User filter settings and the HF filter

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• Which filter setting should I use on Hugo 2, TT2 or Qutest, and what does the HF filter do?

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• 2015-11-21Watts explains Dave's DSD filtering, how out-of-band noise causes noise floor modulation heard as brightness, the 60 kHz HF filter helping even CD, and PCM+ versus DSD+ modes. Head-Fi, Nov 2015
• 2015-12-18Watts says Dave's HF filter is a 60 kHz cutoff set of 16FS-to-256FS WTA coefficients meant to cut ADC noise in hi-res recordings, and it unexpectedly improves 44.1 kHz too. Head-Fi, Dec 2015
• 2016-01-18Watts explains that out-of-band RF noise intermodulates into noise floor modulation that sounds bright, so his DACs are limited to 50 or 60 kHz; Dave's HF filter targets DXD noise. Head-Fi, Jan 2016
• 2016-01-18Watts says Dave's filter targeted ADC noise shaper noise in 176.4 kHz and above recordings, yet audibly warms redbook; he suspects lower noise floor modulation and keeps it on. Head-Fi, Jan 2016
• 2017-01-09Watts explains Dave's 16FS-to-256FS WTA stage replacing IIR filters, says any timing error is audible, notes Hugo 2 filter settings switch that stage, and contrasts 88 nS with 2.6 uS. Head-Fi, Jan 2017
• 2017-01-23Watts says Hugo 2's 256FS filter matches Dave's, and the HF filter is best off with the M scaler and Dave since stop-band rejection is already 130 to 150 dB. Head-Fi, Jan 2017
• 2017-02-15Watts says few headphones need more power than Hugo gives, he added Hugo 2 filters for a softer option, and doubts digital EQ reaches the 350 dB needed for depth. Head-Fi, Feb 2017
• 2017-03-15Watts posts his CanJam Singapore Hugo 2 slides: WTA2 to 256FS, filter options and advice, DSD filtering, noise shapers and depth, crossfeed, and APx555 measurements showing no noise floor modulation. Head-Fi, Mar 2017
• 2017-03-15Watts says white engages WTA2 at 256FS; the second-order HF filter (-3 dB at 40 kHz) removes ADC noise-shaper noise in 96/192 files, preventing noise floor modulation, sounding warmer. Head-Fi, Mar 2017
• 2017-03-15Watts confirms a poster's filter definition and their point about the HF filter on DAVE. needs context Head-Fi, Mar 2017
• 2017-03-15Watts says white to green sounds warmer, and DSD noise shapers delay small transients by tens of microseconds, giving DSD a soft, warm sound; he leaves the filter on green. Head-Fi, Mar 2017
• 2017-03-19Watts says Hugo 2's 'Mojo filter' only selects a 16FS WTA with Mojo-like tonal balance, and the 256FS filter gives DAVE-like incisiveness without making Hugo 2 sound like DAVE. Head-Fi, Mar 2017
• 2017-03-23Watts says the 49,152 WTA1 taps never change and exclude WTA2, refusing 'effective tap' marketing, and the HF filter matters more above 48 kHz in both filter modes. Head-Fi, Mar 2017
• 2017-03-24Watts says white to green is a small change at 44.1 kHz, more useful at 96 or 192 kHz; dropping WTA2 for linear interpolation (orange or red) is large. Head-Fi, Mar 2017
• 2017-04-07Watts says Hugo 2 with the white filter has a tonal balance like his DAVE and M scaler reference, avoids hardness, and the 16FS filter suits hard headphones. Head-Fi, Apr 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
• 2017-06-15Watts says Hugo 2's HF filter matters little at 44.1 kHz but more at 96 to 768 kHz, and the 256FS WTA stage audibly snaps note starts into focus. Head-Fi, Jun 2017
• 2017-07-19Watts explains how coupling capacitors, reference decoupling and LF distortion add bloom, why Hugo 2 avoids them by tackling noise floor modulation, and why its warmer filter options exist. Head-Fi, Jul 2017
• 2017-07-25Watts says Hugo's WTA1 ran 1FS to 8FS at 26,368 taps; Hugo 2's goes 1FS to 16FS at 49,152 taps, then WTA2 to 256FS on white/green. Head-Fi, Jul 2017
• 2017-07-25Watts says he runs the green filter setting 99.9% of the time, but would use red if his headphones were far too bright. Head-Fi, Jul 2017
• 2017-07-26Watts confirms linear interpolation runs 256FS to 2048FS on white/green and 16FS to 2048FS on orange/red; the HF filter changes LPF time constants from 0.7 uS to 2.8 uS. Head-Fi, Jul 2017
• 2017-08-12Watts says he keeps the filter on green, that Hugo 1 let him enjoy poor archive recordings, and advises trusting posts that describe differences in detail over 'different league' claims. Head-Fi, Aug 2017
• 2017-10-23Watts says he finds Hugo 2's filter options huge, and the difference between Chord and other DACs enormous, more so once the brain has broken into the sound. Head-Fi, Oct 2017
• 2017-12-05Watts says no change is measurable from the 16FS to 256FS WTA filter, but the HF filter (green or red) adds -1dB at 20kHz. Head-Fi, Dec 2017
• 2017-12-05Watts says the HF filter is for HD recordings, whose ADC out-of-band noise shaper noise adds noise floor modulation; filtering it sounds noticeably warmer. Head-Fi, Dec 2017
• 2017-12-05Watts confirms the frequency response is the same with the HF filter engaged. needs context Head-Fi, Dec 2017
• 2018-01-09Watts says white to green is very small on 44.1 but a big change with HD recordings, so he leaves it on green for 96k and 192k. 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
• 2018-02-05Watts says the HF filter is only -1dB at 20 kHz. Head-Fi, Feb 2018
• 2018-04-12Watts says the HF filter matters for 96k and 192k, the 256FS filter is easiest heard on piano over extended listening, and changing lights show the filters work. Head-Fi, Apr 2018
• 2018-04-30Watts says white and green differ little without 96k or 192k files, he leaves it on green, and switching the 256FS filter is audible on fast transients. Head-Fi, Apr 2018
• 2018-05-08Watts thinks DAVE treats 705/768 kHz input identically in DSD+ and PCM+ modes, and keeps his DAVEs in PCM+ with M scalers. Head-Fi, May 2018
• 2018-07-01Watts says AAC, short filters, MQA, minimum phase, NOS and DSD sound soft and warm from transient timing uncertainty; turning off the incisive filter similarly sounds warmer. Head-Fi, Jul 2018
• 2018-08-13Watts says he keeps it in PCM+ mode with an M scaler attached. needs context Head-Fi, Aug 2018
• 2018-09-09Watts says the HF filter and WTA2 settings are unaffected by the M scaler, which works from 1FS to 16FS, and explains the vague autumn delivery as distribution time. Head-Fi, Sep 2018
• 2018-09-14Watts advises the green filter: with 192k recordings the M scaler passes ADC noise up to 96 kHz, and the HF filter smooths sound by lowering noise floor modulation. Head-Fi, Sep 2018
• 2018-10-12Watts answers green; red and orange let people hear WTA2 versus IIR filtering, and green suits HD recordings by removing ADC noise above 30 kHz. A new prototype arrived. needs context Head-Fi, Oct 2018
• 2018-11-22Watts suggests setting DAVE to PCM+ mode with the M scaler. needs context Head-Fi, Nov 2018
• 2019-01-20Watts details WTA1 modes, WTA2 versus the three-stage IIR, the HF filter at about -1dB at 20kHz, and says Stereophile's Qutest frequency response was wrong due to latency. Head-Fi, Jan 2019
• 2019-01-20Watts says DAVE cannot switch out WTA2 since its timing errors add artificial softness, and other up-samplers lack taps or WTA-like algorithms and sound unnaturally soft. Head-Fi, Jan 2019
• 2019-01-21Watts drives B&W 803D3 from TT2 single-ended via XLR pins 1 and 2, explains the third-order filter to 2048FS, and uses green for his 96k recordings. Head-Fi, Jan 2019
• 2019-01-23Watts says the M scaler does not affect filter choice as it only replaces WTA1; he uses green and only listens with M scalers, even on flights. Head-Fi, Jan 2019
• 2019-01-24Watts maps TT2 filters to colors: filter 1 white (as Hugo 2), filter 2 green, filter 3 orange, filter 4 red. Head-Fi, Jan 2019
• 2019-01-24Watts says the M scaler preserves ADC noise on hi-res recordings, so the HF filter still helps, and WTA2 is even more attractive with the M scaler. Head-Fi, Jan 2019
• 2019-02-09Watts says the HF filter changes the 2048FS filter's time constants rather than switching a path: -3 dB at 150 kHz without it, 37.5 kHz with it. Head-Fi, Feb 2019
• 2019-02-15Watts says the HF filter is unaffected since it runs at 2048FS, and the M scaler passes ADC HF noise from 96k and 192k recordings like Hugo 2's WTA1. Head-Fi, Feb 2019
• 2019-03-04Watts explains white/green adds a WTA 16FS-to-256FS stage replacing an IIR filter, why sinc accuracy needs long taps, and says preferring orange suggests an overly bright system. Head-Fi, Mar 2019
• 2019-06-16Watts shows by a zero-crossing example why higher rates improve transient timing, says 705/768 kHz is needed, and says hi-res ADC noise causes noise floor modulation the HF filter reduces. Head-Fi, Jun 2019
• 2019-06-16Watts offers three reasons green sounds warmer on RBCD, favoring the HF filter retuning the 256FS-to-2048FS stage from 160 kHz to 40 kHz, lowering noise floor modulation. Head-Fi, Jun 2019
• 2019-08-04Watts says the HF filter uses the 256FS to 2048FS filter with adjusted time constants, so the original input format makes no difference. Head-Fi, Aug 2019
• 2020-01-02Watts says the needed timing accuracy cannot be stated, and cites Qutest, where switching between white/green and orange/red filters switches a 256FS WTA filter. Passion for Sound 2:54
• 2020-01-02Watts says the two Qutest filters measure identically yet sound different; WTA1 outputs every 1.3 microseconds and a second WTA stage outputs every 88 nanoseconds. Passion for Sound 3:38
• 2020-01-02Watts says offering minimum phase, NOS and other filter options would have been easy and commercially sensible, but he will not offer options he knows sound worse; WTA sounds best. Passion for Sound 16:34
• 2020-04-09Watts says mains conditioners neglect RF, a single-blind test tied a new HF filter's warmth to noise floor modulation, and DAVE is about 13-bit accurate, M scaler over 16. Head-Fi, Apr 2020
• 2020-04-11Watts says the M scaler preserves a recording's HF noise, being flat to FS/2 like an ideal sinc, so the DAC's HF filter, run from 16FS to 2048FS, removes it. Head-Fi, Apr 2020
• 2020-05-11Watts says 16FS and 256FS filters measure identically; Hugo 2's HF filter is about -1dB at 20kHz, but its warmer sound comes from less out-of-band noise and noise floor modulation. Head-Fi, May 2020
• 2021-08-19Watts corrects the manual: the HF filter is mostly for sources above 48k PCM and DSD; he recommends filter 2 for DSD and all PCM, with smaller benefits at 44.1k. Head-Fi, Aug 2021
• 2021-11-16Watts says the HF filter uses two banks of noise shaped coefficients, switched synchronously, so turning it on or off causes no problem. Head-Fi, Nov 2021
• 2022-02-14Watts says the HF filter mainly removes noise and distortion in 96/192k recordings, helps 44.1k slightly, and Mojo 2's UHD DSP lets it stay on with flat response. Head-Fi, Feb 2022
• 2022-02-15Watts attributes HF errors to ADC noise shapers and decimation, keeps HF filter off on DAVE via M Scaler, prices the Choral M Scaler at DAVE level, and rejects XMOS. Head-Fi, Feb 2022
• 2022-03-19Watts says crossfeed improves depth, a permanently on DSP HF filter flat to 20 kHz helps all sources, especially 96 and 192 kHz, and UHD DSP loses no depth. MFG Audio Reviews 42:27
• 2022-03-21Watts warns about placebo in listening tests and explains the HF filter reduces noise floor modulation while WTA2 (16FS to 256FS) improves transient timing, neither changing in-band response. Head-Fi, Mar 2022
• 2022-03-21Watts says he is using a Hugo 2 and lists the four filter colors: white HF off WTA2 on, green both on, orange both off, red HF on WTA2 off. Head-Fi, Mar 2022
• 2022-03-21Watts says green (filter 2) is technically best on Hugo 2, other settings add NFM or poorer timing, and WTA2 surprisingly changes only the starting and stopping of notes. Head-Fi, Mar 2022
• 2022-06-27Watts says pure DSD and R2R DACs are fundamentally limited, DAVE's noise shaper is not capped at 17th order, the HF filter sits after WTA2, and car batteries are ideal. Head-Fi, Jun 2022
• 2022-08-02Watts confirms orange and red filters bypass WTA2, with the following filters running 16FS to 2048FS, and green/orange removing more HF noise and distortion above 50kHz. Head-Fi, Aug 2022
• 2022-09-18Watts says on Mojo he has built the filter into it. The Source AV 38:06
• 2022-09-18Watts says the filters remove noise above 20 kHz; old 96 and 192 kHz recordings have noise above 24 kHz, and filtering sounds warmer with less noise floor modulation. The Source AV 38:10
• 2022-09-18Watts says before the DSP EQ, rolling off at 20 kHz would let anyone measuring criticize Chord for not being ruler flat. The Source AV 38:53
• 2022-09-18Watts says the roll-off makes no difference to the performance, so he added the option of flat or rolled off for best sound, going from white to green. The Source AV 39:11
• 2022-09-18Watts says TT2, DAVE and Hugo 2 have a WTA filter from 16FS to 256FS, unlike the 1FS to 16FS WTA, improving speed and the starting and stopping of notes. The Source AV 39:35
• 2022-09-18Watts says a piano key's sharp attack is easier to hear with the 256FS filter engaged, losing it adds softness, and technically you are better off with it. The Source AV 40:13
• 2022-09-18Watts says filter two, the green, is what you need to be moving toward. needs context The Source AV 41:02
• 2023-01-12Watts says he uses positive phase and sets the M scaler's HF filter off with DAVE, and that absolute phase differences are small and depend on recording and transducer. Head-Fi, Jan 2023
• 2023-01-16Watts turns DAVE's HF filter off with the M scaler, doubts a Hugo 2-priced portable scaler-DAC by 2032, sets crossfeed to max, and says more taps add depth. Head-Fi, Jan 2023
• 2023-09-20Watts describes tuning WTA variables to about 100ppm with dedicated test tracks, notes Hugo 2's warm settings remove WTA2, and says Mojo 2's UHD DSP adds warmth without timing loss. Head-Fi, Sep 2023
• 2023-10-01Watts says he could put other filters into the interpolation filter (transcribed 'a nozzle', perhaps NOS) to change the sound, but that would mess it up, so he does not. The Source AV 37:04
• 2024-06-10Watts says Mojo 2 has an HF filter permanently engaged, which sounds much better, and its 20 to 20k bandwidth is flat with EQ off. Head-Fi, Jun 2024
• 2024-06-10Watts explains earlier DACs had switchable HF filters because of a 20kHz drop, while Mojo 2's new DSP core allows a fast roll-off with no in-band change, so no switch is needed. Head-Fi, Jun 2024
• 2024-06-11Watts says the Mojo 2 HF filter's IIR phase change is linear and inaudible, unlike interpolation timing errors, and a listening test against an ADC-project FIR filter confirmed this. Head-Fi, Jun 2024
• 2025-01-28Watts says WTA1's 98,304 taps are unaffected by filter options, red and orange switch out WTA2, and white and green only adjust the 256FS to 2048FS filter time constants. Head-Fi, Jan 2025
• 2025-02-10Watts says to use TT2 filter 1 or 2 (he uses 2) with the Hugo M Scaler, not 3 or 4. Head-Fi, Feb 2025
• 2025-02-18Watts says the HF filter fails a null test but not perceptually, citing a decimation-filter test showing its sound change comes from less out-of-band noise and noise floor modulation. Head-Fi, Feb 2025
• 2025-03-23Watts says pre-Mojo 2 HF filters were second order with about -0.9dB at 20kHz, while Mojo 2's UHD DSP allows an aggressive filter with no drop, reducing noise floor modulation. Head-Fi, Mar 2025
• 2026-10-11Watts says the improvement comes from Quartet's 18 kHz HF filter transparently removing out-of-band noise and signal-correlated distortion, improving transient timing; he had expected digitization to sound worse. Distorsiuni Interioare 1:14:52
• 2026-10-17Watts says to make sure the HF filter is set to 18K. needs context article, Oct 2026