Rogue Audio Sphinx V3 Review (Tube Amplifier)

[charleski]

Stereophile reviewed and measured the V1 release of this amp in 2014.

https://www.stereophile.com/content/rogue-audio-sphinx-integrated-amplifier-measurements

I aint smart enough to compare the measurements above with those from stereophile (have to assume a V3 device is better?)

In that review, the conclusion was

"Even without taking into account its affordable price, Rogue Audio's Sphinx offers excellent measured performance with little sign of the usual compromises made in class-D designs. It also has an excellent, moving-magnet–compatible phono stage.—John Atkinson"

So assuming that the original V1 doesn measure as well as the V3, the respected JA didnt flag it as bad.

Peter

You really need to take JA1's conclusions with a massive pinch of salt. I've only seen him criticise a component when it turns out to be clearly broken.

The distortion measurements he gets are perfectly in line with what Amir found:

For comparison, here's a properly-designed tube preamp (since we want to look at tubes used for line-stage only), the Audio Research Reference 6E:

And here's a badly-designed tube preamp, the PrimaLuna EVO 400 :

The circuit design is what matters. The type of components utilised, whether passive or active and solid- or hollow-state pales into insignificance in comparison.

(The AR Ref6E may be well-designed, but at $17k I wouldn't regard it as a particularly good buy.)

 

[DonH56]

As @charleski said the results are comparable. Note 0.1% THD is -60 dB, and 1% is -40 dB, when comparing numbers (based upon voltage measurements).

The plots are very interesting and revealing. Second harmonic distortion is the largest term for all three amps, but as @amirm noted the Rogue has a "spray" of terms (mostly not harmonic) that are relatively high in amplitude, while the ARC preamp's higher terms drop about 20 dB. The PrimaLuna has high second and third harmonic terms, then higher orders again drop precipitously. The ARC likely has no "tube sound" whereas the PrimaLuna has a pretty classic tube signature. As @SIY would say, it is the design, not the tubes, that are responsible for the distortion and noise.

 

[eardiggler]

I've never really understood why a manufacturer would design a box that looks 'solid state' but hide all the tubes inside it. Let's face it; it would sound a lot better if you could stare into the warm glow of the tubes.

 

[ta240]

.....I get amused by tube rollers, they ascribe all manner of sonic characteristics to the tubes themselves, when a very large part of the effect is that they have not taken into account that the load lines are designed for one tube type, and will not be correct for a different one, and thus the new tube is operating outside of its intended design parameters.

I see that so often, and a lot of times from people that know more about tube amps than I ever will. Some will even acknowledge that the tube is running outside of specs "at this bias, the big KT120 is just loafing along". It isn't as if it is sounding exactly the same as if it were running at the proper voltage and bias but just has less power; it will likely not sound like a KT120 in an amp that is properly designed for it.
I've messed with the power supply in my tube amp way more than anyone should and tried nearly a half dozen different model power tubes in it at the different voltage and bias levels. The same tube can sound really good and clear or muddy depending on where it is running. After realizing that, all the posts about "I put a KT66 in my amp and it sound more amazing than ever!" became useless advice because their prior tube could have been off its optimal settings and the KT66 might have just happened to fall into a better performance section of the load lines. Or maybe they didn't like the cleaner sound of the properly setup tube they had and prefer the muddy sound of one that isn't running optimally. Or they are using the popular tube amp speaker the Klipsch RP-600M and need to do something to tame the sound.

 

[Ruprit]

Stereophile reviewed and measured the V1 release of this amp in 2014.

https://www.stereophile.com/content/rogue-audio-sphinx-integrated-amplifier-measurements

I aint smart enough to compare the measurements above with those from stereophile (have to assume a V3 device is better?)

In that review, the conclusion was

"Even without taking into account its affordable price, Rogue Audio's Sphinx offers excellent measured performance with little sign of the usual compromises made in class-D designs. It also has an excellent, moving-magnet–compatible phono stage.—John Atkinson"

So assuming that the original V1 doesn measure as well as the V3, the respected JA didnt flag it as bad.

Peter

This was the review that convinced me to purchase a Sphinx V2.

Before that, I had been using a pair of Hypex NC400 Monoblocks which come as a diykit, direct from Hypex. After almost two years with them I wanted to try something new but "safe." Seeing that the Sphinx also used Hypex amps, I thought it might be worth a go.

For the most part, I liked the Sphinx. It sounded pretty much the same as the NC400s, to the point where I wasn't sure if the tubes were adding much to the sound. It also had the benefit of being an integrated preamp, which I was very much in need of.

What force me to sell it off after a month of ownership was the background noise. When nothing was playing, there would be a buzz that was very audible from my listening position, six feet away. Even during quiet moments, the buzz would overshadow the audio. The noise from the motorized volume pot would also be picked up in one of the speakers every time I changed the volume. I learned that this was a known issue and seemingly ok for owners. That was unacceptable for me.

Once I sold it, I put the money towards an AHB2 which I have happily owned for coming up on three years now.

I still am always interested in Rogue Audio's products because they always look so interesting, especially their headphone amp. But I'll always remember my experience with the Sphinx. It's a neat idea that could have been done so much better. For me, not everything needs to have record breaking measurements, but it at least needs to be free of annoyances and audible distortion.

 

[aslan7]

To slightly change the subject, Rogue has taken something of a knocking here. But as the former owner of a number of Rogue products I can attest to the fact that the owner is very conscientious and responsive, and Rogue is a pleasure to do business with. I wish everyone was as good as he is in the audio universe. Also, the Sphinx is their lowest ranking component, and as a dealer friend has pointed out, "they stuff that box with a lot of stuff." I'd like to see how the Medusa stacks up in a review here, or one of their other top hybrid models.

 

[aslan7]

I see that so often, and a lot of times from people that know more about tube amps than I ever will. Some will even acknowledge that the tube is running outside of specs "at this bias, the big KT120 is just loafing along". It isn't as if it is sounding exactly the same as if it were running at the proper voltage and bias but just has less power; it will likely not sound like a KT120 in an amp that is properly designed for it.
I've messed with the power supply in my tube amp way more than anyone should and tried nearly a half dozen different model power tubes in it at the different voltage and bias levels. The same tube can sound really good and clear or muddy depending on where it is running. After realizing that, all the posts about "I put a KT66 in my amp and it sound more amazing than ever!" became useless advice because their prior tube could have been off its optimal settings and the KT66 might have just happened to fall into a better performance section of the load lines. Or maybe they didn't like the cleaner sound of the properly setup tube they had and prefer the muddy sound of one that isn't running optimally. Or they are using the popular tube amp speaker the Klipsch RP-600M and need to do something to tame the sound.

I once bought a Rogue preamp that was very highly regarded. It was a demo with full warranty. When I played the thing it sounded horrible--very dry and harsh. I presumed something was out of adjustment from shipping and opened up the unit. Lo and behold, there were two Dutch Amperex vintage tubes installed instead of the factory modern ones. The dealer and I exchanged tubes and I was very happy with the sound with the correct ones installed. Given the common practice tube "rolling" I gather that tube enthusiasts have no set objective definition of the sound characteristics they want and are constantly shuffling the tubes about. Many of them seem to settle on old Mallards. Those little vintage Amperex tubes cost around $95 each used! Anyhow, if you want your components to have a variable set of sound characteristics tube ones are ideal. Tube people appear to have a huge amount of fun "rolling" and it is extremely entertaining to hear them compare notes.

 

[tw99]

Many of them seem to settle on old Mallards.

Those definitely induce a certain "quackiness" in the midrange.

(You mean Mullards!)

 

[ta240]

This seems like a perfect item for a double blind comparison to check for the audibility of the noise.

There is an ongoing quest to find someone that can truly hear a difference between items that test the same; how about a challenge to see if people can hear a difference between this and an amp that tests measurably better.

Step up and prove that the numbers have relevance.

 

[DonH56]

I once bought a Rogue preamp that was very highly regarded. It was a demo with full warranty. When I played the thing it sounded horrible--very dry and harsh. I presumed something was out of adjustment from shipping and opened up the unit. Lo and behold, there were two Dutch Amperex vintage tubes installed instead of the factory modern ones. The dealer and I exchanged tubes and I was very happy with the sound with the correct ones installed. Given the common practice tube "rolling" I gather that tube enthusiasts have no set objective definition of the sound characteristics they want and are constantly shuffling the tubes about. Many of them seem to settle on old Mallards. Those little vintage Amperex tubes cost around $95 each used! Anyhow, if you want your components to have a variable set of sound characteristics tube ones are ideal. Tube people appear to have a huge amount of fun "rolling" and it is extremely entertaining to hear them compare notes.

"Mullards", unless you are just being ducky...

 

[amirm]

On going to the next page of the stereophile reviews, they have in fact also reviewed the V3.

https://www.stereophile.com/content/rogue-sphinx-v3-integrated-amplifier-measurements

As above, I aint smart enough to compare the measurements but the conclusion was:

As a line-level integrated amplifier and headphone amplifier, the Sphinx V3 continues the high standard set by the original. The addition of an MC mode to the phono stage is welcome, though I was puzzled by the noise problem I found at the preamplifier outputs with the MM mode.—John Atkinson

Not pitting Amir against JA, but on the assumption that their two reviews measure the same, there is a difference in opinion on the relative merits of the metrics.

Peter

As noted, there is pretty good correlation between JA's measurements and mine. He for example shows the same rolled off frequency response. Here is what he says about SNR:

"The V3's unweighted signal/noise ratio in the audioband, taken with the line input shorted but the volume control at its maximum, was also the same at 67.7dB left and 66.1dB right, both ref. 2.83V into 8 ohms. "

And what I measured:

Test conditions are a bit different so 68 dB of his correlates well with my 71 dB measurement. The problem with JA's write up is that he provides no reference. It is just a sea of numbers thrown at the reader with no easy way for the reader to know if that is good or bad. Sadly he almost always finishes bad measurements with careful wording to say otherwise. What he giveth with one hand, he taketh away with the other....

 

[Aperiodic]

Reminds me of the Luxman LV-105 hybrid. Prone to overheating and then the solder cracks/crumbles and then lots of soldering is required to get it back operating. I never saw one blow up even with all the bad solder.

Gear that has the tubes sticking out of holes in the top cover (Sometimes with ornate little cages) or windows in the front panel so you can see that it's tube gear always annoyed me for some reason. Possibly because both are completely unnecessary and designed to impress those who make purchase decisions about equipment more by eye than by ear.

 

[aslan7]

"Mullards", unless you are just being ducky...

I stand corrected. Ducks don’t fit into components fortunately.

 

[amirm]

Gear that has the tubes sticking out of holes in the top cover (Sometimes with ornate little cages) or windows in the front panel so you can see that it's tube gear always annoyed me for some reason. Possibly because both are completely unnecessary and designed to impress those who make purchase decisions about equipment more by eye than by ear.

I have never liked horizontal tubes that way either. One would heat up the one above it.

 

[MZKM]

What he giveth with one hand, he taketh away with the other....

What he exposes in one hand, he saves his relationship with the manufacturer with the other.

Not saying I blame him.

 

[jkasch]

This was the review that convinced me to purchase a Sphinx V2.

Before that, I had been using a pair of Hypex NC400 Monoblocks which come as a diykit, direct from Hypex. After almost two years with them I wanted to try something new but "safe." Seeing that the Sphinx also used Hypex amps, I thought it might be worth a go.

For the most part, I liked the Sphinx. It sounded pretty much the same as the NC400s, to the point where I wasn't sure if the tubes were adding much to the sound. It also had the benefit of being an integrated preamp, which I was very much in need of.

What force me to sell it off after a month of ownership was the background noise. When nothing was playing, there would be a buzz that was very audible from my listening position, six feet away. Even during quiet moments, the buzz would overshadow the audio. The noise from the motorized volume pot would also be picked up in one of the speakers every time I changed the volume. I learned that this was a known issue and seemingly ok for owners. That was unacceptable for me.

Once I sold it, I put the money towards an AHB2 which I have happily owned for coming up on three years now.

I still am always interested in Rogue Audio's products because they always look so interesting, especially their headphone amp. But I'll always remember my experience with the Sphinx. It's a neat idea that could have been done so much better. For me, not everything needs to have record breaking measurements, but it at least needs to be free of annoyances and audible distortion.

I decided to give tubes a try with the Rogue Chronos Magnum II. Sent it back for a similar reason. The transformers hummed loud enough to be heard several feet away. Bought a Parasound Hint after that and have been very happy with it. No quirks.

 

[CrankyRat]

Hi

Such amplifers and their various awards/kudos epitomize sadly measurements and how they relate to what we can truly hear.

The differences between a 50 dB SINAD and 100 dB are not as perceptible as we would like to believe, even for us , the objectivists. Many LP chains (TT, Cartridge, RIAA preamp and amp) are likely about 50 dB of SINAD. If it is a tube chain it might even not clear 40 dB... Yet people rave about them and sometimes they're sincere (not often but once in a blue moon). The audiophiles, start chasing the ideals put forth by the reviews. Many (most?) audiophiles do not have the means to acquire the extraordinary expensive products with gushing reviews and industry-wide accolades, owned by influencers (Influencers, have become an important aspect of today's marketing). Those audiophiles, I would surmise the majority, have to resign themselves to lesser products (in term of reviews and price) and that is where brands like Rogue come into play. They are "rogue", they go against the grain. They "challenge" the status-quo by being innovative with a clear eye on the glorious past... when tubes ruled audio. a "rogue" amplifier is modern, efficient and powerful: It uses class D but feed it with "organic", "warm" signals ... to mitigate class d inherent dry, cold and and aseptic sound...
The engineering is not "poor". High objective performance wasn't the design objective. What is reviewed is what they wanted.

I am dreaming of ASR reviews of an expensive High End tubes preamplifier, line Stage or amplifier. I suspect their performance will not be any better.


Thanks Amir.

Peace.

"What is reviewed is what they wanted. "

As an engineer, that's wishful thinking. You get what resources and time allow with sufficient testing always on the chopping block. "Good enough, I think" is the operative phrase here. ASR reviews are effecting some of the industry to improve themselves e.g. Schiit Audio.

Side note, is there anyone else here that thinks tube amps are as ugly as my great grandmother's furniture? For me, they take me back to my 1950's B&W TV. Out of date and poorly performing tech.

 

[MakeMineVinyl]

Out of date and poorly performing tech.

Like a 1965 Mustang?

 

[Frank Dernie]

As noted, there is pretty good correlation between JA's measurements and mine. He for example shows the same rolled off frequency response. Here is what he says about SNR:

"The V3's unweighted signal/noise ratio in the audioband, taken with the line input shorted but the volume control at its maximum, was also the same at 67.7dB left and 66.1dB right, both ref. 2.83V into 8 ohms. "

And what I measured:

Test conditions are a bit different so 68 dB of his correlates well with my 71 dB measurement. The problem with JA's write up is that he provides no reference. It is just a sea of numbers thrown at the reader with no easy way for the reader to know if that is good or bad. Sadly he almost always finishes bad measurements with careful wording to say otherwise. What he giveth with one hand, he taketh away with the other....

My guess is that he knows not everybody will read the measurement section but most of those that do will do so because measurements are important to them. That is why I do anyway.
I think he wants to save the blushes, or avoid the ire, of the subjective reviewers too. It is hardly condusive to smooth running for a reviewer to wax lyrical and his measurements to show it is super innaccurate, like the Volti speaker, and him to pretty well say that anybody liking the Volti prefers No-Fi to Hi-Fi.

 

[magicscreen]

I've never really understood why a manufacturer would design a box that looks 'solid state' but hide all the tubes inside it. Let's face it; it would sound a lot better if you could stare into the warm glow of the tubes.

Nowadays tube amp has a LED below the tube, which is much brighter than the tube itself.
Wait! Solid state amp has LED as well.