Development history of released products

Watts, Chord, community and miscellany

Answers on this topic

• How were Chord's current DACs and the M Scaler developed, and how long did each take?

Everything he said on this topic (311)

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

• 2014-04-01Watts declines a suggested source project as a major effort with no sound-quality gain, noting some Hugo IP began 30 years ago and Hugo is designed from the gate level. Head-Fi, Apr 2014
• 2014-04-15Watts rejects calling Hugo a DAC with a good headphone amp, defines transparency against live music, recounts Hugo's development, and explains its single-stage output, 0.075 ohm impedance and tap length. Head-Fi, Apr 2014
• 2014-04-18Watts explains Hugo's volume preset mode came from matching Qute for comparisons, and that the settings-memory feature was dropped because the FPGA was full after adding crossfeed and DSD. Head-Fi, Apr 2014
• 2014-04-29Watts says Chord supplies precision-soldered prototypes, SPICE simulation meant only 4 components changed, the DAC hit its calculated 120 dB dynamic range, and Christmas went on FPGA coding. Head-Fi, Apr 2014
• 2014-08-03Watts says he always pushes for better performance and expected Hugo to be better, but not revolutionary. article, Aug 2014
• 2014-08-03Watts calls Hugo an accident: over 6 years he had replaced all the digital module code intended for a reference-class DAC. article, Aug 2014
• 2014-08-03Watts says John Franks saw a market for a portable DAC amp, the project began in autumn 2012, and the Spartan-6 LX9 FPGA let Hugo take the reference DAC's code. article, Aug 2014
• 2014-08-03Watts describes being astonished by the Hugo prototype versus his Qute: far more musical, no fatigue, revealing without forcing detail, fast rhythm, piano notes starting and stopping naturally. article, Aug 2014
• 2014-08-29Watts says FPGA DAC design is far harder than using chips, his Verilog RTL serves ASIC or FPGA alike, and Hugo reflects a six-year upgrade of FPGA modules. Head-Fi, Aug 2014
• 2014-10-08Watts discusses Hugo's low fatigue and prototype surprise, says the source matters little via optical, hears no plastic vs glass difference, and mentions Chord projects nearly ready. Head-Fi, Oct 2014
• 2014-10-20On Hugo's first anniversary, Watts recalls its first listening test, credits a six-year Verilog rewrite and the Spartan-6 FPGA, and says pursuing transparency paid off in musicality. Head-Fi, Oct 2014
• 2015-02-02Watts says Hugo was never voiced; he designs for transparency by judging variation in placement, timbre and separation, and recounts how Hugo's musicality after a six-year code upgrade surprised him. Head-Fi, Feb 2015
• 2015-02-02Watts describes TT's floating balanced output, says TT uses batteries for mains isolation though 2Qute proved RF filtering matches it, and lists balanced drive's pros and cons. Head-Fi, Feb 2015
• 2015-08-29Watts says the calibrated output began as a prototype feature for listening tests against earlier DACs set to exactly 3v RMS at 0 dBFS, and was kept for DAC mode. Head-Fi, Aug 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 the Mojo project grew out of Hugo and its success, and that Hugo began as a fun exercise for himself. What Hi-Fi? 7:06
• 2016-01-09Watts says he made Hugo while designing silicon chips in Phoenix, and was surprised studios use it for mixdown: seventy percent of the UK's top one hundred is heard through Hugo. What Hi-Fi? 7:25
• 2016-01-27Watts says linear supplies involve compromises: developing Hugo in 2012, switching regulators sounded smoother with deeper soundstage and measured better than linear ones, so assumptions must be tested. Head-Fi, Jan 2016
• 2016-01-29Watts says Hugo's noise shaping was limited by its four-element pulse array and FPGA; for DAVE each 20 dB improvement from 200 dB deepened the stage, reaching -350 dB. article, Jan 2016
• 2016-01-29Watts describes DAVE's 17th-order noise shaper with 46 integrators, his doubt whether 350 dB was the real cause, and a redesign confirming 350 dB or 48-bit accuracy is needed. article, Jan 2016
• 2016-01-29Watts says a single-stage 16FS WTA first stage sounded much better, by more than 26,000 versus 164,000 taps, and 256FS second-stage filtering improved timing accuracy from microseconds to nanoseconds. article, Jan 2016
• 2016-01-29Watts says Hugo development has stopped because its FPGA is too small, and that after he improved DAVE's WTA filters it sounds faster, tighter, more dynamic, neutral and transparent. article, Jan 2016
• 2016-02-16Watts says Hugo's perception of timing, the starting and stopping of notes, surprised him, and Dave was about identifying and maximizing that factor, which he now understands technically. Head-Fi, Feb 2016
• 2016-03-03Watts says his line count includes hand-copied coefficient data, verification and FPGA timing closure are the hardest parts, and Dave's roughly 100,000 lines took 9 months. Head-Fi, Mar 2016
• 2016-03-07Watts is quoted: developing Hugo in 2013 he thought 1 microsecond accuracy was enough, but developing DAVE he confirmed nanosecond-level accuracy has an effect. article, Mar 2016
• 2016-03-07Watts once thought a 200dB noise shaper, 1,000 times better than high-end DACs, sufficient; developing DAVE he spent 90 days reaching 350dB and found depth improved markedly. article, Mar 2016
• 2016-03-19Watts says Dave has no control electronics beyond the FPGA, cutting RF noise but forcing him to code everything including the display; he ran out of time for remote numbers. Head-Fi, Mar 2016
• 2016-05-13Watts says high-speed internal switchers sounded smoother and warmer than linear regulators in Hugo, forced more RF filtering, and cut DAVE's FPGA supply current from 5 A to 1 A. Head-Fi, May 2016
• 2016-06-02Watts says DAVE sounded too dark and soft late in development until a 256FS WTA stage improved perception of note starts and stops and restored balance. Head-Fi, Jun 2016
• 2016-07-09Watts says final DAVE production PCBs were made in spring 2015, the production BOM released that summer, and code finished in December before serial production. Head-Fi, Jul 2016
• 2016-07-24Watts says a second factor behind DAVE was the unexpected quality he heard from Hugo, whose internal digital modules had been upgraded over a 6 year period. Hifistatement 32
• 2016-07-24Watts says a major code rewrite, with more powerful simulation tools, was intended for a planned reference DAC; he made Hugo for hotel listening, expecting few sales. Hifistatement 1:17
• 2016-07-24Watts says Hugo was a personal project while he did silicon design work in Phoenix; code developed for the reference product went into Hugo, the first product using it. Hifistatement 2:03
• 2016-07-24Watts says Hugo's quality came from perceiving the starting and stopping of transients, not the WTA filter, since earlier 32,000-tap filters lacked it (Hugo had 26,000); DAVE gets bigger FPGAs. Hifistatement 3:31
• 2016-07-24Watts says Hugo is cost constrained while DAVE's FPGA is 10 times larger, allowing longer taps, bigger WTA filters, more advanced noise shapers and a better discrete pulse array DAC. Hifistatement 4:16
• 2016-07-24Watts says Hugo has about 26,000 taps, Mojo similar, and DAVE 164,000 taps on 166 DSP cores filtering to 2048 times; the 100,000-line WTA code repeatedly failed timing closure. Hifistatement 3:15
• 2016-07-24Watts says the DAVE filter took nine months to work on the FPGA, and was better but lacked Hugo's starting and stopping of notes, speed and timbre variation. Hifistatement 4:02
• 2016-07-24Watts says for DAVE he raised noise shaper performance from Hugo's 200 dB through 220, 240 and 260 dB, depth improving each time, reaching -350 dB over 90 days. Hifistatement 3:05
• 2016-07-24Watts says the highest-order noise shaper he had seen was 9th order or DSD, and he worried that the 350 dB gains might be a proxy for some analog-domain effect. Hifistatement 4:40
• 2016-07-24Watts says redesigning DAVE's all-digital noise shapers to 350 dB gave the same results, so the digital path truly needs 350 dB (48-bit) accuracy; it is not a proxy. Hifistatement 5:24
• 2016-07-24Watts says better 2048FS filtering on Hugo also improved timing resolution, so in place of Hugo's 8x-then-16x WTA stages he tried a single 16x WTA stage, which sounded a lot better. Hifistatement 6:51
• 2016-07-24Watts says this mattered more than going from 26 thousand to 164 thousand taps, 16x filtering is accurate only to microseconds, and he added a 16x-to-256x WTA stage. Hifistatement 7:47
• 2016-07-24Watts says the FIR filter now runs at 256 times FS, beyond others' 16 times (he once did 32), using many DSP cores and making a massive change. Hifistatement 8:32
• 2016-07-24Watts says noise shaper design makes a big difference to sound and especially depth, and that WTA and noise-shaping work taught him more in two years than the previous ten. Hifistatement 10:29
• 2016-07-24Watts says analog and noise shaper improvements made DAVE almost too rich and soft, lacking Hugo's immediacy, until improved WTA filters and other changes made it faster, tighter, more dynamic and more neutral. Hifistatement 11:45
• 2016-07-24Watts says Hugo's sound hardened slightly into very low impedance headphones, with higher-order harmonics measurable; since an analog amplifier is a first-order noise shaper, he took a second-order approach. Hifistatement 0
• 2016-07-27Watts says DAVE's first prototype PCB was designed over three years earlier, when the FPGA was chosen on price and availability, and knowledge matters more than FPGA size. Head-Fi, Jul 2016
• 2016-09-17Watts says the amplifier project was delayed by other projects, that DAVE's output stage came from it, and that its prototype must be redone but is planned for 2017. Head-Fi, Sep 2016
• 2016-10-21Watts says adding the 256FS WTA filter turned DAVE from rich, dark and almost soft to sharper and tighter, improving starting and stopping of notes by nearing ideal sinc. Head-Fi, Oct 2016
• 2017-01-07Watts presents the Blu Mk2 slides: why ringing worries are mistaken, the 16-bit case for about 1M taps, delaying launch to reach 1M, and why the scaler is separate. Head-Fi, Jan 2017
• 2017-01-23Watts says Dave's 26,000 to 164,000 tap step disappointed him, algorithm and 16FS mattered more, 0.5M taps was transformational, and explains reducing errors until inaudible with a biscuit-barrel analogy. Head-Fi, Jan 2017
• 2017-05-02Watts says Dave took over 2 man years and he will not repeat that now, as Davina and the amps, to be called Power Pulse Array, will occupy years. Head-Fi, May 2017
• 2017-05-08Watts says the M scaler is 0.234 dB louder (-2.766 dB insertion loss, +3 dB volume) and its 10 A signal-dependent FPGA ground current forces a separate, isolated box. Head-Fi, May 2017
• 2017-05-25Watts explains why pulse array DACs are jitter immune, why femto clocks with PLLs degrade sound, and how a Hugo 2 prototype jitter and element-mismatch test exposed a layout fault. Head-Fi, May 2017
• 2017-06-17Watts calls Hugo 2 a complete redesign of Hugo 1: better DSD filtering, 10 pulse array elements instead of 4, a second-order analog noise shaper output, digital DC servo. Head-Fi, Jun 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
• 2017-08-12Watts says Davina will measure the audible losses of decimation and re-interpolation, recalls underestimating the M scaler's gain, and expects 44.1/16 Davina recordings to beat conventional ADCs. Head-Fi, Aug 2017
• 2017-10-13Watts says a Xilinx FPGA family launched about 3 years ago went into Mojo and Hugo 2; he used it for Davina, then ported that work into Blu 2. miceblue425 23:55
• 2017-10-13Watts says in DAVE's development he started from Hugo's 26,000-tap filter and designed a 164,000-tap one; two designs failed timing closure, which he explains. miceblue425 28:44
• 2017-10-13Watts says the DAVE filter took nine months and sounded only a bit better, so he expected little from the M Scaler and first built an easy half-million-tap version. miceblue425 29:37
• 2017-10-13Watts says the 512,000-tap filter compared with DAVE gave his biggest shock in 5 years, partly due to an improved WTA filter and moving from 8FS to 16FS. miceblue425 30:21
• 2017-10-13Watts says the FPGA could just fit a million taps; timing closure tested fine at double rate, but packing memory efficiently required a completely new filter architecture. miceblue425 31:06
• 2017-10-13Watts disagrees that Head-Fi made Hugo possible, saying Hugo started development when he was only vaguely aware of Head-Fi. Head-Fi, Oct 2017
• 2017-10-17Watts says Blu 2 uses code originally written for Davina, and that code will not change for Davina. Head-Fi, Oct 2017
• 2017-10-20Watts says the Xilinx XC7A200T, launched about three or 4 years ago, became buyable only about 18 months ago; he used it for the Davina project, and it allows a million taps for Blu 2. Hifistatement 0
• 2017-10-20Watts says he did not expect a big sonic change from this project; moving DAVE from 26,000 to 164,000 taps took nine months and 3 redesigns over timing closure. Hifistatement 2:10
• 2017-10-20Watts explains timing closure (nets within 4.8 nanoseconds on this design), says DAVE's filter was redesigned twice to achieve it, and after nine months it sounded only a bit better. Hifistatement 2:52
• 2017-10-20Watts says he expected only incremental gains, so designed a half-million-tap filter on the new FPGA in a couple of months, heard a huge change, and decided to use more taps. Hifistatement 3:36
• 2017-10-20Watts says the FPGA has only just enough processors and memory for a full million-tap filter, but he delayed the project to push on with a full million taps. Hifistatement 4:24
• 2017-10-20Watts says the filter needed a new architecture; 528 processors at 208 MHz met timing closure with 740 DSP cores available, but memory efficiency was the problem. Hifistatement 0
• 2017-10-20Watts describes one coefficient ROM and one data memory feeding eight DSP cores, giving about 97 percent memory efficiency and easier coding of half a million lines. Hifistatement 45
• 2017-10-20Watts says, coding alone, he designed blocks of 8 cores running as separate threads, and that going from half a million to a million taps made an enormous change. Hifistatement 1:22
• 2017-10-20Watts says an external scaler reduces ground-plane noise through galvanic isolation, and that how the isolation and power supply were implemented made a substantial change to sound quality. Hifistatement 55
• 2017-10-28Watts says going from Hugo's 26k to DAVE's 164k taps changed little until WTA algorithm tweaks did; for a given algorithm, doubling taps doubles accuracy against the ideal. Head-Fi, Oct 2017
• 2017-12-05Watts says he once doubted distortion below minus 120 dB mattered, but while designing DAVE he pursued much lower distortion because reduced distortion had always sounded better. RMAF 12:58
• 2017-12-05Watts says DAVE prototypes stalled at minus 120 then minus 130 dB distortion, while he aimed to beat the dCS Vivaldi's minus 130, until one idea cut 20 dB. RMAF 13:41
• 2017-12-05Watts says the fix took DAVE's distortion below minus 150 dB, being the last mechanism he could think of, and the listening test showed a big change in sound quality. RMAF 14:31
• 2017-12-05Watts says he expected cutting eighth to tenth harmonic distortion from 130 to 160 dB to sound warmer, but DAVE sounded brighter and sharper with clearer small details. RMAF 14:59
• 2017-12-05Watts says that, playing Shaun the Sheep through the DAVE prototype, his son, unaware of any change, immediately noticed the improved clarity. RMAF 15:45
• 2017-12-05Watts says any small-signal error is audible, recounting that the first Hugo's code was too big to fit, so he slimmed down the noise shaper, worried about sound quality. RMAF 20:51
• 2017-12-05Watts says Hugo's slimmer noise shaper improved only depth, and with DAVE's ten-times-larger FPGA he raised the noise shaper from 200 to 220 dB and depth deepened. RMAF 21:37
• 2017-12-05Watts says Hugo was a fun project for hotel listening, expected to sell a couple of hundred, that he designs for interest not money, and refuses some Chord requests. RMAF 57:27
• 2017-12-05Watts says John Franks opposed Blu 2, but Watts wanted a million taps, expected a small gain, spent six months, and got a tremendous change, which only listening reveals. RMAF 58:11
• 2017-12-09Watts says he typically goes through 3 to 6 batches of prototypes, especially for new product categories, as a perfectionist who resolves every measurement issue. article, Dec 2017
• 2017-12-09Watts says the idea came from John Franks and calls it a very neat solution to control and display simultaneously. needs context article, Dec 2017
• 2017-12-09Watts names DAVE, over 2 and a half years of work, and the M scaler on Blu 2, having envisioned needing 1,000,000 taps in the 1980s, as his hardest designs. article, Dec 2017
• 2017-12-24Watts says he plans long term: he foresaw a million-tap M scaler ten years ago, designed 1M-tap filters five years ago, and built in features like Dave's DX outputs. Head-Fi, Dec 2017
• 2017-12-31Watts reviews 2017: the M scaler (half-million taps Aug 2016, 1M Dec 2016, heard at CES 2017), Brilliant Classics and Oistrakh recordings, and his MrSpeakers Aeon closed. Head-Fi, Dec 2017
• 2018-01-07Watts says all production units used the same iss5 PCB, while press photos showed iss4 units that were never sold. needs context Head-Fi, Jan 2018
• 2018-01-10Watts lists noise and distortion pass criteria, says Hugo 2 and Qutest are within 0.5 dB of theoretical noise, and explains setting pulse array resistors at a distortion tipping point. Head-Fi, Jan 2018
• 2018-01-11Watts describes balancing warmth and transparency: DAVE sounded too dark until the 256FS WTA filter, cheaper products degrade evenly from BluDave, and Mojo was set warmer for cheaper headphones. Head-Fi, Jan 2018
• 2018-01-22Watts describes a planned transient-error measurement, fearing 164,000 versus 1M taps may measure small, and recounts how cutting Dave's harmonics from -130dB to -150dB was unexpectedly audible. Head-Fi, Jan 2018
• 2018-02-16Watts recounts that Qute owners' PSU reports led him to add regulation and RF filters to 2Qute, which then sounded unchanged on a car battery; try a USB battery pack. Head-Fi, Feb 2018
• 2018-02-23Watts says going from Hugo to Dave took nine months of coding yet gave an important but not night-and-day change, so he thought 164,000 taps neared the limit. MajorHiFi 11:29
• 2018-02-23Watts says after Dave's modest gain he chose 512,000 taps for the Blu upgrade as easy to place and route; it took about three months and sounded completely different. MajorHiFi 15:26
• 2018-02-23Watts recounts deciding to push the FPGA to a million taps despite expected memory and timing closure problems and having to tell John Franks the projects would be delayed. MajorHiFi 16:16
• 2018-02-23Watts recounts telling John Franks the million-tap version would take three months more, noting its marketing appeal; it took longer and needed half a million lines of code. needs context MajorHiFi 16:55
• 2018-02-23Watts says he alone wrote code equal to 5 percent of Windows, and explains that FPGA designs may fail to place and route or reach timing closure. MajorHiFi 17:38
• 2018-02-23Watts says two-thirds of FPGA effort is testing and simulation, and that his biggest problem was inefficient use of memory blocks, not timing closure. MajorHiFi 18:23
• 2018-02-23Watts describes making memory more efficient by feeding eight DSP cores from one memory block and one coefficient block, cutting his coding and data-transfer work by a factor of eight. MajorHiFi 19:06
• 2018-02-23Watts calls the filter the most advanced filter technology, redefining CD, and says he listened alone, sometimes with his sons, first hearing 512,000 taps in August or September. MajorHiFi 21:37
• 2018-02-23Watts says he needed others to confirm what he heard; the million taps worked by Christmas Eve, launched at CES, where Jude was the second person to hear it. MajorHiFi 22:30
• 2018-03-13Watts says he rejected auto switchover because it lost nearly 20 seconds of music while the DC servo reset DC to zero; a 100 mS target failed. needs context Head-Fi, Mar 2018
• 2018-03-17Watts describes DAVE's development: individual RF filtering of digital sections, care over ground-plane return currents and layout, two ground planes, and Chord's patience over time and prototypes. Head-Fi, Mar 2018
• 2018-03-31Watts says Hugo launched in 2014 as a fun project; he expected to sell a couple hundred but over 10,000 sold, which brought him back to high-end products. article, Mar 2018
• 2018-03-31Watts names Mojo as the project he is happiest with, because of how many people bought it for its musical performance; he never expected those sales. article, Mar 2018
• 2018-04-04Watts lists tap lengths: DAC64 (1999) 1,024, Hugo (2013) 26,000, DAVE (2015) 164,000, Blu MKII (2017) 1,015,808; each increase plus WTA algorithm improvements raised sound quality. article, Apr 2018
• 2018-04-04Watts says 90% of Hugo 2's technology came from DAVE through reusable Verilog modules that are simulated, verified and listened to, giving Hugo 2 identical digital internal performance. article, Apr 2018
• 2018-04-04Watts weighs DAVE, the M scaler (1M taps, a lifetime dream) and Mojo (musicality he has heard from no non-Chord DAC), picks Mojo, and says Hugo most changed his listening. 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
• 2018-05-14Watts says the supercaps give the output stage ample current; it was upgraded after the TT was found used with efficient loudspeakers, so TT2 can drive them directly. HIFICLUBE.NET JVH 50
• 2018-05-25Watts says TT2 addresses headphone power (external amps mostly add coloration) and DAVE driving efficient speakers directly; its 18 watts drives any headphones, and he drives speakers from headphone sockets. Darko Audio 50
• 2018-07-21Watts explains FPGA timing closure and placement, saying Dave began at 200,000 taps, failed to place and route, and finally worked at 164,000 (spoken as 'pounds'). c w 20:10
• 2018-07-21Watts says Dave's filter took nine months and was only modestly better than Hugo's; half a million taps on the new FPGA sounded hugely, unexpectedly better than Dave. c w 21:02
• 2018-07-21Watts says the transformational change and good timing closure led him to the full million taps, a goal dating 'back in 1991' (as spoken), requiring a new memory-efficient filter architecture. c w 21:47
• 2018-07-21Watts says the M Scaler filter is half a million lines of hand-written code, using a new architecture where one memory block feeds eight DSPs running as individual threads. c w 22:34
• 2018-07-21Watts says he uses the M Scaler with Hugo 2 on planes, Hugo 2 and Qutest work fine, and he regrets not giving Mojo 768 capability. c w 29:47
• 2018-08-05Watts says Mojo gains from 0.5M taps but upgrading Mojo may be better, and Mojo lacks an extra SPDIF decoder because power mattered and no M scaler existed then. Head-Fi, Aug 2018
• 2018-08-06Watts says the M Scaler uses the exact filter and the same FPGA as the Blu, pulled straight across, because the filter took too long to design to change. Pursuit Perfect System 5:42
• 2018-08-06Watts says he spent a lot of time fine-tuning the filter to get the best sound on the Blu, and once that project was sealed it should not be changed. Pursuit Perfect System 5:55
• 2018-09-20Watts says the first M scaler was built 15 months earlier across four hardware versions, and he heard no hardware break-in, only brain break-in. Head-Fi, Sep 2018
• 2018-12-08Watts says DAVE took two and a half full-time years, he did everything he wanted, and he has not worked out how to fundamentally beat it. Head-Fi, Dec 2018
• 2018-12-12Watts begins the story of how he arrived at a number for small-signal accuracy while developing DAVE, starting with designing Hugo One, the product that put Chord on the map. Pursuit Perfect System 19:47
• 2018-12-12Watts says six years of code from a scrapped reference DAC went into Hugo One, but adding crossfeed at 98% FPGA capacity forced gate-count cuts without losing performance. Pursuit Perfect System 20:32
• 2018-12-12Watts explains shrinking a design by rewriting code or simplifying it, and says a simpler, smaller noise shaper he tried unexpectedly sounded better in a listening test. Pursuit Perfect System 21:26
• 2018-12-12Watts says both noise shapers were 200 dB yet differed; he finished Hugo with crossfeed at 98% capacity, then on DAVE's ten times larger FPGA investigated why depth differed. Pursuit Perfect System 22:58
• 2018-12-12Watts says Hugo One users claimed it could not drive some headphones, but usually they disliked a hard-sounding headphone and used a warm amplifier; he wanted to remove that issue. Pursuit Perfect System 36:40
• 2018-12-12Watts says a high output voltage lets it drive any headphone; supercaps, as in the original Hugo TT, on both rails with an inductor mean the supply draws only DC. Pursuit Perfect System 37:27
• 2018-12-15Watts says TT2's 98,304 taps switch off with an M Scaler, and TT2 was not engineered to sound warm but expected warmer than DAVE and more refined than Hugo 2. Head-Fi, Dec 2018
• 2019-03-28Watts says he is not unhappy with TT2, drives his B&W 802s from it, and was surprised DAVE's lead was so large, from factors other than noise shaping. Head-Fi, Mar 2019
• 2019-03-28Watts says electronic design is his alone, cost limited TT2 with a higher than expected BOM, he hit the price-performance sweet spot, and demand exceeds Chord's expectations. Head-Fi, Mar 2019
• 2019-04-03Watts describes a nonlinear balance between transparency and refinement, recalls DAVE being too warm during development, and links soundstage width to depth and small-signal accuracy. Head-Fi, Apr 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
• 2019-06-01Watts says crossfeed improves depth on Dave, Hugo 2 and TT2, not Hugo, due to 350dB noise shaping; Dave took 2 to 3 years and later DACs reuse its code. Head-Fi, Jun 2019
• 2019-09-09Watts says M scaler accuracy depends on input, far beyond 24 bits on sine waves, at least 16.7 bits on transients; DAVE 2 is unplanned and DAVE took 2.5 years. Head-Fi, Sep 2019
• 2019-11-17Watts remarks it took him 30 years to create the M scaler and says more positive news on the pulse array ADC should come next year. Head-Fi, Nov 2019
• 2019-12-16Watts recounts that adding crossfeed to the Hugo One prototype, at 95 percent FPGA use, forced a simpler 200 dB noise shaper, which he expected to sound worse. Passion for Sound 12:06
• 2019-12-16Watts says the simpler Hugo noise shaper sounded better in depth and detail; DAVE's ten-times-larger FPGA let him test this, and a 220 dB noise shaper improved depth. Passion for Sound 12:52
• 2019-12-16Watts says after three months he reached a final 330 dB versus 350 dB noise shaper, still heard subtle depth changes, and concludes any depth error is audible. Passion for Sound 13:35
• 2020-01-06Watts says TT2 got huge headphone power after complaints about Hugo 2, helping drive speakers, that DAVE and Hugo 2 drive almost any headphone, and no DSP is fully transparent. Head-Fi, Jan 2020
• 2020-01-27Watts says dual-BNC 768k on Mojo was dropped in 2015 to save power and the manual corrected; Mojo takes 768k on USB, and the algorithm matters more than tap length. Head-Fi, Jan 2020
• 2020-06-25Watts says PWM delay varies with signal level, modulating transient timing; the brain perceives 4 microsecond interaural delays; DAVE's interpolation filters originally ran to 16FS (768 kHz). Part-Time Audiophile 22:42
• 2020-06-25Watts says DAVE used a three-stage filter from 768 kHz up to 104 MHz, and he experimented replacing part of it with a WTA filter outputting every 1.6 microseconds. Part-Time Audiophile 23:30
• 2020-06-25Watts says portable designs have a power budget, 2.5 watts for Hugo and 1.7 watts for Mojo, and he shaved milliwatts on Hugo 2 to spend on performance. Part-Time Audiophile 29:37
• 2020-06-25Watts says odd order harmonics sound worse because the ear generates second harmonic the brain compensates for, then recalls DAVE's three or four prototypes aimed at maximum linearity. Part-Time Audiophile 32:35
• 2020-06-25Watts says his semiconductor background made him value measurements as one way to assess transparency, and his first prototype reached about -130 dB, comparable to the best DACs. Part-Time Audiophile 33:21
• 2020-06-25Watts says successive prototypes improved slightly until a breakthrough cut distortion 30 dB, from -130 to -160 dB on higher order harmonics, without expecting a sound change. Part-Time Audiophile 34:05
• 2020-06-25Watts says a listening test showed a surprising difference, and recalls evaluating prototypes in the evening while watching Curious George with his young children. Part-Time Audiophile 34:49
• 2020-06-25Watts says 192 versus 48 kHz is subtle but 768 kHz is a massive change, and Hugo One's filtering to 104 MHz made piano notes' starts and stops audible. Part-Time Audiophile 41:12
• 2020-08-22Watts confirms DAVE 2 is not on his horizon, says projects take at least 18 months and DAVE over 3 years, stresses honesty, and calls dCS's philosophy very different. Head-Fi, Aug 2020
• 2020-08-25Watts says John Franks came up with the name Dave, which Watts turned into an acronym, because they wanted something fun. Head-Fi, Aug 2020
• 2020-12-30Watts says Mojo lacked crossfeed because of button count, power dissipation and his lesser enthusiasm then; Hugo 2's transparency and depth made crossfeed essential for him. Head-Fi, Dec 2020
• 2021-07-19Watts says ADC interpolator tests showed noise floor modulation audible near -360 dB, explains M scaler ferrites and Wave cables' solid ferrites, and suggests battery power plus optical for isolation. Head-Fi, Jul 2021
• 2021-10-22Watts says supplied BNC cables are starters; 2GHz ferrites, Wave cables or battery power cure ground currents; Qutest uses Mojo's output stage; M Scaler was developed with TT2 and DAVE. Head-Fi, Oct 2021
• 2021-10-25Watts says the gap to live sound remains large, his current path began with Hugo 1, which revealed ear/brain sensitivity, and progress depends on large FPGAs. Head-Fi, Oct 2021
• 2022-01-31Watts says COVID slowed the project because of parts shortages, and that it started as a design project in 2018, making it four years old. Darko.Audio 1:06
• 2022-01-31Watts says the design went through five PCB versions, not coding versions, and the longer-than-expected schedule let him make more improvements. needs context Darko.Audio 1:25
• 2022-01-31Watts says the brief required Poly compatibility; a planned second USB-C port for charging conflicted with the optical input, and he refused to drop optical. Darko.Audio 2:22
• 2022-01-31Watts agrees, noting the original Hugos and Mojos did the same, and says the 3.5 mm connector's advantage is that it is very small. Darko.Audio 3:34
• 2022-01-31Watts says one reason for dropping line-level startup was users forgetting it, powering up, plugging in IEMs and blowing their ears out. Darko.Audio 17:18
• 2022-01-31Watts says other reasons were simplifying setup alongside the new DSP and that Mojo's 3 volts is too much for many amplifiers, hence Qutest's 1, 2 and 3 volt settings. Darko.Audio 17:48
• 2022-01-31Watts says DSP also degrades small-signal accuracy, recalling that during DAVE's development around 2014 he thought 200 dB noise shapers were enough since no one hears -200 dB. Darko.Audio 21:22
• 2022-01-31Watts says Mojo 2 replaces the coupling capacitor with Hugo 2's DC servo, losing Mojo's slightly soft, warm sound but becoming fundamentally more transparent. Darko.Audio 34:59
• 2022-01-31Watts says removing the capacitor led him to add EQ for cheaper headphones that are too bright or lack bass, which raised how to make EQ actually work. Darko.Audio 35:47
• 2022-01-31Watts says the improved noise shaper gave better soundstage and detail, and bass is tighter; Mojo's power limit forced him to throttle the FPGA. Darko.Audio 37:17
• 2022-01-31Watts says Mojo 2 runs the FPGA at full capacity, needing 200 milliwatts more, which he saved elsewhere, for example in the relay and circuit efficiency, without losing performance. Darko.Audio 38:02
• 2022-01-31Watts says that is the reason he put the EQ in. needs context Darko.Audio 43:17
• 2022-01-31Watts says four years of development for Mojo 2 is a little untypical; a product normally takes two to three years. Darko.Audio 50:26
• 2022-01-31Watts says that time counts from the first PCBs; he starts thinking about the next product on finishing one, and began considering Mojo 2 as soon as Mojo was finished. Darko.Audio 50:47
• 2022-01-31Watts says Mojo 2's UHD DSP is his own core, balanced outputs would degrade transparency, a USB-C charging port would not fit, and musicality comes first. Head-Fi, Jan 2022
• 2022-02-01Watts says he dropped the feature because many used IEMs in line-level mode, 3V was too hot for some pre-amps, and he wanted simple controls. needs context Head-Fi, Feb 2022
• 2022-02-04Watts describes Mojo 2's desktop mode, 11-day trickle top-up, operation with a failed battery, and his aims for the EQ settings and transparent DSP core. Head-Fi, Feb 2022
• 2022-02-06Watts says he considered an M Scaler mode for DAVE/TT2, TT2's 7W beats DAVE plus power amp, NFM-free treble sounds natural, and he has not started a DAVE replacement. Head-Fi, Feb 2022
• 2022-03-02Watts says he replaced analog PLLs with a DPLL that took six years and sounds identical to a 4-second RAM buffer, so source asynchrony does not matter, only RF noise. Head-Fi, Mar 2022
• 2022-03-19Watts says the theory applies from Mojo 2 to DAVE, and Mojo 2 needed more FPGA power since the original Mojo used a third of its FPGA, being power limited. MFG Audio Reviews 24:26
• 2022-03-19Watts says Mojo's case can dissipate about 1.8 watts; he saved about 300 milliwatts in the analog section, spent 250 more on the FPGA, and battery capacity rose 9%. MFG Audio Reviews 25:11
• 2022-03-19Watts says the result is lower temperature, more processing and longer battery life, and he now uses 98% of the FPGA's capacity. needs context MFG Audio Reviews 25:54
• 2022-03-19Watts says Chord wanted Mojo's coupling capacitor replaced by a DC servo as on Hugo 2, but the capacitor gave Mojo its warm, soft sound, so warmth needed restoring. MFG Audio Reviews 26:14
• 2022-03-19Watts says adjusting the sound meant EQ, but EQ on a 64-bit PC degrades transparency and IIR EQ filters had immense problems he could fix, and he built the UHD DSP. MFG Audio Reviews 26:59
• 2022-03-19Watts says Chord insisted only on the same size and Poly compatibility; Mojo 2 is DC coupled via a digital DC servo, and the original Mojo had 38,000 taps. MFG Audio Reviews 27:42
• 2022-03-19Watts says Mojo 2 has 40,960 taps, an updated WTA architecture and an improved noise shaper, and an improved 4 element pulse array; he was worried about a distortion bump near 70 to 200 kHz. MFG Audio Reviews 28:30
• 2022-03-19Watts says four buttons at the same depth forced cylinders rather than balls, non-rotating is more elegant and less likely to rattle, and button design is not his domain. MFG Audio Reviews 58:17
• 2022-03-22Watts says his work is understanding why things affect performance, then identifying and reducing errors, so his body of knowledge improves over the years. article, Mar 2022
• 2022-03-22Watts says a product in a new category applies new knowledge, while replacement products apply better understanding plus improvements based on user feedback. article, Mar 2022
• 2022-03-22Watts says being active on forums lets him see reactions to his designs, which helps him improve performance, for example with a source issue, and features. article, Mar 2022
• 2022-03-22Watts says all represent his best at their price and time, sharing a common design thread, but Mojo (units reached, musicality) and DAVE stand out. article, Mar 2022
• 2022-03-27Watts recounts redesigning Qutest's regulation after Qute proved PSU sensitive, admits his 2016 USB preference on Dave was RF brightness, and calls optical the reference input. Head-Fi, Mar 2022
• 2022-04-15Watts says he embeds listening options in the FPGA behind bit switches; simulation suits steady-state errors, not transients, and analog changes need SPICE and slow layouts. Head-Fi, Apr 2022
• 2022-04-26Watts says Mojo's limits were size, not technology: its package can dissipate only about 2.5 watts, so the original Mojo got too hot when used while charging. Audio Force 2:44
• 2022-04-26Watts says the original Mojo was limited to about 1.8 watts, so he used only a third of its FPGA; for Mojo 2 he reworked the analog section's efficiency. Audio Force 3:29
• 2022-04-26Watts says he saved 300 or 400 milliwatts and batteries improved about 9 percent, so Mojo 2 uses 98% of the FPGA instead of 33% at lower total power. Audio Force 4:16
• 2022-04-26Watts says he designed an FPGA-driven charging circuit for Mojo 2 so it can be charged while listening without getting hot, bringing Hugo 2 technology into it. Audio Force 4:58
• 2022-04-26Watts says he and John Franks wanted to add crossfeed, which he always uses with headphones, and remove the single coupling capacitor after the pulse array, which adds warmth. Audio Force 5:22
• 2022-04-26Watts says the original Mojo was voiced warm for bright headphones, so neutral Mojo 2 needed EQ; his test: raise a PC EQ 1 dB, lower volume 1 dB. Audio Force 6:09
• 2022-04-26Watts says many original Mojos ran 24/7 as fixed-system DACs, so for Mojo 2 he made the battery fully isolated when the charger is connected. Audio Force 14:06
• 2022-04-26Watts says isolating the battery in desktop use required separate regulation in Mojo 2's analog section, since the original Mojo's analog stage fed directly from the battery. Audio Force 14:51
• 2022-05-01Watts says Mojo 2's USB decoder has its own regulation and RF filters, he is independent of Chord, and two headphone sockets were kept for reliability and sharing. Head-Fi, May 2022
• 2022-07-25Watts recounts DAVE's nearly 3-year development, questions Stereophile's 16-bit measurements, cites -127dB A-weighted, calls SINAD worthless, and says filters must reconstruct transient timing. Head-Fi, Jul 2022
• 2022-08-19Watts says as FPGAs grew he increased tap length and improved the WTA algorithm, each doubling of tap length improved the sound, and the 200T device arrived around 2015. AVstore 6:11
• 2022-08-19Watts says going from DAVE's 164,000 taps to the Hugo M Scaler's 1 million made a bigger difference than expected, opening the soundstage, and that 16-bit accuracy is not enough. AVstore 6:55
• 2022-08-19Watts says the intent was Chord DACs; the 96 and 192 kHz outputs were mainly for recording, e.g. 44.1 run at 'one seven four kilohertz', though universality helps. AVstore 25:51
• 2022-08-31Watts says TT2 had no cost-saving compromises, DAVE proved more transparent than he expected, Chord is engineer-run, and noise floors are about -400 dB (digital) and -350 dB (best noise shapers). Head-Fi, Aug 2022
• 2022-09-18Watts says the Mojo 2 project started 5 years ago, and John Franks wanted to get rid of the coupling capacitor. The Source AV 33:15
• 2022-09-18Watts says a transparent DSP lets users make Mojo 2 warmer and softer or sharper and brighter with EQ; it took a year or two and a custom 104-bit core. The Source AV 34:07
• 2022-09-18Watts says it works really well, and Chord were hesitant when he showed them the buttons that would control the filter. needs context The Source AV 34:49
• 2022-10-12Watts begins explaining that he and John Franks were trying to figure out the name. needs context Upscale Audio 7:32
• 2022-10-12Watts says John Franks owns Chord and does all the power amplifier design, and that both think high-end audio takes itself too seriously, hence playful names like Hugo. Upscale Audio 7:37
• 2022-10-12Watts says that with the Hugo name already used they wanted something different, and John Franks suggested Dave, a fun name in the UK. Upscale Audio 8:07
• 2022-10-12Watts says his father and uncle were called Dave and he coined 'digital to analogue veritas in extremis', truth in extreme, reflecting DAVE's aim to close the gap to unamplified sound. Upscale Audio 8:37
• 2022-12-01Watts says Mojo 2 has no analog gain change; he raised volume steps from 96 to 128 for sensitive IEMs, with the menu button showing high or low range. Head-Fi, Dec 2022
• 2022-12-19Watts says no one in the Mojo 2 speculation thread predicted its big change, the UHD DSP EQ. Head-Fi, Dec 2022
• 2023-02-04Watts says until 2015 his improvements made the best recordings better and the worst worse, then Hugo brought a dramatic change because FPGAs let him create his own digital circuit. Dusty Audio 15:25
• 2023-02-04Watts says older FPGAs limited his filters and noise shapers; 2015 FPGAs had three or four times the capacity, and in Hugo poor recordings improved more than good ones. Dusty Audio 16:13
• 2023-02-04Watts says improving small-signal amplitude accuracy improved depth, and developing Dave with a bigger FPGA after Hugo let him try better noise shapers. Dusty Audio 20:50
• 2023-02-04Watts says a 220 dB noise shaper audibly improved depth over 200 dB, so over three months of Dave development he kept improving it until the sound stopped improving. Dusty Audio 23:10
• 2023-02-04Watts describes raising Dave's noise shaper through 240, 260, 280, 300 and 330 dB with daily coding, simulation and listening tests, eventually reaching 350 dB. Dusty Audio 23:57
• 2023-02-04Watts says updates were impossible in 2015, now technically possible; FPGA code is optimized to the hardware, and Dave took two and a half to 3 years before he moved on. Dusty Audio 1:03:33
• 2023-02-05Watts says DAVE was developed with its switching supply, showing no noise floor modulation or 100 Hz issues and with extensive internal RF filtering; TT2 got more supply work. Soundnews 36:34
• 2023-02-05Watts says 2Qute was supply-sensitive, which does not mean linears beat switching; for Qutest he improved regulation and RF filtering so a switching supply matched a 12-volt battery. Soundnews 39:49
• 2023-02-05Watts says the difference is tiny; of many TT2 supplies measured at 100 kHz bandwidth all degraded performance except one, at half a dB, which sounded like a car battery. Soundnews 41:34
• 2023-02-05Watts says DAVE was two and a half years in development and launched around 2015. Soundnews 52:07
• 2023-02-05Watts says he perfects a project for its FPGA through repeated testing and listening, then finishes it and moves on; he lacks time for constant changes and upgrades. Soundnews 52:20
• 2023-02-05Watts criticizes firmware updates that keep changing the sound; when DAVE launched he argued with John Franks, saying it needed replacing in 3 years, while Franks wanted at least 5. Soundnews 53:19
• 2023-02-05Watts says he told Franks a high-performance digital product cannot be expected to last that long. needs context Soundnews 54:05
• 2023-02-05Watts says DAVE, in its seventh or eighth year, is still the best DAC available, and he is working on a much more expensive reference DAC of unknown price. Soundnews 54:15
• 2023-02-05Watts says DAVE was constrained by size but aimed at a sound quality and technical performance target regardless of cost. Soundnews 55:00
• 2023-03-26Watts says he aims for supplies that sound like a car battery; around 2016 he was shocked how much better 2Qute sounded on one, and addressed this with Qutest. Eric's Hi-Fi 18:34
• 2023-03-28Watts says errors of a thousandth of a dB in amplitude or a thousandth of a degree in phase are audible, and recalls DAVE's development starting from 200 dB noise shapers. The Headphone Show 43:19
• 2023-04-03Watts says DAVE's transparency and depth come from small-signal accuracy, and that before DAVE he assumed noise shapers needed only 200 dB (32-bit) performance. Amplify Audio 4:53
• 2023-04-03Watts says on DAVE he heard depth improve from 200 to 220 dB noise shapers and up to 350 dB, leading to his rule that modules reproduce -301 dB perfectly. Amplify Audio 5:34
• 2023-04-03Watts says transparent EQ needs -301 dB performance in amplitude and phase; after a couple of years' work, the DSP core in this unit is 104 bits. Amplify Audio 8:57
• 2023-04-03Watts says improving Mojo meant adding crossfeed, essential for headphones, and moving toward Hugo 2's sound by going DC coupled, dropping the coupling capacitor that gave Mojo its warmth. Amplify Audio 10:23
• 2023-05-20Watts says improving DAVE prototype harmonics from -120 dB to below -150 dB sounded brighter and more transparent; white volume cannot clip but deeper can, at ear-damaging levels. Head-Fi, May 2023
• 2023-07-28Watts rejects full parametric EQ and conventional EQ, says Mojo 2's 104-bit EQ core was his idea, and describes its modest FPGA cost. Head-Fi, Jul 2023
• 2023-10-01Watts says products are priced from performance and bill of materials cost, and that when designing Mojo he had to stay within a budget. The Source AV 2:49
• 2023-10-01Watts says Mojo was hard work and that the Mojos are the exception, since normally he picks a performance target first. The Source AV 3:00
• 2023-10-01Watts says he would not have spent the three or four months developing and evaluating the DSP core unless he knew it could be used in other products. The Source AV 37:34
• 2023-10-01Watts says that once Chord gets pre-production prototypes, it runs its own evaluations. The Source AV 39:59
• 2023-10-01Watts says he uses few sources, so Chord tests compatibility with every source available plus EMC and power supply regulation tests, hopefully without needing changes from him. The Source AV 40:20
• 2023-10-01Watts says a prototype heatsink performed poorly because it was not anodized; anodizing, whatever the color, doubles performance through radiative cooling, which he verifies by measuring thermal resistance. The Source AV 46:08
• 2023-10-05Watts says unanodized Hugo M Scaler prototypes showed anodizing doubles heat-sink performance, and Choral scaler heat issues led to a redesign of metalwork, PCB and FPGA code. Head-Fi, Oct 2023
• 2023-11-13Watts says Mojo's first batch had USB connectors breaking off, fixed with through-hole connectors and tighter machining used on Mojo 2, rated for 10,000 insertions. Head-Fi, Nov 2023
• 2024-01-14Watts says Chord's 3 V standard dates from 1990s passive pre-amps, Qutest added 1/2/3 V options, and a Mojo 2 line-level output was dropped to keep controls simple. Head-Fi, Jan 2024
• 2024-01-19Watts says early DAVE prototypes had slightly worse harmonic distortion than the dCS Vivaldi, which he improved on, but his only sound target is live unamplified music. Head-Fi, Jan 2024
• 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 begins recounting his work developing DAVE. MFG Audio Reviews 43:09
• 2024-03-20Watts says he measures designs digitally down to -400 dB by FFT and listens as errors are removed; while developing DAVE his noise shapers performed at 200 dB. MFG Audio Reviews 43:16
• 2024-03-20Watts says listening tests must decide whether something is better, and that DAVE gave him a brand new FPGA with plenty of capacity. MFG Audio Reviews 44:51
• 2024-03-20Watts says moving to a 220 dB noise shaper changed only depth, with distant instruments sounding more distant on his depth test tracks, and he kept improving until 350 dB. MFG Audio Reviews 45:02
• 2024-03-20Watts says a battery in DAVE is a good idea, mentions someone feeding a 120-volt battery into DAVE's mains input with good results, and would design DAVE differently today. MFG Audio Reviews 56:32
• 2024-07-12Watts says FPGAs could run interpolation filters by 1999 and a million taps by 2015, leading to the Hugo M Scaler; his role was more taps and a better algorithm. HIFICLUB 11:31
• 2026-03-17Watts says reflections' amplitude and timing must be perfect, with no lower limit to errors that damage depth, which he learned developing DAVE in 2014. ecoustics 33:25
• 2026-03-17Watts says he thought 200 dB, versus 140 dB in chip DACs, was over-specified, but DAVE's larger FPGA finally gave him capacity to try better. ecoustics 35:41
• 2026-03-17Watts says his first improved noise shaper simulated at 220 dB; switching against 200 dB, separation, focus and timbre sounded identical. ecoustics 36:23
• 2026-03-17Watts says that for about three months in summer 2014 or 2015 he kept improving and listening, eventually reaching 330 dB to 350 dB. ecoustics 37:55
• 2026-03-17Watts says many designers just tweak, but for Mojo 2 he knew beforehand what he wanted: the best within budget, closer to Hugo 2, with set benefits over Mojo. ecoustics 1:19:59
• 2026-03-17Watts says he guessed Mojo 2 would have around two-thirds the performance of a Hugo 2 compared to Mojo, and listening tests matched, with no surprises. ecoustics 1:20:45
• 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 Quartet took 8 years of constant development, changed his understanding of interpolation filters, and brings listeners closer to the sound of live music. Audio Force 4:40
• 2026-03-24Watts says Quartet as a project started in 2018 and has taken 8 years. Audio Force 9:36
• 2026-03-24Watts says Quartet began as a better Hugo M Scaler but became a study of interpolation filters; his unique WTA algorithm was tuned through thousands of listening tests. Audio Force 9:47
• 2026-03-24Watts says the ideal is impossible with a standard filter, so he developed a completely new type of interpolation filter called Blackbird WTA. Audio Force 13:51
• 2026-03-24Watts says even the cabling went through half a dozen prototypes to find the best construction and best sounding cable, as tiny details matter. needs context Audio Force 27:12
• 2026-03-24Watts says the most important thing is understanding, and Quartet radically improved his understanding of how interpolation filters work. Audio Force 27:43
• 2026-03-24Watts says musicality is ultra important, but radically improved understanding means future products will sound much better; he begins mentioning developing Mojo 2 4.4. Audio Force 27:59
• 2026-03-24Watts says he used Quartet in listening tests for the various changes and was amazed. needs context Audio Force 28:45
• 2026-03-24Watts says adding USB-C charging was complex because charging must be switchable to avoid depleting a phone, and isolating the two charging voltages was non-trivial. Audio Force 33:05
• 2026-05-03Watts says he is showing the Quartet M Scaler, developed over the last 8 years, with new interpolation filter technology that he says raises digital reproduction to a new level. Audio Force 1:05
• 2026-08-30Watts says the biggest project is a pro audio interface using Quartet's pulse array ADC; Quartet took him 8 years and is his most complicated product. The Source AV 2:17
• 2026-08-30Watts says that after the Hugo M Scaler, more taps (1,000 in 1999) and a better WTA kept sounding better; a million taps gives 16-bit reconstruction, but more is needed. The Source AV 6:00
• 2026-08-30Watts says research into reconstructing transient timing perfectly showed the number of taps needed is much bigger than 1 million, and asks the host to guess. The Source AV 6:47
• 2026-10-02Watts says his informal relationship with Chord dates from 1997, Chord pays only once products are in production, and he spent 8 years developing Quartet with his own finance. HiFi Buys 2:01
• 2026-10-02Watts says everything changed with Hugo, the first Hugo, in 2014. HiFi Buys 25:30
• 2026-10-02Watts says in 2014 he had an FPGA about 10 times larger than before. HiFi Buys 25:39
• 2026-10-02Watts says designing DAVE in 2014 with a much bigger FPGA and spare capacity, he believed noise shapers needed 200 dB in-band performance, better than 32-bit accuracy. HiFi Buys 1:17:08
• 2026-10-02Watts says with 16-bit sources limited to 96 dB, needing 200 dB seemed pointless, but that was an assumption. HiFi Buys 1:17:52
• 2026-10-02Watts says he tests assumptions by listening; he added integrators for a 220 dB noise shaper and used a toggle switch because each Xilinx place and route then sounded different. HiFi Buys 1:18:06
• 2026-10-02Watts says the result blew his mind because it disproved an assumption and opened a new avenue, making the following three months one of his best summers. HiFi Buys 1:20:36
• 2026-10-02Watts says 2Qute sounded dramatically better on the car battery, so Qutest got better regulation and RF filtering, after which he heard no difference from the battery. HiFi Buys 2:22:57
• 2026-10-02Watts says forum reports of USB sources sounding different led to galvanic isolation on DAVE, the first product with it, still at 768 kHz. HiFi Buys 2:23:47
• 2026-10-02Watts says his Mojo 2 target was two-thirds of the way from Mojo (0%) to Hugo 2 (100%) in sound quality, which he can predict on paper. HiFi Buys 2:29:40
• 2026-10-02Watts says Mojo 2's digital EQ drew on his work on small-signal phase shift, since EQ changes phase, and making it transparent was much harder than expected. HiFi Buys 2:30:22
• 2026-10-02Watts says Mojo 2 needed many board iterations, and the first prototype hit his two-thirds target, a gap clear enough to protect Hugo 2 sales. HiFi Buys 2:31:58
• 2026-10-02Watts says had Mojo 2 turned out better than expected he would have kept it, even if Chord complained about selling fewer Hugos. HiFi Buys 2:32:57
• 2026-10-02Watts says he never de-engineers a product to sell a pricier one, calling it ethically wrong, and Quartet was a research exercise into interpolation accuracy and its limits. HiFi Buys 2:33:16
• 2026-10-11Watts says Quartet took longer because his son Daniel built unlimited-precision coefficient tools; a test sine computed to 3,000 decimal places showed distortion and noise about 3 thousand dB down. Distorsiuni Interioare 8:25
• 2026-10-11Watts says the new tools let them see incredibly small effects, change coefficients and listen, which opened a can of worms. Distorsiuni Interioare 9:20
• 2026-10-11Watts says newly identified issues added 2 years; Quartet was finished when every possibility was explored, with no deadline from Chord, as research plus product development. Distorsiuni Interioare 9:38
• 2026-10-11Watts says Quartet includes a pulse array ADC so vinyl can be recorded, making it a digital preamp; finishing required perfecting this discrete ADC with flash ADCs and integrators. Distorsiuni Interioare 15:29
• 2026-10-11Watts says his research from 2018 asked how many taps give subjectively perfect reconstruction, and why his five-variable WTA coefficient formula had a sweet spot. Distorsiuni Interioare 17:04
• 2026-10-11Watts adds the output stages (transcribed 'animal', likely analog) to what he designed. needs context Distorsiuni Interioare 25:50
• 2026-10-14Watts says the ADC has been a background project since 2016; hearing the pulse array ADC built into Quartet's analog input made him wish he had done it years earlier. Part-Time Audiophile 50:30
• 2026-10-14Watts says his big project has been Quartet, the 4 million tap upsampler. Part-Time Audiophile 52:29
• 2026-10-14Watts says Quartet began about 8 years ago after the 1 million tap Hugo M Scaler, which guarantees 16-bit accurate reconstruction; 6 years of research went into improving interpolation filters. Part-Time Audiophile 52:36
• 2026-10-14Watts says the algorithm was radically improved, and they are calling it a Blackbird WTA. Part-Time Audiophile 53:23
• 2026-10-14Watts says Blackbird WTA with 4 million taps consumed most of his time; the next big project is the pro audio ADC, with others including the very high-end Ultima DAC. Part-Time Audiophile 53:34
• 2026-10-17Watts says hardware was a problem but the first part was research into why interpolation filters change the sound, which began in 2018 when the M Scaler was finished. article, Oct 2026
• 2026-10-17Watts says after finishing a project he reappraises design decisions and old listening tests, so his design work is an iterative, ongoing process as assumptions change. article, Oct 2026
• 2026-10-17Watts says after the M Scaler he wanted to know how many taps give the best sound, and whether it would take 10 million or 100 million. article, Oct 2026
• 2026-10-17Watts says separating the two problems into different filters, each optimized, led to the Blackbird WTA structure. article, Oct 2026
• 2026-10-17Watts lists Quartet's hardware problems: heat removal, nine prototypes, over 2,000 components, BNC cables sounding the same, and a supply as good as battery power. article, Oct 2026
• 2026-10-17Watts says budget was not an issue for Quartet, which had to meet technical and sound-quality requirements and then took whatever price resulted. article, Oct 2026
• 2026-10-17Watts says the name Quartet comes from the four million taps. article, Oct 2026
• 2026-10-17Watts confirms it and says they could have called it Quintet but Quartet rings better. article, Oct 2026
• 2026-10-17Watts says the name is from the SR-71, the fastest production jet, built in the 1960s in 18 months, and he wanted a really good name. article, Oct 2026
• 2026-10-17Watts says Davina was a low-priority background project, scrapped when parts were discontinued, leaving him without a replacement for a crucial flash converter, so he parked it. article, Oct 2026
• 2026-10-17Watts says Chord asked for an analog input on Quartet, expecting about 20% more scaler sales, and they weighed a separate ADC against integration. article, Oct 2026
• 2026-10-17Watts says integrating the ADC costs little, a rounding error in the bill of materials beside the FPGA, supplies and metalwork, so the selling price would not change. article, Oct 2026
• 2026-10-17Watts says he doubted the 20% sales claim but it forced Quartet and the ADC to be finished, turning a wish into a required project. article, Oct 2026
• 2026-10-17Watts says two test recordings so far show an extraordinary difference, and he wishes he had finished Davina, started in 2016, years earlier. article, Oct 2026
• 2026-10-17Watts says he has proven the ADC technology, his recording-engineer son works on it full-time, and it will combine mixing functions, more a mixing desk than a processor. article, Oct 2026