The last phone I got was the Nexus 5 which I measured back in early 2014. As you can see, it doesn't measure too well using the standard test bench but adequate for busy environments. Not inspiring 16/44 performance and it does accept 24-bit audio but can't really perform beyond close to 16-bit dynamic range. It's also limited to standard resolution 44kHz only.
Last year, my wife got the iPhone 6 which I also examined. Up to 24/48, it performed well subjectively and with objective measures. Clearly a step above my Nexus 5 in terms of achieving >16-bit dynamic range. In terms of output impedance, Ken Rockwell measured the iPhone 6+ as 3.18-ohms and the Nexus 5 is probably around an unimpressive 10-15-ohms.
Well, after close to 2 years, here then is my phone upgrade:
|Shown in Otter Box case.|
In the picture above, I have it nestled in the excellent but bulky Otter DEFENDER Case - it provides a nice rugged secure belt clip; essential for day-to-day work. The rubberized feel of the case is also good since the body of the phone is now made of glass front and back which could be a little slippery when wet. The thickness might compromise wireless Qi charging; my more expensive Panasonic QE-TM101 charger actually fails to charge with the case on but my cheap generic charging pad from eBay actually works fine!
Here's a look at the size compared to the old Nexus 5 and wife's iPhone 6 (not Plus):
|Each phone rendering this blog in Dolphin browser at full brightness.|
|Nexus 5 left, then iPhone 6 (a very pretty phone IMO), and Note 5 right.|
An obvious and substantial handful size-wise, my friends. Five years ago you'd look like a total dork lugging this around (first Samsung Note came out 2011), but these days, it's pretty well standard around here. Especially useful I believe for those reading complex Asian fonts. You've probably seen in other reviews that although having a slightly larger screen than the iPhone 6+ (Note 5 5.7" vs. iPhone 6+ 5.5"), it is actually shorter, about the same width, and slightly thicker; overall it feels similar in my hand.
Let's get to it with the audio. Notice that there are some results out already using the Note 5 and and AudioPrecision APx525! The output impedance is 4.6-ohms. Not far off from the iPhone 6... That's an encouraging start. "Willyman" called it "an audiophile's dream"! We'll see about that.
Although I don't have such esteemed equipment, let's see what my results look like and compare the Note 5 with the iPhone 6, the previous Nexus 5, a few of the other DACs, and of course the PonoPlayer.
I. Oscilloscope Square Wave @ 0dBFS, Impulse Response, Digital FilterAs usual, let's start with a few preliminary evaluations. First up is the ol' digital oscilloscope to see the maximum voltage and channel balance:
Nice channel balance, peak voltage at ~1V, or 0.7Vrms. This is essentially the same as the PonoPlayer (single ended mode) and a bit lower than the iPhone 6 which is capable of about 1Vrms.
Minimum phase filtering is being used with Apple's iPhone 6 and now I see it with the Samsung Galaxy Note 5 - seems like the "norm" with expensive cell phones these days. Absolute phase maintained.
Stereophile has been using an overlay graph with wideband measurements of white noise and a 19kHz signal over the last few years to look at filter roll off, and aliasing products based on discussions with Juergen Reis (the "Reis Test"). Here's a similar version (with 19kHz and 20kHz components to scare up some intermodulation as well), signal constructed as 24/44:
Since this is the first time I've posted something like this (beyond just wideband white noise), I've annotated it with some details. As you can see, I have 3 spectra overlaid. The green FFT is the twin 19kHz and 20kHz sine waves at -6dBFS [peak amplitude -0.02dB, no clipped samples] in the test signal but I've set the peaks at -20dB on my ADC to prevent any overloading - I'm going to use this as the standard volume calibration for these tests. The purple is with the device playing digital silence. As you can see, there's a bit of very low level noise from 20Hz to 20kHz. Notice the noise floor increases when I play the 19 & 20kHz test tones in green. The new noise peaks in the green FFT (compared to the purple digital silence tracing) represent added distortion (aliasing, harmonic distortion, intermodulation distortion, spurious noise). I've also added a solid horizontal line at -120dB as a marker; any noise products below this means the signal is less than 100dB below the peaks at -20dB. In the case of the Note 5, even though there are quite a number of peaks <20kHz, all except one at 13kHz appear to be at or more than 100dB below the 19 and 20 kHz primary signals. I think that's pretty good.
Finally, there is the yellow tracing. This is the wideband white noise tracing used to look at the steepness of the digital filter. With the Note 5, notice that the overall noise floor appears to increase with signal complexity from silence, to dual tones, to random noise. I've seen this kind of thing happen with other portable devices but had not reported it. Ideally, it would be nice to see the noise floor remain stable irrespective of what signal is being played (which is the case with the excellent DACs I've tested). This is an example of a suboptimal digital filter design. As the signal gets louder and more complex, the DAC digital filter becomes "overloaded" resulting in increased distortion and restriction of dynamic range can be seen... This makes it difficult to get a handle on the impact on playing real music since the dynamic range will fluctuate through the course of a piece; whether this is an audible problem is unclear to me but certainly this is not ideal performance.
Now, for some context, here's what the same test looks like with the PonoPlayer:
Notice again the weak digital filter (yellow) with a very gradual roll-off instead of the sharp filter with the Note 5 around the 22kHz Nyquist frequency. The result of this is the presence of strong aliasing images at 24 and 25kHz (green tracing). Compared to the Note 5, there are a number of signal spikes poking through the solid horizontal line down at -120dB (or 100dB below the sine wave peaks calibrated to -20dB)... Basically, a demonstration of more distortion products present; still lowish levels so I'm not claiming this is audible although the 24 and 25kHz aliasing peaks could cause significant problems with nonlinear speakers and headphones.
The nice characteristic demonstrated by the PonoPlayer is how the noise floor remains stable irrespective of the signal being played. I like this stability! (And as I commented on the PonoPlayer review, I wish Pono would come out with firmware that lets me turn off the Ayre filter and run a more typical steeper filter which would clean up much of the aliasing distortion with 44/48kHz signals!)
II. RightMark Tests & ComparisonsAs usual, I'll be using the measurement equipment "chain" as such:
Phone/DAP/DAC Device --> 6' single-ended cable (shielded phono-RCA or RCA-RCA) --> E-MU 0404USB --> 6' shielded USB cable --> Windows measurement computerSome devices like the PonoPlayer are of course capable of balanced operation, I will indicate this as appropriate.
RightMark 6.4.1 PRO software for acquisition and analysis; some of the older devices would have been measured with earlier versions and data saved in a compatible format.
The big summary chart with a number of comparison DACs:
Scanning through this summary, one cannot help but be reminded that 16/44 audio is generally not a problem at all! The only device that clearly struggled with the full 16-bit resolution was the Nexus 5 phone. We see the frequency response idiosyncrasy with the PonoPlayer of course. And the Dragonfly's higher stereo crosstalk.
|IMD test tone|
The summary chart:
The reason I'm doing 24/48 is mainly to compare to the iPhone 6 (with the Onkyo HF Player app) which peaks out at this bit-depth and samplerate. As you can see, the Note 5 holds its own remarkably well at this setting... For all the complex electronics inside, it actually achieves a very low noise level reading. However, I do believe this low noise / high dynamic range result is exaggerated with simple test signals like RightMark as suggested in Part I above.
Lots of DACs tested over the years at this almost universal "high-resolution" setting:
What can I say, the Note 5 remains very accurate compared to the others based on this test. With a dynamic range of 111dB, we're looking at slightly more than 18.5-bits of resolution (again, remember the caveat from Part I about the noise floor). Again, some excellent measured results from a compact mobile device. Interestingly the Note 5's frequency response has a gentle roll-off earlier than the others... Not a big deal since we're only looking at -0.75dB at 20kHz (much less than the PonoPlayer at 44/48kHz of course).
|Noise Level. You can see a bit of 60Hz mains hum with the Transporter and TEAC which are of course plugged into the wall socket.|
|IMD test tone|
|Stereo Crosstalk. There's that Dragonfly again... And the benefit of balanced operation.|
Yes ladies and gents... The Samsung Note 5 phone does indeed support and play back 24/192 files.
Like the 24/96 results above, that gentle roll-off is again notable for the Note 5 compared to the others.
|Noise Level. Curious that the Note 5 has a 60Hz component here which was not seen with the 24/96 test. I double checked this and it appears to be a real finding though not of concern at -120dB down.|
III. Jitter - Dunn J-Test
I expected to see a little more of the jitter modulation pattern in the 16-bit spectrum. But otherwise, there's no evidence of significant "skirting" of the primary signal base nor sidebands as seen in SPDIF interfaces which are more prone to jitter (eg. TosLink, Coaxial). As I have noted before, I'm not sure we need to be concerned about jitter these days with the vast majority of devices (despite all the claims out there)...
IV. Subjective Impressions
The Spotify app works well as expected. Nothing special to report... Sounds fine.
V. ConclusionsAs a Samsung Note large-screen phone, this baby is fast, has 4GB RAM, and can handle whatever LTE Advanced (450Mbps) network you might want to throw at it. The screen is gorgeous so long as you desire the larger size of course! This screen size is great as an all-in-one "phablet". Plus the S-Pen works really well to jot the occasional note or doodle. And for those wondering, the USB data transfer speed is about 19MB/s copying music to storage (vs. 4MB/s with PonoPlayer). Remember that unlike previous Note phones, this one does away with the removable battery and microSD slot. Non-replaceable battery is typical these days but my feeling is that the loss of the SD slot is a bit unfortunate since it would be nice to store more music or movies on the machine itself with an interchangeable card. Consider getting the 64GB model if you intend to store a bunch of media. Do not underestimate the power of streaming of course! Just make sure you have a good data plan if you're going to be consuming a bunch of lossless audio or video...
Now as for the audio performance, let's say it's more than adequate for me personally as a portable music player. Remember, I'm pragmatic about portable audio. Even if the player outputs the most accurate sound possible, I do not believe I'm actually going to be able to appreciate this with headphones sitting on the subway, taking the bus, or walking down the street - 256kbps MP3 sounds great. Lossless is overkill for me in these settings (no need to even mention 24-bits or 88+kHz sampling rate)! I guess I might appreciate lossless better in the quiet of my own home at night with the kids asleep but frankly speaking, as much as I've invested in headphones over the years, no headphone can take the place of real speakers recreating the soundstage in front of me for high-fidelity enjoyment.
Personal preferences aside, the objective results from the headphone output of this phone is excellent with standard measurements. It can handle high-resolution audio all the way to 24/192 and is capable of >16-bit audio resolution. However, if we only use standard test signals, we would miss out on the issue with the noise floor and effective loss of dynamic range as shown in the digital filters FFT's in Part I. Unfortunately we see limitations of the digital filter (fixed-point overload/overflow?). You can read more about the technical details and pitfalls of digital filters here (BTW: for DIY guys, here's an interesting blog post with lots of filter settings/coefficients to test out with the Soekris R-2R DAC). Honestly, I'm not sure I can hear this effect through my headphones with the music selection I listened to. I e-mailed JR_Audio about this and he likened the effect to a lossy codec - the more complex and higher the signal level the more low level details will lose definition... Again, not the kind of thing I want to see with "high fidelity" audio in my main system, but it seems fine for my portable needs. I suppose listening tests with real music would be interesting (like maybe equalizing the volume and using a headphone amp with multiple inputs doing quick A/B switching between this device and something that has better filters that do not overload). If anyone has more technical info / experience with this kind of effect, let me know!
Audiophiles... Here is an audio device that's modern with all the bells and whistles, sounds good subjectively, measures reasonably well overall (with the digital filter limitation caveat of course), and doubles as your PDA / personal communication device :-). If the iPhone 6 and now the Note 5 are examples of objective improvements in devices yet to come, I'd say that the needs of audiophiles will be well taken care of in the days ahead.
PS: I'm now very curious about the digital filter FFTs and will try running a few of these tests with the iPhone, Nexus 5, etc...
Addendum: January 30, 2016
Measured the output impedance - using 1kHz signal and 20-ohm load. 1.3-ohms - good.