EQ, tone controls and room correction

Features, settings and controls

Answers on this topic

Everything he said on this topic (123)

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2016-09-27Watts is unsure about the EQ asked about, explains IIR bi-quads repeatedly truncate tiny bass coefficients, risking low-level distortion, and advises trying it without assuming digital means transparent. Head-Fi, Sep 2016
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
2017-02-19Watts doubts ultrasonics matter for realism, crediting higher rates' gains to timing, plans 50 kHz microphones for Davina, and says transparent EQ would need 350 dB at 768 kHz. Head-Fi, Feb 2017
2017-04-07Watts says Hugo 2 truncates its 48-bit crossfeed to 24 bits with noise shaping at 705/768 kHz, which preserves depth better than PC dither, and EQ apps can compromise transparency. Head-Fi, Apr 2017
2017-07-20Watts says he plans to investigate EQ after the digital power amps, if it gives a subjective benefit, and has designed bi-quad DSPs before. Head-Fi, Jul 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
2017-11-11Watts recounts a friend dropping ADC/DSP/DAC speaker EQ after a Hugo demo showed DSP losses outweighed benefits, and advises fixing room problems with room treatment. Head-Fi, Nov 2017
2019-02-20Watts says Qutest is surge protected, element count does not set resolution, Davina has no date, DSD sounds unnaturally soft, and explains FIR for reconstruction versus IIR for EQ. Head-Fi, Feb 2019
2019-03-29Watts says TT2 filters are interpolation tweaks not EQ, argues NOS DACs are not truly bit perfect, explains transient timing errors, and warns IIR EQ and dithered volume are not transparent. Head-Fi, Mar 2019
2019-11-27Watts says Roon DSP EQ will not upset M Scaler transient reconstruction, but EQ is never fully transparent, risking loss of depth and detail. Head-Fi, Nov 2019
2020-01-06Watts says TT2 got huge headphone power after complaints about Hugo 2, helping drive speakers, that DAVE and Hugo 2 drive almost any headphone, and no DSP is fully transparent. Head-Fi, Jan 2020
2020-02-22Watts says truncating volume changes degrade depth and detail, dither is not transparent, only 705/768 kHz with 11th-order noise shaping works, DSP isn't transparent, and mastered files are best. Head-Fi, Feb 2020
2020-07-26Watts says IIR filters used for EQ and DSP run out of bits as signals shrink, so small signals are treated differently from large ones, a major sound quality issue. Head-Fi, Jul 2020
2020-07-29Watts proposes testing a 64-bit floating-point PC EQ by setting all bands to -1 dB and raising DAC volume 1 dB; he heard added brightness, worse separation and flatter depth. Head-Fi, Jul 2020
2020-07-29Watts says EQ quality depends on implementation; IIR filters worry him most, FIR filters can also harm depth and separation, and FFT convolution depends on accuracy and truncation handling. Head-Fi, Jul 2020
2020-08-04Watts says long term yes, if the bi-quad DSP engine can be made transparent, as digital loudspeaker crossovers need one, and says Dave has withstood his own newer designs. Head-Fi, Aug 2020
2020-09-11Watts says he once designed a transparent no-clip compression algorithm but has not included it, and doubts a volume leveller could suit wide-dynamic-range classical music. Head-Fi, Sep 2020
2021-01-02Watts says he dislikes DSP room correction because the brain compensates for room acoustics while DSP degrades imaging, depth, separation and timbre; he prefers acoustic room setup. Head-Fi, Jan 2021
2021-10-05Watts says to maintain the sample rate, current EQ and 64-bit float are not transparent; in M Scaler tests his 11th-order truncation noise shaper beat rectangular, triangular and pseudo-Gaussian dither. Head-Fi, Oct 2021
2022-01-31Watts says EQ cannot be bit perfect, 64-bit floating point on a PC is not good enough for EQ, and proposes a test: all bands +1 dB, volume -1 dB. Darko.Audio 19:43
2022-01-31Watts says that test sounds harder, brighter and less deep despite flat response, because floating-point arithmetic creates very low but audible noise floor modulation, making conventional DSP sound bright. Darko.Audio 20:36
2022-01-31Watts says chip DACs use noise shapers of -140 dB and lose anything lower, and DSP EQ is worse because bass EQ multiplies the signal by very small coefficients. Darko.Audio 23:00
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 COVID-era listening tests revealed very small audible effects, so the DSP had to reproduce -301 dB perfectly in phase and amplitude, requiring a different core. Darko.Audio 26:13
2022-01-31Watts says he built a 104-bit DSP core rather than the usual 64 bits; it passed -301 dB amplitude but failed phase until each node got a noise shaper. Darko.Audio 26:59
2022-01-31Watts says removing the capacitor led him to add EQ for cheaper headphones that are too bright or lack bass, which raised how to make EQ actually work. Darko.Audio 35:47
2022-01-31Watts says EQ fails on transparency because adjusting it audibly degrades sound; lossless DSP lets you change bass or warmth without degrading musicality or transparency. Darko.Audio 36:26
2022-01-31Watts lists the EQ: 20 Hz and 20 kHz peak filters of +/-9 dB, a +/-9 dB bass shelf from 125 Hz to DC, and a 3-20 kHz treble shelf. Darko.Audio 39:52
2022-01-31Watts says the peak filters use a Q of 0.5, so +6 dB at 20 Hz gives +3 dB at 40 Hz, following a first-order characteristic. Darko.Audio 40:45
2022-01-31Watts says a shelf filter has no Q in a biquad; it has a fixed slope designed to be as sharp as a biquad allows. Darko.Audio 41:07
2022-01-31Watts says peak filters cover 20 Hz and 20 kHz and shelves cover bass and treble, chosen after headphone plots showed mass-market Japanese headphones rolling off from 125 Hz. Darko.Audio 41:29
2022-01-31Watts says the bass controls fix low-frequency problems, high-end headphones are flat, and cutting the treble shelf 2 or 3 dB while boosting 20 kHz 3 dB tames sibilance. Darko.Audio 42:13
2022-01-31Watts says to adjust the shelf by a couple of dB and the 20 Hz filter by about 1 dB to make it sound warmer and softer. needs context Darko.Audio 43:03
2022-01-31Watts says that is the reason he put the EQ in. needs context Darko.Audio 43:17
2022-01-31Watts says forums show how people use products within days of launch, unlike 20 years ago, and notes one Mojo buyer will call it way too bright. Darko.Audio 43:20
2022-01-31Watts says another buyer calls Mojo too soft and warm; analog tone controls and conventional DSP degrade performance, while this approach adjusts response without harming transparency. Darko.Audio 44:00
2022-01-31Watts says the Harman curve suits headphone makers, but his EQ was informed by plain frequency response, mainly bass; it cannot fix a resonance at 9.52 kHz. Darko.Audio 44:48
2022-01-31Watts says you can tweak it and it will be fascinating to see how people use it. needs context Darko.Audio 45:52
2022-01-31Watts says yes; he needs no EQ for his speakers but would use it on headphones, which sound brighter than speakers, and live unamplified music sounds a lot warmer than speakers. Darko.Audio 46:24
2022-01-31Watts says Mojo 2's UHD DSP is his own core, balanced outputs would degrade transparency, a USB-C charging port would not fit, and musicality comes first. Head-Fi, Jan 2022
2022-01-31Watts presents Mojo 2: coupling capacitor removed, new noise shaper, and a UHD DSP EQ he says passes -301dB amplitude, phase and NFM transparency tests that 64-bit DSP fails. Head-Fi, Jan 2022
2022-01-31Watts says the UHD DSP runs at 705/768 kHz on the output of WTA1 or the DSD filter, and there is no WTA2. Head-Fi, Jan 2022
2022-02-01Watts says Mojo 2's DSP core passes bit-perfect data when EQ and crossfeed are off, it still uses the 15T FPGA, and lists Hugo 2's advantages over it. Head-Fi, Feb 2022
2022-02-03Watts says Mojo 2's battery has 9% more capacity, its peak EQ filters use Q 0.5, and the EQ targets headphone bass problems and overall balance, not sharp treble resonances. Head-Fi, Feb 2022
2022-02-03Watts says peak filters are defined by Q but shelf filters are not, and shares AP plots referenced to 0dB at 1kHz. Head-Fi, Feb 2022
2022-02-04Watts describes Mojo 2's desktop mode, 11-day trickle top-up, operation with a failed battery, and his aims for the EQ settings and transparent DSP core. Head-Fi, Feb 2022
2022-02-08Watts says the UHD DSP has 3 overload bits so EQ never clips internally, but boosts require lower volume: Mojo 2 can clip at white, or violet with +6 dB. Head-Fi, Feb 2022
2022-02-14Watts says 64-bit floating-point EQ creates noise floor modulation and small-signal errors; Mojo 2 uses 104-bit noise-shaped fixed point; his DACs need no warm-up or break-in. Head-Fi, Feb 2022
2022-02-18Watts says a poster's per-filter numbers match his plots, notes that summing magnitudes ignores phase, and plans to check on his APx555 with Mojo 2. needs context Head-Fi, Feb 2022
2022-02-21Watts says DSD is filtered and converted to 705.6 kHz PCM before the UHD DSP, so EQ, crossfeed and volume work identically. Head-Fi, Feb 2022
2022-03-10Watts says no Mojo 2 EQ setting replicates Mojo, whose warmth and bass coloration came from one coupling capacitor, not frequency response; a 125Hz boost adds warmth only. Head-Fi, Mar 2022
2022-03-19Watts says adjusting the sound meant EQ, but EQ on a 64-bit PC degrades transparency and IIR EQ filters had immense problems he could fix, and he built the UHD DSP. MFG Audio Reviews 26:59
2022-03-19Watts says lower out-of-band noise makes Mojo 2 slightly warmer, existing DSP is not transparent, and proposes a test: each EQ band up 1 dB, volume down 1 dB. MFG Audio Reviews 29:18
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 DSP EQ uses biquad filters whose small bass coefficients and truncation errors grow through feedback, so very small signals are lost and phase shifted. MFG Audio Reviews 33:55
2022-03-19Watts says floating point DSP inherently creates noise floor modulation, about -300 dB for 64-bit, which is audible; he has heard noise floor modulation at -400 dB. MFG Audio Reviews 34:48
2022-03-19Watts says 64-bit float sounds brighter, and transparent EQ DSP must reproduce -301 dB perfectly in amplitude and within a thousandth of a degree in phase, without floating point. MFG Audio Reviews 35:31
2022-03-19Watts says he calculated the DSP needed 104 bits, but tests showed it failed -301 dB in phase though not amplitude, so he added noise shaping. MFG Audio Reviews 36:12
2022-03-19Watts explains that a noise shaper feeds each error back to correct the next sample rather than discarding it, which requires oversampling, so the DSP runs at 705 kHz. MFG Audio Reviews 36:44
2022-03-19Watts says noise shaping cannot work at 44.1 kHz, bass coefficients are tiny, and noise shaping each node separately fixed the 104-bit design's phase failure so it passed. MFG Audio Reviews 37:33
2022-03-19Watts says the digital simulation is the real output, and shows the DSP reproducing -301 dB within thousandths of a dB and thousandths of a degree. MFG Audio Reviews 38:18
2022-03-19Watts says the test used +9 dB at 20 Hz, -9 dB at 20 kHz and a 6 kHz sine; volume now spans -108 to +18 dB for sensitive IEMs. MFG Audio Reviews 39:06
2022-03-19Watts describes the tone controls: 20 Hz bass peak, bass shelf below 125 Hz, 3 kHz treble shelf, 20 kHz peak, each 9 dB either way in 1 dB steps. MFG Audio Reviews 40:04
2022-03-19Watts says the broad tone controls can fix headphone bass but not a 6 kHz resonance, and that crossfeed was added; with Hugo 2 he cannot listen without crossfeed. MFG Audio Reviews 40:53
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
2022-03-19Watts says the EQ can fix headphone bass or sibilance at 3 kHz, skips the menus, will post the slides on Head-Fi, and notes plus and minus together mutes. MFG Audio Reviews 43:15
2022-03-26Watts says desktop mode isolates the battery, and that recursive IIR EQ needs 104 bits plus noise shaping while FIR filters need fewer bits to reproduce -301 dB accurately. Head-Fi, Mar 2022
2022-03-30Watts says the better output bit depth depends on how the source dithers EQ, suggests trying 24 and 32 bit, and needs no EQ with Stealth on Hugo 2. Head-Fi, Mar 2022
2022-04-04Watts says WTA1 filters carry 2.76 dB of overload headroom for Gibbs ringing and inter-sample overs (measured worst cases 2.41 dB and 3 dB); a single 0.8dB clip was inaudible. Head-Fi, Apr 2022
2022-04-26Watts says the original Mojo was voiced warm for bright headphones, so neutral Mojo 2 needed EQ; his test: raise a PC EQ 1 dB, lower volume 1 dB. Audio Force 6:09
2022-04-26Watts says a flat but active PC EQ still sounds flatter in soundstage, less detailed, brighter and worse in timbre, so he set out to design a lossless DSP. needs context Audio Force 7:01
2022-04-26Watts says Mojo 2's EQ DSP uses 104 bits and noise-shaped internals, making it far more transparent, and that forum users report EQ changes do not degrade sound. Audio Force 7:49
2022-05-14Watts cannot discuss future products but designed the UHD DSP with future uses in mind; he needs no EQ on his DCA Stealth or B&W 803 D3. Head-Fi, May 2022
2022-09-18Watts says the big thing they have not touched on is that the key feature of Mojo 2 was the DSP. The Source AV 33:08
2022-09-18Watts says a transparent DSP lets users make Mojo 2 warmer and softer or sharper and brighter with EQ; it took a year or two and a custom 104-bit core. The Source AV 34:07
2022-09-18Watts says that after launch, buyers' feedback the next day was how cool the DSP was and what a game changer. needs context The Source AV 35:20
2022-12-19Watts says no one in the Mojo 2 speculation thread predicted its big change, the UHD DSP EQ. Head-Fi, Dec 2022
2023-03-12Watts quotes the Mojo 2 factory reset procedure that clears EQ and crossfeed, and says he left out an EQ on/off option to keep operation simple. Head-Fi, Mar 2023
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
2023-04-03Watts says changing the frequency response with EQ also changes the phase. Amplify Audio 8:52
2023-04-03Watts says transparent EQ needs -301 dB performance in amplitude and phase; after a couple of years' work, the DSP core in this unit is 104 bits. Amplify Audio 8:57
2023-04-03Watts says the DSP runs at 768 kHz, or 705 kHz for 44.1 material, and is noise-shaped, so the EQ is transparent. Amplify Audio 9:29
2023-04-03Watts says the ability to tune the sound, for example the bass, is really useful. Amplify Audio 10:16
2023-05-30Watts says Mojo 2's bass EQ range covers IEMs rolling off at 125 Hz, he sets +3 or +4 dB shelf on his Stealth, and a shutdown pop is harmless. Head-Fi, May 2023
2023-07-23Watts says a more complex EQ is technically possible for the new M scaler given its FPGA capacity. Head-Fi, Jul 2023
2023-07-28Watts agrees Mojo 2 drives the Stealths perfectly and says he runs the 125 Hz shelf at +3 dB with other EQs at 0. Head-Fi, Jul 2023
2023-07-28Watts rejects full parametric EQ and conventional EQ, says Mojo 2's 104-bit EQ core was his idea, and describes its modest FPGA cost. Head-Fi, Jul 2023
2023-07-29Watts says transparent EQ needs 16FS processing, noise shaping at each node and large fixed-point word lengths, and that Class D's transient timing distortions make it unfit. Head-Fi, Jul 2023
2023-07-30Watts says 64-bit floating point creates noise floor modulation, unlike his noise-shaped fixed point in Mojo 2's UHD DSP, and suggests Class H for efficient amplification. Head-Fi, Jul 2023
2023-08-06Watts says Mojo 2 can sound peppy or rich, warm and leisurely depending on the music, headphones and EQ settings. Head-Fi, Aug 2023
2023-09-14Watts explains why Mojo 2's EQ is loss-less rather than bit perfect, advises against source upsampling, and says an M scaler improves Mojo 2 though algorithm matters more than taps. Head-Fi, Sep 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
2023-10-01On the EQ, Watts says he tests with a -301 dB signal, far below audibility, because the brain can perceive it if the quality of that signal is slightly wrong. The Source AV 8:39
2023-10-01Watts says EQ uses infinite impulse response filters, which ideally keep processing an event forever as it gets smaller and smaller. The Source AV 9:33
2023-10-01Watts says conventional IIR filters stop resolving at about -140 to -150 dB, so very small signals get wrong amplitude and phase shift. The Source AV 9:55
2023-10-01Watts says 64-bit floating-point EQ has noise floor modulation around -300 dB that is audible as brightness, and proposes a +1 dB EQ with -1 dB volume test. The Source AV 10:40
2023-10-01Watts says Mojo 2 has his own custom 104-bit noise-shaped DSP core running at 705/768 kHz, whose noise shaper keeps impulse-response tails that fall below the noise floor. The Source AV 11:22
2023-10-01Watts says signals below the DSP's 104-bit resolution are remembered by the noise shaper and carried inside the noise, making a true infinite impulse response. The Source AV 12:08
2023-10-01Watts agrees and says the DSP core also performs the volume control and crossfeed. The Source AV 13:05
2023-10-01Watts says he would not have spent the three or four months developing and evaluating the DSP core unless he knew it could be used in other products. The Source AV 37:34
2023-11-20Watts says 64-bit floating point creates audible noise floor modulation, and Mojo 2's EQ runs at 16FS with noise-shaped nodes in 104 bits. Head-Fi, Nov 2023
2023-11-20Watts says conventional digital EQ is flawed, especially bass EQ where small biquad coefficients are truncated and errors accumulate in IIR feedback. Head-Fi, Nov 2023
2024-03-07Watts explains Mojo 2's bass shelf and 20Hz peak settings were chosen to compensate a first-order bass roll-off at 125Hz found in many Japanese IEMs, keeping EQ simple. Head-Fi, Mar 2024
2024-03-28Watts says Quartet will have more complex lossless EQ built in, which he is finishing now. Head-Fi, Mar 2024
2024-05-17Watts says it already has this: the DSP EQ has 5 settings, off plus 4 settings the user can set. Head-Fi, May 2024
2024-12-11Watts says both indicators must be white for clipping, assuming no boost EQ; with +3dB EQ, go three steps down to avoid clipping at 0dBFS. needs context Head-Fi, Dec 2024
2025-02-17Watts says FIR EQ has problems tied to tap length and processing power, he dislikes room EQ because the brain subtracts the room, and bad rooms should be treated instead. audio-2G 13:59
2025-02-17Watts says Mojo 2's transparent EQ uses a 104-bit DSP core at 768 kHz with every IIR node aggressively noise shaped, recirculating rather than discarding truncated bits. audio-2G 14:59
2025-02-17Watts says transparent EQ needs at least '108 bits, at 104 bits' and aggressive noise shaping, not floating point, which creates audible noise floor modulation heard as unnatural brightness. audio-2G 15:44
2025-02-17Watts says modern DSPs miss that accuracy but his Mojo 2 cores and a similar Quartet core do, so EQ keeps depth intact; he tests with alternating half-dB bands. audio-2G 18:39
2025-02-17Watts says his 10-band alternating half-dB EQ sounds transparent against flat, a standard EQ would be audible, and transparent EQ is a nightmare people misjudge because they do not listen. needs context audio-2G 19:23
2025-03-26Watts explains causal versus symmetric acausal filters, says interpolation pre-ringing at 22kHz is not an issue but EQ should be causal, and lists his CanJam schedule. Head-Fi, Mar 2025
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 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 contact him by Head-Fi PM; next year begins an active-loudspeaker project, and since Mojo 2's EQ is transparent, replacing passive crossovers should greatly improve speakers. ecoustics 1:28:33
2026-03-24Watts says he always uses Mojo 2's lossless EQ, especially flying since things sound different at 8,000 feet, and unlike normal EQ it does not damage sound quality. Audio Force 36:34
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
2026-10-02Watts says Mojo 2's digital EQ drew on his work on small-signal phase shift, since EQ changes phase, and making it transparent was much harder than expected. HiFi Buys 2:30:22
2026-10-02Watts says getting the EQ's measurements right was hard; the EQ was really built for his IP library for future pro audio, where subjectively lossless EQ will be profoundly important. HiFi Buys 2:31:10
2026-10-11Watts says such players convert DSD to PCM and apply the EQ in PCM. Distorsiuni Interioare 1:00:20
2026-10-17Watts says he uses the EQ a lot; a ten-band test alternating plus and minus half dB gave no loss in transparency, detail, depth, separation or focus. article, Oct 2026
2026-10-17Watts says the EQ at extreme settings passes a minus 301 dB test, phase within a thousandth of a degree and level within a thousandth of a dB, so it is transparent. 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