Rogue Audio Pharaoh II integrated amplifier Measurements

Sidebar 3: Measurements

I performed the measurements of the Rogue Audio Pharaoh II with my Audio Precision SYS2722 system. As the Rogue's output stages operate in class-D, all the measurements other than frequency and RIAA responses were taken with Audio Precision's auxiliary AUX-0025 passive low-pass filter, which reduces the level of noise above 80kHz and eliminates noise above 200kHz. Without the filter, 376mV of ultrasonic noise was present at the loudspeaker terminals, with a center frequency of 428kHz.

Looking first at the line-level inputs, the Rogue Pharaoh II preserved absolute polarity, ie, was noninverting from its loudspeaker output with both balanced and single-ended inputs but inverted polarity from the headphone output. With single-ended input signals, the maximum voltage gain at 1kHz was 37dB from the loudspeaker output into 8 ohms and 21.4dB from the headphone output. The gains with the balanced input were 6dB lower rather than the usual 6dB higher. The balanced input impedance was a very high 380k ohms at 20Hz and 1kHz and still very high at 310k ohms at 20kHz. The single-ended input impedance was still usefully high, at 28.5k ohms at 20Hz and 1kHz, 23.5k ohms at 20kHz.

The headphone output's source impedance was a low 1 ohm across the audioband. The loudspeaker output impedance was very low, at 0.05 ohms at low and middle frequencies, increasing very slightly to 0.075 ohms at the top of the audioband. The variation in the Rogue amplifier's small-signal frequency response with our standard simulated loudspeaker was therefore less than ±0.1dB (fig.1, gray trace). Into resistive loads (fig.1, blue, red, cyan, magenta, and green traces), the Pharaoh II's frequency response was down by 1dB at 25kHz. Fig.1 was taken with the volume control set to its maximum and the balance control centered. The right channel was 0.2dB higher in level than the left; this slight imbalance was the same at lower settings of the volume control. The Pharaoh II's reproduction of a 10kHz squarewave (fig.2) showed only the slightest hint of overshoot, with no ringing.

1222RogPharfig01

Fig.1 Rogue Audio Pharaoh II, frequency response at 2.83V into: simulated loudspeaker load (gray), 8 ohms (left channel blue, right red), 4 ohms (left cyan, right magenta), and 2 ohms (green) (1dB/vertical div.).

1222RogPharfig02

Fig.2 Rogue Audio Pharaoh II, small-signal 10kHz squarewave into 8 ohms.

The Pharaoh II's channel separation (not shown) was >70dB in both directions below 1kHz but decreased to 36dB, R–L, and 40dB, L–R, at 20kHz. Taken with the AUX-0025 filter installed, the unbalanced inputs shorted to ground, and the volume control set to its maximum, the unweighted, wideband signal/noise ratio (ref. 1W into 8 ohms) was 64.2dB (average of the two channels). This ratio only improved by 1dB when the measurement bandwidth was restricted to 22Hz–22kHz and by another 2dB when A-weighted.

Spectral analysis of the low-frequency noisefloor while the Rogue amplifier drove a 1kHz tone at 1Wpc into 8 ohms, with the volume control set to the maximum (fig.3, blue and red traces), revealed a relatively high level of AC-related spuriae at 60Hz and its odd-order harmonics, which will be due to magnetic interference from the large toroidal power transformer, perhaps entering via the steel pins of the 12AU7 input tubes. Setting the volume control to –12dB (fig.3, green and gray traces) reduced the levels of these spuriae by approximately the same 12dB, which means that the noise pickup occurs before the volume control. Repeating the spectral analysis with the balanced input (not shown) reduced the levels of these supply-related spuriae by the same 6dB as the reduction in gain with this input.

1222RogPharfig03

Fig.3 Rogue Audio Pharaoh II, spectrum of 1kHz sinewave, DC–1kHz, at 1Wpc into 8 ohms with volume control set to its maximum (left channel blue, right red) and to –12dB (left green, right gray) (linear frequency scale).

Rogue specifies the Pharaoh II's maximum power as 250Wpc into 8 ohms (24dBW) and 400Wpc into 4 ohms (23dBW), both powers equivalent to 24dBW. With our usual definition of clipping—when the THD+noise reaches 1%—I measured clipping powers of 240Wpc into 8 ohms (23.8dBW, fig.4), and 380Wpc into 4 ohms (22.8dBW, fig.5) with both channels driven. (I don't hold the AC wall voltage constant in these tests; it had dropped from 119.1V with the Pharaoh II idling to 117.4V with the amplifier clipping into 8 ohms and to 116.8V with it clipping into 4 ohms.) The shape of the traces in these graphs suggests that the measured THD+N is dominated by noise below 2W and that the amplifier uses a limited amount of loop negative feedback, presumably, given the high linearity of the NCore output stage, in the tubed stage.

1222RogPharfig04

Fig.4 Rogue Audio Pharaoh II, distortion (%) vs 1kHz continuous output power into 8 ohms.

1222RogPharfig05

Fig.5 Rogue Audio Pharaoh II, distortion (%) vs 1kHz continuous output power into 4 ohms.

Fig.6 shows how the percentage of THD+N in both channels varied with frequency into 8 and 4 ohms at 20V, equivalent to 50W into 8 ohms (blue and red traces) and 100W into 4 ohms (green and gray traces). The THD+N was close to 0.2% (–34dB) across the audioband into both load impedances. This level of distortion might be audible if it was comprised of high-order harmonics like the 5th and 7th. Fortunately, the distortion waveform was predominantly the subjectively innocuous second harmonic (figs.7 and 8). Intermodulation distortion, even at high powers, was relatively low, with the 1kHz difference product produced by the Pharaoh II driving an equal mix of 19 and 20kHz tones at 100Wpc peak into 4 ohms lying at –60dB (0.1%, fig.9). The higher-order products at 18 and 21kHz were much lower in level.

1222RogPharfig06

Fig.6 Rogue Audio Pharaoh II, THD+N (%) vs frequency at 20V into 8 ohms (left channel blue, right red), 4 ohms (left green, right gray).

1222RogPharfig07

Fig.7 Rogue Audio Pharaoh II, left channel, 1kHz waveform at 50W into 8 ohms, 0.19% THD+N (top); distortion and noise waveform with fundamental notched out (bottom, not to scale).

1222RogPharfig08

Fig.8 Rogue Audio Pharaoh II, spectrum of 50Hz sinewave, DC–1kHz, at 50Wpc into 8 ohms (left channel blue, right red; linear frequency scale).

1222RogPharfig09

Fig.9 Rogue Audio Pharaoh II, HF intermodulation spectrum, DC–30kHz, 19+20kHz at 100Wpc peak into 4 ohms (left channel blue, right red; linear frequency scale).

To examine the behavior of the Rogue's phono input, I connected a wire from the Audio Precision's ground terminal to the grounding lug on the Rogue's rear panel to obtain the lowest noise. The phono input inverted absolute polarity at the headphone output in both MM and MC modes but preserved polarity at the loudspeaker outputs. The maximum gain at 1kHz at the speaker outputs was 76.8dB (MM) and 97.5dB (MC). At the headphone output, the maximum gain was 61.2dB (MM) and 81.9dB (MC). I performed all the subsequent testing using the headphone output, and, other than S/N ratio, with the volume control set to –20dB in order to avoid clipping.

With the input impedance set to 47k ohms, I measured 47k ohms from 20Hz to 20kHz. With the impedance set to 1000 ohms, I measured 986 ohms across the audioband; set to 300 ohms, the impedance was 302 ohms; and set to 100 ohms, it was 101 ohms. The phono input's audioband RIAA error was very low in the right channel (fig.10, red trace), though a little higher above 2kHz in the left channel (blue trace). The low frequencies rolled off below 80Hz, reaching –3dB at 20Hz.

1222RogPharfig10

Fig.10 Rogue Audio Pharaoh II, phono input, response with RIAA correction (left channel blue, right red) (1dB/vertical div.).

With the MM phono input, the wideband, unweighted S/N ratio with the inputs shorted to ground and the volume control set to the maximum was a very good 74.1dB in both channels, ref. 1kHz at 5mV. Restricting the measurement bandwidth to the audioband increased the ratio to 75dB, while an A-weighting filter further increased the ratio to 80dB. The S/N ratios in MC mode were 20dB lower, but this is still a relatively quiet phono stage.

Measured at the headphone output, the phono input's overload margins were relatively high at all audio frequencies: >16dB in both MM and MC modes, ref. 1kHz at 5mV for MM and ref. 1kHz at 500ÊV for MC. The phono distortion signature was pure second harmonic, lying at –60dB (0.1%) with the nominal MM input level of 1kHz at 5mV (fig.11). The level of the 1kHz difference product with an equal mix of 19 and 20kHz tones (fig.12) was similar to that with the line inputs, though high-order intermodulation products were much lower in level.

1222RogPharfig11

Fig.11 Rogue Audio Pharaoh II, MM phono input, spectrum of 1kHz sinewave, DC–10kHz, for 5mV input, measured at headphone output (left channel blue, right red, linear frequency scale).

1222RogPharfig12

Fig.12 Rogue Audio Pharaoh II, MM phono input, HF intermodulation spectrum, DC–30kHz, 19+20kHz for 100mV input, measured at headphone output (left channel blue, right red; linear frequency scale).

The Rogue Audio Pharaoh II's measured performance indicates that it resembles an intriguing marriage between a low-distortion, low-noise, high-power class-D output stage and a higher-distortion, higher-noise, tubed input stage. At the time of writing I had not seen HR's review; I'll be interested to read his take on the Pharaoh II's sound character.—John Atkinson

COMPANY INFO
Rogue Audio Inc.
PO Box 1076
Brodheadsville, PA 18322
info@rogueaudio.com
(570) 992-9901
ARTICLE CONTENTS

COMMENTS
Glotz's picture

I really appreciate your personal insights on this as well as SET Tube-based amplification.

But what about single-ended transistor-based amps?

I've had my eye on the Audio By Van Alstine DVA-225 monos (SET), and I'd really like to put my ear on them sometime. Given their direct, custom order business model, it takes a bit more courage to audition.

I'm also searching out the Rogue hybrid power amps to feel them out as well.

I'd really like to see the market put out a GaN-based power amplifier for under $5k as well. I'm sure one day that will happen, given their burgeoning presence in the market now.

Very nice column as usual; I always feel like we know your brain and soul a bit more with every month's writing.

Happy Holidays to Herb and the rest of the Stereophile staff!

Herb Reichert's picture

My solid-state reference amplifier for use with the Falcon speakers is the Nelson Pass-designed First Watt F8; which is single-ended, and uses a touch of 'tidy-up' feedback.

To my way of looking, the F8, and its First Watt sibling, the J2 (also single-ended), and the SIT-3 are among the most innovative amp designs of this era.

In audio we must always champion innovation and engineering diversity. If we don't, the listening party is over.

hr

Jack L's picture

Hi

Indeed.

F8 employs current feedback intead of voltage feedback used in J2.

As Nelson Pass said: "I enjoy amplifiers with a little personality",
the power output coupling capacitors he used are "2 big electrolytic & one PP capacitor with a roll-off of 1Hz."

All capacitors get their own "personality" sound qualtiy. The last type of caps I would ever use for music signal coupling is electrolytic due to its complex dissipation factor & ESR etc etc due to its dielectric used. Not sooo good sounding at all.

For F8 $4,000 selling price, Nelson could have used better sounding coupling capacitors than electrolyitic.

FYI, I don't even electrolytic capacitors for power supply ripple filter caps for its sonic issue. I've used motor-run OIL capacitors instead !

Listening is believing

Jack L

georgehifi's picture

JA:"The Pharaoh II's reproduction of a 10kHz squarewave (fig.2) showed only the slightest hint of overshoot, with no ringing."

Is this the reason there is no hint of overshoot, because you can't see it when it's measured at low level + - 1v output, with the AUX-0025 bench testing filter installed on the amps output?

Cheers George

John Atkinson's picture
georgehifi wrote:
JA:"The Pharaoh II's reproduction of a 10kHz squarewave (fig.2) showed only the slightest hint of overshoot, with no ringing."

Is this the reason there is no hint of overshoot, because you can't see it when it's measured at low level + - 1v output, with the AUX-0025 bench testing filter installed on the amps output?

No. You can see from the frequency response curves in fig.1, which were taken without the auxiliary filter, that the Rogue's output rolls off smoothly above the audioband into higher impedances. There is is only a hint of an ultrasonic peak into 2 ohms (green trace).

John Atkinson
Technical Editor, Stereophile

georgehifi's picture

that's odd

John Atkinson's picture
georgehifi wrote:
Sorry JA, I beg to differ, maybe you forgot the AUX-0025 was used to do the square wave shots.

I didn't forget. But without the AP auxiliary filter the squarewave response is obscured by the ultrasonic noise that I mentioned in the measurements. That is why I use the filter for the published 10kHz squarewave. The filter removes the ultrasonic noise without significantly affecting the shape of the waveform.

I don't use the filter for the frequency response measurement as I want to see the actual behavior of the class-D amplifier's own low-pass filter. The Rogue amplifier's filter is well-behaved, with the shape of the ultrasonic rolloff correlating with the squarewave response.

georgehifi wrote:
As the response curves and square waves shots look the same and level for all other Hypex NC500 equipped amps you've measured but stated you used the AP AUX-0025 on their outputs still at the same + - 1v. (why measure the Rogue' square wave output at only 1vpp if the AUX-0025 wasn't used?)

The frequency response and squarewaves I publish in amplifier reviews all show the small-signal behavior, ie, the amplifier is operating at an output level where it is linear. The level of the squarewave doesn't affect its shape.

Note, BTW, that the scaling on fig.2 is arbitrary, as the digital 'scope is being fed from the Audio Precision SYS2722's Monitor output. It is not the actual level I use for this measurement, which was actually 2W into 8 ohms.

John Atkinson
Technical Editor, Stereophile

windansea's picture

I enjoyed Herb's ruminations on Class A and D (which he's discussed in other reviews). I have both types of amps, as well as a 12AU7 based preamp, so this review really spoke to me. I imagine that a NOS tube would sound even nicer in the Rogue than the JJ tubes. As long as you're spending a few grand, spring for some Siemens or Telefunken or bugle boys.

Now that the weather has gotten a bit chilly where I live, I brought my "winter amp" (Class A) out to the living room where the wasted heat is welcome for 3 months.

A technical question: does it really matter for an ncore unit if it's a switching power supply or a toroidal? I've heard that switchers might have more EMI, but a regular transformer has ripple that needs to be tamed by caps and chokes. I think we can stipulate that linear is simpler and thus more reliable.

Jack L's picture

Hi

Yes, NOS or old Telefunken or even made-in-UK new Mullards would sound better than JJ tubes. I used both for my design/built phono-preamp !

BUT from pure technical viewpoint of designing Mu-Follower which is used in the Rogue integrated amp, I would NOT used ECC82/12AU7 which got too much Mu for the lower half of the twin triode which would work not sooo stable in the event of the operating plate voltage drop due to power surge etc.

The much better twin-triode I would recommend is ECC81/12AT7 which get good gm but not too high Mu & still works stably in the event of plate voltage drop for whatever HVPS issues.

Yes, Mu-Follower is efficient & high gain & gets super lower harmonic distortion provided it is NEVER overdriven to clipping !!!! Once overdriven, it produdces tons of even & odd harmonic BLOCKING distortions considering the hi-gain op-amps are used for its RIAA phonostage !!!!!!!

I don't mind discuss the design issues of this Rogue amp with its whoever designers. For a bit more cost money using discrete devices, best using triodes, it would sound even much better, IMO.

Listening is believing

Jack L

MatthewT's picture

I'm interested in this amp, but am not willing to spend any money on it until you fix it for them.

"I don't mind discuss the design issues of this Rogue amp with its whoever designers."

Jack L's picture

.

MatthewT's picture

Pal.

georgehifi's picture

Yes it does to my ear, as I have the NC500's in mono-block form (used with no buffers) because my discrete R2R MSB dac (with volume control)and can put out enough bal volts direct into the NC500's for the loudest that I would ever listen to on my 89db speakers

And with Hypex's own SMP (switching supply) they had, while good, it could not equal the Linear Toroidal power supplies I substituted for them. Much less sterility and more body to the sound, the only place the SMP's equaled the linear supplies was in the bass slam, but again not for body detail. EG: double bass being bowed, both as taught as each other, but the gut of the bow comes through far better on the Linear Supply.
I'm all behind Rogue etc for using linear supplies for their Class-D Intergrated and power-amps, while much more expensive and using far more real estate they sound far better, if designed correctly.

Cheers George

windansea's picture

I've got one amp with NC1200 modules and maybe I'll try a linear power supply. My class A amp has a giant toroid and big caps-- wonder if I could divert that as an experiment. Time to call my electrical engineer buddy...

Jack L's picture

Hi

BINGO ! NEVER ever use any SMPS for any audio amps, period. It is a last stage of RFI/EMI cancer for any audio amps !

Any SMPS emits RF noises airborne & thru hardwiring into any powerlines associated with it. Any other audios plugged in the same & even remotedly connected powerlines in the same premises get in as free bonus.

Don't need any costly powerlines noise testers, like the wideband powerline noise analyzer I use all the time to test the RF noise there or not. Any AM radio will get extremely noisy when placed near any those SMPS wallwarts !

That said, I still use a SMPS wallwart to recharge the bias batteries for all the tubes inside my design/built SET power amp - convienient & cheap ! But surely the wallwart, plugged in a wall outlet totally detached from my audio rig dedicated powerlines.

For RFI/EMI noises, never take for granted !!!!!!

Jack L

PeterG's picture

Finally! A rave review of a Class D that does not ignore the elephant in the room--Class A. I love my tubes too much to switch, but it's great to see the new tech emerge. Thanks

georgehifi's picture

Hmmm! Please don't delete, comments are for debating + & -'s also.

Sorry JA,I have these NC500 modules here, and they vhf ring (just like this at only 1khz!! https://ibb.co/R2NPzHQ ) with (switching noise) with even 1khz let alone 10khz square wave on the scope without using a low power external AP AUX-9925 type filter or similar, as will/do any other amp that uses the NC500 modules.

Cheers George

georgehifi's picture

Submitted by Jack L: "Any SMPS emits RF noises airborne & thru hardwiring into any powerlines associated with it."

So true, all they achieve is more profit, as they are cheaper and take up less real estate than good Linear Supplies.

Cheap Test:
With an old portable transistor AM radio (that doesn't auto mute off channel)
Tune it down low 600khz-700khz off channel with the volume up and go near any smps with it, and hear what's bombarding your audio signal.

Cheers George

Jack L's picture

Hi

My small 33-years-young Panasonic pocket radio always tuned to 680KHz (our local gas price forcast channel) gets noisy like hell whenever placed near any plugged-in SMPS wallwart.

You can imagine same RF noises airborne into yr HIFi system - no execption !!!!

Any cheapie yet very effective way to safeguard yr HIFI from RF noise airborne invasion ???

Of course, there is. I already DIY-installed such anti-RFI devices to
ALL my audio components even including all my pure silver interconnects, power cords, loudspeaker cables etc etc etc. since day one.

Never befriend with RF/powerline nosies !!!!!

Jack L

windansea's picture

Benchmark Audio offers the contrary view:
google for full version:
AUDIO MYTH - "SWITCHING POWER SUPPLIES ARE NOISY"

THIS MYTH GOES SOMETHING LIKE THIS:
"Switching supplies are noisy."

"Linear power supplies are best for audio."

We disagree!

About 5 years ago, Benchmark stopped putting linear power supplies into our new products, and we replaced them with switching power supplies. We did this because linear supplies are too noisy. Yes, you read that correctly, linear supplies are noisy! A well-designed switching power supply can be much quieter than a linear supply.

LINEAR POWER SUPPLIES CAUSE HUM
The noise problem is due to the fact that linear power supplies have large transformers and other magnetic components that operate at the AC line frequency (50 Hz to 60 Hz). These line frequencies are audible, and we are all too familiar with the hum and buzz that audio products can produce. It is no secret that this noise is caused by the power supply, but few people understand why it can be so hard to eliminate. Most people think that hum is caused by conducted interference (AC ripple on the power supply rails), but this is rarely the case. Most AC hum is caused by magnetic interference, and this can be very hard to eliminate.

HUM IS USUALLY CAUSED BY MAGNETIC INTERFERENCE
Transformers are magnetic devices. Power is magnetically transmitted between a transformer's input and output windings. In a linear supply, power is transmitted from the AC line side of a transformer to the low-voltage secondary side using an AC line-frequency magnetic field. Unfortunately, transformers are never perfect, and some energy always escapes through stray magnetic fields. These stray fields can interfere with virtually every electrical conductor in an audio product. Magnetic shielding is expensive and it has limited effectiveness when sensitive circuits are located in close proximity to a strong field.

POWER AMPLIFIERS ARE THE WORST OFFENDERS
The power supplies in high power devices, such as audio power amplifiers, can emit very strong magnetic fields. These strong fields tend to limit the noise performance (SNR) of power amplifiers. These magnetic fields can also cause interference with audio products that happen to be too near the amplifier. Audio cables that enter, exit, or pass near the amplifier may also pick up unwanted hum and buzz. For this reason, it is usually very important to keep the power amplifier well separated from cables and other components in the audio system.

BREAKING ALL THE RULES!
Benchmark's new AHB2 power amplifier breaks the rules. It can even be located adjacent to sensitive audio components without causing interference! The AHB2 is a high-power device, but it emits almost no magnetic interference. What makes it different?

The secret inside the AHB2 is the switching power supply. This power supply has several high-power transformers, but they are very small, and their stray magnetic fields are correspondingly small. The reason for this is that the magnetics operate at 200 kHz to 500 kHz. For a given power rating, transformer size decreases as the operating frequency increases. High-frequency transformers have smaller cores and fewer turns of wire. As the physical size decreases, there is a corresponding reduction in stray magnetic field strength.

SIZE MATTERS
When transformers are physically small, there are more options for magnetic shielding. For example, the small transformers used in the AHB2 are completely encased in a ferrite material which helps to contain stray magnetics. These techniques are so effective that the AHB2 achieves a SNR of 130 to 135 dB. No power amplifier is quieter than the AHB2. Even more amazing is the fact that the switching power supply board is less than an inch above the amplifier board. This product proves that switching power supplies can be very quiet! The AHB2 could not achieve this level of performance with a linear supply unless the supply were housed in a completely separate box a couple of feet away.

OUT-OF-BAND NOISE
One major advantage of switching supplies is that the operating frequency is above the range of human hearing. If interference occurs, it will not cause audible interference. This interference can even be removed with a filter without infringing on the audio band. But, the power supply in the AHB2 is so quiet that we do not need to filter the audio output. The AHB2 delivers a 200 kHz bandwidth without evidence of any significant switching noise, to a measurement limit of 500 kHz.

LINEAR AMPLIFICATION WITH SWITCHING SUPPLIES
Please note that the AHB2 is not a class-D switching amplifier. The AHB2 is a linear class-AB amplifier. It is only the power supplies that operate in a switched mode. The power supplies simply provide steady and constant regulated DC voltages for the linear audio amplifier.

MatthewT's picture

They didn't consult Jack.

Jack L's picture

.

MatthewT's picture

To defend your argument. So far you know more than Rogue and Nelson Pass. Go for the trifecta and add Benchmark?

Jack L's picture

HI

Anybody knows the basic of Switched-Mode Power Supply (SMPS) will disagree what Benchmark reportely stated per your above post!

Instead of standard linear power supply rectifying the grid power (50/60Hz) to DC, SMPS generates the required power by switching a tuning coil at a very high frequency (from many hundred KHz to many mega Hz) & then rectified it to DC. Such HF switching produces a rippling voltage with high harmonics = electromagnetic interference EMI which is transmitted in the air & pass out via direct wiring, e.g. via its power cord.

There why when you open up any SMPS, you will always see a metal cover to cover up the switching electronics therein to shield off the airborne EMI, & a low-pass filter comprising coil(s), capacitor(s) to filter off the EMI from going out the SMPS with the rectified DC.

The problem is it is indeed a big deal to contain the EMI effectively inside the SMPS. In fact SMPS for commercial application are required to have their own very effective EMI suppression in order to be allowed to be usesd without affecting the existing electrical/electronic establishment.

Airborne EMI: a small battery-powered AM radio easliy detects airborne EMI from a working SMPS wallwart, like cellphone/tablet charger & the like. The radio get very noisy when placed nearby the wallwart !!

Powerline EMI: take an common example of any CD/DVD player which most most, if not all, come with built-in SMPS. Whenever the player is switched on, the built-in SMPS discharge EMI into the wallout/powerline which I detect without fail in my brandname wideband powerline & EMI noise digital analyzer.

Yes, SMPS is extremely power efficient up to 95%, stable output voltage & current (provided not overloaded!!) & compact in size relative to standard linear power supplies. BUT its EMI is hard to control!!

"Out-of-band" noises

EMI intermodulation products, 2nd, 3rd..orders of the switching frequency & its HARMONICS can go into the audio spectrum. Sensitve ears can find such intermoduations much more annoying than normal harmonic distortion due to the characteristic of our auditory system.

That's why. taking the example of a brandname powerline filters (made-in England), which I installed in the dedicated powerlines for my audio rig, are super wideband: 20KHz - 100MHz & way way beyond to GHz (out of the bandwidth chart) with max insertion loss of 52dB @ 32MhZ & 35dB @ 100MHz. This would cover EMI noises from any UPS & cellphones (1GHz - 6GHz+++).

Yes, standard linear power supplies do get 50/60Hz hum noise, which can be reduced to be ear inperceptible if done properly. But such noise is ear friendly vs EMI intermoduation products can sound from annoying to irritating.

YES, SMPS with really efficient (but costly) EMI suppression can measure superb but stil can NOT match the ear-friendly analogue noise produced by standard linear power supplies in music reproduction.

SMPS may win the noise-level battle but lose the war musically !!!!

Listening is believing

Jack L

windansea's picture

Please explain further how the intermodulation distortion of extremely high frequencies can get back into the audible spectrum? You may have a point there but I don't get it. Aren't the harmonics happening at even higher inaudible frequencies? And therefore doesn't the low-pass filter cut these off from reaching the listener?

Also, Benchmark made a point about magnetic interference from linear supplies. Any reply to that? Personally I can't stand any hum. I had hum with a Jolia amp two decades ago, found it intolerable for hifi. My current systems (SET, tube pre, Pass class A, nCore class D) all have zero hum and that's a top priority for me.

Jack L's picture

...... can get back into the audible spectrum?" qtd windansea.

Hi

Michael Fremer commented on the same question you just asked in his review of Yunyata Denali power conditioners:
"But Shunyata doesn't explain how noise at a frequency of 1MHz can affect the audioband (20Hz–20kHz)."

So let me do the explanation:-

The intermodulation products are spurious frequency components generated when two or more signals pass through a non-linear device. The intermodulation products can be of different orders, such as second-order or third-order, depending on the non-linearity, number, and frequency of signals present in the system.

For SMPS, the high orders of harmonics generated with the switching frequency spread over pretty wideband frequency spectrum down to audio range.

The low-pass filteres inside a SMPS, if done properly, should remove any EMI noise from the DC coming out from the SMPS. As I already said above,
SMPS for commercial use MUST equipped with EFFECIVE EMI suppressors in order to be allowed to use in commercial establishsements.

For for audio amps & other digital gear, e.g. CD/DVD/DAC etc, the built-in EMI filters may not be effective enough to do the job right. That's why I can detect such EMI discharged from the SMPS into the powerlines with my EMI analyzer.

As I already said in my above post, the 50/60Hz hum noise & the magnetic flux leakage from the power transformers can be eliminated beyond ear perception if done properly. But such noise is analogue, friendly to our ears vs EMI noise annoys or even irritates our ears due to the chararteristics of our auditory system.

My design/build TUBE phono-preamp & SET power amp & my upgraded brandname tube phono-preamp & tube power amp got no audible hum at all.

Please read between the lines to differentiate sales pitch from electrical physics !!

Listening to analogue is believing

Jack L

tenorman's picture

Dear Jack ,
Overview. Grandiose Narcissistic personality disorder is a mental health condition in which people have an unreasonably high sense of their own importance. They tend to brag and be elitist .Those with grandiose narcissism are arrogant , aggressive, dominant and exaggerate their importance.

Jack L's picture

Hi

Don't need to throw me such mentality terminology! Sourgrapes !

KNOWLEDGE is the power of domination!

Lack of knolwedge will dwarf whoever into inferiority complex.

My question to YOU: do you own the audio knowedge needed to show your domination here ???????

How many post(s) of yours in audio technology, if any at all, ever got published in Stereophile journal??? Show us, please.

If you don't got any here at at all, please learn such audio technology knowedge before you stick your head out to be chopped literally.

You are more than welcome to show off your audio electronic knowledge provided you really got it !!!

I am all eyes !

Jack L

Jack L's picture

Hi

KNOWLEDG is the power of domination !

(Sorry, Mr. Editor, I am way out of audio here. Please bear with me. Thanks)

As an electrical engineer dealing in the electral power industries for decades in USA/Canada, audio electronics to me is a piece of cake !

Just show off to YOU my power of domination in electrical power engineering:-

Many many years back, a field engineer from a neigbour city power company called me up frantically for help in restoring electrical power to a regional blackout! He told me the VHV overhead transmission line was brown down by the snow storm. He needed miles of such particular overhead power like yesterday to reverse the blackout. The problem the power company engineer did not even know what cable was it exactly !

I requested a short piece of cut sample of the down powerline which arrived within one hour to my office.

On checking the over diameter & strand number of the cable, I made a phone call & within 2 days the miles of brandnew replacement powerline was thrown in by air & delivered to site !

Needless to say, I made excellent money for my employer for such emergency solution !

KNOWLEDGE is the power of domination !

Jack L

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David Harper's picture

You described Trump perfectly.

stungun's picture

... particularly compared to the Sphinx v3. Wondering if that's because the Sphinx moved HR more in absolute terms, or if it is the combo of Sphinx sound and its value quotient that make it the more exciting product.

DrGregC's picture

The $64,000 question - How does the Pharaoh II sound compared to the original Pharaoh? In looking for the correct amp for my KEF LS-50's, I was surprised and blown-away when the dealer hooked-up the original Pharaoh. I always thought of it as a well-kept secret. Unlike his other products, Mark never tweaked or offered upgrades to the original since the introduction in 2015. Pretty good first effort. The model II is so different, that he doesn't offer an upgrade path. This review doesn't make me want to run out and buy the new version.

asherrick's picture

Greg,

The Pharaoh II is a substantial improvement over the original. Is it worth the upgrade cost from the original Pharaoh? That's a question only you can decide (and hopefully your dealer can help you by taking your amp on trade).

klangyog's picture

Thanks Herb for the as-always excellent review! I am a happy Sphinx V3 owner but I am having "impure thoughts" now about the Pharaoh II. BTW I share your enthusiasm for Television's "Marquee Moon" - a great, life-changing record that I have also loved since it came out. Nerd alert! Elektra Records is not spelled "Electra," but has a "k" in the name. Thanks for listening!

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