Power supplies and battery packs

RF noise, grounding and power

Answers on this topic

• Can I take DAVE, Hugo 2, an M Scaler and a power bank on a plane, and how does Rob listen on flights?
• Is battery power better than mains, and can I power the M Scaler or Qutest from a power bank?
• Should I replace the supplied power supply with a linear or aftermarket one, and will that affect my warranty?
• Will a better supply than the 5V USB adapter shipped with Qutest improve it, and what voltage does it accept?

Everything he said on this topic (291)

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
• 2014-06-09Watts 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
• 2014-07-10Watts 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
• 2014-07-21Watts warns that the 12.8V Red Wine Audio Black Lightning battery supply may damage Hugo's input protection, which triggers at that voltage. Head-Fi, Jul 2014
• 2015-02-02Watts describes TT's floating balanced output, says TT uses batteries for mains isolation though 2Qute proved RF filtering matches it, and lists balanced drive's pros and cons. Head-Fi, Feb 2015
• 2015-04-15Watts says Hugo TT differs from Hugo in beefier batteries, better reference supply circuitry that reduces noise floor modulation, and galvanic isolation on USB. article, Apr 2015
• 2016-01-11Watts says TT beats Hugo via supercaps lowering PSU impedance, heavier metalwork, USB galvanic isolation and a better flip-flop reference supply that cuts distortion and noise some 4 dB. Head-Fi, Jan 2016
• 2016-01-27Watts says linear supplies involve compromises: developing Hugo in 2012, switching regulators sounded smoother with deeper soundstage and measured better than linear ones, so assumptions must be tested. Head-Fi, Jan 2016
• 2016-01-27Watts heard no difference on 2Qute between its stock switching PSU and a car battery, unlike Qute, expects none with Dave, and says internal DAC RF noise dwarfs PSU noise. Head-Fi, Jan 2016
• 2016-05-13Watts says high-speed internal switchers sounded smoother and warmer than linear regulators in Hugo, forced more RF filtering, and cut DAVE's FPGA supply current from 5 A to 1 A. Head-Fi, May 2016
• 2016-05-14Watts clarifies that DAVE's below-0.5 milliohm supply is a discrete linear reference circuit, not the switcher, with 0.22 uV noise to avoid measurable noise floor modulation. Head-Fi, May 2016
• 2016-07-24Watts likens the output stage to a noise shaper with one global feedback path, and says the music envelope modulates the output flip-flops' reference power, changing the gain. Hifistatement 3:20
• 2016-07-24Watts says reference modulation is not measurable but very audible; his reference has 0.5 of a milliohm impedance to each flip-flop; a digital DC servo removes coupling capacitors and offset. Hifistatement 4:13
• 2016-08-05Watts describes DAVE's power system: multistage RF filtering, a 3 milliohm output-stage supply and a discrete reference under 0.1 milliohm; he says noise floor modulation is audible to -200 dB. Head-Fi, Aug 2016
• 2016-08-14Watts says DAVE's switch-mode supply works from 90 to 263 V and 47 to 440 Hz, so DAVE sounds the same on mains in Japan, the US, UK and Europe. Head-Fi, Aug 2016
• 2017-01-09Watts says WTA processing is identical from 44.1 to 384 kHz, explains mounting the FPGA core switching regulator underneath to limit ground-plane noise, and Blu Mk2 needing 12A. Head-Fi, Jan 2017
• 2017-02-19Watts says Hugo TT beats Hugo mainly through better references, USB isolation and more Class A bias, the PSU being about 20%, and Hugo drives all headphones below white. Head-Fi, Feb 2017
• 2017-02-20Watts explains how rail currents through PSU impedance and limited PSRR cause distortion and bass smear, why DAVE uses milliohm supplies and high PSRR, and why big supplies miss this. Head-Fi, Feb 2017
• 2017-03-21Watts says an external PSU will make Hugo 2 sound worse or no different, citing its stereo separation as proof of supply immunity and warning of RF noise. 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
• 2017-06-27Watts says the reason is that he found a much more elegant way of isolating the amplifier from the power supply; the design choice being explained is not stated. needs context Head-Fi, Jun 2017
• 2017-10-23Watts says Hugo 2's battery is not bypassed; a regulated boost PSU replaced Hugo's super caps, cutting PSU distortion 10,000 times, and a linear PSU is inaudible with headphones. Head-Fi, Oct 2017
• 2017-12-02Watts calls the reference voltage the key internal supply, explains 2Qute's upgraded regulation and RF filtering, his jitter-removing DPLL, and pulse array jitter tolerance (DAVE 128 to 128.5 dB). Head-Fi, Dec 2017
• 2018-01-09Watts says Qutest ships with a 2A supply but works on 1A 5V; pressing both buttons during the rainbow start-up sets output voltage, otherwise it changes display brightness. Head-Fi, Jan 2018
• 2018-01-10Watts explains the boost-voltage and linear-regulator supply that isolates the amplifier gain section from the output stage in Hugo 2 and Qutest, and the digital DC servo replacing coupling capacitors. Head-Fi, Jan 2018
• 2018-01-11Watts says a supply meeting USB specifications will not void the warranty, expects no gain from other supplies as the design is supply immune, and calls a USB battery ultimate. Head-Fi, Jan 2018
• 2018-01-11Watts says supercaps lower PSU impedance and distortion crosstalk, but Hugo 2 and Qutest avoid that by regulating from a boost voltage, and a DAC needs no supercap current. Head-Fi, Jan 2018
• 2018-01-11Watts says supercaps' power delivery is needed for current-hungry headphones. needs context Head-Fi, Jan 2018
• 2018-01-12Watts says USB power was chosen partly because batteries are cheap; Qutest draws 2.5W so 100Wh lasts 40 hours, and batteries give the lowest RF and LF noise. Head-Fi, Jan 2018
• 2018-01-13Watts says super caps would not help Dave, defends Hugo 2's output stage, and says Dave below +4 and Hugo 2 below white never clip with headphones. Head-Fi, Jan 2018
• 2018-01-14Watts agrees running off a battery would be a desirable feature but says big practical issues need solving; the product is not named. needs context Head-Fi, Jan 2018
• 2018-01-16Watts says his listening tests support this but others differ; some amplifiers may be sensitive to Qutest's PSU, so try a USB battery and skip upgrades if no difference. Head-Fi, Jan 2018
• 2018-01-25Watts recalls hearing no difference between 2Qute's supplied PSU and a car battery, notes a supply could affect sensitive amps, and advises comparing with and without the charger before upgrading. Head-Fi, Jan 2018
• 2018-01-25Watts advises comparing a USB battery pack with Qutest's included PSU, saying a battery pack outperforms a linear PSU by eliminating mains RF noise. Head-Fi, Jan 2018
• 2018-02-16Watts recounts that Qute owners' PSU reports led him to add regulation and RF filters to 2Qute, which then sounded unchanged on a car battery; try a USB battery pack. Head-Fi, Feb 2018
• 2018-02-17Watts says his car battery was a portable jump-starter rated at 300A; what matters is ultra low impedance and noise, far better than any mains linear PSU. Head-Fi, Feb 2018
• 2018-02-24Watts heard a difference grounding the output phonos with USB versus optical, but none with the supplied PSU, likely because RF filtering on the charging input removed the loop. Head-Fi, Feb 2018
• 2018-03-08Watts says it is not an issue if the PSU has effective RF filtering and the galvanic isolation works at GHz frequencies, but these effects are extremely sensitive. needs context Head-Fi, Mar 2018
• 2018-03-11Watts says switchers beat linear regulators on Hugo 1 through lower RF noise, which causes noise floor modulation heard as brightness, and advises trying a USB battery bank first. Head-Fi, Mar 2018
• 2018-03-11Watts says transformer-coupled PSUs give negligible RF isolation, so multistage RF filtering is needed; 1MHz to GHz noise matters more than 50 to 100 kHz switching leakage. Head-Fi, Mar 2018
• 2018-03-26Watts says channel separation figures matter less than crosstalk distortion, which he tested on Hugo 2 as a check of PSU-induced distortion; DAVE's low PSU impedance avoids it. Head-Fi, Mar 2018
• 2018-04-29Watts says he used a 100W/h battery bank with 5v/2.1A USB output, more than Qutest needs. Head-Fi, Apr 2018
• 2018-04-29Watts says he uses stock mains cables, heard no difference adding 300 MHz ferrites on the mains input, and DAVE has extensive supply RF filtering and regulation. Head-Fi, Apr 2018
• 2018-05-01Watts says his battery bank is actually an 85W/h Poweradd Pilot Pro 2, the best he has had for reliability and build. Head-Fi, May 2018
• 2018-05-11Watts says TT2 measures like Hugo 2 in DAC mode, gives 18W balanced and 7W SE without degradation, describes its supercap PSU, and denies working on a Dave 2. Head-Fi, May 2018
• 2018-05-11Watts gives just over 18V RMS at 1% THD in amp mode and 5V in DAC mode, estimates 98 dB from LS3/5a speakers, and explains why supercaps replace batteries. Head-Fi, May 2018
• 2018-05-13Watts posts his Munich TT2 presentation: larger FPGA, a noise shaper 100 times better than Hugo 2's, supercap PSU, output stage from the power pulse array project, measurements. Head-Fi, May 2018
• 2018-05-14Watts says TT2 has an FPGA 5 times as capable as the original TT's and twice Hugo 2's, a 98,000-tap WTA filter, a more advanced noise shaper, and 30 farads of supercaps. HIFICLUBE.NET JVH 7
• 2018-05-20Watts explains TT2's 18V RMS balanced output, estimates power into 6 ohms, describes the supercaps and second-order analog noise shaper benefits, and says the output is protected. Head-Fi, May 2018
• 2018-05-24Watts says the supplied PSU sounds as good as a battery in his setup, linear supplies often pass mains RF, and a hard bright sound signals RF-driven noise floor modulation. Head-Fi, May 2018
• 2018-06-15Watts reports a Hugo 2 battery under 0.25A load measured 670nV whether connected or not, versus about 60uV for a quality linear regulator. Head-Fi, Jun 2018
• 2018-06-15Watts says his Poweradd Pilot Pro2 has noisy internal regulators, but what matters is no mains RF; it made no difference on Hugo 2 and prevents ground loops and leakage. Head-Fi, Jun 2018
• 2018-06-24Watts says TT2 weighs 2.7 kg and travels well, its supplied PSU was chosen after much testing, and a linear PSU would almost certainly sound worse. Head-Fi, Jun 2018
• 2018-06-25Watts confirms TT2 worked fine when run from a battery pack. needs context Head-Fi, Jun 2018
• 2018-06-26Watts says an 85Wh pack should run TT2 about 6 hours at 13W, a pack of 85Wh or more with 3A at 12 to 15V works, and batteries were avoided. Head-Fi, Jun 2018
• 2018-07-21Watts says the DX amps are pulse-array-topology DACs of 400 or 500 watts, with volume set by the M Scaler, which he runs from a battery bank on flights. c w 25:32
• 2018-07-29Watts hears no difference between battery and the supplied PSU, warns non-supplied PSUs may void warranty (never above 15V), and found laptop battery vs mains and optical vs USB identical. Head-Fi, Jul 2018
• 2018-07-29Watts uses a Poweradd Pilot Pro 2 at 12V, says batteries are not worth it for TT2, and hears no change with his mobile in airplane mode. Head-Fi, Jul 2018
• 2018-07-29Watts says the supplied PSU is doubly insulated with no ground; a grounded PSU caused ground-loop problems measured with the Audio Precision, and the filter module is identical. Head-Fi, Jul 2018
• 2018-08-26Watts says power banks beat mains on RF noise (10 MHz to 10 GHz), linear supplies lack RF filtering, RF causes audible noise floor modulation, and batteries avoid ground loops. Head-Fi, Aug 2018
• 2018-08-29Watts says TT2's doubly isolated 15V 60W PSU works worldwide with a 2-pin mains input, and normal dissipation is 13W, more when driving speakers. Head-Fi, Aug 2018
• 2018-09-14Watts says linear PSUs lack RF filtering and sound brighter, Qutest benefits hugely from the M scaler but an M-scaled Dave easily beats an M-scaled Qutest. Head-Fi, Sep 2018
• 2018-09-18Watts says the M scaler PSU came from TT2 testing, grounded C13 PSUs caused ground loops, quality SMPS beat linears, the Chord driver works, and auto low-power mode exists. Head-Fi, Sep 2018
• 2018-10-13Watts names the Poweradd Pilot Pro 2, which powers the M Scaler at 12 V and Qutest from USB; at 85 Wh it passes airports, giving 35 hours on Qutest. Head-Fi, Oct 2018
• 2018-10-14Watts says the input protection handles only transients or short overvoltage; above the rated 15 V the diode could blow, which is why he sets 12 V on battery. needs context Head-Fi, Oct 2018
• 2018-10-17Watts says battery power sounds the same in his system, YMMV, but battery banks are the best supply, better than linear, with no leakage currents or RF noise. Head-Fi, Oct 2018
• 2018-10-18Watts says supercaps isolate audio frequencies but do nothing for RF and leakage, so the M scaler, not being analog, has none; he also mentions heavy workload. Head-Fi, Oct 2018
• 2018-11-01Watts says yes, he often uses it that way on very long flights, powering or charging Hugo 2 and the M scaler together. needs context Head-Fi, Nov 2018
• 2018-11-02Watts says Chord would deny warranty for failures caused by a non-supplied PSU, detectable by a failed protection diode, and advises setting the PowerAdd to 12 V. Head-Fi, Nov 2018
• 2018-11-07Watts says a warmer or smoother-sounding supply is always technically better for digital sources, indicating lower noise floor modulation from less RF noise. Head-Fi, Nov 2018
• 2018-11-17Watts says TT2's 30F supercap and large inductor make the external PSU supply only DC current, isolating the electronics from mains along with RF filtering, likely helping via amplifier PSRR. Head-Fi, Nov 2018
• 2018-11-22Watts says the M scaler PSU is deliberately ungrounded to avoid earth loops, grounded PSUs sound brighter, overvoltage failures void warranty, and 15 V is the maximum input. Head-Fi, Nov 2018
• 2018-12-11Watts says the supercaps are in TT2 and he wouldn't bother with another PSU, since disconnecting the supplied one is inaudible; linear PSUs sound falsely brighter and measure worse. Head-Fi, Dec 2018
• 2018-12-12Watts says canceling clock edges eliminates master-clock jitter effects, and explains the reference supply: a DAC modulates a reference voltage, so its noise or variation directly affects performance. Pursuit Perfect System 33:24
• 2018-12-12Watts says discrete parts allow a very low-noise, low-impedance reference to avoid noise floor modulation and distortion, and that RF noise, a big NFM source, needs filtering throughout. Pursuit Perfect System 34:07
• 2018-12-12Watts says a high output voltage lets it drive any headphone; supercaps, as in the original Hugo TT, on both rails with an inductor mean the supply draws only DC. Pursuit Perfect System 37:27
• 2018-12-12Watts says TT2's inexpensive supply was customized after trying four or five to match battery performance; batteries sound warmer because they lack mains RF noise, which creates NFM. Pursuit Perfect System 38:09
• 2018-12-13Watts lists Hugo M Scaler features (pass-through, video and auto modes, remote, DX), says it runs from 9 to 15 volts, and that he uses it with a battery on flights. Pursuit Perfect System 14:11
• 2018-12-13Watts says he carries his M Scaler on 10 to 13 hour flights and chose the 15 volt input so a standard laptop battery backup could power it. Pursuit Perfect System 15:04
• 2018-12-16Watts explains why a DAC's reference supply needs zero noise and impedance, says chip DACs hide poor references, and describes TT2's DAVE-standard discrete reference and its warmer sound. Head-Fi, Dec 2018
• 2018-12-16Watts advises against replacing TT2's supplied PSU, saying he hears no change when it is pulled for 10 seconds and an earthed supply would likely degrade sound. Head-Fi, Dec 2018
• 2019-01-06Watts says the symptom is the PSU entering hiccup mode from supercap charge currents, meaning either a faulty PSU or a fault in TT2. needs context Head-Fi, Jan 2019
• 2019-01-31Watts says TT2 supercaps last over 11 years, it can stay on, warm-up takes about 10 minutes, pre-amps cost transparency, and linear PSUs at best sound the same. Head-Fi, Jan 2019
• 2019-02-04Watts says TT2 driving headphones draws about the same power as the M Scaler, giving about 6 to 7 hours from a Poweradd Pilot Pro 2. Head-Fi, Feb 2019
• 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
• 2019-03-17Watts says Qutest's supplied PSU is ungrounded, and SMPS have low coupling capacitance and RF filters linear supplies lack; a USB battery pack removes mains coupling, with tiny differences. Head-Fi, Mar 2019
• 2019-08-06Watts mocks upgrading the supply chain, saying TT2's real PSU is its internal inductor, supercap, RF filtering and regulation, and he hears no difference pulling the brick. Head-Fi, Aug 2019
• 2019-08-22Watts says setting a Pilot Pro 2 to 12 V limits peak output only above +7 dB, with no change in THD and noise, though tests of the filter show differences better. needs context Head-Fi, Aug 2019
• 2019-10-16Watts says TT2 shuts down below about 11 V and errors above 15.5 V, the M Scaler accepts about 5 to 15.5 V, and linear PSUs degrade sound and void warranty. Head-Fi, Oct 2019
• 2019-11-12Watts says 16 V from a PowerAdd could destroy the protection diode, 15 V is fine, and higher voltage is not better since everything becomes 5 V internally. Head-Fi, Nov 2019
• 2019-11-17Watts says his Poweradd, his third power bank, is the best, used over two years without capacity loss, though its output sometimes stays on until the plug is reseated. Head-Fi, Nov 2019
• 2019-11-17Watts says linear PSUs will sound worse than the supplied PSU on mains, batteries give complete isolation, and the handbook's toroidal note is generic, not an M scaler problem. Head-Fi, Nov 2019
• 2019-11-22Watts says 4.9 V on the micro USB supply is fine, since all rails are regulated internally, so long as it meets USB's 5 V +/- 0.25 V spec. Head-Fi, Nov 2019
• 2019-11-27Watts explains 2 GHz loop currents through the DAC ground plane, why clip-on ferrites stopped helping after his M scaler treatments, and why linear PSUs degrade sound. Head-Fi, Nov 2019
• 2019-12-30Watts uses the stock Aeon 2 cable, cannot discuss future products, and says TT2 sounds and measures the same on stock PSU, a power bank, or with PSU disconnected. Head-Fi, Dec 2019
• 2019-12-31Watts corrects a poster's energy math: TT2's super caps store 375 Joules, its 60W PSU covers 7.3W into 8 ohms plus about 13W quiescent, with dynamic bursts from the caps. Head-Fi, Dec 2019
• 2020-01-02Watts says 12v works with TT2, a 100W/h power bank gives over 7 hours driving headphones, warns about power-bank limits on flights, and suggests Hugo 2 for portability. Head-Fi, Jan 2020
• 2020-01-03Watts warns 18v or more destroys the Hugo M scaler's protection diode and voids that warranty, says a 9 or 12v power bank works fine, and notes Poweradd flight limits. Head-Fi, Jan 2020
• 2020-04-01Watts says 55 kHz PSU noise is irrelevant to the M scaler; 2 pF isolation coupling at 2 GHz matters, the ungrounded supplied SMPS helps, and linear PSUs worsen it. Head-Fi, Apr 2020
• 2020-04-01Watts says he chose TT2's SMPS as the only one matching a battery's measured HF performance; being ungrounded raises 2 GHz loop impedance, slightly helping the M scaler too. Head-Fi, Apr 2020
• 2020-04-23Watts says Chord can tell from the failure mode if an incorrect PSU has been used. Head-Fi, Apr 2020
• 2020-05-04Watts says a TT2 rebooting at start-up likely has a PSU failing the 3A draw; return to the dealer, try another PSU, else suspect a regulator fault. Head-Fi, May 2020
• 2020-05-07Watts says a car battery is the best PSU but a power bank suffices, TT2 gains nothing, and a battery helps the M scaler by removing 2GHz ground return currents. Head-Fi, May 2020
• 2020-05-25Watts says 13.2V works with M scaler and TT2 on separate supplies, TT2 is supply-insensitive, and a battery on the M scaler removes the ground loop into the DAC. Head-Fi, May 2020
• 2020-05-26Watts says he does not need battery power at home because his Wave BNC cables give enough isolation that battery use brings negligible improvement. Head-Fi, May 2020
• 2020-06-05Watts says the tingle is a safe 100 uA PSU leakage depending on local mains wiring, and grounding the chassis or a BNC input, away from the DAC, cures it. Head-Fi, Jun 2020
• 2020-06-25Watts says Qutest's BNC inputs take 768 kHz without transformers at 75 ohms, it was not designed for slow-ramping PSUs, and non-stock supplies void Chord's warranty. Head-Fi, Jun 2020
• 2020-07-04Watts says linear PSUs do change TT2's sound but worse, adding hum and RF noise that sounds brighter, and notes TT2 sounds and measures the same with the PSU disconnected. Head-Fi, Jul 2020
• 2020-07-06Watts says linear PSUs add mains hum, vibration, magnetic fields and coupling; TT2's chosen SMPS showed no noise degradation in a 96kHz bandwidth, is unearthed, and matched a battery. Head-Fi, Jul 2020
• 2020-07-07Watts says TT2's real PSU is internal (inductor, supercaps, RF filters), recommends XLR pins 1 and 2 for speakers, and warns some subs short pins 1 and 3. Head-Fi, Jul 2020
• 2020-07-20Watts says that is not possible with +/-75 V supplies for high-power amps, and he will make them work with the supplied PSU so a perfect supply brings negligible improvement. Head-Fi, Jul 2020
• 2020-07-24Watts says conventional phase shift seems unimportant but phase varying with time or amplitude is audible, defends sinc ringing for bandlimited signals, and discusses SMPS design and USB isolation. Head-Fi, Jul 2020
• 2020-08-03Watts says PSU leakage current causes the amp issue, which a battery avoids; earth Qutest via BNC, RCA, an earthed USB PSU or a chassis bolt, or earth the amp. Head-Fi, Aug 2020
• 2020-08-10Watts says 2 m BNC cables beat 1 m, solid-core 2 GHz ferrites help most, clip-on ferrites hurt with the M Scaler, and battery power breaks its ground loop. Head-Fi, Aug 2020
• 2020-08-17Watts says Hugo 2 has no signal-path capacitors to upgrade thanks to the DC servo, and its noise shaper output and separate rails give 214 dB PSU rejection in SPICE. Head-Fi, Aug 2020
• 2020-09-07Watts advises running the M Scaler from the 12 V battery and not worrying about TT2, since breaking the current path once suffices; keep the battery isolated from ground. Head-Fi, Sep 2020
• 2020-09-09Watts calculates a battery on a desk has about 0.1 pF to ground, 796 ohms at 2 GHz; a Poweradd battery on the M Scaler nearly eliminates BNC cable differences. Head-Fi, Sep 2020
• 2020-09-13Watts confirms the Hugo M Scaler needs only 1 A at 12 V. Head-Fi, Sep 2020
• 2020-09-30Watts says his DACs use switching regulators, which sounded better than linear ones from Hugo onward, and that random RF noise, not fixed switching noise, causes noise floor modulation. Head-Fi, Sep 2020
• 2020-09-30Watts says a linear supply will make no difference or degrade TT2's sound, and will invalidate the warranty. Head-Fi, Sep 2020
• 2020-09-30Watts says overvoltage damage from out-of-spec PSUs voids warranty cover, many audiophile PSUs are unregulated, and the supplied TT2 and M Scaler PSU measured as quiet as a battery. Head-Fi, Sep 2020
• 2020-10-01Watts says 12 V is fine for the Hugo M Scaler; damage occurs only at 16 V and above. Head-Fi, Oct 2020
• 2020-11-27Watts says TT2's unearthed PSU was chosen for the best measurements and battery-like sound; full isolation attenuates ground loop currents, at the cost of a 100uA leakage tingle. Head-Fi, Nov 2020
• 2020-11-28Watts says a TT2 that only starts on a 12V battery likely has a poor inrush limiter tripping the PSU; get it replaced, though running from 12V battery is fine. Head-Fi, Nov 2020
• 2020-12-14Watts says 6 V would destroy the FPGA; the supply must be USB compliant at 5 V +/- 0.25 V. Head-Fi, Dec 2020
• 2021-01-20Watts says balanced adds amplifiers that cost transparency, so his DACs are single-ended; halving gain halves noise for IEMs; linear PSUs add RF and noise floor modulation. Head-Fi, Jan 2021
• 2021-01-25Watts says the treble extension and tighter bass heard with an Sbooster supply are noise floor modulation from more RF, and SMPS RF filters give softer, warmer, less fatiguing sound. Head-Fi, Jan 2021
• 2021-03-05Watts explains TT2 draws only DC from the brick because a large inductor isolates the supercaps, keeping audio currents and PSRR distortion out; big toroids are not inherently better. Head-Fi, Mar 2021
• 2021-03-06Watts says he cannot imagine any mechanism by which a faulty stock PSU would cause channel imbalance in TT2. Head-Fi, Mar 2021
• 2021-04-01Watts says disconnecting the M scaler charger avoids the source-M scaler-Dave loop, CD players inject RF into mains, and changing Dave's PSU invalidates the warranty. Head-Fi, Apr 2021
• 2021-06-26Watts says a linear PSU only degrades or matches TT2's stock unit, since random mains RF raises noise floor modulation and brightness, and regrets not adding more RF filtering. Head-Fi, Jun 2021
• 2021-10-04Watts describes SPICE RF filter work showing random RF noise, unlike switching noise, causes noise floor modulation audible to -350dB; linear PSUs pass it, SMPS and batteries do not. Head-Fi, Oct 2021
• 2021-10-20Watts uses Dolby off on Shield, says 2go is not his project, recommends a power bank for Hugo 2 desktop use, and describes his DIY solid-core PTFE interconnects. Head-Fi, Oct 2021
• 2021-10-21Watts says longer M Scaler BNC cables sound better by suppressing 2GHz ground current, 2m beats 1m markedly, his PowerAdd supplies while charging, and the app sends 192k. Head-Fi, Oct 2021
• 2021-10-22Watts says supplied BNC cables are starters; 2GHz ferrites, Wave cables or battery power cure ground currents; Qutest uses Mojo's output stage; M Scaler was developed with TT2 and DAVE. Head-Fi, Oct 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 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 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
• 2022-02-09Watts says switching noise from DC-DC converters is easily filtered while random mains RF passes through linear supplies, so power banks are fine and linear PSU warmth is NFM. Head-Fi, Feb 2022
• 2022-02-09Watts says the power bank would run Qutest about 100 hours per charge but is too powerful for flying and lacks 12v for M scaler; he suggests a Krisdonia 25000mAh. Head-Fi, Feb 2022
• 2022-02-11Watts says audiophile linear supplies lack RF filters while SMPS need them for EMC approval, batteries off the mains avoid the issue, and active charging might explain the poster's report. Head-Fi, Feb 2022
• 2022-02-12Watts says SMPS tones do not cause NFM unlike random RF, recalls switching regulators beating linear in Hugo, and prefers power banks for isolation from RF ground currents. Head-Fi, Feb 2022
• 2022-02-13Watts says battery power on the M Scaler removed his need for ferrited BNC cables, and Wave cables removed the need for batteries, both cutting GHz ground currents into DAVE. 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
• 2022-02-26Watts reports 6.5 hours powering his M Scaler from a new power bank, warns against its DC out for Hugo 2, and explains annealing his DIY PTFE-insulated cable. Head-Fi, Feb 2022
• 2022-03-14Watts says linear supplies with large transformers and electrolytic capacitors filter RF poorly and add magnetic noise, so switch-mode supplies are always better for RF and stray magnetic fields. Head-Fi, Mar 2022
• 2022-03-22Watts says the units have internal regulation and RF filtering, so better supplies make no difference or sound worse (brighter) from RF noise of big linear PSUs. article, Mar 2022
• 2022-03-22Watts says he spends only on parts that improve sound quality, so the devices are designed to work with their supplied power supply unit. article, Mar 2022
• 2022-03-27Watts recounts redesigning Qutest's regulation after Qute proved PSU sensitive, admits his 2016 USB preference on Dave was RF brightness, and calls optical the reference input. Head-Fi, Mar 2022
• 2022-04-12Watts says DAVE is earthed because its PSU is inside the chassis, TT2's double-insulated supply needs no earth, and earthing is moot since GHz noise is the main problem. Head-Fi, Apr 2022
• 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
• 2022-06-15Watts says the M scaler regulates input to 5 V, 16 V could damage it, and he will try a Krisdonia at 9 V, preferring warmer sound to RF brightness. Head-Fi, Jun 2022
• 2022-06-19Watts says he would never design a power bank; his focus is making his designs immune to attached sources and supplies, which he admits needs more work. Head-Fi, Jun 2022
• 2022-06-19Watts says his designs already use many RF filters and separate regulators to prevent source and PSU problems, but perfect immunity may prove impossible. Head-Fi, Jun 2022
• 2022-06-21Watts says he preferred the Krisdonia's 9 V setting on his Chicago flight, distrusts Krisdonia reliability, found only PowerAdd reliable, and battery power removed the need for better BNC cables. 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
• 2022-06-22Watts says any charger usually makes little difference; test by disconnecting it, and if it matters, power Mojo 2 from a power bank unplugged from mains. Head-Fi, Jun 2022
• 2022-06-29Watts explains a swollen 1000uF clock-regulator filter cap in a DAVE is very unlikely as a wear failure and suggests miswiring during a PSU change, which he does not recommend. Head-Fi, Jun 2022
• 2022-07-01Watts says the new display needs a different protocol so the FPGA is updated, with no change to sound quality, and warns not to assume a linear PSU is better. Head-Fi, Jul 2022
• 2022-07-18Watts calculates DAVE's PSU-induced errors at -198dB from the linear regulator and -234dB from the SMPS, saying RF noise is what changes sound with supplies, and SMPS has less. Head-Fi, Jul 2022
• 2022-07-21Watts says non-supplied PSUs void Chord's warranty, linear supplies lack 100 kHz to 10 GHz RF filtering, and transient timing reconstruction differs from transient response, which only listening tests reveal. Head-Fi, Jul 2022
• 2022-10-12Watts says the discrete conversion components are fed from a different power supply and the digital components are completely isolated. Upscale Audio 2:30
• 2022-10-18Watts says Krisdonia noise is the likely problem, power-bank tests wait until after his Asia trip, and a 100 Wh Bixpower would run an M Scaler 8 hours. Head-Fi, Oct 2022
• 2022-11-03Watts says a car battery is the best PSU and his target for an upcoming product's PSU is to sound the same as one, noting his negativity about linear PSUs. needs context Head-Fi, Nov 2022
• 2023-01-04Watts reports the Bixpower BP90-12v ran an M Scaler nearly 10 hours and clearly beat the Krisdonia on depth and separation, the Poweradd less clearly. Head-Fi, Jan 2023
• 2023-01-04Watts says he connected the Bixpower using a regular cable plus the adaptor supplied with it. Head-Fi, Jan 2023
• 2023-01-06Watts says with a Poweradd powerbank and optical on the M Scaler, quality BNC sounded like Wave Stream, since no ground currents can reach the DAC's ground plane. Head-Fi, Jan 2023
• 2023-01-08Watts says only an optical source plus battery on the M Scaler guarantees noise-free operation, as mains units leak noise even via optical; the Choral M Scaler addresses this. Head-Fi, Jan 2023
• 2023-02-05Watts says he did, with a new power bank lasting 10 hours where the previous one lasted four or five, useful on 13-hour flights to Asia or Los Angeles. Soundnews 48
• 2023-02-05Watts says in 2013 or 2014 he would have chosen linear supplies, since switching creates RF noise, which causes noise floor modulation and a brighter sound. Soundnews 24:50
• 2023-02-05Watts says Hugo must keep power low: linearly regulating 8 volts to a 1 volt, one amp FPGA core dissipates 8 watts; a Mojo-style unit manages 3 watts at most. Soundnews 25:32
• 2023-02-05Watts says Hugo can dissipate about 4 watts without fans; a 95% efficient switch-mode regulator from 8 volts to 1 volt cuts dissipation to about one and a half watts. Soundnews 26:15
• 2023-02-05Watts says portables must use switching regulators, and they surprisingly sounded warmer and smoother than linears, but switching regulators need RF filters. Soundnews 26:49
• 2023-02-05Watts says RF filters go on both the input and output of the switching regulator to remove switching noise, which helps RF noise. Soundnews 27:41
• 2023-02-05Watts says 8 watts dissipated from a 1 V core creates much more circuit noise, so linears magnify digital core noise; he has recently been doing SPICE modeling. Soundnews 27:55
• 2023-02-05Watts says a switch-mode supply's regular PWM signal is easy to filter to nanovolts with a few parts, but filtering random noise needs a filter orders of magnitude more complex. Soundnews 29:53
• 2023-02-05Watts says regulator PWM intermodulates into discrete harmonics outside the audio band, but random RF noise creates in-band products and noise floor modulation; switch-mode supplies' filters help. Soundnews 30:41
• 2023-02-05Watts says better RF filtering and less analog noise make 3 MHz switching regulators sound much better than linears, so he uses them even where dissipation is no concern. Soundnews 31:43
• 2023-02-05Watts says, turning to power amplifiers, that audiophile linear power supplies have no built-in RF filters. Soundnews 32:29
• 2023-02-05Watts says SPICE showed filtering random mains RF from 100 kHz to 10 GHz to nanovolts is very hard; linear supplies have no filtering, switching supplies filter both ends. Soundnews 32:43
• 2023-02-05Watts says EMC and safety rules force RF filters into switching supplies, making them better than unfiltered linears, which also suffer 50 Hz ripple harmonics. Soundnews 33:28
• 2023-02-05Watts says the ripple comes from the triangular waveform on the capacitors after the transformer. needs context Soundnews 34:09
• 2023-02-05Watts says in a power amplifier the ripple grows with output, so noise from 50 Hz to 10 kHz pumps with the music signal, which is very audible. Soundnews 34:22
• 2023-02-05Watts says this measures badly and sounds worse; measurements serve to reduce identified problems, and switch-mode supplies have much lower ripple that does not vary with signal level. Soundnews 35:05
• 2023-02-05Watts says DAVE was developed with its switching supply, showing no noise floor modulation or 100 Hz issues and with extensive internal RF filtering; TT2 got more supply work. Soundnews 36:34
• 2023-02-05Watts says around 2016 people began using linear supplies with 2Qute, illustrating how forums help his work. Soundnews 37:22
• 2023-02-05Watts says people heard differences between supplies on the DAC (he says Qutest, later correcting to 2Qute) despite its power supply rejection, so he tried the best supply available. Soundnews 37:46
• 2023-02-05Watts says the best supply is a car battery. needs context Soundnews 38:15
• 2023-02-05Watts says a car battery has no RF noise, 300 amps of delivery and under one milliohm impedance, measuring like a short on the Audio Precision: the reference supply. Soundnews 38:19
• 2023-02-05Watts says a car battery is the reference, the best power supply possible. Soundnews 39:05
• 2023-02-05Watts says the unit's 12 volt input (he says Qutest, later corrected to 2Qute) let him try a car battery after reports favoring linear supplies, and he was astonished. Soundnews 39:13
• 2023-02-05Watts says 2Qute was supply-sensitive, which does not mean linears beat switching; for Qutest he improved regulation and RF filtering so a switching supply matched a 12-volt battery. Soundnews 39:49
• 2023-02-05Watts says Qutest's supplied unit equals a 12-volt car battery, so linear supplies that sound different degrade it; TT2 runs ten seconds on supercaps with the supply unplugged. Soundnews 40:35
• 2023-02-05Watts says unplugging and replugging for those 10 seconds gives no audible difference from the switch-mode supply. needs context Soundnews 41:26
• 2023-02-05Watts says the difference is tiny; of many TT2 supplies measured at 100 kHz bandwidth all degraded performance except one, at half a dB, which sounded like a car battery. Soundnews 41:34
• 2023-02-05Watts says people complain that TT2 comes with a cheap power supply. Soundnews 42:27
• 2023-02-05Watts says he cares only about actual performance; TT2's supply is as good as a car battery, so a linear supply's audible difference on TT2 is to him a degradation. Soundnews 42:43
• 2023-02-05Watts says DAVE is different: he has not done battery tests on it, as its supply is more complicated, plus and minus 15 volts and 5 volts. Soundnews 43:18
• 2023-02-05Watts says a brighter or more transparent change is a degradation and a warmer, smoother one a benefit; reports are mixed, and 'brighter' suggests people prefer distortion. Soundnews 43:45
• 2023-03-26Watts says car batteries are the best. Eric's Hi-Fi 12:32
• 2023-03-26Watts says a car battery is the best supply, with zero noise, sub-milliohm impedance and 300 amps capability, and is his reference for past and future DACs. Eric's Hi-Fi 12:36
• 2023-03-26Watts says switch mode supplies have RF filters on input and output while audio linear supplies lack them; RF makes sound brighter, an artificial illusion of transparency and detail. Eric's Hi-Fi 13:22
• 2023-03-26Watts says reducing RF noise makes sound warmer, softer and quieter, allowing louder playback, less impressive but more natural; audiophiles should use car batteries as a reference. Eric's Hi-Fi 14:07
• 2023-03-26Watts says homes and streets hold many switch mode supplies, but the main worry is random RF noise from fluorescent tubes and LEDs, while switchers produce a regular PWM waveform. Eric's Hi-Fi 14:59
• 2023-03-26Watts says he aims for supplies that sound like a car battery; around 2016 he was shocked how much better 2Qute sounded on one, and addressed this with Qutest. Eric's Hi-Fi 18:34
• 2023-03-26Watts says Qutest and TT2 sound the same on a car battery as on the supplied switch mode supply, except TT2 with an M Scaler; better supplies would add RF. Eric's Hi-Fi 19:18
• 2023-03-26Watts says he prefers solving problems fundamentally to selling costly supplies; DAVE predates his power supply work but has more RF filtering than TT2, and he is satisfied with it. Eric's Hi-Fi 20:03
• 2023-03-26Watts says TT2 has supercaps and RF filters, but the supercaps do not help with RF noise. Eric's Hi-Fi 20:47
• 2023-03-26Watts says supercaps help low frequency noise but not RF noise because their impedance is too high, so specialist RF treatment is still needed. Eric's Hi-Fi 20:56
• 2023-03-26Watts says supercaps act like a battery only at 50 or 100 Hz; above 20 kHz internal inductance raises impedance, about 50 milliohms versus a car battery's sub one milliohm. Eric's Hi-Fi 21:18
• 2023-03-26Watts says claiming a supercap supply is perfect is wrong; at gigahertz RF what matters is minimal inductance, tracking impedance and capacitor connections, using extremely small capacitors. Eric's Hi-Fi 22:02
• 2023-03-26Watts says capacitors must be about half a millimeter to filter gigahertz noise; 100 MHz to 10 GHz was hardest, and this work is for the Ultima DAC's separate supply. Eric's Hi-Fi 22:44
• 2023-03-26Watts says the Ultima DAC's power supply, the best in RF noise terms, still uses switch mode supplies and is working really well. Eric's Hi-Fi 23:29
• 2023-05-27Watts says reducing RF noise lowers perceived volume by one or two dB, since noise floor modulation sounds brighter, and is convinced a linear supply on TT2 adds RF noise. Head-Fi, May 2023
• 2023-06-01Watts says a PowerAdd power bank and the supplied SMPS sounded and measured the same in the audio band, while other SMPS tested for TT2 measured poorly at high bandwidth. Head-Fi, Jun 2023
• 2023-06-02Watts says the filters together with the supercaps filter from 5 Hz to GHz with no switching-frequency notches, and the mains-connected APx555 suffers from mains and earthing noise loops. Head-Fi, Jun 2023
• 2023-06-18Watts says an isolated power bank or Wave cables break the M Scaler's GHz ground loop, longer standard BNC sounds better via common mode inductance, and Krisdonia sounded worse. Head-Fi, Jun 2023
• 2023-06-18Watts says TT2 is fine on its supplied PSU, a power bank made no difference, and earthing is largely irrelevant at RF once mains connects everything via transformer winding capacitance. Head-Fi, Jun 2023
• 2023-08-07Watts says Class H cost depends on the PSU, all analog electronics suffer noise floor modulation, and Mojo 2's battery charger uses a simple Class H type design. Head-Fi, Aug 2023
• 2023-09-04Watts names the Bixpower BP90-12v as the best-sounding pack, used only on flights; supplied PSU and Wave cables sound the same with optical input. Head-Fi, Sep 2023
• 2023-12-16Watts says Qutest needs 5v +/-0.25v, a USB power bank is safe, and over 5v would blow an easily replaced protection diode, with no such failures reported. Head-Fi, Dec 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
• 2024-02-22Watts says galvanic isolation fails at GHz via capacitance, optical breaks the link, and an LPS on TT2 would be a downgrade that sounds etched due to no RF filtering. Head-Fi, Feb 2024
• 2024-02-29Watts says two new products took over 5 man-years, he had no involvement in Suzi, and his new PSUs isolate RF both ways and remove modulated mains ripple. Head-Fi, Feb 2024
• 2024-03-01Watts says the new PSUs must stay independent, as their high impedance from 1MHz to 10GHz blocks RF currents that shared supplies would couple between scalers and DACs. Head-Fi, Mar 2024
• 2024-03-02Watts confirms the base PSU design has variants for future products, notably the Ultima DAC. Head-Fi, Mar 2024
• 2024-03-20Watts says Toslink optical, usually considered the worst digital connection, is in his opinion the best, and introduces the contentious myth that linear power supplies must beat switch mode. MFG Audio Reviews 45
• 2024-03-20Watts previews his points: linear power supplies create distortion, passive components can measure perfectly yet change sound, and cables and sources can differ despite bit-perfect data. MFG Audio Reviews 1:32
• 2024-03-20Watts says optical cables working at 192 kHz sound the same with his DACs, unlike jitter-sensitive DACs, then calls 'linear supplies are best' his most contentious myth. MFG Audio Reviews 27:01
• 2024-03-20Watts says he used linear regulators on the DAC64 expecting switchers to sound worse, but Hugo One needed internal switch mode supplies for efficiency, so he compared the two. MFG Audio Reviews 27:50
• 2024-03-20Watts says the switching regulators sounded considerably better, warmer and smoother, because switchers force thorough RF filtering at input and output, and begins a noisy-current example. MFG Audio Reviews 28:35
• 2024-03-20Watts says 1 amp of noisy current through a linear regulator from 1 V to 5 V stays 1 amp, while a switcher outputs 200 milliamps, limiting noise propagation. MFG Audio Reviews 29:24
• 2024-03-20Watts says he gets into trouble saying switch mode supplies are fine, and starts listing what an ideal power supply needs, first zero random RF noise. MFG Audio Reviews 30:08
• 2024-03-20Watts says amplifiers with significant output need zero supply impedance in the audio band, because push-pull stages draw current from one rail at a time, creating distorted voltage drops. MFG Audio Reviews 30:52
• 2024-03-20Watts says zero supply impedance avoids power-supply-induced distortion, and that linear power supplies have no RF filters, letting large amounts of random mains RF noise through. MFG Audio Reviews 31:36
• 2024-03-20Watts says unregulated linear supplies have 60 Hz ripple, a few volts on a power amplifier, that grows as the signal gets larger. MFG Audio Reviews 32:18
• 2024-03-20Watts says signal-dependent ripple feeds through power amplifiers, visible as ripple harmonics in Stereophile measurements, audibly softening bass definition; regulated linear supplies still pass significant ripple. MFG Audio Reviews 33:04
• 2024-03-20Watts says switch mode supplies always have input and output RF filters for EMC, fixed-frequency switching matters little, and during COVID he SPICE-modeled filters for noise up to 10 GHz. MFG Audio Reviews 33:55
• 2024-03-20Watts says his SPICE models included parasitics; a two-stage LC filter cut fixed-frequency switching noise to picovolts, but random noise up to 10 GHz needed very complex filtering. MFG Audio Reviews 34:50
• 2024-03-20Watts says a current project needs 75 amps at 1 volt from 24 volts, which would mean 1.8 kilowatts dissipation with linears, while his switch mode design uses 80 watts. MFG Audio Reviews 36:38
• 2024-03-20Watts summarizes that linear supplies create distortion, lack RF filters (so noise floor modulation, measurable or not), add signal-related hum harmonics, and toroidal transformers buzz and radiate signal-dependent magnetic fields. MFG Audio Reviews 37:31
• 2024-03-20Watts says switch mode supplies' small transformers have little stray field, and a car battery is the best power-amp supply: 300 amps, sub-milliohm impedance, no RF if screened. MFG Audio Reviews 38:19
• 2024-03-20Watts says lithium-ion batteries are ideal for low-power DAC amps, supplies should be judged against battery operation, and a switch mode supply sounding identical to a car battery is perfect. MFG Audio Reviews 39:06
• 2024-03-20Watts says adding a linear supply makes the sound brighter, crystalline and sharper-edged, fooling listeners into thinking it is better; separation, focus and listening fatigue reveal it is worse. MFG Audio Reviews 39:52
• 2024-03-20Watts says supplies for a DAC amp depend on its internal regulation and RF filtering, need a holistic approach, and that battery operation is always the ideal reference. MFG Audio Reviews 40:30
• 2024-03-20Watts says a battery in DAVE is a good idea, mentions someone feeding a 120-volt battery into DAVE's mains input with good results, and would design DAVE differently today. MFG Audio Reviews 56:32
• 2024-03-20Watts says DC on the mains makes toroidal transformers buzz badly, recalling that his toroidal transformer supplier attributed intermittent buzzing to DC offsets. MFG Audio Reviews 57:28
• 2024-03-20Watts says yes: inverters are not RF filtered, and his SPICE modeling showed that eliminating random RF noise requires extremely complex filters. MFG Audio Reviews 1:01:13
• 2024-05-10Watts says a power supply feeds Quartet and has a very sophisticated RF filter built into it. Reactcore 0
• 2024-05-16Watts says Quartet has a power supply delivering 75 amps to the FPGAs, plus a separate power supply of his own design whose key element is an RF filter covering DC to 10 gigahertz. ConvinceMeAudio 1:31
• 2024-05-16Watts lists five FPGAs, two million lines of code, 2,500 discrete components and a 75 amp supply of his own design, with RF filters from DC to 10 GHz. The Speaker Shack 4:00
• 2024-05-16Watts says the RF filter has over 200 components and the same filter sits at Quartet's input and at the power supply output, controlling noise in and out. The Speaker Shack 4:43
• 2024-05-17Watts says Quartet is as complex as a PC in a small box and has a separate 75 amp power supply to feed its FPGAs' power requirements. AVstore 1:13
• 2024-06-18Watts says Quartet will cost more than DAVE, and describes Spice-modeled 'pinch-off' RF filters in its separate supply and input, isolating DAVE from its noise and making the sound warmer and smoother. article, Jun 2024
• 2024-06-18Watts says the supply is switch-mode because the core needs 75 amperes at one volt; a linear supply would dissipate 1.8 kilowatts and add more RF noise. article, Jun 2024
• 2024-06-25Watts says iFi's 1uV PSU noise figure is meaningless without FFT bandwidth, implying 141 uV broadband; TT2's noise floor is 9nV and Chord's Li-ion batteries measure below the APx555. Head-Fi, Jun 2024
• 2024-07-12Watts says the M Scaler was noticeably sensitive to BNC cables (ferrites helped) and sources, from current injected into the DAC despite galvanic isolation; a battery power bank solves it. HIFICLUB 45:42
• 2024-07-12Watts says he developed a supply with special RF filters giving battery-like isolation, reducing sensitivity to BNC cables and sources, and raises why he does not build a network player. HIFICLUB 46:35
• 2024-07-12Watts says with a perfect M Scaler and DAC every bit-perfect source would sound the same, so he hardens DACs and scalers against source noise, focusing on the power supply. HIFICLUB 47:23
• 2024-07-12Watts rejects criticism that audible source differences mean the M Scaler is badly designed: it passes EMC and has galvanic isolation; Quartet is isolated further. HIFICLUB 48:49
• 2024-07-25Watts says it is two boxes, with a separate supply, because its five large FPGAs need 75 amps; it has 4 million taps, 4 times the Hugo M Scaler. Hifi Pig TV 1:28
• 2024-11-04Watts says his in-DAC switching regulators run at 500kHz to 1MHz, while Quartet's mains supply runs at 70k followed by a regulator above 500k and a passive RF filter. Head-Fi, Nov 2024
• 2024-12-03Watts says the third supply is the reference voltage supply feeding the pulse array flip-flops, which needs the lowest possible noise and impedance. needs context Head-Fi, Dec 2024
• 2025-01-04Watts says the M Scaler regulates input to 5v, so falling BixPower voltage neither changes sound nor risks damage; he recommends the supplied PSU or BixPower. Head-Fi, Jan 2025
• 2025-01-08Watts says valve amps easily sound musical but bipolar can sound better, estimates 38 to 76 hours of Hugo M Scaler use per car battery, and says measurements ignore transients. Head-Fi, Jan 2025
• 2025-01-13Watts says Quartet's price is unknown but it will ship with its own PSU, the only one meeting its demands after extreme RF filtering work. Head-Fi, Jan 2025
• 2026-03-17Watts says a car battery (12 volts, 300 amps, sub one milliohm) is the perfect supply, and his benchmark is that a DAC on mains should sound like on battery. ecoustics 1:08:48
• 2026-03-17Watts says sounding the same as battery shows the supply is good, though not that all RF issues are solved, and mentions Quartet was very challenging. ecoustics 1:09:32
• 2026-03-17Watts says the expensive scaler for DAVE has 'five two hundred T' FPGAs and a 75 amp supply that can create a lot of noise, which he had to keep from corrupting the DAC. ecoustics 1:10:13
• 2026-03-17Watts says he designed a separate power supply for the unit with complex RF filtering and a new RF filter architecture. needs context ecoustics 1:10:38
• 2026-03-17Watts says he wanted RF rejection down to nanovolts, actually picovolts, given the noise levels inside a processor. needs context ecoustics 1:10:54
• 2026-03-17Watts says in listening tests the mains supply sounded better than a 24-volt lithium-ion battery, so he repeated the test carefully, focusing on noise floor modulation. ecoustics 1:11:12
• 2026-03-17Watts says warmer sound and better separation indicate less noise floor modulation and RF; mains won, which he traced to the battery's high RF impedance and poorer cables. ecoustics 1:11:58
• 2026-03-17Watts says adding low shunt capacitors and special RF cables brought parity, the battery then slightly better than the mains supply. ecoustics 1:12:50
• 2026-03-24Watts says Quartet has five 200T FPGAs, five times the Hugo M Scaler's chip count, with 75 amp peak currents, so the supply must block noise both in and out. Audio Force 24:08
• 2026-03-24Watts says he developed a complex new 'pinch-off RF filter' to keep RF in and out of Quartet, aiming at battery sound, since lithium-ion or car batteries are the ultimate source. Audio Force 25:45
• 2026-03-24Watts says Quartet's supply makes it sound the same as running on batteries, so owners cannot upgrade it: it already has the best possible power supply. Audio Force 26:36
• 2026-10-02Watts says forum reports that power supplies changed 2Qute's sound worried him, so he tested it on a car battery, as a 12 volt input device. HiFi Buys 2:21:42
• 2026-10-02Watts says a car battery is a perfect power supply: under one milliohm, no measurable noise, and 300 amps available almost instantly. HiFi Buys 2:22:31
• 2026-10-02Watts says 2Qute sounded dramatically better on the car battery, so Qutest got better regulation and RF filtering, after which he heard no difference from the battery. HiFi Buys 2:22:57
• 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 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
• 2026-10-17Watts lists Quartet's hardware problems: heat removal, nine prototypes, over 2,000 components, BNC cables sounding the same, and a supply as good as battery power. article, Oct 2026
• 2026-10-17Watts calls one chassis a nightmare because processing noise upsets the DAC; hence separate supplies and a new two-way pinch-off RF filter of about 200 components each. needs context article, Oct 2026
• 2026-10-17Watts says keeping it separate with its own supplies avoids the issue, and he compared against a large lithium-ion battery, meeting his target of equal sound quality. article, Oct 2026