconstruction is crucial but wrong to think 16-bit reconstruction accuracy would give perfection because recordings were 16-bit. ecoustics 3:13
• 2026-03-17Watts says FIR filters did not then exist, analog reconstruction filters were very poor because they cannot see the future, and he thought digital was fatally flawed. ecoustics 11:41
• 2026-03-17Watts says noise shaper performance depends on its running rate and number of integrators, and since the 1990s he designed noise shapers to 200 dB performance. ecoustics 34:57
• 2026-03-17Watts says in the 1980s he designed interconnect and loudspeaker cables and found high-purity copper, silver solder and silver plating improved depth and detail. ecoustics 45:56
• 2026-03-17Watts says in the mid-1980s he dismissed the claim, since his preamp had cascaded regulators and about 300 dB of supply rejection, but tried it one afternoon. ecoustics 54:06
• 2026-03-17Watts says he then built RF filters, shrinking inductors and capacitors down to hand-wired solid-core PTFE inductors and tiny ceramic caps, each step sounding warmer. ecoustics 56:33
• 2026-03-17Watts says he turned 65 in September and never expected still to be discovering new things. ecoustics 1:27:36
• 2026-03-17Watts says he is still excited designing new products after 40 years, with huge challenges ahead and progress made. ecoustics 1:27:50
• 2026-03-24Watts says he met John Franks at a Las Vegas show in 1995, a family coincidence led to their partnership, and in 1999 they released the DAC64. Audio Force 3:19
• 2026-03-24Watts says DAC64 was revolutionary, he has worked with Chord since, also designed audio chips as a semiconductor designer, now works full time on Chord development, and Quartet took 8 years. Audio Force 4:07
• 2026-03-24Watts says the simple question has a complex answer, and his original interest was audio. Audio Force 6:41
• 2026-03-24Watts says he was a hi-fi fanatic as a teenager and wanted, as an electronics designer, to shrink the massive gap between live, amplified sound and reproduced audio. Audio Force 6:52
• 2026-03-24Watts says he began with analog preamps and power amps, designed DACs from 1989 with Philips PDM chips that had severe problems, and by 1992 used FPGAs. Audio Force 7:36
• 2026-05-03Watts introduces himself as the designer of Chord Electronics' digital products, designing DACs since 1989, over four decades. Audio Force 41
• 2026-10-02Watts says he is an independent design consultant who owns his own IP, not a Chord employee, and spent 14 years under contract to major semiconductor companies, selling them patents. HiFi Buys 26
• 2026-10-02Watts says consulting gives him freedom to focus on design, recalling that running an undercapitalized manufacturing company in the 80s and 90s was a struggle. HiFi Buys 1:16
• 2026-10-02Watts says he was interested in audio as a young teenager but could not afford it, earning a small income from a paper round. HiFi Buys 3:39
• 2026-10-02Watts says he built his own hi-fi from kit amplifiers and speakers, and was first impressed by his sixth-form electronics lecturer's real hi-fi system. HiFi Buys 4:01
• 2026-10-02Watts says hearing Sheffield Labs direct-cut discs convinced him to pursue audio, and he studied electronics as a science at Cardiff University. HiFi Buys 4:43
• 2026-10-02Watts says it did: designs must be producible with decent yields so the manufacturer survives, and yield and reliability are lifelong lessons. HiFi Buys 5:55
• 2026-10-02Watts says he met John Franks at Winter CES in Las Vegas through a shared distributor, and Franks said he came from Maidstone in Kent. HiFi Buys 14:29
• 2026-10-02Watts says Franks, with an aerospace background, was intrigued by his FPGA-based discrete DAC technology, leading by 1999 to the DAC64, which had five FPGAs. HiFi Buys 16:16
• 2026-10-02Watts says DAC64 had his first WTA interpolation filter, and at university he read 1950s physiology-of-hearing texts on interaural delay in the psychology library. HiFi Buys 17:01
• 2026-10-02Watts says his view in the 1980s was that digital was fundamentally flawed, given 1980s technology. HiFi Buys 21:09
• 2026-10-02Watts says in those days there were no PCs, DSPs or FPGAs, and he first programmed a mainframe using punched cards. HiFi Buys 21:20
• 2026-10-02Watts says he wrote an oil-flow computer program from scratch in machine code on an 8-bit microprocessor with about 2K of memory during summer work. HiFi Buys 21:41
• 2026-10-02Watts says digital filters arrived in the nineties; in the 80s interpolation filters were made of inductors and capacitors. HiFi Buys 22:26
• 2026-10-02Watts says on one chip program with $10 million invested, the board demanded five cents off the die cost, which took nine months of work. HiFi Buys 29:15
• 2026-10-02Watts says he developed the pulse array in 1994 to 1995, using PDM256 (DSD256) chips fed by several randomized noise shapers summed in the analog domain. HiFi Buys 1:41:42
• 2026-10-02Watts says DSD sounds natural as distortion vanishes into noise, but he wanted its benefits without its problems: a faster noise shaper and no signal-dependent switching causing NFM. HiFi Buys 1:42:15
• 2026-10-14Watts says he was born in Dorset and has lived in Wales since coming to study electronics at university in Cardiff. Part-Time Audiophile 4:29
• 2026-10-14Watts says early A to D converters were poor 1980s technology; he hated CD and digital recordings, preferring vinyl, especially 1960s recordings made before Dolby. Part-Time Audiophile 43:16
• 2026-10-14Watts says in the early eighties he thought digital would never sound good, having learned at university that transients matter and sampling would damage them, until Philips's 1989 PDM DAC. Part-Time Audiophile 43:52
• 2026-10-14Watts says Philips's PDM DAC, equivalent to DSD256, sounded musical and warm, and he could not understand how 256 one-bit pulses could encode a 22 kHz sine wave. Part-Time Audiophile 44:32
• 2026-10-14Watts says a PDM DAC built from eight individually dithered PDM DACs showed PDM resolution was insufficient, leading him to develop the pulse array on mid-nineties FPGAs. Part-Time Audiophile 45:20
• 2026-10-14Watts says 1999 Xilinx FPGAs could hold an interpolation filter and the DAC, so he launched DAC64 with a pulse array and a thousand-tap WTA filter. Part-Time Audiophile 46:08
• 2026-10-14Watts says early CD, before what is transcribed as 'CD Rock', sounded diabolically bad; at launches he ran from the room because it sounded bright and hard. Part-Time Audiophile 47:18
• 2026-10-14Watts says DAVE and Mojo are his most famous, Mojo for audiophile performance at a phone-like price, but Quartet is his most important design, partly for its built-in ADC. Part-Time Audiophile 1:03:03