Rogue Audio Sphinx V3 Review (Tube Amplifier)

[EXIF68]

Im using an 2nd hand Yamaha A-S2100. Costs €1100.— Condition like new.
The measurements (what i have read on a polian site) not the best but also not bad.
in comparison to this unit here, I did notwant to change

 

[aslan7]

It is a like for like comparison. They are all amplifiers whose job is to amplify the signal without introducing noise or distortion. If tubes perform worse, then that's a fact. People can still make their decisions accordingly and if they want to buy tubes, then fine. But it is an engineering reality that tubes have more noise / distortion than modern solid state amps.
Why try to beautify that?

And some people simply like old stuff for nostalgia. My father was a big auto enthusiast and could easily have bough a Porsche. What did he get? A Morgan. He also liked tubes but did venture into solid state. Here where I live the Amish ride around in horses and buggies.

 

[KSTR]

Tubes are relatively linear compared to other active devices. That’s VERY different than the linearity of an amplifier- remember that they will also have relatively lower open loop gain.

Exactly. And that's why IMHO the best tube designs use the most linear tubes at their most linear operation conditions and apply zero feedback, be it global or local/degenerative. Stuff like Lynn Olson's Karna amplifier, with a lot attention to details. This is an excellent and beefy amplifier, with a low complexity and very stable distortion profile plus rock solid operation points. FR change from not so low output impedance is the least thing to worry about as it can be fully compensated by pre-EQ.

But a low-gain stage or buffer with 12AU7's in front of an UCD180... meh :-(

 

[SIY]

And some people simply like old stuff for nostalgia. My father was a big auto enthusiast and could easily have bough a Porsche. What did he get? A Morgan. He also liked tubes but did venture into solid state. Here where I live the Amish ride around in horses and buggies.

Trivia: the Morgan is the only car that can fail due to termites.

 

[H-713]

A cathode follower should have devastatingly low distortion. If they're smart, what they'll do is use one triode section as the cathode follower and the other to form a current source. In this application, even a 12AU7 will have good distortion performance.

I still maintain that this particular amplifier measures well enough that it probably doesn't sound half bad.

 

[anmpr1]

It is a like for like comparison. They are all amplifiers whose job is to amplify the signal without introducing noise or distortion. If tubes perform worse, then that's a fact. ...but it is an engineering reality that tubes have more noise / distortion than modern solid state amp.

You are wrong on principle. It's like saying a Jeep can be compared with a Porsche because they both have four wheels and can take you somewhere. They are two completely different designs and must be judged with different criteria.

Please try and understand what I am getting at. And please, no one ever said anything as ridiculous as, or tried to make the point that, tubes make less distortion than a properly designed SS amp. Where did that come from?

On the other hand, if the purpose of an amp is what you say it is (and no more) then why would anyone even care about a tube in the first place? Why would anyone even waste their time?

Certainly it is not my place to tell Amir how to paste his graphics or what he ought to be testing. But when I see a tube amp's numbers compared against the distortion characteristics of an AHB-2 I really have to ask myself, again, what exactly is he trying to communicate? What is he telling us that we don't already know (or suspect)? It's like when you took trig or calculus. The teacher didn't begin his class with the basics of number theory. You were supposed to already know that before you walked through the door. It's the same when dealing with tube gear. You don't need to be told that it won't measure as good as the best (or even average) solid state gear.

On the other hand, from an engineering (and possibly academic) standpoint, it might be helpful to know how one tube amp compares against another tube amp. Other than that, from an 'audio science' engineering standpoint there is really no purpose in running tests on tube gear. At least there is no purpose that I can understand. It's why my old audio friend Peter Aczel refused to review tube gear toward the end of his career. As he used to say--if you are looking for the fastest land animal you'd check out the thoroughbred race horse, some of the wild cats, possibly a gazelle. But why would you waste your time on any given sloth or tortoise.

 

[brandall10]

I think one reason is: there is simply something else being evaluated. A Lamborghini looks much more streamlined than a Porsche, but the Porsche still has a much better drag coefficient. That is measurable. Is that why people are more likely to buy a Porsche than a Lamborghini? They can't use the maximum speed with either (not even here in Germany). Some millionaires simply like a Lamborghini better, the sound, the look. It's twice as expensive as a Porsche, but no one who buys it will complain afterwards about bad measurement results. It's the same with tube amplifiers: most people know that the measurement results are bad. But if they feel that they sound better, why not?

I don't know if that's really a good comparison, or at least, use specific examples... for example, the Aventador has a .23 which is crazy low. And it's well known that at a certain point downforce becomes the overriding issue, which means drag has to go up. I get the point you're making, but it's still largely an engineering concern at the supercar level, which isn't the case w/ tube amps.

 

[BostonJack]

I would agree with that... however, I wouldn't ever be in the market for this amp because if I'm looking for tubes and willing to sacrifice transparency for that cause... then I want to see the tubes, and I don't want class-D amps doing the heavy lifting. Maybe I'm in the minority there, but to me the greatest reason for going with tubes is because of the aesthetics. The sound has always been objectively bad on almost everything that employed them (at least that's even remotely in my budget). If I'm paying for something that looks just like any other SS amp... then I expect the same performance as well.

Someone should have the brass to make a tube amp with solid state amplification and a very showy presentation of glowing tubes with fancy guards around them that do *absolutely nothing*!
Maybe pass a signal through them to detect if one is kaput to help maintain the illusion.

patent search.......

 

[Crohnic]

I was really close to buying one of these. Glad I went with my Technics SU-G700, although I don't know how it measures, but I'm guessing it is a lot better than the Sphinx

 

[amirm]

Certainly it is not my place to tell Amir how to paste his graphics or what he ought to be testing. But when I see a tube amp's numbers compared against the distortion characteristics of an AHB-2 I really have to ask myself, again, what exactly is he trying to communicate? What is he telling us that we don't already know (or suspect)? It's like when you took trig or calculus.

This product is not the place to make this argument. This is not a pure tube amplifier. The output stage is class D amplification. If I had a category for tube amps and had put this in there, there would be loud cries that this doesn't use tubes for the actual amplification. I also made no direct comparison to AHB2 but rather, just the performance of the UcD amplification modules.

I have created separate category for AVRs for both their DACs and amps. I did this because they have ton more functionality and some of that functionality forces degradation of system performance (e.g. by allowance of digital headroom for processing). They are also used in multi-channel mode, and not just stereo. None of that holds in this scenario.

You used the analogy of cars. Magazines don't user a separate category for turbo vs supercharged vs naturally aspirated engines. How the power is made is the business of the designer. They evaluate the car as a whole if one design goes faster than the other, that is fair gain. Same here. All of these are amplifiers with no more or less functionality. How they get to the end point is a decision designer makes in the context of engineering and marketing. We get to evaluate that purely from engineering point of view. Like is compared with like. People pick these amps purely on basis of fidelity and amplification as a utility.

 

[amirm]

I know usually amplifiers are tested as just power amplifiers, but it does seem unfortunate to ignore two other capabilities that, had it been a standalone HP amp or phono-amp would have been tested. People buying something like this probably care about phono and HP capabilities.

Pretty sure vast majority of their customers could care less about the headphone amp. On phono, they may or may not value and use it. The issue here is that the amplifier doesn't perform. That would be the high order bit that would rule it out as a consideration. It is not like you would buy it just to use the phono stage with a different amp.

Each subsystem you mention takes as much as this review to test and document, taking time away from testing two other products. My time is something we can't get more of so I have to focus it on where it matters the most. And that is to move on to testing other products.

 

[eardiggler]

A cathode follower should have devastatingly low distortion. If they're smart, what they'll do is use one triode section as the cathode follower and the other to form a current source. In this application, even a 12AU7 will have good distortion performance.

I still maintain that this particular amplifier measures well enough that it probably doesn't sound half bad.

I bet it sounds great. But once Sphinx owners read this review it will suddenly sound just 'OK'. Bummer. I may be wrong here but I bet it takes a very trained ear to hear the difference between this integrated amp and something that measures much better.

 

[DualTriode]

If I don't review them, all search results would point to subjectivist reviews with random evaluations within. Pretty sure many people buy these products because they think they are much better than they are. So I review them to show the reality of them.

I have measured more tube amps than anything else.

I own and have used the U8903B, the AP 2522, the APx 555 and the QA401.

The thing that bugs me the most with tube amplifiers is noise. Hum and buzz is the worst, hiss does not lag much either.

Distortion is not nearly so bad as it is said to be. The less than humble GedLee shows that low order distortion (H2 and H3 even IM distortion) is masked by the fundamental frequency. The masking of distortion increases as the fundamental magnitude increases to mask even mask H4 and H5 distortions. Some are baffled by this and say that the distortion is more audible at low levels of fundamental. What is wrong with this assumption is that at low levels of fundamental there is much less distortion to mask.

GedLee shows in his published AES research that low level distortions are not audible well into the double percentage digits. Do not argue with me, argue with GedLee.

Objectivists do as much arm waving as anyone else, it is just hard to quantify.

JFETS can be very quiet and make nice RIAA amplifiers even with a little distortion. Just because you can measure it does not mean that you can hear it.

Thanks DT

 

[Ken1951]

You are wrong on principle. It's like saying a Jeep can be compared with a Porsche because they both have four wheels and can take you somewhere. They are two completely different designs and must be judged with different criteria.

Please try and understand what I am getting at. And please, no one ever said anything as ridiculous as, or tried to make the point that, tubes make less distortion than a properly designed SS amp. Where did that come from?

On the other hand, if the purpose of an amp is what you say it is (and no more) then why would anyone even care about a tube in the first place? Why would anyone even waste their time?

Certainly it is not my place to tell Amir how to paste his graphics or what he ought to be testing. But when I see a tube amp's numbers compared against the distortion characteristics of an AHB-2 I really have to ask myself, again, what exactly is he trying to communicate? What is he telling us that we don't already know (or suspect)? It's like when you took trig or calculus. The teacher didn't begin his class with the basics of number theory. You were supposed to already know that before you walked through the door. It's the same when dealing with tube gear. You don't need to be told that it won't measure as good as the best (or even average) solid state gear.

On the other hand, from an engineering (and possibly academic) standpoint, it might be helpful to know how one tube amp compares against another tube amp. Other than that, from an 'audio science' engineering standpoint there is really no purpose in running tests on tube gear. At least there is no purpose that I can understand. It's why my old audio friend Peter Aczel refused to review tube gear toward the end of his career. As he used to say--if you are looking for the fastest land animal you'd check out the thoroughbred race horse, some of the wild cats, possibly a gazelle. But why would you waste your time on any given sloth or tortoise.

While I'm not in the market for any equipment and am about 5% competent compared to many others here, I'm sort of with you on this. I would like the ABH-2 on the graph as a reference, but would like other tube amps on there as well. I'd love to see what a Mac 275 or an AR Dual 51 or 76 looked like compared to this amp and what the current SOTA SS looks like. I had experience with the tube amps I mentioned way back in the day and would enjoy seeing such reviews.

 

[Matias]

While I'm not in the market for any equipment and am about 5% competent compared to many others here, I'm sort of with you on this. I would like the ABH-2 on the graph as a reference, but would like other tube amps on there as well. I'd love to see what a Mac 275 or an AR Dual 51 or 76 looked like compared to this amp and what the current SOTA SS looks like. I had experience with the tube amps I mentioned way back in the day and would enjoy seeing such reviews.

Here you go:
https://docs.google.com/spreadsheets/d/1ZlTOYxmPs938gqHjtDABkWS-MApu7uJjzIGnJ2Elm6Y/edit?usp=sharing

 

[DonH56]

ARC Reference 75 Stereophile review, measurements page: https://www.stereophile.com/content/audio-research-reference-75-power-amplifier-measurements

About what you'd expect... I owned a D-79 for many years and it sounded OK to me but I never expected it to be in the same class as SS amps for distortion and drive capability (output impedance).

Personally I have no problem see all amplifiers compared across the board and am tired of car analogies for stereo equipment. That said it might be nice to have comparisons of all tubes and all SS amps, but in my mind that is beyond the scope of what Amir is doing. And he is already plenty busy... We do not have many tube amps to compare (want more, send in yours) so probably not worth the effort. And as Amir said this one is a hybrid, and such debates are outside the scope of this thread.

IMO - Don

 

[charleski]

You can certainly get a tube line stage to produce a lot better than a SINAD of 70dB. This is just another example of a deliberately defective tube design.

 

[Ken1951]

Here you go:
https://docs.google.com/spreadsheets/d/1ZlTOYxmPs938gqHjtDABkWS-MApu7uJjzIGnJ2Elm6Y/edit?usp=sharing

Fabulous! Thanks so much for the link!

 

[Putter]

I have measured more tube amps than anything else.

I own and have used the U8903B, the AP 2522, the APx 555 and the QA401.

The thing that bugs me the most with tube amplifiers is noise. Hum and buzz is the worst, hiss does not lag much either.

Distortion is not nearly so bad as it is said to be. The less than humble GedLee shows that low order distortion (H2 and H3 even IM distortion) is masked by the fundamental frequency. The masking of distortion increases as the fundamental magnitude increases to mask even mask H4 and H5 distortions. Some are baffled by this and say that the distortion is more audible at low levels of fundamental. What is wrong with this assumption is that at low levels of fundamental there is much less distortion to mask.

GedLee shows in his published AES research that low level distortions are not audible well into the double percentage digits. Do not argue with me, argue with GedLee.

Objectivists do as much arm waving as anyone else, it is just hard to quantify.

JFETS can be very quiet and make nice RIAA amplifiers even with a little distortion. Just because you can measure it does not mean that you can hear it.

Thanks DT

Frankly I have no dog in this fight, but it seems like the real test of tube vs. SS is a blind tests to first determine if you can distinguish between tube and SS amps operating within their power limits and if so which are preferred. The measured levels of distortion, noise and hum are less important than their audibility.

 

[aslan7]

Trivia: the Morgan is the only car that can fail due to termites.

Indeed it had a wooden suspension. It had the lowest ground clearance of any of the British cars of the time and the ride would rattle your teeth. If you didn't use the leather "bonnet strap" the hood flew open. But it was a lot of fun on the few occasions it worked. He replaced it with a Jag XK-120 that seldom worked but was beautiful to look at, sort of like those tubes glowing in the dark. Back to audio, I can see very well how people enjoy tube components and if that satisfies them good.