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FX-Audio Tube 02 Pro Review (Headphone Amp)

Rate this product:

  • 1. Poor (headless panther)

    Votes: 73 39.2%
  • 2. Not terrible (postman panther)

    Votes: 64 34.4%
  • 3. Fine (happy panther)

    Votes: 38 20.4%
  • 4. Great (golfing panther)

    Votes: 11 5.9%

  • Total voters
    186

pseudoid

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Thank you @amirm, u da man!:)
The first look at the photo by @Helicopter makes me think it is a wonderful work of art for the $80, even if it has some glaring shortcomings.
Almost makes a mockery of my Yamaha WXC-50.
I am all for "CHEAP" DACs, etc.
 

saich

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Could you include crosstalk as part of the standard measurement? Together with channel balance they give a pretty good overview of the quality of volume pots in each amp.
 

SuicideSquid

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Except that according to Amir’s listening impression, it sounds like c**p. Sizzly, grungy… Don’t sound like fun to me.
Yes, that's the sound of a tube being pushed. If you don't like it, that's fine. Amir also notes that with the high-impedance Sennheiser headphones listening at low or moderate levels was distortion-free.

It's no different than vinyl records. They have a 'sound'. Some people find that sound pleasing. If it gets you off your butt and listening to more music and enjoying it (and buying more music and supporting artists), more power to you. As long as you're not dropping $10,000 on magic cartridges and telling me how much more "real" your vinyl records sound than "fake" digital recordings, cool. It's about listening to and enjoying music first.
 

PeteL

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Yes, that's the sound of a tube being pushed. If you don't like it, that's fine. Amir also notes that with the high-impedance Sennheiser headphones listening at low or moderate levels was distortion-free.

It's no different than vinyl records. They have a 'sound'. Some people find that sound pleasing. If it gets you off your butt and listening to more music and enjoying it (and buying more music and supporting artists), more power to you. As long as you're not dropping $10,000 on magic cartridges and telling me how much more "real" your vinyl records sound than "fake" digital recordings, cool. It's about listening to and enjoying music first.
I disagree with that. People that like tube gear are plenty, never I heard an audiophile say, I like my sound grungy or sizzly, or I like distortion or anything like that. They may be mislead into imagining that it does something special to their music, they may be biased, they may be all of that but good tube gear don't make music sound like that, sorry, if it does it's a bad product. This is a bad product.Guitar players like that for their guitar amps, not Audiophiles, they may not be getting that but they like Hi Fidelity and that's what they believe their tube gear gear gives them.
 

SuicideSquid

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I disagree with that. People that like tube gear are plenty, never I heard an audiophile say, I like my sound grungy or sizzly, or I like distortion or anything like that. They may be mislead into imagining that it does something special to their music, they may be biased, they may be all of that but good tube gear don't make music sound like that, sorry, if it does it's a bad product. Thios is a bad product.Guitar players like that for their guitar amps, not Audiophiles, they may not be getting that but they like Hi Fidelity and that's what they believe their tube gear gear gives them.
"Amir also notes that with the high-impedance Sennheiser headphones listening at low or moderate levels was distortion-free."

This is an $80 product that is able to drive high-impedance headphones at reasonable volume levels without audible distortion. Again, if that's what you're interested in, this seems perfectly fine to me.
 

PeteL

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"Amir also notes that with the high-impedance Sennheiser headphones listening at low or moderate levels was distortion-free."

This is an $80 product that is able to drive high-impedance headphones at reasonable volume levels without audible distortion. Again, if that's what you're interested in, this seems perfectly fine to me.
Comon, in 2 of the 3 use case, it was characterised as "unlistenable" on the 3rd one, it was "OK at low volume" Who is it those peoples for who "if it's what you want"? Nobody wants that. I don't get the: "The amp simply does what audiophiles are asking: deliver them distortion and tons of it" Who are these people? I have been in the audio business my whole life and I have never met anybody asking for that. Even the most Biased. subjectivist tube enthusiasth there is.
 

SuicideSquid

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Comon, in 2 of the 3 use case, it was characterised as "unlistenable" on the 3rd one, it was "OK at low volume" Who is it those peoples for who "if it's what you want"? Nobody wants that. I don't get the: "The amp simply does what audiophiles are asking: deliver them distortion and tons of it" Who are these people? I have been in the audio business my whole life and I have never met anybody asking for that. Even the most Biased. subjectivist tube enthusiasth there is.
Amir's been very clear that he's not fond of the way tubes sound. That's fine - but interpret his subjective impressions through that lens.

Distortion is what tubes do. All tube amplifiers have far higher levels of distortion than solid state gear. It's their nature. When you push tubes hard, they break up, which is what guitarists want. When you push them gently, they provide a small amount of distortion that some people find pleasing, which is what nutter audiophiles are always raving about with tube gear, whether they're aware that the "warmth" and "body" they're claiming their tube gear has is actually distortion or not. It's objectively worse than properly-designed solid state gear, but some people like it.

In this case, based on Amir's review, this looks like an amplifier that measures well for its price bracket in all respects outside the tubes, which measure like tubes, and provides "tube sound" when you're pairing it with high-impedance headphones. If you want to try messing around with tube gear and you have a set of headphones that will play nice, for $80 this seems like a good value to me. If that's not something that interests you, fine, but I don't see where "$80 headphone amplifier has some upsides and some downsides, may appeal to the right person" is a statement worth arguing over.
 

AluminiumEar

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they provide a small amount of distortion that some people find pleasing
That's bull shit, distortion is distortion, is there even a teeny tiny distortion you find pleasing when you listen to Pavarotti?

Or, is this “small amount of distortion” works for already severely distorted doom metal music?

The musican is like: No, thank you, if i need distortion, i'll add it myself.
 

Xyrium

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I hate to not like this little guy.

Thanks for bringing it to us Amir!
 

ayane

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"Tubes sound good!" they said. "Tubes have even order distortion products which are pleasing!!11!" they said.

As far as I'm concerned, distortion products that high is like having dead bugs in the soup. Splitting hairs over even and odd is like picking which are less yucky: gnats or ants. Spoiler, you get both.

Why bother eating bugs when you can just get a good bowl of soup for the same price without any flies in it.
 

PeteL

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Amir's been very clear that he's not fond of the way tubes sound. That's fine - but interpret his subjective impressions through that lens.

Distortion is what tubes do. All tube amplifiers have far higher levels of distortion than solid state gear. It's their nature. When you push tubes hard, they break up, which is what guitarists want. When you push them gently, they provide a small amount of distortion that some people find pleasing, which is what nutter audiophiles are always raving about with tube gear, whether they're aware that the "warmth" and "body" they're claiming their tube gear has is actually distortion or not. It's objectively worse than properly-designed solid state gear, but some people like it.

In this case, based on Amir's review, this looks like an amplifier that measures well for its price bracket in all respects outside the tubes, which measure like tubes, and provides "tube sound" when you're pairing it with high-impedance headphones. If you want to try messing around with tube gear and you have a set of headphones that will play nice, for $80 this seems like a good value to me. If that's not something that interests you, fine, but I don't see where "$80 headphone amplifier has some upsides and some downsides, may appeal to the right person" is a statement worth arguing over.
It's just broad generalisations, a "us vs them" type cliché. Good tube gear keep distortion under control. There's nothing grungy about my Freya+ tube preamp. Nothing remotely close to what's being described here even for anybody "not fond of the way tube sound". Something this audible is unacceptable. unless those subjective impressions are untrue and biased. This is a throwaway useless product, tube lover or non-tube lover will hate it just as much if Amir really heard what he said he heard.
 

Billy Budapest

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Amir's been very clear that he's not fond of the way tubes sound. That's fine - but interpret his subjective impressions through that lens.

Distortion is what tubes do. All tube amplifiers have far higher levels of distortion than solid state gear. It's their nature. When you push tubes hard, they break up, which is what guitarists want. When you push them gently, they provide a small amount of distortion that some people find pleasing, which is what nutter audiophiles are always raving about with tube gear, whether they're aware that the "warmth" and "body" they're claiming their tube gear has is actually distortion or not. It's objectively worse than properly-designed solid state gear, but some people like it.

In this case, based on Amir's review, this looks like an amplifier that measures well for its price bracket in all respects outside the tubes, which measure like tubes, and provides "tube sound" when you're pairing it with high-impedance headphones. If you want to try messing around with tube gear and you have a set of headphones that will play nice, for $80 this seems like a good value to me. If that's not something that interests you, fine, but I don't see where "$80 headphone amplifier has some upsides and some downsides, may appeal to the right person" is a statement worth arguing over.
See my earlier comment for what “tube sound” in audio gear most likely comes from. Largely, it’s not distortion, IMHO—instead, it’s rolled off frequency response at the high and low ends of the spectrum and a far lower damping factor than solid state gear, especially at the high and low ends of the spectrum. I am sure that the distortion profile contributes to the sound signature if it’s high enough, but I think that’s secondary to the frequency response and damping factor deficits which are definitely audible.
 

ayane

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I think the characteristic tube sound that some people describe as “euphonic” has less to do with the distortion measurements and more to do with high frequency roll off and the much lower damping factor than solid state, especially on the high and low frequency ends of the spectrum. If the harmonics are high enough to be audible, they will contribute too, but I don’t think they are the main things people are hearing when they describe “euphonic tube sound.”
I'm not sure the roll-off is as relevant, considering most playback-side tube-amp afficionados are middle-aged adults who probably have considerable HF hearing loss, but I do agree on the damping factor front. Damping factor plays a huge role in coloring the sound, especially of headphones that have relatively low but highly variable impedance. Old article by nwavguy, but nonetheless relevant.

In this case though, the distortion is high enough that it's going to bleed through and be audible on good headphones, especially on acoustic recordings where there isn't enough masking by synth instruments.
 
G

GoneToPlaid

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How concerned should I be to see those... umm... semiconductor devices that are made to be mounted to a heat sink... that aren't mounted to a heat sink?

They even highlight two of them!

View attachment 188599

Just curious... ;)
They don't have to be mounted to heat sinks since these transistors drive the line level outputs and the headphone outputs at very low current and total power.
 

PeteL

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See my earlier comment for what “tube sound” in audio gear most likely comes from. Largely, it’s not distortion, IMHO—instead, it’s rolled off frequency response at the high and low ends of the spectrum and a far lower damping factor than solid state gear, especially at the high and low ends of the spectrum. I am sure that the distortion profile contributes to the sound signature if it’s high enough, but I think that’s secondary to the frequency response and damping factor deficits which are definitely audible.
True, but I think to some extent, distortion too but It has to be very subtle. To me, not as much because there is more distortion, but more about the fact that it is gradually, slowly, and linearly increasing THD. It’s just a very unfounded hypothesis, but would it be possible that it could artificially create an exaggerated sense of dynamics that is not on the recording? like when you hit a snare drum hard, there are more and more harmonics the louder you hit. This of course is on the recording, but with tubes, loud transients will have momentary more THD than soft segments, it’s not going from perfect to clipped, the THD will constantly move with the dynamics. that’s how tubes behave. In other words, the harmonic content is modulated by the signal. Of course, it’s still artifacts, still not hifi reproduction, but wondering if psychologically, this smooth raise in harmonics as. stuff gets loud may contribute to this idea of tube sound.
 
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Mnyb

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What does Euphonic even mean?… I have a Freya+ Tube preamp. It sounds really good. Does it sound different thans the other modes? I wouldn’t know, because it don’t have the same gain, but it doesn’t sound distorted, tubes don’t have to. It does have measurably higher THD than the other SS stage tough. It don’t matter to me, it’s a good sounding preamp tube or not.
It’s sounds “better” than it is , a kind of sound quality that flatter certain recordings .
Sounds “nice” with many recordings ?

There is an idea about “sounds good” rather than reproduction as faithfully as possible what’s on the record what we normally would call HiFi.

The idea has an inbuilt logical contradiction. Many audiophiles thinks you can have a “make everything sound good” machine . Certain frequency response deviations impedance variations THD patterns migth flatter some recordings but not others , and make them sound worse.
 

Billy Budapest

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True, but I think to some extent, distortion too but It has to be very subtle. To me, not as much because there is more distortion, but more about the fact that it is gradually, slowly, and linearly increasing THD. It’s just a very unfounded hypothesis, but would it be possible that it could artificially create an exaggerated sense of dynamics that is not on the recording? like when you hit a snare drum hard, there are more and more harmonics the louder you hit. This of course is on the recording, but with tubes, loud transients will have momentary more THD than soft segments, it’s not going from perfect to clipped, the THD will constantly move with the dynamics. that’s how tubes behave. In other words, the harmonic content is modulated by the signal. Of course, it’s still artifacts, still not hifi reproduction, but wondering if psychologically, this smooth raise in harmonics as. stuff gets loud may contribute to this idea of tube sound.
That’s interesting, but the harmonics would have to be pretty high in level to be audible, and even then they would probably be masked by the fundamental because it is so much higher in level. But who knows?
 

solderdude

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At 'normal' listening levels distortion will be much lower and mainly 2nd and 3rd harmonic.

When increasing the 'audiophile caps' in value one can extend the lower frequency response.

more pics of the inside
 

PeteL

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At 'normal' listening levels distortion will be much lower and mainly 2nd and 3rd harmonic.

When increasing the 'audiophile caps' in value one can extend the lower frequency response.

more pics of the inside
I was talking generally, « normal« for a peace of gear may not be for all tube gear. In this particular case, This amp is out of it’s linear zone at 1 mW in 30ohms. Under normal listening conditions, it will certainly be in that increasing THD zone for all or most peaks. How much is audible I don’t know but based on Amir impressions, It’s fair to assume it is, in this case, too much even, but it doesn’t translate the same for everything with tubes out there.
 

Rja4000

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Nice and cheap effect machine.
Add an 'effect level' knob or selector, and that would make it excellent.

Actually, the volume control may behave like that on the aux output ?
@amirm Do you have a plot for THD vs volume on line out ? Or can we guess it follows the high impedance phone out ?
 
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