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Old 06-11-2018, 06:52 PM   #7
delceer
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Part 0: Obligatory photo



From left to right: Super X-Fi, Ganaha Hibiki (CV: Numakura Manami), GTX 1060 screaming "You took me out of the PC to install a WHAT?", unused NS50 vouchers
Part 1: Analog performance

Outputting at ~1.90Vrms

Unloaded
20Hz THD=0.0016% THD+N=0.029%
1kHz THD=0.00021% THD+N=0.00063%
10kHz THD=0.00083% THD+N=0.0011%

33 ohm resistive load on both channels
20Hz THD=0.0019% THD+N=0.029%
1kHz THD=0.00090% THD+N=0.0012%
10kHz THD=0.0014% THD+N=0.0017%

Output impedance
Around ~0.4 ohm @ 1.9Vrms 33 ohm, limited by Arta reporting down to only 0.1dB precision

I'll just take the result as less than 1 ohm, I'm sure other reviewers with their own websites and stuff and their audio analyzers can get a more accurate number.

RMAA summary


The noise numbers look a bit weird, the spectrum shows some weirdness which does not happen with Arta. Comparing the Arta spectrums, it is around 5dB worse than my Xonar DX, so it should still be getting -105dB or better.

Of course, having the same noise level as a computer soundcard is not a good thing for an earphone amplifier, because computers are meant to be connected to speakers with volume controls, while earphones are sensitive and connected to the output of the, erm, earphone amplifier, which means noise levels need to be way lower. Somebody once said the more meaningful measurement of noise is in terms of volts. But what if this amp also has a digital volume control inside? That can change the amount of noise in terms of volts. Noise is not easy to quantify (hence why sometimes you can hear noise coming from a system that supposedly has -80dB or -100dB or better noise), and I'm feeling lazy. We shall see.

Results discussion
The numbers are unbelievable, but the graph checks out: A tiny bit of 3rd harmonic poking slightly above -120dB line.

One thing I noticed and remembered is that Arta and RMAA give slightly different numbers. And this is why I keep both measurements - Arta for the RMAA haters, and RMAA for comparison with other RMAA users.

I forgot I was supposed to use 16 ohm, not 33 ohm. But since I already did that might as well. I still have to collect max output power data anyway.

Back to the SXFi, unbelievable numbers. I didn't know my Xonar STX can measure this low, and because of this these numbers may actually be the limit of the measuring soundcard and not the SXFi.

The goal is to verify Creative's claim of THD+N=0.00036% IMD=0.0022% and crosstalk=-75dB and so far it seems to check out. I give an allowance of up to 6dB, if my numbers are worse than the claims (as is usually the case) it can be due to settings and equipment. Especially when THD+N of 0.0006% is the lowest that I have actually seen from Xonar STX self-loopback.

-75dB crosstalk without load is however pretty mediocre. Let's hope it is due to the cables/connectors/adapters, there is still chance for measurements. I have a feeling that this is the actual unloaded specs however. In which case it is really really bad, I mean because lots of cheap stuff can do at least this good with load.

I'm going to assume the SXFi should hit all the claimed specs. These are amazing numbers. The amp is amazing too, taking just a minor hit in performance from a 33 ohm load at slightly over 100mW in output power. LG has a smartphone that can hit the same number, but it doesn't have as much output power. This level of performance can win many desktop setups, and is packed into the tiniest package possible. Poor crosstalk requires further investigation, would be interesting to check if it is power supply related.
Part 2: Accuracy of ear mapping

So here's the plan:

Record:
My profile A
My profile B
My profile C
Other guy profile A (Or I'll call it profile O)

Diffmaker original with each of the 4 profiles
Get 4 files: Diff A, Diff B, Diff C, Diff O

Diffmaker Diff A with diff B
Diffmaker Diff A with diff C
Diffmaker Diff B with diff C
Diffmaker Diff O with A, B, and C

Compare results

BTW if you don't know what Diffmaker is:
https://www.diyaudio.com/forums/ever...t-effects.html

For "other guy", I'm going to use David Bowie's mugshot.

Spoiler!

Result
After some problems and lots of retries and changes to the plan which I am not going to write, I arrived at two files:

Diff4 minus Diff3.wav
and
Diff4 minus Diff David.wav

And... Diff4 minus Diff David.wav is much softer than Diff4 minus Diff3.wav

Hmm... this isn't supposed to happen

However here's a disclaimer: When comparing the original file and the recorded file (SXFi off), I noticed the amount of difference recorded was varying with time - It goes from nearly the loudness of a normal file, to nearly silent, and back to the original loudness again. I think there is something in the setup causing this long-term variance. Or I just suck at Diffmaker. In any case, the plan was a failure.
Part 3: Stereo content

So I enabled SXFi

...

And disabled it

And enabled it again...

...

And disabled it again

I get that the goal is to reproduce speakers in a room. But if you're reproducing cheap speakers in a large hall, I'd rather you not.

A large part is related to that frequency response. (Keyword: Related, but not necessarily caused by. The FR itself may be the result of that other root cause.) The "cheap" sound. It is unfortunate that I don't have any SXFi-certified headphone / earphone. I only got, like, some obscure models from unknown brands like Alessandro MS-1 and Klipsch X11, I mean what has Klipsch even done before, like manufacturing loudspeakers since 1946?

But looking at the FR data above, the selected headphone / earphone only contributes to a small fraction of the FR, the bulk of it is still due to the SXFi effect. And testing different selected headphone / earphone confirms this - Selecting different headphones / earphones results in a noticeable and possibly important difference, but the effect is still small compared to the whole SXFi effect.

The sound also feels more distorted (as in the high THD kind of distorted) and details are lost. Definitely sounds more hollowy and reverb-y.

More importantly, this is what the SXFi effect does: Soundstage is compressed towards the center and moved forward. But not all of the sounds get this treatment. Some are spread around you including to the back.

The normal headphone sound sounds like sound hard-panned to the left and right, and in terms of front-back positioning it feels like right in the middle. The SXFi does take the sound out of this position and moves it more outside, some more forward and some more around. But still feels like it is coming from the headphones.

And I'm not sure if this can already be achieved by other competing effects, or if it can be done without resulting in such a big change to the sound. It does shift the sound forward which is relatively unique, most likely thanks to the included surround-sound technology. One thing I will say, and will say again in the 3D part of the review, is that the SXFi effect is very aggressive.

Here's the thing. I have earphone / headphone. I have speakers. My earphone / headphone have sounds that sound like my speakers, except they sound like they are coming from the sides of my head but otherwise they sound pretty much the same. And I believe most of you reading will agree with this statement.

So, why did the creators of SXFi feel like they need to change the sound *THIS* much? This is not "experience thatís indistinguishable from a dedicated set of surround speakers" or "high-end multi-speaker system in a professional studio", to be blunt I don't know wtf this is. Maybe an attempt at the feeling of magical immersion beyond the normal speakers sound? Then they should have written that instead of trying to simulate speakers, because it gives less things for people to pick at, and less things to fail.

Btw just for the lolz, if you apply SXFi effect on speakers, you get a soundstage that is even more compressed into the center and even further away from you forward. Logical, because the sound of speakers is already more center and forward, unless you are lucky enough to have a big studio with speakers far apart.

Also, you can recreate the headphone sound on speakers by putting your head right in between the speakers and pointing them at you. And even without pointing them at you (i.e. leaving the speakers pointing forward) the effect is already pretty close. (because speakers can be considered point sources, after ignoring that the frequency response certainly changes with direction, and baffle effects, and cabinet depth... and multi-driver interactions... but for the most part, speakers can be considered point sources)
Part 4: 3D

A good analogy would be: "3D displays"
(More accurately, stereo displays, but most people call them 3D displays)

You know how 3D displays have solid science behind, but when you watch them they still feel weird? Like you have to know how to look at the screen then the 3D effect will work? Be it Nintendo 3DS display, or those double pictures that you have to cross-eye and overlap the image or something.

It's the same here.

Left and right is easy to differentiate, but front and back is going to be hard. So we look out for audio cues that suggest the sound is coming from the back. Like maybe more "round", "dark", "reverby", "hollowy" or something. This has been done in games. And it is being done here.

In other words, you need to know how to listen to virtualized surround sound in order to hear what is being done here.

But SXFi's effect is very aggressive, that's fairly unique. It also creates an image in front, this is also fairly unique. It also seems to do better with multichannel content (Less things to fake and more things to work with I guess), but it still causes a significant quality drop in sound quality. Again likely due to the high aggressiveness.

In the best case, I would call this sound an acquired taste. In the normal case, I would disable it. Because the cost to SQ is too great and not worth whatever benefit it brings. It is like taking a pair of awesome front stereo speakers, and cutting it up into 7.1 crap ones. (And it doesn't even produce real 7.1 but I'm just saying.) So it is beneficial for like 3.5% of the time, but when the movie or game is doing nothing and is just having smooth music and a person talking in front, you want good sound for that but you can't get it. How about 7.1 good speakers instead? I don't know how hard this would be, but this would be the holy grail.
Very nice and details review.
Thanks for the effort.
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