Internal batteries, charging and desktop mode

RF noise, grounding and power

Answers on this topic

Can I use Hugo, Mojo or Mojo 2 while it is charging, and is it OK to leave it plugged in all the time?
How does desktop mode work on Hugo 2 and Mojo 2, and will Mojo 2 drain on the shelf?
What do the colored indicators mean (volume, sample rate, charging), and is a volume color the same level across Chord DACs?
Why does my Hugo 2 switch itself off, and how does standby work on the battery-powered DACs?

Everything he said on this topic (133)

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

2014-04-09Watts clarifies that the PSU improvement under discussion is for the AP2 USB, not Hugo, and that Hugo is always powered from its batteries, never from USB. Head-Fi, Apr 2014
2014-04-16Watts leaves Hugo plugged in and on permanently, and says the QBD76 replacement will be ready when perfected; he has prototypes and is chasing FPGA timing closure on many taps. Head-Fi, Apr 2014
2014-05-16Watts says leaving it plugged in has no significant effect on sound quality, based on his listening tests. Head-Fi, May 2014
2014-05-19Watts says charger sound depends on RF noise, he hears no difference in trickle charge, Hugo runs from the battery when plugged in, and repairs go through Chord or distributors. Head-Fi, May 2014
2014-06-09Watts cites his 1980s mains cable work, says AB tests found no significant difference with Hugo's charger connected, and describes its PSU of batteries, 9 regulators and 12 RF filters. Head-Fi, Jun 2014
2014-06-09Watts says the battery stays connected as a 0.1 ohm low-noise source, the charger path has regulation and RF filtering, and he AB tested to confirm no audible downside. Head-Fi, Jun 2014
2014-06-09Watts revises himself: his PSU test was at line level, but the external PSU sounded better with Hugo driving 8 ohm loudspeakers, by supporting battery voltage. Head-Fi, Jun 2014
2014-06-09Watts says there are two 2.2AH Li-ion cells; driving 8 ohm loads flat out sags the voltage, so the charger makes it sound fuller. Head-Fi, Jun 2014
2014-06-11Watts explains that a fully depleted Hugo battery charges at very low current, too little to run the FPGA, then switches to full charge mode; it is safe. Head-Fi, Jun 2014
2014-06-19Watts describes Hugo's three charging modes and says leaving it on with the charger connected gives zero net battery current while keeping low-noise battery operation. Head-Fi, Jun 2014
2014-06-19Watts says leaving it plugged in extends battery life, he hears no difference with the charger connected, and dissipation is well below 2W. Head-Fi, Jun 2014
2014-06-19Watts gives Hugo battery temperature ratings (45 deg C charging, 60 discharging), 2W dissipation and 3.2 deg C per W, and advises charging with nothing on top. Head-Fi, Jun 2014
2014-07-10Watts says a prototype unused for months turned on fully charged at blue, and a unit switched off should not discharge in 24 hours. Head-Fi, Jul 2014
2014-07-10Watts says Hugo over-voltage protection failures came from non-supplied, too-high-voltage chargers; a damaged unit goes back to the dealer, and other PSUs bring no sound benefit. Head-Fi, Jul 2014
2014-09-06Watts says a completely flat lithium battery charges at very low current, so charge for several hours with the unit switched off. Head-Fi, Sep 2014
2014-11-10Watts says the charger should stay on while using Hugo because it matches Hugo's current draw, and it shuts down when Hugo is off until the batteries deplete. Head-Fi, Nov 2014
2015-04-20Watts gives each input's maximum data width and rate (SD USB and Bluetooth 16-bit/48 kHz, HD USB 32-bit/384 kHz, optical 192 kHz, coax 384 kHz) and battery life by input. Head-Fi, Apr 2015
2015-05-04Watts says there are two 4.2V batteries, giving an 8.4V supply. Head-Fi, May 2015
2015-12-28Watts says with the charger connected Hugo's batteries get current matching its draw, so they last long; other numbered replies say 'it' is not working and to contact Chord. needs context Head-Fi, Dec 2015
2015-12-29Watts says all connectors loosen with time, the 9mm one is fine, and the gold-plated switch is rated at 10,000 operations; he kept his on until Dave replaced it. Head-Fi, Dec 2015
2016-01-25Watts says he left his Hugos on all the time and that at about 1.5W the power draw is nothing to worry about. Head-Fi, Jan 2016
2016-05-09Watts says fully depleted batteries put Hugo in safety charge mode and gives a reset procedure: switch off, disconnect the charger 10 seconds, reconnect, and charge overnight with Hugo off. Head-Fi, May 2016
2016-06-13Watts suggests the unit may be in safety charge mode and gives a reset and overnight charge; if still flashing, contact the dealer, as a failing charger can cause it. Head-Fi, Jun 2016
2017-02-28Watts says USB galvanic isolation may help when driving a power amp depending on source noise, and charging makes no measured and no reliably audible difference. Head-Fi, Feb 2017
2017-03-14Watts describes Hugo 2's charging: 1 A half charge (cyan), 2 A full charge (white), and desktop mode (magenta) after 24 hours, matching current draw and holding 8.1 to 8.2 V. Head-Fi, Mar 2017
2017-03-20Watts says Hugo 2's battery should last a very long time: it works with the battery disconnected, and desktop mode holds 8.0 to 8.2 V without using charge cycles. Head-Fi, Mar 2017
2017-03-20Watts says full charge is 8.4 V, desktop mode drops to 8.2 to 8.0 V where life is unaffected, and Mojo was run at 8.2 V for long life. Head-Fi, Mar 2017
2017-03-21Watts says it will work without batteries from a 2A USB charger, but he has not listened to this and does not recommend it. Head-Fi, Mar 2017
2017-03-21Watts says the batteries supply large dynamic currents for low-impedance loads; desktop mode only changes charging voltage, and double over-voltage protection is built in. Head-Fi, Mar 2017
2017-03-23Watts says any 2A USB supply should work, or 1A in half-charge mode, but some are noisy or have power-saving modes, which is why a quality supply is included. Head-Fi, Mar 2017
2017-03-26Watts confirms auto shut-off is disabled in desktop (magenta) mode, entered after the charger is connected for over 24 hours. Head-Fi, Mar 2017
2017-04-15Watts says Hugo 2's FPGA 12-bit ADC monitors battery voltage and shuts down at 6.5 V, a level safe for full-current recharge, so the battery cannot be drained. Head-Fi, Apr 2017
2017-05-19Watts says the substituted parts differed only in voltage rating, in the charger's PSU section, with the same dielectric, so sound quality will not change. needs context Head-Fi, May 2017
2017-06-05Watts says Hugo 2 remembers its last settings and explains desktop mode: charger current matches draw, sustaining voltage drops, auto shutdown is disabled, and it runs with no battery. Head-Fi, Jun 2017
2017-06-05Watts says Mojo does not need desktop mode, as it charges at a lower voltage and the charger simply matches Mojo's consumption when left connected. Head-Fi, Jun 2017
2017-06-08Watts says Hugo 2 stays in desktop mode while charging, drawing 2W; switching it off charges to 100%, and it runs on the charger even at 0% battery. Head-Fi, Jun 2017
2017-07-10Watts says top-up charging is normal and Hugo 2 has three thermal trips; an FPGA trip forces 1A cyan charging, and charging at blue reduces heat. Head-Fi, Jul 2017
2017-07-22Watts says the indication is caused by the charger voltage collapsing; reconnect the charger, and if the light is white all is well, but flashing means the PSU is faulty. Head-Fi, Jul 2017
2017-07-23Watts explains Hugo 2 charging colors (cyan for 1A, blue when full and on, magenta for desktop mode) and says partial discharges give proportionally more cycles. Head-Fi, Jul 2017
2017-08-31Watts says it auto shuts down after 10 minutes without SPDIF lock or valid USB 5V on the USB input, in case it is switched on in a bag. Head-Fi, Aug 2017
2017-09-14Watts says a flashing charge light means the charger detected a timeout or low voltage; reset by removing the PSU for 10 seconds and charge overnight with Hugo switched off. Head-Fi, Sep 2017
2017-09-23Watts says it shuts down so the battery does not go flat in standby waiting for the remote, but the remote can restart it when the charger is connected. Head-Fi, Sep 2017
2017-10-22Watts says Hugo 2 auto shut-off triggers on digital silence on SPDIF but not on USB while 5V is present, because some OSes crash when the USB DAC disappears. Head-Fi, Oct 2017
2017-12-16Watts says desktop mode holds Hugo 2's battery at a reduced voltage to maximize battery life; turning it off lets it fully charge for portable use. Head-Fi, Dec 2017
2017-12-23Watts says Hugo 2 auto-shuts down only with no USB 5V present and digital silence on SPDIF, to avoid app crashes and flattening the battery in a bag. Head-Fi, Dec 2017
2018-01-09Watts confirms everything must be shut down to save the battery. needs context Head-Fi, Jan 2018
2018-01-10Watts says connecting the charger sets the desktop-mode timer, and turning Hugo 2 off fully charges the battery then stops, since constant full voltage wears it. Head-Fi, Jan 2018
2018-01-17Watts says turning it off with the charger connected fully charges the battery then disconnects the charger; the intent is to leave it on in desktop mode. Head-Fi, Jan 2018
2018-01-23Watts says the Hugo 2 and Mojo battery gauges need no recalibration cycles, as the FPGA's ADC and the charger reference are very accurate. Head-Fi, Jan 2018
2018-01-25Watts says Hugo 2 draws 1.9A worst case when fast charging from flashing red, falling as the battery charges, with 2.1A specified to cover tolerances. Head-Fi, Jan 2018
2018-02-26Watts says the batteries use plug-in connectors, and declines to comment on another point. needs context Head-Fi, Feb 2018
2018-03-15Watts says the turn-off charging behavior assumes next use is mobile, and battery temperature in desktop mode is barely above ambient, with batteries rated for high temperature. Head-Fi, Mar 2018
2018-03-26Watts advises keeping it on, as desktop mode holds the battery at a safe voltage for longevity and supplies most current from the charger. Head-Fi, Mar 2018
2018-03-26Watts says he cannot hear the charger connected on headphones, USB tweaks only add RF noise and brightness, and Chord dealers can supply replacement batteries. Head-Fi, Mar 2018
2018-04-24Watts says heat leaves via the PCB ground plane to the case through six M2 screws, and dissipation peaks when on and charging from flashing red. Head-Fi, Apr 2018
2018-05-01Watts says a cable limiting charge current to 1A has too much resistance, and describes Hugo 2's reinforced USB connector construction, with no failures he knows of. Head-Fi, May 2018
2018-05-01Watts says it will fully charge but take double the time. needs context Head-Fi, May 2018
2018-06-09Watts explains desktop mode keeps Hugo 2's battery near 80% for about 10 years of use, a charger fault means under 1A, and thermal shutdown when charging at red. Head-Fi, Jun 2018
2018-06-22Watts says playing while charging from flat is the worst case for battery temperature, though thermal trips protect it; on long flights he recharges Hugo 2 at blue. Head-Fi, Jun 2018
2018-06-25Watts says lock detection needs only a valid SPDIF signal, turning Hugo 2 off tops the battery to 100% for mobile use, and batteries last 500 to 1000 cycles. Head-Fi, Jun 2018
2018-06-25Watts says auto shutdown is disabled in desktop mode; in normal mode Hugo 2 stays on with SPDIF lock or USB connected in the past 10 minutes. Head-Fi, Jun 2018
2018-09-04Watts says desktop mode engages when the charger port has uninterrupted power for longer than 24 hours. Head-Fi, Sep 2018
2018-09-11Watts says it will work because the charger circuit can supply 0.7 A, more than enough to power the amp as well. needs context Head-Fi, Sep 2018
2018-09-24Watts says a fully charged Hugo 2 left on goes into trickle charge, drawing only 0.5 A, so 1A or 2.1A chargers make no difference. Head-Fi, Sep 2018
2019-05-06Watts says it cannot overheat and lists reset, battery-check and overnight-charge steps, with service if it will not recharge. Head-Fi, May 2019
2019-07-01Watts says desktop mode is for 24-hour charging and use; turning the unit off is fine, as it recharges then disconnects the battery from the charger. Head-Fi, Jul 2019
2019-09-23Watts says shutdowns can happen near battery depletion or in trickle charge mode; turn it off and charge, overnight if needed, or the charger may lack current. needs context Head-Fi, Sep 2019
2019-09-23Watts says a blue power button without charger suggests a battery fault needing service, while cyan means half charge mode; charge overnight or try another 2A 5V charger. Head-Fi, Sep 2019
2019-09-24Watts says auto shutdown powers down after 10 minutes of no input or digital silence to protect the battery, and shutdown during music needs service. Head-Fi, Sep 2019
2020-02-26Watts says a battery backup for blackouts is fine, but if Hugo 2 is turned off when unused, desktop mode is unnecessary since the charger disconnects. Head-Fi, Feb 2020
2020-03-12Watts says Hugo 2 batteries are robust, advises using its own volume rather than a passive, and says certified USB cables suffice; heard differences are placebo or RF noise. Head-Fi, Mar 2020
2020-03-13Watts revises his desktop mode advice by daily use, calls it splitting hairs, and estimates battery capacity of about 70% after 13 years if turned off daily versus 65% if left on. Head-Fi, Mar 2020
2020-03-16Watts says with a charger connected Hugo 2's power switch shows white, cyan or magenta; yellow means below 50%; a switcher working at 192k is fine. Head-Fi, Mar 2020
2020-05-06Watts says USB bit errors are rare and obvious, Hugo 2 and Mojo need at least 6.5v and 8v for best output, and non-original battery swaps risk fire. Head-Fi, May 2020
2020-06-25Watts says Mojo's small size limits dissipation: 1.7 watts raises temperature about 15 degrees C from memory, charging is more like 3 or 4 watts, and about 3 watts is comfortable. Part-Time Audiophile 31:24
2020-11-09Watts says remote power control needs only the charger connected; desktop mode just lowers battery voltage for longer life and stops auto shutdown. Head-Fi, Nov 2020
2020-11-12Watts says no cheaper, better FPGAs exist to replace Hugo 2's 7 series part, and desktop mode charges the battery to only 80%. Head-Fi, Nov 2020
2021-07-11Watts says charging is done by discrete charge pump circuits under FPGA control, which can multiply voltage by integers efficiently. Head-Fi, Jul 2021
2021-10-15Watts explains desktop mode's battery voltage and charge current, dismisses capacitor life concerns, guesses about 20 years excluding the battery, and advises against running without the battery. Head-Fi, Oct 2021
2021-11-04Watts advises not charging and playing at once; listening then charging overnight with Hugo 2 off gives slightly longer battery life, and the batteries are very reliable. Head-Fi, Nov 2021
2022-01-31Watts says the analog stage is nearly unchanged; the supply changed so Mojo 2 runs without the battery, which original Mojo needed to keep supply noise from the amplifier. Darko.Audio 13:48
2022-01-31Watts says he improved the charging supply for dynamic currents and added separate regulation for better PSRR, improving performance even with the battery, and introduces intelligent desktop mode. Darko.Audio 14:39
2022-01-31Watts says that in desktop mode, once the battery is fully charged it is physically disconnected. Darko.Audio 15:26
2022-01-31Watts says the unit can run three or four years on one charge with the battery disconnected, avoiding wear, and many people used Mojo One on desktops. Darko.Audio 15:38
2022-01-31Watts says constant trickle charging on a desktop wears a battery out; desktop mode removes it, so the supply and PSRR had to work harder to replace the battery. Darko.Audio 15:59
2022-01-31Watts says desktop mode brings neither gain nor loss; mains connection via the charger always costs a little, pure battery sounds best, and he minimized that drop. Darko.Audio 16:39
2022-01-31Watts says Mojo 2 auto-offs after 10 minutes without inputs, stays in desktop mode while powered, trails Hugo 2, uses a digital DC servo, and improved 16FS-to-2048FS filtering. Head-Fi, Jan 2022
2022-01-31Watts says fully charged Mojo 2 enters desktop mode with the battery disconnected, unlike Hugo 2, so he improved PSU rejection and made the charger a low-impedance source. Head-Fi, Jan 2022
2022-02-01Watts answers Mojo 2 questions: 2G buzz mitigation, dual-data ring contact, 0.35S latency, DSP cores, 9 hours 11 minutes battery on USB, and 99.5dB SPL into HD800. Head-Fi, Feb 2022
2022-02-02Watts explains Mojo 2's FPGA charger, 0.5A to 2A charging, 99.3dB SPL with the HEKV2, why coupling caps soften bass, why Mojo lacked a DC servo, and USB-C for Poly. 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
2022-02-04Watts 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
2022-02-15Watts says running without a battery will be fine, and on Windows advises installing Chord's driver rather than generic drivers, with ASIO also available. Head-Fi, Feb 2022
2022-02-19Watts says an adaptor costs a little transparency through extra contacts, and Mojo 2 shuts down after 10 minutes without SPDIF lock or USB VBUS, by design. Head-Fi, Feb 2022
2022-03-19Watts says Mojo's case can dissipate about 1.8 watts; he saved about 300 milliwatts in the analog section, spent 250 more on the FPGA, and battery capacity rose 9%. MFG Audio Reviews 25:11
2022-03-19Watts gives measurements: 125 dB dynamic range and distortion much as on Mojo, but 118 dB stereo separation from better supply isolation, so the battery is isolated when running permanently. MFG Audio Reviews 44:22
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
2022-03-29Watts says Mojo needed topping up after weeks on the shelf, but Mojo 2's standby current is an order of magnitude lower, taking 7 months to go flat. Head-Fi, Mar 2022
2022-04-26Watts says Mojo's limits were size, not technology: its package can dissipate only about 2.5 watts, so the original Mojo got too hot when used while charging. Audio Force 2:44
2022-04-26Watts says he saved 300 or 400 milliwatts and batteries improved about 9 percent, so Mojo 2 uses 98% of the FPGA instead of 33% at lower total power. Audio Force 4:16
2022-04-26Watts says he designed an FPGA-driven charging circuit for Mojo 2 so it can be charged while listening without getting hot, bringing Hugo 2 technology into it. Audio Force 4:58
2022-04-26Watts says many original Mojos ran 24/7 as fixed-system DACs, so for Mojo 2 he made the battery fully isolated when the charger is connected. Audio Force 14:06
2022-04-26Watts says isolating the battery in desktop use required separate regulation in Mojo 2's analog section, since the original Mojo's analog stage fed directly from the battery. Audio Force 14:51
2022-04-26Watts says with added power supply rejection and regulation, the new unit used 24/7 on the charger isolates the battery without trickle charging, preserving battery life. Audio Force 15:33
2022-04-26Watts says auto shutdown follows 10 minutes without signal, meaning no USB VBUS or no SPDIF lock, not digital silence. Head-Fi, Apr 2022
2022-04-29Watts says Mojo was never double; the USB decoder draws 253 mW and the optical receiver 13 mW, giving about 15% more battery life on optical or coax. Head-Fi, Apr 2022
2022-06-01Watts says Mojo 2 in desktop mode runs from the charger via its regulator with the battery disconnected, topping the battery up every 11 days. Head-Fi, Jun 2022
2022-06-22Watts says Hugo 2's charger is a simple generic unit, while for Hugo TT2 he spent much time on PSU selection so supercap listening sounds unchanged. Head-Fi, Jun 2022
2022-10-03Watts says a failed battery need not be removed: the charger detects a shorted or worn-out battery, disconnects it, and runs the unit in desktop mode. Head-Fi, Oct 2022
2022-10-26Watts advises turning Hugo 2 off when unused, especially for 12 hours or more, notes its batteries are reliable, and says 10-year-old Hugo 1 batteries worked fine. Head-Fi, Oct 2022
2022-11-05Watts expects two Hugo 2 charges from a 25,600mA power bank, citing charger and power bank losses, unknown 2Go draw, and possibly an incompletely charged bank. Head-Fi, Nov 2022
2022-11-21Watts agrees with a poster's figure, saying he calculated 48 hours with Mojo 2 on and somewhat more with it off. needs context Head-Fi, Nov 2022
2023-03-17Watts advises buying the original-rate release since WTA cannot undo non-integer SRC, and says the 2A charger advice is about holding 5 V at Mojo 2's port. Head-Fi, Mar 2023
2023-03-30Watts explains SPDIF locking and the lock flag, which Mojo 2 uses to switch data sources and disable auto shutdown, regardless of whether the data is silent. Head-Fi, Mar 2023
2023-05-23Watts says all buttons flashing red indicates the over-temperature trip and asks whether the poster was playing and charging at once. Head-Fi, May 2023
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
2023-05-31Watts says the battery's own protection cutting out before Mojo 2's FPGA shuts down is no cause for worry. Head-Fi, May 2023
2023-08-28Watts says the pulsing battery or charge status LED represents a heartbeat pumping charge into the battery. Head-Fi, Aug 2023
2024-02-19Watts says Mojo 2 desktop mode disconnects the battery, trickle charges it every 11 days, charges below full capacity for longevity, and adds a regulation stage with RF filters. Head-Fi, Feb 2024
2024-02-19Watts says Mojo 2's desktop mode is new; Hugo 2 relies on its batteries for dynamic currents, and waiting for magenta rather than blue gives longer battery life. Head-Fi, Feb 2024
2024-03-30Watts says the 24-hour charge applies to Hugo 2, not Mojo 2, whose charge time depends on initial state, with the final 95% to 100% trickle taking hours. Head-Fi, Mar 2024
2024-07-15Watts weighs lower battery voltage when on against higher temperature, advises turning Hugo 2 off if unused two days or more, and says its batteries are over-specified. Head-Fi, Jul 2024
2024-11-13Watts says Hugo 2's charger chip may or may not work without a battery, unlike Mojo 2, and that Hugo 2 battery failures are extremely rare. Head-Fi, Nov 2024
2026-03-24Watts says the older Mojo 2 needed adapters, and every metal-to-metal interface damages sound, so the dedicated connector improves detail and soundstage; USB-C charging is the other major benefit. Audio Force 32:33
2026-03-24Watts says adding USB-C charging was complex because charging must be switchable to avoid depleting a phone, and isolating the two charging voltages was non-trivial. Audio Force 33:05
2026-03-24Watts says the USB-C charging options required an FPGA change, but all of the audio parts are identical to the original Mojo and unchanged. Audio Force 34:28
2026-05-03Watts says the built-in 4.4 mm connector sounds better than adapters, since any metal-to-metal interface hurts detail and depth, and adds a programmable USB-C charging option. Audio Force 21:35
2026-05-03Watts says the programmable USB-C charging feature can be turned off when using a mobile phone over USB-C so the battery is not depleted, and turned back on when needed. Audio Force 22:22
2026-10-11Watts says Hugo 2's desktop mode lowers battery voltage for safe constant charging; Mojo 2 isolates the charged battery, so RF filtering on its power input was improved. Distorsiuni Interioare 40:27
2026-10-11Watts says better local regulation gives battery-like impedance, so mains loss is much lower; isolation solves battery lifetime, with a trickle charge every eleven days. Distorsiuni Interioare 41:15
2026-10-11Watts says the periodic trickle charge has minimal effect on battery lifetime. needs context Distorsiuni Interioare 42:02
2026-10-11Watts says the battery versus charger difference is very low, depending on system RF sensitivity; if heard, use a power bank into Mojo 2; forums report no losses. Distorsiuni Interioare 42:28
2026-10-11Watts says connecting the charger audibly caused problems on Mojo 1, which does not happen with Mojo 2. Distorsiuni Interioare 43:23