Davina and ADC design

Formats, recordings and ADCs

Answers on this topic

• What is Davina, and what happened to the pulse array ADC?
• Why are half-band decimation filters and studio sample-rate conversion a problem, and how much aliasing rejection is enough?

Everything he said on this topic (195)

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

• 2014-04-17Watts says content above 22.05 kHz is inaudible (he hears to 16 kHz) but 4uS transient timing matters, and describes a planned pulse array ADC with multiple sample-rate outputs. Head-Fi, Apr 2014
• 2015-02-14Watts says ADC anti-aliasing filters need about 2K taps for -144 dB, ADC chip aliasing near 21 kHz is audible, and his pulse array ADC project has run five years. Head-Fi, Feb 2015
• 2015-02-15Watts expects longer ADC filters to improve recordings by removing aliasing and noise floor modulation, says listening tests have not started, and recalls Chord's pro audio sales. Head-Fi, Feb 2015
• 2015-05-20Watts says next year's pro audio A to D converter needs decimation filters better than 140 dB, while some pro audio filters attenuate only 6 dB. HIFICLUBE.NET JVH 4:50
• 2016-01-09Watts says the A to D converter will match DAVE as the first commercial product, followed by pro audio versions, using DAVE's technology for better musicality in recordings. What Hi-Fi? 6:39
• 2016-02-25Watts says he is designing an ADC to match Dave, and shows a Verilog simulation of Dave's noise shaper reproducing a -301 dB sine over a -380 dB floor. Head-Fi, Feb 2016
• 2016-02-26Watts says Davina, his ADC project prototyped in 2001, tackles noise floor modulation, aliasing (half-band filters give only -6 dB; he hears it at -140 dB) and noise shaper resolution. Head-Fi, Feb 2016
• 2016-02-27Watts says Davina will run 44.1 to 768 kHz with two simultaneous outputs at different rates without SRC, and user-selectable 16, 24 or 32-bit depth. Head-Fi, Feb 2016
• 2016-02-29Watts says Davina is an ADC for analog inputs, letting one hear vinyl at 768k while recording at 44.1, and is a first step toward a pro audio interface. Head-Fi, Feb 2016
• 2016-03-02Watts says 44.1/16 could in principle be near perfect, going from -330 to -350 dB noise shaping changed little, and 1M taps gives 16-bit sinc accuracy but needs costly FPGAs. Head-Fi, Mar 2016
• 2016-03-06Watts says Davina will test whether ADC bandlimiting changes sound once reconstruction is perfect, and whether dither can carry Dave's -301 dB, 64-bit-like small-signal accuracy at 44.1 kHz. Head-Fi, Mar 2016
• 2016-03-30Watts says perfect reconstruction needs an infinite-tap, infinitely oversampling sinc filter; he does not know how many taps suffice, and Davina will let him test 768k to 48k and back. Head-Fi, Mar 2016
• 2016-04-01Watts lists what Davina should answer (aliasing limits, lifelike depth with 350 dB noise shapers, transparent WTA round trips, 16-bit dither) and says the power amp will initially matter most. Head-Fi, Apr 2016
• 2016-04-01Watts says the Davina ADC will have 40 elements to reach 350 dB noise-shaper resolution and DAVE-level distortion; generally, doubling elements cuts noise 3 dB and improves resolution 6 dB. Head-Fi, Apr 2016
• 2016-04-20Watts says his ADC runs at 104.25 MHz so analog anti-alias filtering is easy, but he does not know how much decimation rejection suffices (-140 dB is not). Head-Fi, Apr 2016
• 2016-04-24Watts says the best ADC chips manage -122 dB SNR while Davina targets 135 dB, naming depth (350 dB noise shaping), noise floor modulation and audible aliasing as main problems. Head-Fi, Apr 2016
• 2016-04-24Watts says Davina is the code word for the ADC project notionally intended for DAVE and will be the first product to use his pulse array ADC. Head-Fi, Apr 2016
• 2016-05-17Watts says an ideal sinc reconstruction filter adds no ringing, but theory says nothing on how an ADC should bandlimit; Davina will test aliasing rejection beyond 140 dB. Head-Fi, May 2016
• 2016-06-06Watts says his ADC plus DAVE at 768 kHz could beat an analog pre-amp, and describes a WTA FIR decimation filter from 104 MHz to 768 kHz for two prototypes. Head-Fi, Jun 2016
• 2016-06-10Watts says Davina ADC schematics are almost finished and layout about 75% done, shows the layout, and notes DIP switches to switch all 11 analog integrators. Head-Fi, Jun 2016
• 2016-06-12Watts calls Davina a proof of concept, possibly followed by an 8-channel pro interface, aimed at reproducing recorded depth accurately, with Chord staff advising on recording. Head-Fi, Jun 2016
• 2016-07-28Watts says Davina will initially take mic or line level only, and digital-domain RIAA is a possible later project once Davina is complete. Head-Fi, Jul 2016
• 2016-09-17Watts recalls Doug Sax's Mastering Lab, and says a Moscow recording engineer's request will add vari-speed to the pro Davina, noting engineers' complaints about pitch effects and DC filters. Head-Fi, Sep 2016
• 2016-09-19Watts outlines Davina test recordings: two prototypes on one mic feed to compare configurations for depth, home and village sounds, then pro engineers, with 768 kHz originals for decimation testing. Head-Fi, Sep 2016
• 2016-09-19Watts plans Davina test recordings of guitar, fireworks and wood blocks, says current ADCs decimate crudely with moving averages, and plans Earthworks QT50 omni mics with a Schneider disc. Head-Fi, Sep 2016
• 2016-10-18Watts says he has bottomed out depth, needing -350 dB capable paths with no small-signal linearity issues, but expects more timing discoveries with Davina, especially in ADC decimation. Head-Fi, Oct 2016
• 2016-10-20Watts says 768/705.6 kHz 24-bit is best and 32 bits unnecessary, reports noise shaping beat Gaussian and triangular dither on the Blu Mk2 prototype, and Davina will study 44.1/16 losses. Head-Fi, Oct 2016
• 2016-12-29Watts says Davina has a recording mode (analog in, digital out) and a post-processing mode that decimates, upsamples or converts rates, aiming at 768 kHz 24-bit recordings. Head-Fi, Dec 2016
• 2016-12-30Watts says the input is configurable as a mic input with switchable 48V phantom power or as line level, avoiding a separate mic pre-amp stage that would degrade transparency. needs context Head-Fi, Dec 2016
• 2017-01-08Watts says Davina's bi-directional USB can send 768 kHz M scaler output to a PC, but Dave is meant to receive 768 kHz via isolated BNC, as with Blu Mk2. Head-Fi, Jan 2017
• 2017-01-10Watts contrasts a one-tap NOS filter's roughly 100 uS worst-case timing error with an ideal infinite filter, plans Davina round-trip files, and links 1M-tap 16FS filters to Fourier uncertainty. Head-Fi, Jan 2017
• 2017-01-13Watts says Davina has a relay-adjustable gain mic input with switchable phantom power so he can control more of the signal chain. Head-Fi, Jan 2017
• 2017-01-24Watts says Blu Mk2's design came from Davina, which started first, the code is shared with Davina's M scaler mode, and proper SRC needed a powerful FPGA. Head-Fi, Jan 2017
• 2017-01-29Watts says the only digital-mode task Davina can do that Blu cannot is converting 768k down to 44.1k, and notes family members named David. Head-Fi, Jan 2017
• 2017-02-13Watts says interpolated transient timing depends on sample timing unless the filter is ideal, and plans a Davina null test with half-sample-delayed white noise to measure the error. Head-Fi, Feb 2017
• 2017-02-14Watts says the likely lesson is how far decimation and interpolation are from transparency, and doubts Davina-sourced recordings would change the WTA algorithm, though future gains may follow. needs context Head-Fi, Feb 2017
• 2017-03-19Watts says Blu Mk2 took its M scaler design from Davina, so 1M taps is Davina's limit, and Davina will show how much quality the M scaler loses. Head-Fi, Mar 2017
• 2017-04-08Watts says noise shaping at 44.1 kHz is ineffective above about 4 kHz, unlike at 705/768 kHz; truncating to 44.1 for Davina is unresolved, with Gaussian dither best so far. Head-Fi, Apr 2017
• 2017-04-24Watts says commercial ADCs are not transparent, hence Davina, which will also convert Red Book to M scaled files he plans to play on Hugo 2 during flights. Head-Fi, Apr 2017
• 2017-04-24Watts says Davina's USB is bi-directional and can receive and transmit data at the same time. Head-Fi, Apr 2017
• 2017-04-27Watts says image upscaling like RAISR does not carry over to audio, where only transient timing must be recovered with longer filters, and plans Davina tests of 1M-tap losses. Head-Fi, Apr 2017
• 2017-05-12Watts says a remeasured DAVE was perfect on an APx555, suspects aliasing in JA's analyzer ADCs, and says Davina has zero noise floor modulation and around 15 dB less noise. Head-Fi, May 2017
• 2017-05-12Watts explains that an ADC contains a DAC, a delta-sigma noise shaper serving as either, and that the poor DAC inside an ADC chiefly limits ADC performance. Head-Fi, May 2017
• 2017-06-10Watts says a native 768 kHz test recording from Chord's Japanese distributor sounded like M-scaled playback, unlike DXD so far, though its high ADC noise made DAVE's HF filter matter. Head-Fi, Jun 2017
• 2017-06-11Watts says a planned Davina test will give a measured number for the transient error, though not why taps above 0.66M improve the soundstage, which is perceptual. Head-Fi, Jun 2017
• 2017-06-16Watts admits -350 dB depth sensitivity seems irrational but says repeated noise-shaper tests, including digital-only truncators, confirm it, and plans a blind Davina test with different noise-shaper settings. Head-Fi, Jun 2017
• 2017-07-24Watts says EQ should not affect timing reconstruction, but truncation after DSP matters: noise-shaped truncation at 16FS beats triangular dither, so he applies EQ and volume at 16FS or higher. Head-Fi, Jul 2017
• 2017-08-11Watts praises un-remastered 1960 to 1967 Decca recordings, says modern ADCs' half-band filters allow aliasing that degrades transient timing, and says Davina will have no aliasing. Head-Fi, Aug 2017
• 2017-08-11Watts says Davina will match DAVE in size and be comparable in price, and that he awaits its prototype; he also says native DSD's timing errors and poor small-signal resolution make it soft and flat. Head-Fi, Aug 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
• 2017-08-13Watts says Davina will test how many taps are enough and whether ADC bandwidth limiting matters, noting sinc reconstruction is required and his IIR decimation filter gives 300 dB rejection. Head-Fi, Aug 2017
• 2017-08-21Watts says only a sinc reconstructs correctly, short filters sound soft and warm, and he will post blind Davina files comparing FIR and IIR decimation filters with 300 dB attenuation. Head-Fi, Aug 2017
• 2017-10-09Watts says Davina will be able to convert files from 768 kHz down to 48 kHz and M scale them from 48 kHz back up to 768 kHz. Head-Fi, Oct 2017
• 2017-10-13Watts turns to the future: the Davina A-to-D converter project, familiar to readers of his blogs. miceblue425 35:35
• 2017-10-13Watts says Davina differs from conventional ADCs for three reasons; the first is aliasing, since standard ADCs decimate 1-bit or 5-bit 3 MHz output with crude moving-average sinc filters. miceblue425 36:03
• 2017-10-13Watts says these decimation filters attenuate only about 20 dB, and the resulting aliasing changes the timing of transients audibly; his second Davina point concerns depth. miceblue425 36:50
• 2017-10-13Watts says DAVE's noise shapers needed 350 dB accuracy to preserve small signals, that 330 versus 350 dB is still audible, and that Davina's noise shapers reach 360 dB. miceblue425 37:35
• 2017-10-13Watts says standard ADC noise shapers manage 140 dB, hopes Davina recordings will convey depth, and says ADCs have heavy noise floor modulation, audible even at -200 dB. miceblue425 38:19
• 2017-10-13Watts says Davina tests at zero noise floor modulation versus about 4 to 5 dB in standard ADCs, and that the APx555 uses four ADCs and a notch filter to avoid it. miceblue425 39:02
• 2017-10-13Watts says Davina will record at 768 kHz, the M Scaler's rate, letting him check how good the M Scaler is. miceblue425 39:48
• 2017-10-13Watts says Davina lets him bandwidth-limit a native 768 kHz recording to 48 kHz while keeping 768 kHz, to test whether bandwidth limiting and its filter type matter. miceblue425 40:47
• 2017-10-13Watts says he can decimate the bandlimited file to 48 kHz, rescale it to 768 kHz through the M Scaler, and compare, finally knowing how big the problem is. miceblue425 41:33
• 2017-10-13Watts opposes using distortion to shape sound, says Davina will let him control the chain from microphone to loudspeaker, and says every listening test must be backed by theory. miceblue425 51:40
• 2017-10-17Watts says Blu 2 uses code originally written for Davina, and that code will not change for Davina. Head-Fi, Oct 2017
• 2017-10-18Watts says inadequate bandwidth limiting harms sound via aliasing; Davina's first decimation filter has 260 dB rejection, and non-decimating FIR and IIR versions will let listeners hear bandwidth limiting. Head-Fi, Oct 2017
• 2017-10-20Watts agrees microphone choice and positioning are crucial but says current ADCs have vast problems that Davina will solve, with a post on them to follow. Head-Fi, Oct 2017
• 2017-11-04Watts says current ADCs measure poorly; bandwidth limiting removes HF noise that causes brightening noise floor modulation, but Davina's noise rises only above 500 kHz, and tests need careful evaluation. Head-Fi, Nov 2017
• 2017-11-16Watts says only controlled listening tests settle whether CD is good enough, and that Davina will let him publish original versus decimated and M scaled tracks to gauge the loss. Head-Fi, Nov 2017
• 2018-01-03Watts says Hugo 1's DSD filter had audible aliasing at -150dB, the new one is better than -240dB, and this work informs Davina, which will make aliasing negligible. Head-Fi, Jan 2018
• 2018-01-09Watts says the HF filter matters because ADC noise shaper noise above about 25 kHz causes noise floor modulation; Davina's noise will rise only above 768 kHz. Head-Fi, Jan 2018
• 2018-01-12Watts says BluDave, his untuned reference, came from minimizing aberrations; going from 0.5M to 1M taps is audible, and Davina will show how far BluDave is from perfect. Head-Fi, Jan 2018
• 2018-01-12Watts says he has designed an ADC, the Davina project, and its prototype is waiting for him to test it. Head-Fi, Jan 2018
• 2018-01-16Watts says a sinc only perfectly reproduces signals with zero output at FS/2, but modern ADC half-band filters leave -6dB, causing unrepairable aliasing; Davina will reach -240dB. Head-Fi, Jan 2018
• 2018-01-19Watts says doubling pulse array elements halves correlated jitter error, cuts noise 3dB and improves THD and small-signal resolution; Davina uses 40 elements to reach 135dB dynamic range. Head-Fi, Jan 2018
• 2018-01-25Watts says 44.1 will be supported: the intent is to record at 705 kHz and decimate later, with uniquely aliasing-free decimation from 104.25 MHz down to 44.1 kHz. Head-Fi, Jan 2018
• 2018-02-14Watts says Davina will let a 44.1 source be recorded at 705.6 as WAV, hoping 16-bit 705 kHz sounds as good as 24-bit; output bit size is an option. Head-Fi, Feb 2018
• 2018-02-24Watts says SRC and half-band decimation damage timing, triangular dither degrades depth, so he buys 96k originals; Davina's filters reach about -240 dB and will test bandlimiting and dither. Head-Fi, Feb 2018
• 2018-04-27Watts responds to a review calling Hugo 2 merciless, contrasts live drums with reproduction, states Davina's goals of depth and speed, and says all design is his. Head-Fi, Apr 2018
• 2018-05-05Watts explains 1-bit DSD noise shapers are signal-dependent and unstable, unlike N-bit designs; Davina's N-bit pulse array ADC has 400 dB noise shaper performance and signal-independent activity. Head-Fi, May 2018
• 2018-06-09Watts says doubling a WTA filter's tap length doubles reconstruction accuracy, but how much accuracy the ear needs is open; Davina will show how close the M scaler is. Head-Fi, Jun 2018
• 2018-07-04Watts says Davina's 705/768 to 44.1/48 decimation filters tested perfectly with no aliasing; 104 MHz to 705/768 decimation design comes next, then hardware testing. Head-Fi, Jul 2018
• 2018-07-04Watts says current ADCs have aliasing, NFM and small-signal nonlinearity, so Davina recordings may show big changes even on Mojo; he benchmarks Dave with headphones and TT2 on 803 D3s. Head-Fi, Jul 2018
• 2018-07-19Watts says modern ADCs' -6dB at FS/2 causes unrepairable aliasing, yet all recordings benefit from an M scaler; Davina will decimate without aliasing, and he will release randomly named files. Head-Fi, Jul 2018
• 2018-07-21Watts says Dave owners have the Blu 2, or could use Davina, the AD converter, which will have an M scaler built in. c w 31:16
• 2018-07-21Watts says it is not job done: the gain from half a million to a million taps suggests going further, which Davina's native, bandlimited and decimated files will test. c w 31:47
• 2018-07-26Watts says the M scaler reconstructs to better than 16 bits; after the big change from 0.5M to 1M taps he cannot say whether more taps help; Davina will show. Head-Fi, Jul 2018
• 2018-08-10Watts says Davina is on the back burner; 768 to 48 kHz decimation is done, a non-integer 104 MHz decimation filter exceeds 250 dB, and recordings are targeted next year. Head-Fi, Aug 2018
• 2018-08-10Watts says Davina has its own mic pre-amp with adjustable gain and phantom power, so only microphones are needed, and he will probably make his own cable. Head-Fi, Aug 2018
• 2018-08-16Watts says the new DSD decimation filter sounds slightly better than DSD+ through better RF suppression; Davina work showed decimating to 16FS is lossless if aliasing stays below -220 dB. Head-Fi, Aug 2018
• 2018-09-01Watts says reconstruction would match the analog signal to 16 bits in principle, but ADC aliasing from poor decimation cannot be repaired; he expects Davina to manage it. needs context Head-Fi, Sep 2018
• 2018-09-22Watts says it is an ADC with mic inputs for making recordings, which can also M scale and convert digital formats. needs context Head-Fi, Sep 2018
• 2018-09-26Watts says he designed IIR and FIR Davina decimation filters with over 250 dB rejection to test bandlimiting; he expects pre-ringing at 22.05 kHz to prove a red herring. Head-Fi, Sep 2018
• 2019-02-05Watts says the prototype's 104MHz to 768kHz decimation filter failed in simulation, so he must redesign it from scratch, with little time due to other projects. Head-Fi, Feb 2019
• 2019-02-06Watts says true DSD has no decimation filter, conventional decimation gives about 20 dB rejection, and his FIR decimation is below -300dB; fractional 705/768 decimation was the problem. Head-Fi, Feb 2019
• 2019-02-06Watts says QBD76 used 112.896 MHz, but Davina's M scaler mode could not meet timing closure at that rate, and a future pro design needs word clock and asynchronous operation. Head-Fi, Feb 2019
• 2019-02-06Watts says a PLL would add low-frequency jitter seen as skirts around fundamentals, explains timing closure, and says the M scaler mode processes already-recorded files. needs context Head-Fi, Feb 2019
• 2019-04-11Watts compares his FIR and IIR Davina decimation filters on a square wave, explains phase linearity, says both reach 250 dB rejection, and expects FIR to sound better. Head-Fi, Apr 2019
• 2019-05-17Watts says separate supply pins on DAC chips do not solve substrate noise; pulse array mismatch creates only fixed noise, and Davina will record at 705/768 kHz. Head-Fi, May 2019
• 2019-06-21Watts explains how delta-sigma ADC modulators work, why 1-bit DSD modulators lack headroom, cannot be dithered and delay small signals more, and says pulse array and Davina avoid this. Head-Fi, Jun 2019
• 2019-06-21Watts says most recordings, even most DSD ones edited as DXD, use n-bit delta-sigma ADCs, and a 5-bit 128FS fifth-order ADC still has significant amplitude-related timing errors. Head-Fi, Jun 2019
• 2019-07-24Watts says Davina has a USB output and full digital inputs, so it can work as analog to digital, digital upscaling (M scaling) or digital decimation, at illustrative rates. Head-Fi, Jul 2019
• 2019-07-25Watts says the M scaler function is intended only for digital inputs and is not used when recording, which uses a different FPGA program. needs context Head-Fi, Jul 2019
• 2019-11-17Watts says the number is an integer multiple of 44.1 and 48 kHz to ease USB clock synthesis, and state-of-the-art ADCs suffer aliasing, poor small-signal accuracy and noise floor modulation. needs context Head-Fi, Nov 2019
• 2020-05-29Watts explains choosing an AEA R88mk2 stereo ribbon mic for Blumlein recording over Earthworks QTC50 capsules, and says another ADC prototype should allow recording late this year or next. Head-Fi, May 2020
• 2020-06-04Watts says modern ADCs suffer aliasing from half-band decimation filters, noise floor modulation and poor small-signal accuracy, which his pulse array ADC will solve; the next prototype PCB is underway. Head-Fi, Jun 2020
• 2020-07-09Watts says the initial ADC will be a two-channel stereo test-bench for the technology, with a multi-channel pro device to follow once the technology is proven. Head-Fi, Jul 2020
• 2021-01-25Watts says the ADC prototype had adjustable mic inputs with phantom power and digital outputs to a DAC, and the pro model is not yet specified. Head-Fi, Jan 2021
• 2021-01-29Watts says his ADC uses a pulse array DAC in its feedback loop at 104 MHz, and converting to 768k synced to studio clocks needs a complex fractional interpolation filter. Head-Fi, Jan 2021
• 2021-01-30Watts says pro interfaces have 8 ADCs and must sync via external word clocks, so his pro ADC model must support that. Head-Fi, Jan 2021
• 2021-02-01Watts says recording engineers press him for Davina, contrasts N-bit 104 MHz modulation with 1-bit DSD64, won't disclose plans, and names depth and attack as audio's key challenges. needs context Head-Fi, Feb 2021
• 2021-05-04Watts says MP3 encodes transients poorly and sounds soft, phase or frequency response errors are not damaging, and his ADC work will test 768k to 48k and back. Head-Fi, May 2021
• 2021-05-08Watts says he plans headphone tests of depth, impact and timbre for his ADC, microphones and headphones, plus a 768k-to-48k-to-768k test of decimation and WTA filters. Head-Fi, May 2021
• 2021-05-08Watts says content above half FS must be removed by decimation filters to avoid aliasing, and he must redo his -240 dB filters since -350 dB aliasing proved audible. Head-Fi, May 2021
• 2021-08-29Watts recommends a 768kHz ADC, plans pulse array ADC tests, favors digital volume over analog, and says grounding via Dave shorts its isolation; ground elsewhere, battery-power, or use a resistor. Head-Fi, Aug 2021
• 2021-12-21Watts says the ADC will be free of mains hum but he cannot answer for the microphones. Head-Fi, Dec 2021
• 2021-12-31Watts says the pulse array modulator takes two's complement PCM so it can be filtered and decimated, with 10 elements on and 10 off at zero, internally using offset binary. Head-Fi, Dec 2021
• 2022-01-07Watts says 768k test recordings sounded reminiscent of an M scaler but imperfect, and his ADC will be pulse array based, with stability and decimation aliasing the tricky parts. Head-Fi, Jan 2022
• 2022-03-16Watts describes recording an amateur orchestra with a Blumlein ribbon mic into a Focusrite ADC, compares playback with live, and blames lost depth, transients and timbre on the ADC. Head-Fi, Mar 2022
• 2022-03-19Watts says an ADC is mathematically the same as a DAC with analog integrators, he is respinning his ADC, and the fourth iteration failed due to power supply issues. MFG Audio Reviews 51:01
• 2022-04-10Watts describes twisting eight PTFE solid cores per conductor, hopes to finish the xM scaler and ADC later this year, and says the next ADC prototype will take ribbon mics. Head-Fi, Apr 2022
• 2022-05-09Watts says decimation filters need only adequate aliasing rejection and FIR pre-ringing was inaudible, but DAC interpolation needs a sinc, so he offers one WTA1 filter, no options. Head-Fi, May 2022
• 2022-05-13Watts agrees conventional ADCs soften sound through limited HF accuracy and aliasing, says minimum-phase, MQA, apodizing and NOS filters soften it far more, and defends sampling theory. Head-Fi, May 2022
• 2022-05-23Watts says DAVE's DX outputs carry 705/768 kHz from its 164,000-tap WTA1 filter and should sound better than Qutest's 48k taps; Qutest ignores the embedded volume data. Head-Fi, May 2022
• 2022-07-19Watts says the amp is in the background, old recordings involve via M Scaler and DAVE, and his Blumlein test recordings showed ADC losses: less depth, softer transients, warmer balance. Head-Fi, Jul 2022
• 2022-08-19Watts says he has made his own recordings with Blumlein stereo ribbon mics because he is developing a pulse array ADC for pro audio and must assess its transparency. AVstore 10:41
• 2022-08-19Watts says required accuracy came out a very silly number, and his ADC project will let him decimate 768 kHz recordings to 48 kHz, rescale to 768 kHz, and compare. AVstore 12:31
• 2022-08-19Watts says ADC decimation from 768 to 48 kHz is poorly done with inadequate anti-aliasing filters, and the planned test will measure both decimation and interpolation losses. AVstore 13:13
• 2022-08-19Watts adds that the test would also show how transparent the scalers actually are. needs context AVstore 14:05
• 2022-08-19Watts says live music varies enormously in space and timbre, his task is closing the gap to reproduced music, and the ADC project would let him maximize the A-to-D, cables and storage. AVstore 45:23
• 2022-08-19Watts says he controls everything in the chain except microphones and headphones, including DAC and scalers, which he calls a very exciting prospect. needs context AVstore 46:09
• 2022-09-18Watts says his recordings test the playback chain and his pulse array ADC (begun about 2005); ADCs suffer noise floor modulation, poor small-signal accuracy suppressing depth, and sharpness-dulling aliasing. The Source AV 20:30
• 2023-01-23Watts explains his recording program to test his pulse array ADC and compare live with reproduced sound, says pro ADCs limit performance, and notes listeners differ in sensitivity. Head-Fi, Jan 2023
• 2023-02-04Watts asks whether 16-bit accuracy is enough, says he has spent five years exploring how many taps are needed, and is building his own ADC because ADC quality limits recordings. Dusty Audio 44:38
• 2023-02-04Watts says ADCs share DACs' three issues, differing in analog versus digital integrators; his ADC will record at 768 kHz, decimate to 48 kHz and upsample back to find losses. Dusty Audio 45:25
• 2023-02-04Watts says he will test his ADC within weeks, and makes his own recordings with ribbon microphones and one pro ADC, unedited, to compare against the live sound. Dusty Audio 46:13
• 2023-03-26Watts says he is doing his own recording sessions while developing a pulse array A to D converter, aiming to control the whole chain from microphone to headphones or loudspeakers. Eric's Hi-Fi 41:36
• 2023-03-28Watts says he wishes studios would not record in DSD; he is testing his own pulse array ADC and making recordings to compare reproduction with the live sound. The Headphone Show 53:51
• 2023-09-29Watts says 7W from TT2 should not damage speakers unless clipping, and a stereo ADC in design will offer SRC-based external word clock sync and possibly Dante. Head-Fi, Sep 2023
• 2023-10-01Watts says he is a big Stealth fan and makes his own recordings partly to test the pulse array ADC he is developing for pro audio and domestic markets. The Source AV 24:59
• 2023-10-01Watts says left-right placement was accurate but depth was not, and he hopes his ADC will solve that and give proper depth. The Source AV 27:41
• 2023-10-30Watts says the ADC is a simple 2-channel unit for Blumlein ribbon recording, separate clocking is solved, and non-delay asymmetric FIR filters give poor transient reconstruction. Head-Fi, Oct 2023
• 2024-05-04Watts says Quartet replacing a Hugo M Scaler on another listener's Dave made instruments sound real, and describes ADC decimation filter work and the 104MHz pulse array ADC. Head-Fi, May 2024
• 2025-03-15Watts says the pulse array ADC earlier unit worked to -20dB, new boards should fix that, and a pro-audio product spec is underway, 18 months to two years minimum. Head-Fi, Mar 2025
• 2025-03-25Watts argues comparing DAC output with original sampled data is pointless since an ideal DAC reconstructs the original signal, and says his son Daniel is building the pro ADC project. Head-Fi, Mar 2025
• 2025-09-14Watts says his pulse array A to D converter, a six or 7 year project, was recently tested and is progressing well; his son is a Tonmeister student. The Source AV 1:34
• 2025-09-14Watts describes a high-end pulse array A to D converter with two DACs in one chassis, a studio parametric EQ, post-processing, targeting 192 kHz and 768 kHz recordings. The Source AV 2:20
• 2025-09-14Watts says microphones can be connected to the unit, making it a really flexible unit. The Source AV 3:07
• 2025-09-14Watts says many studios use DAVEs, Mojo 2s and Hugos, recording engineers keep asking when the A to D converter will come out, and his son understands their needs. The Source AV 3:15
• 2025-09-14Watts says he argues that doing things his way gains benefits, and that the aim is to change the horizon for recording engineers in what they do and how. The Source AV 5:01
• 2025-09-14Watts says that if they wanted something simple, like a high-end mastering two-channel A to D converter, it would not have the EQ built in. The Source AV 5:17
• 2026-03-17Watts says much of his work is now pro audio: he is developing a pro ADC and will compare its recordings, played on his DACs, with the live event. ecoustics 18:59
• 2026-03-17Watts says a cello recorded four meters away sounds two meters on DAVE and 2.5 to 3 with Quartet; commercial ADCs noise-shape to 140 dB, his ADC about 301 dB. ecoustics 45:04
• 2026-03-24Watts says Mojo 2 is inexpensive and limited by its source, then introduces Quartet's analog input, a pulse array A-to-D converter, prompted by recording engineers praising DAVE. Audio Force 29:11
• 2026-03-24Watts says engineers wanted the best A-to-D using DAVE's technology, which now works in Quartet, and he has been making test recordings of its performance. Audio Force 29:58
• 2026-03-24Watts says his mother immediately heard the difference between a high-performance ADC and Quartet's ADC on a phone speaker, so recording quality will improve for everyone. Audio Force 30:22
• 2026-05-03Watts says major studios use Chord DAVE (transcribed 'CordDave'; possibly 'Chord DACs') for its transparency, and recording engineers ask when he will make a pulse array A to D converter. Audio Force 15:17
• 2026-05-03Watts says the pulse array's small-signal accuracy and lack of noise floor modulation matter for ADCs too; Quartet is the first product using his pulse array ADC, and a Pro Audio ADC is in development. Audio Force 16:00
• 2026-05-03Watts says the Pro ADC will offer lossless EQ and 768 kHz and 192 kHz recording; he wants studios to adopt 768 kHz, which needs FPGA post-processing. Audio Force 16:46
• 2026-05-03Watts says Chord aims to create future hi-res standards; recordings with the new pulse array ADC sound much better than high-end pro ADCs, audibly even on phone loudspeakers. Audio Force 17:34
• 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 they spent a studio day recording piano and a singer at 768 kHz with Quartet, and he has never heard piano sound as good. The Source AV 3:00
• 2026-08-30Watts says recording like this has been his aim since the 1980s; the concept is proven and must now become a product pro audio people can use. needs context The Source AV 3:46
• 2026-08-30Watts says their prototype, with experimental boards added for its unique 768 kHz outputs, worked fine while the studio's normal equipment kept stopping. The Source AV 20:34
• 2026-10-02Watts says they have not yet talked about the ADC, which is in Quartet. HiFi Buys 1:40:55
• 2026-10-02Watts says having a pulse array ADC working and making recordings with it has been fascinating. HiFi Buys 1:41:11
• 2026-10-11Watts says to develop a pulse array ADC he made his own recordings with a stereo ribbon mic and a standard ADC, comparing playback against his memory of the event. Distorsiuni Interioare 10:33
• 2026-10-11Watts says Quartet contains a pulse array ADC; two test recordings at 768 kHz were made with it, and he expected better separation, depth and power. Distorsiuni Interioare 11:57
• 2026-10-11Watts says an ADC has a DAC in its feedback loop; the surprise was far more accurate pitch of female vocalists than pro ADCs give, which he attributes to aliasing. Distorsiuni Interioare 12:51
• 2026-10-11Watts says aliasing errors are not harmonically related to the signal, confuse the brain's pitch tracking and degrade transient timing; Quartet eliminates aliasing unlike standard pro ADCs. Distorsiuni Interioare 13:35
• 2026-10-11Watts says the next step is a Pro ADC enabling digital mixing and EQ, up to sixteen channels, with units cascadable and synced for more channels. Distorsiuni Interioare 14:33
• 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 having proven the principle, sound quality and technology, they can now move on to the Pro ADC. Distorsiuni Interioare 16:18
• 2026-10-11Watts says the ADC sounds better even on a phone because of decimation: conventional ADCs turn four or 5 bits at 3 MHz into twenty-four bits at 192 kHz. Distorsiuni Interioare 53:53
• 2026-10-11Watts says his biggest challenge now is the Pro ADC, mostly being done by his son Daniel, and its test recordings excite him about the technology. Distorsiuni Interioare 1:18:54
• 2026-10-11Watts says the pro ADC will change engineers' work: current ADCs are too bright and tamed with EQ, while accurate timbre from the start changes post-processing. Distorsiuni Interioare 1:31:20
• 2026-10-11Watts says the pro unit will also have full mixdown capability independent of the DAW, running at 108 bits, 768 kHz internally. Distorsiuni Interioare 1:32:10
• 2026-10-14Watts says the recording truncated depth by about 50 percent (a cello four metres away sounded two) and softened transient edges, a reason for his pulse array ADC work. Part-Time Audiophile 14:32
• 2026-10-14Watts says the pulse array ADC now yields 768 kHz recordings with immediate, fast transients and live-like power, with more test recordings planned over the coming months. Part-Time Audiophile 15:18
• 2026-10-14Watts says tests are recorded at 768 kHz; the pro ADC in development has 16 inputs and outputs, FPGA mixing and subjectively lossless EQ; compression and reverb are being considered. Part-Time Audiophile 49:46
• 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 a delta-sigma ADC is mathematically a DAC with analog integrators, so pulse array benefits apply: lower noise floor modulation, better separation, accuracy to a -301 dB signal. Part-Time Audiophile 54:50
• 2026-10-14Watts says that accuracy gives better detail and depth, the pulse array ADC shows the same benefits as the DACs, but differs because a DAC oversamples a low-rate input. Part-Time Audiophile 55:39
• 2026-10-14Watts says the pulse array ADC samples at 104 MHz, 5 bits, decimating to 48 or 768 kHz at 24 or 32 bits; decimation filtering is critical to transient reconstruction. Part-Time Audiophile 56:23
• 2026-10-14Watts says his ADC's aliasing is vanishingly small; comparing standard, high-end and pulse array ADCs on a female vocal from Daniel's simple analog tape, pitch was the surprise. Part-Time Audiophile 57:48
• 2026-10-14Watts says the singer sounds out of tune on one ADC (transcribed 'Pro ADC') but in tune on the pulse array ADC, a pitch error indicating transient timing problems. Part-Time Audiophile 58:34
• 2026-10-14Watts says Quartet solved interpolation filters for him; with the ADC and 768 kHz recordings he can decimate (to '24 kHz' as spoken), re-interpolate and compare, controlling microphone to transducer. Part-Time Audiophile 1:03:53
• 2026-10-17Watts says one recording is 768 kHz 24-bit and one 192 kHz 24-bit from an analog tape, made to set up the ADC and compare it with commercial pro ADCs. article, Oct 2026
• 2026-10-17Watts says the current test ADC is Mojo standard through a 1970s Neve desk, while the pro ADC will be DAVE standard, with digital mixing, EQ and a single op amp. article, Oct 2026
• 2026-10-17Watts says 768 kHz Pulse Array ADC recordings can be decimated to 48 kHz and brought back to 768 kHz to measure losses, improving decimation and interpolation filters. article, Oct 2026
• 2026-10-17Watts says the Pro ADC will have mic inputs, one op amp into the ADC and 108-bit digital mixing, changing how recording is done. 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 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
• 2026-10-17Watts says panning, EQ and possibly compression and reverb will give engineers tools beyond existing DAWs, and a Pulse Array ADC reduces the need to compensate for ADC losses. article, Oct 2026
• 2026-10-17Watts says that is why Warner let them into its studios for a day with a pianist and vocalist to test the ADC, and they are keen. article, Oct 2026