Burn-in, warm-up and brain break-in

Perception and sound character

Answers on this topic

• Do Chord DACs need burn-in or warm-up?

Everything he said on this topic (41)

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

• 2014-04-01Watts says Hugo seems to sound better over months, possibly his brain adapting, but tests of old versus new units show little difference; DoP is decoded on all inputs. Head-Fi, Apr 2014
• 2014-10-25Watts gauges an improvement by how long it stays noticeable, from one day to over three months, rates the Olimex isolator a one-week change, and calls Hugo's break-in mental adaptation. Head-Fi, Oct 2014
• 2016-01-24Watts compares 2 Qute and Hugo: similar on optical or coax, 2 Qute's galvanic isolation helps with a PC on USB, Hugo can feed power amps directly; output stages match. Head-Fi, Jan 2016
• 2016-02-25Watts says the right button must be held at least a second to change the PCM+/DSD+ mode, and the unit should sound fabulous straight out of the box. Head-Fi, Feb 2016
• 2016-03-29Watts says DAC inconsistency and break-in 25 years ago led him to pulse array; Mojo units measure and sound alike, and brain break-in is now the biggest variable. Head-Fi, Mar 2016
• 2016-03-30Watts doubts Dave has much physical break-in, describing improvement over 8 weeks after new code as possibly brain break-in, and says Dave makes headphone differences more pronounced. needs context Head-Fi, Mar 2016
• 2016-05-21Watts says brain break-in matters far more than hardware break-in, DAVE's FPGA must be soldered rather than socketed, a replacement is years away, and code updates need significant gains. Head-Fi, May 2016
• 2016-05-23Watts says he uses Mojo while traveling and sets up DAVE in hotels, where from cold its sound quality reaches full form within about 10 minutes. Head-Fi, May 2016
• 2016-06-16Watts doubts DAVE has significant hardware break-in, lists causes such as bias drift, electrolytic capacitors and RF noise, and says every DAVE measures about -127 dB THD and noise. Head-Fi, Jun 2016
• 2016-07-09Watts finds a new DAVE slightly brighter and more transparent than his pre-production unit, credits nitrogen production soldering, and says brain break-in outweighs physical break-in. Head-Fi, Jul 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
• 2016-08-19Watts hypothesizes that brain break-in, first noticed with Hugo, is the brain unlearning coping strategies for sampled-data timing errors, which DAVE showed must be accurate to nanoseconds. Head-Fi, Aug 2016
• 2016-10-28Watts says DAVE sounds great out of the box, otherwise taste or a flawed system is to blame; it highlights headphone differences, and listeners should question their own impressions. Head-Fi, Oct 2016
• 2017-03-15Watts says Hugo 2 noise is mostly resistor thermal noise, so units match within 0.2 dB; halving it would raise distortion 16 times, and he hears no warm-up or break-in. Head-Fi, Mar 2017
• 2017-03-26Watts says Hugo 2 needs no burn-in beyond its first full charge, brain break-in takes about a month, and it lacks the caps, RF and bias effects behind break-in. Head-Fi, Mar 2017
• 2017-06-25Watts says Hugo 2 sounding better over time is almost certainly brain break-in, since new and old units sounded identical, though the experience of improvement is real. Head-Fi, Jun 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
• 2017-12-09Watts says break-in, especially when measurable, reveals problems whose cause should be removed, leaving better performance with no break-in or significant warm-up. article, Dec 2017
• 2018-05-03Watts says pulse array was designed so every unit measures identically, attributes perceived break-in to the brain, notes a slight warming after ten minutes, and says 192k remains inaccurate. Head-Fi, May 2018
• 2018-05-07Watts says Hugo 2's DSD filter exceeds 200 dB at 88.2 kHz, used on Blu 2; he heard only brain break-in; the M scaler outputs 705.6 kHz PCM from DSD. Head-Fi, May 2018
• 2018-09-20Watts says the first M scaler was built 15 months earlier across four hardware versions, and he heard no hardware break-in, only brain break-in. Head-Fi, Sep 2018
• 2018-09-21Watts says cable placement once upset his AB tests, brain break-in is real, Hugo 2 warms up in 10 minutes, and he has seen no evidence of hardware break-in. Head-Fi, Sep 2018
• 2018-10-13Watts says TT2's supercaps work from the start, he has no experience of hardware break-in and would not expect a big change, but brain break-in differs. Head-Fi, Oct 2018
• 2019-02-25Watts says battery power is the reference, optical and USB sound nearly identical on the M scaler, TT2 gains nothing from batteries, and 10 minutes of warm-up is needed. Head-Fi, Feb 2019
• 2020-01-01Watts says the DACs use a third overtone crystal by the flip-flops and no PLLs, so measurements need no warm-up, though Hugo 2 seemed slightly different after ten minutes. Head-Fi, Jan 2020
• 2020-08-15Watts says he has heard no change between new and old units, but brain burn-in, adapting over a few weeks to a sound, is possible. Head-Fi, Aug 2020
• 2020-09-08Watts says analog PLL capacitors in older DACs settle over hours and cause correlated jitter, while his DPLL designs measure identically over time and reach optimum sound within 10 minutes. Head-Fi, Sep 2020
• 2020-09-09Watts says John Franks designs the amps; Hugo 2 sounds slightly warmer after ten minutes, and he lists RF, capacitors, bias and jitter as variability causes, mostly eliminated. Head-Fi, Sep 2020
• 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
• 2022-02-14Watts says PSU break-in signals RF noise causing noise floor modulation, better fixed by RF filters, and that design knowledge matters far more than parts cost. Head-Fi, Feb 2022
• 2022-09-18A chat question, read aloud, asks whether it takes 30 minutes to warm up properly. The Source AV 41:50
• 2022-09-18Watts says it takes about 10 minutes, and all the products take about 10 minutes. The Source AV 41:54
• 2022-09-18Watts says warm-up is standard, there is no break-in time; a change heard after purchase is the brain adapting, and warm-up takes about 10 minutes. The Source AV 42:02
• 2023-01-04Watts says his portable DACs sound bright and flat for about 10 minutes on flights, perhaps from cabin pressure, though they measure identically from cold; warm-up is not a problem. Head-Fi, Jan 2023
• 2023-02-26Watts says a cold-start test found no significant change, so Hugo 2's 10-minute warm-up on planes is more about his ears and headphones adjusting to cabin pressure. Head-Fi, Feb 2023
• 2023-03-01Watts says the M Scaler needs no warm-up, Hugo 2's in-flight change was ear pressure, describes flying with his battery rig and thermal trip, and says battery plus optical isolates. Head-Fi, Mar 2023
• 2023-10-01Watts says output-stage bias must not drift with heat, notes he began as an analog designer, self-taught in digital, and says the DACs sound the same at switch-on and later. The Source AV 47:35
• 2023-10-01Watts says many parameters alter sound quality, and a sound that changes after switch-on signals something adrift, even if the temperature change happens to sound better. The Source AV 48:23
• 2023-10-01Watts says such variation is a clue: find and fix the cause for better sound, with the further benefit that the unit sounds the same from switch-on. The Source AV 48:50
• 2024-01-07Watts says the 10-minute warm-up he heard on flights was most likely his ears adjusting to cabin pressure or the headphones, not the DACs, and that Mojo 2 exposes headphones with poor LF distortion. Head-Fi, Jan 2024
• 2024-09-25Watts says a cold Hugo 2 showed no warm-up change, so in-flight brightness was headphones or ears, and Mojo 2 saves settings to FLASH only after menu mode times out. Head-Fi, Sep 2024