Depth and soundstage

Perception and sound character

Answers on this topic

• How do microphones, studio conversion and mastering limit what a DAC can reproduce?
• What does Rob mean by depth, and what in a DAC improves or collapses it?
• What does crossfeed do, which setting should I use, and why didn't the original Mojo have it?
• Why does Rob design to -301 dB, how can that be verified, and how does small-signal accuracy relate to depth?

Everything he said on this topic (252)

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

• 2014-06-24Watts reports the 33-pound Olimex USB-ISO on Hugo's SD USB input (44.1/48 kHz only) gives better depth, focus and separation, consistent with better RF isolation. Head-Fi, Jun 2014
• 2014-06-25Watts suggests USB isolation also removes signal-dependent ground noise from the computer, which, unlike RF noise, can change perceived sound stage depth. Head-Fi, Jun 2014
• 2014-09-13Watts says USB isolation gives smoother sound and better depth by blocking correlated ground noise; two USB cables still join grounds; the new QBD has galvanic isolation. Head-Fi, Sep 2014
• 2014-09-21Watts says Hugo driving Axjet horn loudspeakers gave extraordinary depth, with a solo violin in The Lark Ascending sounding 40 feet away. Head-Fi, Sep 2014
• 2014-10-01Watts says USB cables change sound through RF noise causing NFM and brightness, while signal-dependent ground currents degrade depth; galvanic isolation addresses both. Head-Fi, Oct 2014
• 2015-05-20Watts says that tuning Hugo, better noise shaper performance improved perceived depth, limited by Hugo's gates; for DAVE he began listening tests from Hugo's roughly 200 dB. HIFICLUBE.NET JVH 5:32
• 2015-05-20Watts says raising noise shaper performance to 220, 240 and 260 dB each improved depth with no apparent limit, so he redesigned the noise shapers, reaching 350 dB. HIFICLUBE.NET JVH 6:30
• 2015-05-20Watts says he cannot understand why this attribute changes perceived depth, which is easy to hear: on a cathedral organ recording the organ moves backward and forward. needs context HIFICLUBE.NET JVH 7:59
• 2015-05-20Watts says the depth is accurate, not added reverb: dry recordings stay at the speakers. He is unsure whether 350 dB is truly needed or an analog mechanism explains it. HIFICLUBE.NET JVH 9:00
• 2015-09-25Watts argues DSD is flawed by its format: limited noise-shaper resolution loses small signals and depth, and level-dependent timing non-linearity softens transients and compresses timbre. Head-Fi, Sep 2015
• 2015-10-01Watts says metal contacts and noise shapers cause the same small-signal distortion that truncates depth, the brain detects levels no instrument measures, and HF distortion alters transient timing. Head-Fi, Oct 2015
• 2015-10-22Watts says the update gives more depth and detail from improved internal noise shapers, but most work was non-audio: displays, control, dual data mode and dual programs. needs context Head-Fi, Oct 2015
• 2015-10-30Watts says Dave's depth, about four times Hugo's, comes from small-signal accuracy of its -350 dB noise shapers; timing gains offset the darkness that reducing noise floor modulation brought. Head-Fi, Oct 2015
• 2015-11-10Watts says Dave's key gain is timing: WTA filtering to 256FS reconstructs timing to 88 nS, improving starting and stopping of notes, while depth comes from the noise shapers. Head-Fi, Nov 2015
• 2015-11-15Watts says speakers suppress depth but trained listeners hear small depth changes; depth is a small-signal non-linearity problem in electronics, valuable for film soundtracks. Head-Fi, Nov 2015
• 2015-11-22Watts recounts developing Dave: smoothness from reduced noise floor modulation, Hugo-derived timing gains from 256FS WTA (88nS), and noise shapers raised from 200 to 350 dB for depth. Head-Fi, Nov 2015
• 2015-12-01Watts ties depth to small-signal linearity, distinguishes it from noise floor modulation, and describes raising Dave's noise shapers from 200 to 350 dB with depth improving throughout. Head-Fi, Dec 2015
• 2015-12-01Watts says recordings either have depth or not, studio depth comes from reverb, classical usually has good depth, and film and TV soundtracks have great spatial layering. Head-Fi, Dec 2015
• 2015-12-01Watts says depth is now about a third deeper and slightly smoother after upgrading internal noise shapers, the only audio change; the rest was control work. needs context Head-Fi, Dec 2015
• 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 says he had a non-audiophile engineer compare 190 dB and 200 dB noise shapers to convince a company he worked with; the engineer heard the difference easily. article, Jan 2016
• 2016-03-01Watts says Dave is source-insensitive through bit-perfect data and immunity to jitter and noise, that depth needs perfect small-signal accuracy (350 dB noise shapers), so no pre-amp sounds better. Head-Fi, Mar 2016
• 2016-03-07Author says DAVE's enhanced noise shaper reproduces fine signals for spatial recognition; Watts contrasts hearing an organ's distance in church with recordings, saying recovering depth was his concern. 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
• 2016-03-28Watts says headphones have much poorer depth than loudspeakers but often better inner detail, and many are too bright and lean, though smooth, linear ones exist. Head-Fi, Mar 2016
• 2016-03-29Watts says AB tests struggle to tell transparency from noise floor modulation, that better noise shapers in DAVE improved depth, and that Verilog simulation can quantify very small errors. Head-Fi, Mar 2016
• 2016-03-31Watts says DAVE's volume is fully digital because analog controls have small-signal errors that degrade depth, and describes his 350 dB noise shaper and -301 dB test targets. Head-Fi, Mar 2016
• 2016-03-31Watts says DAVE's maximum attenuation is -75 dB with truncation noise near -350 dB, and explains how noise shapers attenuate signals near their resolution, harming depth. Head-Fi, Mar 2016
• 2016-04-26Watts says DAVE adds no artificial depth, since flat recordings stay flat, and attributes compressed depth in DACs to small-signal amplitude errors rather than ringing. Head-Fi, Apr 2016
• 2016-04-28Watts speculates that hunters evolved precise auditory depth placement, to about a foot, because locating prey by sound mattered for survival. Head-Fi, Apr 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
• 2016-07-09Watts describes brain break-in as gradually improving perceived depth and note starts and stops, citing depth returning a month after adding a bookshelf, while smoothness changes are hardware. Head-Fi, Jul 2016
• 2016-07-24Watts says changing the noise shaper while optimizing Hugo made a large, easily heard difference to depth perception, which audio reproduces badly, citing a cathedral organ 100 meters away. Hifistatement 0
• 2016-07-24Watts says his noise shaper resolves about a thousand times more than normal DAC noise shapers and 10 thousand times more than DSD's; information below its floor is lost. Hifistatement 1:43
• 2016-07-24Watts says dithered PCM keeps small signals within the noise, but noise shapers cannot be dithered properly and discard them; Hugo's 4E pulse array and gate count limited it. Hifistatement 2:23
• 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 brain detects tiny errors as poorer instrument placement, depth needs perfect accuracy, and he ended with a new 17th-order noise shaper with 46 integrators. Hifistatement 3:54
• 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
• 2016-09-13Watts clarifies that the -350 dB figure is the noise shaper's exact Verilog-simulated digital performance, mattering for preserving tiny signal amplitudes rather than noise, which he ties to depth. Head-Fi, Sep 2016
• 2016-09-14Watts admits he cannot explain why depth needs 350 dB noise shapers, gives a -120 dB signal's attenuation for 160 to 340 dB shapers, yet still hears the change. Head-Fi, Sep 2016
• 2016-09-19Watts says headphone depth is suppressed versus loudspeakers, names AudioQuest NightHawks and a defunct German speaker brand as his own, and says Chord tests prototypes with many transducers. Head-Fi, Sep 2016
• 2016-09-21Watts explains the brain uses high-frequency air absorption as a depth cue, so a bright microphone foreshortens depth, and praises the QT50's polar, frequency and impulse response. Head-Fi, Sep 2016
• 2016-10-20Watts shows an FFT of DAVE's noise shaper output resolving a -301 dB 6 kHz signal, stands by his listening-based claim that depth needs this, and plans Davina tests. Head-Fi, Oct 2016
• 2016-11-10Watts says DAVE's depth comes from preserving small-signal amplitudes, not its -128 dB noise floor; timbre from no noise floor modulation and accurate transient timing; hard USB from non-bit-perfect data. Head-Fi, Nov 2016
• 2016-11-14Watts says the Goldmund's Linkwitz-based crossfeed is very similar to his setting 3, and he would like a more advanced scheme bringing loudspeaker depth to headphones. Head-Fi, Nov 2016
• 2016-11-16Watts says live music has far more depth, dry close-miked vocals should sound flat on DAVE, which focuses vocals tightly and tolerates wider speaker spacing than TT. Head-Fi, Nov 2016
• 2016-12-11Watts says a 33-ohm load barely changes DAVE's THD+N (-127 to -124 dB), and argues a wider soundstage usually signals lost depth and transparency, except where recordings encode out-of-the-box cues. Head-Fi, Dec 2016
• 2017-01-15Watts recounts M scaler development and CES demos, discusses judging the scale of changes, lists gains in timbre, bass pitch and depth, and describes improving stop-band rejection. Head-Fi, Jan 2017
• 2017-04-04Watts says crossfeed EQ boosts LF by 1.5dB for head shadowing, explaining a warmer balance, and he finds crossfeed essential for depth when using Hugo 2 on flights. Head-Fi, Apr 2017
• 2017-04-05Watts says crossfeed settings boost DC to 1 kHz by about 1, 1.5 and 1.9 dB, and improved depth shows transparency is not lost, since DSP problems collapse depth. Head-Fi, Apr 2017
• 2017-05-16Watts notes the M scaler's 2.76 dB insertion loss and says 0.5M versus 1M taps, or video mode, changes depth greatly, hypothesizing coefficient truncation over reverb-length periods. Head-Fi, May 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
• 2017-09-06Watts says crossfeed on Hugo 1 suited only older recordings, but on Hugo 2 it gives better soundstage depth on all recordings. Head-Fi, Sep 2017
• 2017-09-09Watts says Hugo 2's crossfeed code is unchanged from Hugo, but better depth makes crossfeed have a big impact on perceived depth, as also happens with Dave. Head-Fi, Sep 2017
• 2017-09-19Watts says crossfeed tames hard-panned early stereo; on Hugo 1 it gave normal recordings no depth benefit, but on Hugo 2 depth is deeper and sounds seem outside the head. Head-Fi, Sep 2017
• 2017-09-19Watts explains headphone depth perception, why Hugo 2 crossfeed gives out-of-head sound, and why small-signal accuracy to -301 dB lets the brain use depth cues. Head-Fi, Sep 2017
• 2017-10-11Watts says WTA reconstructs transients regardless of origin; DAVE's 164,000-tap delay is about 0.2 s and 1M taps 1.4 s, and his RT60 explanation for depth is speculative. Head-Fi, Oct 2017
• 2017-10-13Watts describes hearing performers three feet apart in depth at a concert with eyes shut, calls the brain's depth placement extraordinary, and says high-end audio does not understand this processing. miceblue425 3:00
• 2017-10-13Watts says depth cues include the natural attenuation of sound by air and reverberant detail, and that the 4 microsecond threshold implies the brain processes at a 250 kHz sampling rate. miceblue425 7:18
• 2017-10-13Watts says the M Scaler deepens the soundstage enormously, which puzzles him because filter changes never altered depth before; depth depends on small-signal nonlinearity, which filters can avoid. miceblue425 33:17
• 2017-10-13Watts suspects the soundstage opens because the filter now spans 1.4 seconds, about a hall's RT60 reverberation decay time, and reverberation is an important depth cue. miceblue425 34:01
• 2017-10-13Watts calls the depth change a puzzle and says the most powerful listening test is a null result, since hearing something as better can mislead. miceblue425 34:45
• 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 this will tell him how far he needs to go and may explain why depth and soundstaging suddenly improved. needs context miceblue425 42:25
• 2017-10-13Watts says the soundstage change fascinates him because he does not understand it, and finding out why may reveal another way to improve sound quality. miceblue425 52:26
• 2017-10-13Watts says his girlfriend's blind result, smoother and warmer, matched his, and that the 330 versus 350 dB depth finding seemed too crazy to post. miceblue425 53:52
• 2017-10-13Watts says a non-audiophile engineer compared 180 dB and 200 dB noise shapers: the 180 dB sounded harder and brighter from noise floor modulation; the 200 dB had better depth. miceblue425 55:42
• 2017-10-20Watts says longer taps improved bass definition, timbre and pitch as usual, but the million-tap M Scaler also opened up depth and soundstage beyond DAVE's. Hifistatement 2:03
• 2017-10-20Watts says the USB video mode, two-thirds of a million taps on the same architecture, collapses the soundstage, though architecture and small-signal work carried over from DAVE also matter. Hifistatement 2:57
• 2017-10-20Watts says small-signal integrity was verified by passing the -301 dB test, so he cannot explain why longer taps change depth, which he has tied to small-signal integrity. Hifistatement 3:43
• 2017-10-20Watts says depth concerns small-signal amplitude, not timing, and speculates that the million taps spanning 1.25 seconds, roughly a reverb time, may explain the depth change. Hifistatement 4:30
• 2017-10-20Watts hopes the Davina project will explain why extra taps change depth, calling the soundstage opening with the Blu an unexpected shock revealing a hole in his knowledge. Hifistatement 5:17
• 2017-11-29Watts explains that 2 GHz ferrites improve depth by blocking signal-correlated ground bounce from FPGA logic transitions, while random RF causes noise floor modulation and brightness. Head-Fi, Nov 2017
• 2017-12-05Watts introduces small-signal nonlinearity and depth perception as a fascinating and very bizarre subject. RMAF 17:18
• 2017-12-05Watts says since the 1990s he has found fundamental linearity affects depth perception, and defines the test: set minus 60 dB, play a minus 100 dB signal, measure its amplitude. RMAF 17:37
• 2017-12-05Watts says pulse array eliminated the fundamental linearity problem of his 1990s DSD256 DACs; a minus 120 dB signal now measures within a thousandth of a dB, Mojo to DAVE. RMAF 18:43
• 2017-12-05Watts contrasts the immense depth of a cathedral organ and choir heard from 150 to 200 feet away with reproduction, where five feet behind the speakers is doing well. RMAF 19:30
• 2017-12-05Watts says he can tell dogs barking two miles away are that far, whereas audio gives nothing like that depth, so hi-fi systems have a massive depth problem. RMAF 20:13
• 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 depth kept improving with noise shapers at 240, 260, up to 330 to 350 dB, a 0.0000001 dB change at minus 120 dB, easily heard blind. RMAF 22:21
• 2017-12-05Watts says repeated tests confirm it, and putting a 350 dB noise shaper in a purely digital truncator, 56 bits in and 24 out, gave the same deeper depth. RMAF 23:07
• 2017-12-05Watts says DSD sounds flat in soundstage versus PCM on his DACs; it needs no WTA filter but has timing problems, as tiny transients leave the modulator output unchanged. RMAF 37:24
• 2018-02-14Watts says Hugo 1 and Mojo have similar depth because they share the same pulse array, noise shapers and truncators, which set small-signal linearity and hence depth. Head-Fi, Feb 2018
• 2018-02-23Watts says putting this FPGA in Dave would inject signal-correlated noise from 528 DSP cores into the ground plane, peaking at the smallest signals and degrading depth perception. MajorHiFi 20:02
• 2018-05-17Watts says a high-end server had better tonal balance than a slightly dark battery laptop, but he hears its RF noise clearly; the laptop's depth improvement was easy to hear. Head-Fi, May 2018
• 2018-07-21Watts says the M Scaler gives better bass definition, instrument separation and focus, and unexpectedly opens up the soundstage so reverb is heard from different walls. c w 27:48
• 2018-07-21Watts says past WTA changes never altered depth, and suspects the 1.3-second analysis span, similar to concert-hall RT60 times, explains it; he hopes Davina will show why. c w 28:33
• 2018-07-30Watts says a 'fuller' coax sound, if brighter, is extra noise floor modulation mistaken for transparency, and coax can give flatter, wider staging with less depth. Head-Fi, Jul 2018
• 2018-09-01Watts says a wider soundstage often means truncated depth from correlated source noise, which optical prevents; the better source has more warmth and deeper depth. Head-Fi, Sep 2018
• 2018-12-12Watts explains small-signal amplitude error: a minus 90 dB signal measured against minus 20 dB comes out slightly high or low, and this changes perceived depth and detail resolution. Pursuit Perfect System 11:46
• 2018-12-12Watts says small-signal non-linearity changes depth at ridiculously small levels, any such error is audible as collapsed depth, and contrasts a cathedral organ 100 meters away with hi-fi's six feet. Pursuit Perfect System 12:32
• 2018-12-12Watts says reproduced audio never conveys true distance, a problem he has pursued since the 1980s, and that however small the small-signal errors are, depth is truncated. Pursuit Perfect System 13:15
• 2018-12-12Watts says the change was in depth perception, a surprise because in 2014 he thought 200 dB noise shaper performance, better than 32-bit, was more than anyone could hear. Pursuit Perfect System 22:12
• 2018-12-12Watts says he built a 220 dB noise shaper, verified it in simulation, heard deeper depth on switching against the 200 dB one, then spent three months improving it. Pursuit Perfect System 23:38
• 2018-12-12Watts says 240 dB sounded better than 220, he pushed on through 260 to 300, a new design reached 330 and 350 dB, and depth deepened at each of those. Pursuit Perfect System 24:32
• 2018-12-12Watts says he hesitated to publish the numbers for fear of the Sound Science Brigade, but released them because everyone hearing DAVE comments on its deeper depth. Pursuit Perfect System 26:01
• 2018-12-12Watts says replacing the first-order noise shaper truncating the WTA filter's 56-bit output to 24 bits with 350 dB noise shapers also improved depth, showing small-signal accuracy is fundamental. Pursuit Perfect System 26:51
• 2018-12-12Watts says simpler analog improves depth and detail; the pulse array's 104 MHz rate gives noise shaper resolution and allows an output of one amplifier, two resistors and two capacitors. Pursuit Perfect System 30:58
• 2018-12-12Watts says TT2 has 10 elements and a 12th-order noise shaper beyond 300 dB, better than Hugo 2 but short of DAVE, with one 7 watt amplifier, giving better depth. Pursuit Perfect System 35:36
• 2018-12-13Watts gives tap lengths of DAC64 (1,000), QBD76 (18,000), Hugo in 2013 (26,000) and DAVE (164,000), saying each increase improved bass definition and soundstage. Pursuit Perfect System 9:06
• 2018-12-13Watts says longer taps improved bass, timbre and left-right staging but never depth, which he ties to small-signal accuracy, yet at half a million taps the soundstage opened up. Pursuit Perfect System 19:49
• 2018-12-13Watts says he cannot explain why going from DAVE's 164,000 taps to the M Scaler's 1 million opens the soundstage, suggesting its 1.3 second window matches concert-hall reverberation time. Pursuit Perfect System 20:30
• 2018-12-13Watts says listening without the M Scaler, for the first time in two years, sounded flat, and that the soundstage opening is what surprises people. Pursuit Perfect System 21:14
• 2018-12-13Watts says he listens to more electronic music lately; its artificial depth still opens up, and its abrupt stops let the M Scaler show starting and stopping of notes clearly. Pursuit Perfect System 22:17
• 2018-12-13Watts says live amplified music sounds poor in many ways, completely flat with no soundstage at a big concert for 50,000 people. Pursuit Perfect System 23:23
• 2018-12-23Watts clarifies he called live amplified music awful, not genres; he loves prog rock, electronica and classical, says the M Scaler enhances depth, and asks for tolerance. Head-Fi, Dec 2018
• 2018-12-27Watts says the M scaler unexpectedly improves reverb and depth perception, normally tied to small-signal accuracy, speculating about its 1.438 s of data versus concert-hall RT60, unconvinced. Head-Fi, Dec 2018
• 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
• 2019-06-01Watts 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
• 2019-12-16Watts says DAC64 and QBD76 had 200 dB noise shapers while the best chip DACs reach only 140 dB, so they reproduce small signals poorly, degrading depth and detail. Passion for Sound 11:25
• 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
• 2019-12-16Watts says we know the brain's depth cues but not how it locates instruments in space, so audibility cannot be asserted either way. Passion for Sound 15:05
• 2020-06-01Watts says ear-spaced mics would need ear-like polar response, notes separation is normally wider, and plans to buy condenser mics to compare which gives more realistic depth. Head-Fi, Jun 2020
• 2020-06-25Watts says separate instruments placed in a soundstage are an illusion created by the brain from ear data, and nobody knows how the brain separates sounds. Part-Time Audiophile 9:19
• 2020-06-25Watts says listeners can perceive a three-foot depth difference in a 60-foot concert hall with eyes shut, which no computer program can do. Part-Time Audiophile 10:04
• 2020-07-08Watts says the next ADC prototype PCB will be built in early autumn and muses that brain correlation may explain why depth depends on impossibly small signal accuracy. Head-Fi, Jul 2020
• 2020-07-09Watts defines depth as how far away a sound seems and describes his depth tests using a cathedral organ, judging only which version sounds farther away. Head-Fi, Jul 2020
• 2020-07-10Watts says he solved the DX amp's signal-dependent switching issue, a Dave DX amp is one to five years away, and explains frequency response and phase as depth cues. Head-Fi, Jul 2020
• 2021-01-03Watts says the ear/brain responds to errors roughly as log(log), citing 164k to 1M taps and depth error steps, and ranks interpolation filter, DAC design and analog design. Head-Fi, Jan 2021
• 2021-04-16Watts sets crossfeed to maximum on headphones and to minimum on his office HMS and Dave speaker system, saying depth improves in both. Head-Fi, Apr 2021
• 2021-07-25Watts says more work is ongoing with news expected next year, and depth needs cues preserved in amplitude and timing; why -301dB accuracy matters remains a mystery. needs context Head-Fi, Jul 2021
• 2021-07-25Watts describes his -301.03dBFS FFT test requiring +/-0.001dB and +/-0.001 degree accuracy, saying phase that varies with amplitude degrades depth while constant phase shift does not. Head-Fi, Jul 2021
• 2022-01-07Watts says HRTF works if your own HRTF is modeled with very accurate DSP, 64 bit floating point is inadequate, and HRTF fixes direction but degrades depth. Head-Fi, Jan 2022
• 2022-01-31Watts says depth improved at each noise shaper step, 220 dB, 240 dB, up to DAVE's 350 dB, even 330 to 350; noise shapers shrink his -301 dB test signal. Darko.Audio 22:09
• 2022-01-31Watts says the attenuated signal is summed thousands of times so small errors become large; conventional DSPs cannot resolve -301 dB signals, degrading depth and detail. Darko.Audio 23:50
• 2022-01-31Watts says two or three years ago he found amplitude-dependent phase shift is audible as suppressed depth, while investigating why 1 million taps beat DAVE's 164 thousand for depth. Darko.Audio 24:34
• 2022-01-31Watts says DSP filters give small signals a different phase; his formal test compares phase at 0 dB and -301 dB, and 0.002 of a degree audibly suppresses depth. Darko.Audio 25:21
• 2022-01-31Watts says ears detect such tiny effects; he ran blind tests with his son, who independently heard better depth and focus, matching Watts's own impression. Darko.Audio 29:21
• 2022-01-31Watts says he now mostly tests on headphones; speakers give better sensitivity and accuracy, but he can still hear it, and closed-back headphones shut out household noise. Darko.Audio 30:28
• 2022-01-31Watts says inner detail and separation are easier on headphones; he tests timbre variation, separation and focus, and depth, likening depth to hearing a distant cathedral organ. Darko.Audio 31:09
• 2022-01-31Watts says reproduced audio comes nowhere near that, and his goal in life is a realistic sense of depth from reproduced audio. Darko.Audio 31:54
• 2022-01-31Watts says depth perception is easy to judge: something is deeper or not. Darko.Audio 34:42
• 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 the extra 200 milliwatts funded the digital DC servo, a better WTA filter and noise shaper, and the EQ DSP core; the noise shaper improves depth and detail. Darko.Audio 38:46
• 2022-01-31Watts says the listener should also have heard significantly better depth. needs context Darko.Audio 39:31
• 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 explains small signal non-linearity: a -120 dB signal may come out at -121 or -119 dB, an amplitude error that confuses the brain and impairs depth perception. MFG Audio Reviews 9:00
• 2022-03-19Watts contrasts an organ heard 200 feet away in a cathedral, or a distant dog, with reproduced audio, where depth reaches six feet at best. MFG Audio Reviews 9:52
• 2022-03-19Watts says inaccurate small signals are one cause of lost depth, the smallest error collapses depth, and his test is reproducing -301 dB, a figure he hesitated to publish. MFG Audio Reviews 10:36
• 2022-03-19Watts says he expected to be called a liar over -301 dB, but hundreds of listening tests show depth degrades without it, and science explains evidence. MFG Audio Reviews 11:30
• 2022-03-19Watts says conventional EQ adds noise floor modulation and collapses the soundstage as small signals lose amplitude accuracy, and recounts puzzling over why an M Scaler markedly improves depth. MFG Audio Reviews 30:09
• 2022-03-19Watts says the M Scaler's depth gain cannot come from small signal amplitude, set by quantization and noise shaping, so depth must involve timing; he tested a detuned noise shaper. MFG Audio Reviews 30:53
• 2022-03-19Watts describes quickly listening to four settings of a detuned noise shaper without simulation: setting three sounded best, two and four degraded depth, and one was flat. MFG Audio Reviews 31:36
• 2022-03-19Watts says crossfeed on Hugo 1 gave no out-of-head sense, but on Hugo 2 it improved depth, and Mojo 2 is similar thanks to better small signal accuracy. MFG Audio Reviews 41:42
• 2022-04-07Watts says M scaler depth gains led him to test phase shift with amplitude (2uS, 100nS, 10nS errors), so modules must now pass -301 dB in amplitude and phase. Head-Fi, Apr 2022
• 2022-04-13Watts describes his -301 dB Verilog simulation test with an 80 bit 768 kHz source, explains not publishing, and ties poor reproduced depth to small signal accuracy. Head-Fi, Apr 2022
• 2022-06-12Watts recounts crossfeed giving an out-of-head experience with a Hugo 2 prototype on a flight, never with the original Hugo, linking better small-signal accuracy to more effective crossfeed. Head-Fi, Jun 2022
• 2022-08-19Watts says DAVE with his prototype scaler and Dan Clark Audio Stealth headphones came close to his live recordings, but depth was one-third or 50 percent less. AVstore 46:35
• 2022-08-19Watts says material recorded four meters away sounded two meters away, which he thinks is the ADC, and the bright church recording sounded warmer, with softer transients, on headphones and on his speakers (transcribed 'BMWs'). AVstore 47:20
• 2022-09-18Watts says his test recordings, downloadable from his blog, give very good left-right placement accuracy when heard on Stealth headphones. The Source AV 17:50
• 2022-09-18Watts says with DAVE and a prototype of the new scaler, left-right accuracy of his recordings is identical to perfect, but depth is not. The Source AV 18:19
• 2022-09-18Watts says Chord is different because of depth perception. needs context The Source AV 18:46
• 2022-09-18Watts says that in his recording a cello was four meters from the microphone, which he uses to judge reproduced depth. The Source AV 18:49
• 2022-09-18Watts says the cello sounded about 2.5 meters away on DAVE, about 2 on Hugo 2, about two with M Scaler (as transcribed), half a foot on conventional DACs. The Source AV 19:00
• 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
• 2023-01-21Watts says his Blumlein recordings show lateral imaging is already perfect with crossfeed on Mojo 2 and Stealth; depth, attack and timbre need improving, digital sounding too soft. Head-Fi, Jan 2023
• 2023-02-04Watts says such measurements take three or four hours, that better small-signal accuracy gave better detail and depth, and that reproduced depth collapses compared with a distant cathedral organ. Dusty Audio 20:06
• 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 says going from 330 to 350 dB was the first step where depth differences became hard to hear, and that small-signal accuracy is vital to depth and detail. Dusty Audio 24:38
• 2023-02-05Watts says closed backs give better precision and a better sense of depth, certainly Dan Clark's closed backs. Soundnews 2:12
• 2023-02-05Watts says soundstage and depth are very important. Soundnews 8:14
• 2023-02-05Watts says that emotional effect is the drug he is after, and that if a system lacks decent depth it will not work for him emotionally. Soundnews 8:30
• 2023-02-05Watts says that click is the buzz he is after, and that a recording with good depth might work. Soundnews 9:13
• 2023-02-05Watts says if a recording or system lacks good depth, it is not going to work. Soundnews 9:30
• 2023-03-19Watts says phase shift with amplitude, found after the M scaler work, affects depth; tuning Mojo's noise shaper for minimal -301dB phase error led to Mojo 2's UHD DSP. Head-Fi, Mar 2023
• 2023-03-23Watts says the DCA Stealth is now his serious listening choice: tonally closer to live, more detail, equal depth discrimination to speakers, and less external noise. Head-Fi, Mar 2023
• 2023-03-28Watts says DSD's linearity problems degrade depth, DSD64's noise shaper reaches about -126 dB, and though DSD needs no sinc filter, large signals pass its quantizer faster than small ones. The Headphone Show 22:11
• 2023-03-28Watts says reproduced depth falls far short of live, small-signal nonlinearity is crucial, and all his digital parts are tested in simulation with a -301 dB signal. The Headphone Show 42:34
• 2023-03-28Watts says DAVE's noise shapers going from 200 to 220 dB, and later 330 to 350 dB, improved depth; fixed noise is fine but signal-dependent noise creates noise floor modulation. The Headphone Show 44:02
• 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 before the M Scaler he thought depth depended only on small-signal amplitude; raising WTA tap length had never changed depth before, suggesting timing matters for depth. Amplify Audio 7:04
• 2023-04-03Watts says in listening tests, removing a phase shift error from noise shapers improved depth, and notes EQ introduces a large phase shift. Amplify Audio 8:35
• 2023-10-01Watts says that if amplitude and phase of tiny signals are slightly wrong the brain detects it, compressing soundstage depth and hiding detail. The Source AV 9:21
• 2023-10-01Watts says crossfeed makes listening more speaker-like, makes hard left-right-center mixes on 1960s Beatles recordings less annoying, and opens up the soundstage so depth is better. The Source AV 13:19
• 2023-10-01Watts says you want both, starting to say a close-miked vocalist should sound close. needs context The Source AV 14:15
• 2023-10-01Watts says a distant recording, such as a cathedral organ 200 feet away, should sound 200 feet away: you want variation in depth. The Source AV 14:22
• 2023-10-01Watts says depth is completely about accuracy, which reproduced audio lacks, and that at 16 he already wondered why reproduction sounded so flat. The Source AV 14:35
• 2023-10-01Watts says poor depth in reproduced audio always bugged him, and that if a track with encoded depth sounds flat within seconds, it will be a poor recording. The Source AV 15:13
• 2023-10-01Watts says Mobile Fidelity could always add reverb. The Source AV 16:11
• 2023-10-01Watts says the trouble with adding reverb is that close-miked sounds no longer sound close. The Source AV 16:15
• 2023-10-01Watts says that when first hearing the M Scaler open up the soundstage, he thought engineers recording at 48 kHz never heard this at all. The Source AV 16:56
• 2023-10-01Watts says the engineers prefer Mojo 2 to any other DAC for its soundstage depth and refined transparency, hearing faults and subtle adjustments immediately, which improved their efficiency. The Source AV 20:48
• 2023-10-01Watts says driver matching makes a big difference to lateral accuracy, and on his recordings left-to-right placement on playback matched what he heard under the microphones. The Source AV 27:01
• 2023-10-01Watts says live sound is not that precise left to right, since a cello radiates from its body as well as its strings. The Source AV 27:24
• 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
• 2023-10-01Watts says an unmiked drum kit up close is very fast and sharp, reproduced audio softens transients, and both depth and speed/impact must be solved. The Source AV 31:05
• 2024-03-20Watts says a live cello images slightly rounded, while noise floor modulation artificially sharpens imaging and sounds crystalline and brighter, mistaken for transparency; removing it allows louder listening. MFG Audio Reviews 13:57
• 2024-03-20Watts says correlated noise makes small signals slightly bigger or smaller than they should be, which degrades the perception of depth. MFG Audio Reviews 21:06
• 2024-03-20Watts says reproduced audio lacks depth (a cathedral organ 200 feet away does not sound so on headphones), calls depth his biggest challenge, and says tiny small-signal errors degrade it. MFG Audio Reviews 21:17
• 2024-03-20Watts says noise signals correlated to small signals in the digital domain degrade the perception of depth. MFG Audio Reviews 22:00
• 2024-03-20Watts says amplitude errors and phase shift varying with amplitude strongly affect depth perception, and asks how he knows this. MFG Audio Reviews 42:51
• 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 even 330 to 350 dB was audible in blind tests, so tiny signals' amplitude and phase must be perfect or depth changes; analog components show similar errors. MFG Audio Reviews 45:45
• 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
• 2024-06-01Watts explains transients and localization, how crossfeed narrows headphone width, and ranks rectangular, triangular and pseudo-Gaussian dither below noise shaping, best for depth. Head-Fi, Jun 2024
• 2024-06-18Watts says the first Quartet installation outside the family, in Singapore, gave a night and day difference on a 1957 Coltrane track, with instruments instantly placed in space. article, Jun 2024
• 2024-07-12Watts says a slight amplitude or phase error at minus 301 dB is perceived as truncated soundstage depth, and normal engineers call this mad. HIFICLUB 19:36
• 2025-02-17Watts says more accurate location, especially greater depth variation with close-miked sounds staying close, signals a fundamental improvement, and that tuning took thousands of listening tests. audio-2G 9:43
• 2025-05-12Watts says the brain uses the interaural time delay to place sounds left to right within one degree, and also uses timing information to judge depth. Audiophile Junkie 1:56
• 2025-05-12Watts says timing helps the brain judge distance; textbooks gave a 4 to 6 microsecond interaural timing limit, but recent research shows the brain responds however small the difference. Audiophile Junkie 2:39
• 2026-03-17Watts says hi-fi bears no resemblance to live unamplified music, especially depth: an organ 100 feet away in a cathedral sounds barely two feet behind speakers at home. ecoustics 17:24
• 2026-03-17Watts says reproduction loses timbre variation, so trumpets sound less bright and saxophones brighter than they should, and instruments cannot be located accurately; he aims to reconstruct the acoustic event. ecoustics 18:08
• 2026-03-17Watts says DSD sounds artificially soft and loses depth through poor small-signal accuracy, then begins explaining how finely the brain perceives depth, as with a phone moved half an inch. ecoustics 29:55
• 2026-03-17Watts says the brain locates sources from many cues, simplest the direct-to-reflected ratio; outdoors it uses the timing difference between the ground reflection and the direct sound. ecoustics 31:05
• 2026-03-17Watts says the brain also uses air absorption of high frequencies over distance, a loss at 20 kHz every fifteen meters, as a distance cue. ecoustics 31:53
• 2026-03-17Watts says the biggest depth cue is reverberant-to-direct energy from myriad ever-smaller reflections, so a DAC must reproduce very small signals from many sources very accurately. ecoustics 32:34
• 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 bass pitch was also identical but depth was obviously deeper with the 220 dB noise shaper on an organ recording, which made no sense to him. ecoustics 37:08
• 2026-03-17Watts says a subtle depth change was still audible between 330 dB and 350 dB, though the amplitude accuracy difference is minuscule. ecoustics 38:34
• 2026-03-17Watts says purely digital noise shapers, such as 192 bits down to 68 bits, show the same thing in listening tests: better than 350 dB is needed to reproduce depth. ecoustics 40:09
• 2026-03-17Watts agrees it is inaudible and unmeasurable, and says three or four years ago he found the phase of small signals relative to 0 dB also affects depth. ecoustics 41:49
• 2026-03-17Watts says small-signal phase must be within one thousandth of a degree of the 0 dB phase, harder than the amplitude test, and failing it audibly loses depth. ecoustics 42:36
• 2026-03-17Watts suggests the brain may resolve depth by something like autocorrelation, and says we do not understand how it judges distance, nor can computers do it. ecoustics 43:20
• 2026-03-17Watts says depth from audio is nothing like live sound, a huge gap that motivated his work. ecoustics 44:16
• 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 Blackbird WTA massively improves pitch, timbre, separation and location, especially depth, and a quiet background instrument is no longer swamped when a loud one enters. Audio Force 15:32
• 2026-05-03Watts says the brain uses transient timing to locate instruments left to right, judge depth, form timbre and calculate low-frequency pitch, which the ear resolves poorly. Audio Force 6:04
• 2026-10-02Watts says a dog barking two miles away in a valley is located precisely in depth, yet on reproduced audio it is lucky to sound two feet behind the speakers. HiFi Buys 9:38
• 2026-10-02Watts says the suppression of depth in reproduced audio is obviously wrong. HiFi Buys 10:24
• 2026-10-02Watts says he finds it weird that nobody talks about the loss of soundstage depth in reproduced audio. HiFi Buys 10:30
• 2026-10-02Watts says depth perception is complex, with early reflections signaling closeness, yet through open Velux windows behind his speakers he perceives a dog a mile away perfectly. HiFi Buys 10:48
• 2026-10-02Watts says that sound through point-source windows scattering in the room still conveys distance immediately, showing loudspeakers could do much better on depth. HiFi Buys 11:38
• 2026-10-02Watts says reproduced audio has no innate inability to convey depth; poor depth comes from many complexities he will discuss later. HiFi Buys 12:26
• 2026-10-02Watts says upset transient timing degrades instrument separation, timbre, low-frequency pitch and depth, and his goal is the emotional involvement of live unamplified music. HiFi Buys 27:40
• 2026-10-02Watts says moving from 200 to 220 dB left separation, detail and timbre identical but depth clearly better, which he tested with an organ recording heard in a cathedral. HiFi Buys 1:19:47
• 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 he would code, simulate, measure digitally and listen; each step from 220 to 240 to 260 dB gave better depth, ending at 330, then 350 dB. HiFi Buys 1:21:26
• 2026-10-02Watts says intellectually it makes no sense, but under blind conditions other listeners independently report that depth sounds better. HiFi Buys 1:22:59
• 2026-10-02Watts says DAVE, 11 years old next May, is still the best depth-resolving DAC at any price because its noise shaper runs at 104 MHz. HiFi Buys 1:23:25
• 2026-10-02Watts says going from half a million to 1 million taps gave a profound depth change, whereas earlier WTA improvements had affected timbre, separation and imagery, never depth. HiFi Buys 1:25:05
• 2026-10-02Watts hypothesizes, not from textbooks, that the brain infers depth from the time difference between direct and reflected sound. HiFi Buys 1:25:41
• 2026-10-02Watts says a short direct-to-reflected delay implies a small room and closeness, a long one a big room and likely greater distance. HiFi Buys 1:26:30
• 2026-10-02Watts says the brain also uses frequency response, since beyond fifteen meters air absorbs high frequencies. HiFi Buys 1:26:47
• 2026-10-02Watts says another cue is the reverberant-to-direct ratio; in a large concert hall the critical distance is about six to eight meters. HiFi Buys 1:27:09
• 2026-10-02Watts says the brain computes depth from timing and reverberant ratio, suggesting small-signal timing matters for depth, which the WTA filter improves. HiFi Buys 1:27:36
• 2026-10-02Watts says better timing means better phase accuracy, so he quickly added an adjustable small-signal delay with a toggle switch, without simulating first. HiFi Buys 1:28:26
• 2026-10-02Watts says the best setting was accurate within a couple of nanoseconds versus 10 to 30 for others, so nanosecond timing at -301 dB is perceivable as depth. HiFi Buys 1:29:40
• 2026-10-02Watts explains reverberant sound reaches the ears via chaotic, random reflections off walls, ceiling and floor, getting smaller with each reflection. HiFi Buys 1:37:12
• 2026-10-02Watts says a hall's RT60 decay to -60 dB takes a couple of seconds, so small, chaotic reverberant tails must be reproduced perfectly for the brain. HiFi Buys 1:38:00
• 2026-10-02Watts says his early DACs were within a couple of dB at -90 dB, when others fell off a cliff, and better small-signal accuracy gave better depth and detail. HiFi Buys 1:38:42
• 2026-10-02Watts says modern pulse array DACs measure perfectly, a -120 dB signal within a thousandth of a dB, yet ultra-small errors still matter profoundly for depth. HiFi Buys 1:39:33
• 2026-10-02Watts says he has noticed that about one second before he falls asleep, depth collapses. HiFi Buys 2:00:13
• 2026-10-11Watts says the digital recording lost soundstage depth and was warmer than the original, partly from the ribbon mic, with much of the difference being speed, impact and power that Quartet brings out. Distorsiuni Interioare 11:17
• 2026-10-11Watts says these baked-in errors make DSD sound unnaturally soft and flatter in depth than good PCM and cannot be recovered, which is why he opposes DSD. Distorsiuni Interioare 58:38
• 2026-10-14Watts says he listens for variation: if a change enlarges the difference between a close-miked voice and a distant object, it is a fundamental improvement. Part-Time Audiophile 7:33
• 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 depth perception is his main test of digital module options; with practice, AB switching reveals very subtle changes, one flat and one deeper. Part-Time Audiophile 22:46
• 2026-10-14Watts says the deeper option is better, provided a dry, close-miked recording stays flat in front, since added reverb could artificially enhance depth. Part-Time Audiophile 23:27
• 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