Rogue Audio Sphinx V3 Review (Tube Amplifier)

[Francis Vaughan]

The manufactures' web site also says:

The Sphinx v3 contains a discrete MOSFET headphone amplifier capable of driving even the most demanding headphones. An excellent user adjustable phono with 44/60dB of gain will accommodate your favorite MM or MC cartridge.

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.

Other than the two tubes, there seem to be a lot of op-amps present. That plus UCD power amps suggests that calling this a "tube amplifier" in the review title is probably inaccurate. If it had a tube phono stage and tube power amp, but a semiconductor buffer we would not call it a transistor amplifier.

I suspect the tube stage is set up as a unity gain buffer. Two 12AU7 is two dual triodes. Just a simple cathode follower in the circuit would have done the job. There are not many components around the tubes, so I wonder if they have not just paralleled the two triodes in each. Gets you a pretty reasonable buffer. Although the measured numbers are not particularly good, they are probably near inaudible.

 

[aslan7]

Why do people buy tube gear, then?

Honestly I think because they find the distinctive distorted sound attractive. They always allude to the “sweet transparent” sound. A lot of the fascination is purely nostalgia for the old Macs and Fishers. That whole tube rolling business is really peculiar. Give me Class D any day.

 

[aslan7]

Are you sure that they know that the measurement results are bad? Perhaps many of them feel that in order to be called an 'audiophile' you must have an expensive turntable (because digital is not audiophile) and an expensive tube amp (because solid state is not audiophile). Audiophile peer pressure ...

You are very right in all respects. I would love to see a review here of a Prima Luna component. The tube people love them and they weigh around 40 lbs. I greatly enjoyed this review because I was formerly a Rogue fan but after reading ASR saw the great light. Anyhow, the tube mania is quite bizarre.

 

[gsp1971]

Anyhow, the tube mania is quite bizarre.

Don't expect audiophile beliefs that have been around for 30 years to vanish in one day. It will take time. One step at a time.

 

[FrantzM]

Where is the innovation?


'organic', 'warm', 'dry', 'cold', 'aseptic' - Am I still on an ASR forum or did I just join www.audio_stereotypes_revival.com?

The sarcasm was , perhaps lost but …?

 

[enricoclaudio]

Who cares about measurements.... What matters is that it's Made In The USA

 

[gsp1971]

You are very right in all respects. I would love to see a review here of a Prima Luna component. The tube people love them and they weigh around 40 lbs. I greatly enjoyed this review because I was formerly a Rogue fan but after reading ASR saw the great light. Anyhow, the tube mania is quite bizarre.

Ideally, you want your amplifier to take a voltage signal and amplify it. That's it. Nothing added. Nothing taken away. The closest we have ever got to that ideal is with class D NCore / Purify. It is bound to become the standard. Just like electric cars. It is the new standard, no matter how much we will miss the roaring sound of a 6-litre engine.

 

[gsp1971]

The sarcasm was , perhaps lost but …?

Nothing personal towards you, FrantzM.

I was just being sarcastic regarding the selection of these words. They reminded me of some magazine reviews I used to read.

 

[dfuller]

This is the guts of it:

Well, at least looks like it's built alright.

 

[raindance]

The manufactures' web site also says:


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.

Other than the two tubes, there seem to be a lot of op-amps present. That plus UCD power amps suggests that calling this a "tube amplifier" in the review title is probably inaccurate. If it had a tube phono stage and tube power amp, but a semiconductor buffer we would not call it a transistor amplifier.

I suspect the tube stage is set up as a unity gain buffer. Two 12AU7 is two dual triodes. Just a simple cathode follower in the circuit would have done the job. There are not many components around the tubes, so I wonder if they have not just paralleled the two triodes in each. Gets you a pretty reasonable buffer. Although the measured numbers are not particularly good, they are probably near inaudible.

Cathode follower would be typical and generates lots of nasty "solid state -like" odd harmonics. Not even remotely tubey...

 

[TNT]

Many claim that toobs are among the most linear that exists.... time to fess up!?

Where are the exquisite implementations?

//

 

[SIY]

Cathode follower would be typical and generates lots of nasty "solid state -like" odd harmonics. Not even remotely tubey...

A cathode follower has 100% feedback. There’s no excuse for having significant distortion.

 

[SIY]

Many claim that toobs are among the most linear that exists.... time to fess up!?

Where are the exquisite implementations?

//

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.

 

[Frank Dernie]

Don't expect audiophile beliefs that have been around for 30 years to vanish in one day. It will take time. One step at a time.

Well they appeared fairly suddenly.
Jean Hiraga, who presumably had neither the kit nor expertise to measure hifi started off the subjective audio phase and it caught on fairly quickly and has resisted all attempts to point out the folly of it for a long time.
It certainly suits reviewers because they don't need any test equipment or technical expertise to write a review ang generally they and their readers have bought into the narrative.
I don't expect the approach to go back to the way it was 50 years ago.

 

[JoetheLion]

Are you sure that they know that the measurement results are bad? Perhaps many of them feel that in order to be called an 'audiophile' you must have an expensive turntable (because digital is not audiophile) and an expensive tube amp (because solid state is not audiophile). Audiophile peer pressure ...

My opinion is that it doesn't matter as long as they don't sound worse. If device A measures better than device B but the difference is not audible: buy the device you like better. No car magazine would advise against buying a Lamborghini because the drag coefficient is "bad" (in comparison to another car). Most owners of a NAD T 758 are happy because they find it sounds far better than a Denon AVC-X3700H. But look at the measurement results. It is very important what is done here on ASR. But it should not be seen so absolutely.

 

[gsp1971]

Well they appeared fairly suddenly.
Jean Hiraga, who presumably had neither the kit nor expertise to measure hifi started off the subjective audio phase and it caught on fairly quickly and has resisted all attempts to point out the folly of it for a long time.
It certainly suits reviewers because they don't need any test equipment or technical expertise to write a review ang generally they and their readers have bought into the narrative.
I don't expect the approach to go back to the way it was 50 years ago.

To my knowledge, there are still to this day 'product of the year' awards for RCA cables, USB cables, and hi-fi racks. I don't expect this will go away in one day.

 

[gsp1971]

My opinion is that it doesn't matter as long as they don't sound worse. If device A measures better than device B but the difference is not audible: buy the device you like better.

If the sonic difference is not audible, what does 'like better' refer to? aesthetics? connectivity? Common economic sense would argue that if A and B sound the same, and connectivity is not an issue, buy the cheaper one.

 

[JoetheLion]

If the sonic difference is not audible, what does 'like better' refer to? aesthetics? connectivity? Common economic sense would argue that if A and B sound the same, and connectivity is not an issue, buy the cheaper one.

That would also be my decision, but if someone likes the chrome front better, or the glow of a tube...

 

[gsp1971]

That would also be my decision, but if someone likes the chrome front better, or the glow of a tube...

Oh yes, the good ol' glow ...
And if people buy electronics based on whether the faceplate is chrome, black, or silver, then what can I say other than there is lot more work to be done.

 

[eardiggler]

Great review!
Selfishly, I would love to see a SET amplifier like a 300B measured. Maybe the Decware Zen that's become popular on youtube would also be interesting.