Smartphone Audio Quality Testing
by Chris Heinonen on December 8, 2013 5:15 PM EST- Posted in
- Smartphones
- Audio
- Mobile
- Tablets
- Testing
In many of the examples you have seen so far, you notice that the Nexus 5 has a large issue with the left channel at peak volume levels. As Brian mentions in his Nexus 5 review, it is based on a similar platform to the LG G2 but it isn't identical. Because there are similarities I want to test it out and see if it has the same issue that I see on the Nexus 5.
The test that is causing the large issue on the Nexus 5 is a 1 kHz sine wave, at -0dBFS, at maximum volume. This is the loudest sound that any device will be asked to produce. If you're familiar with the trends in music mixing the past two decades you'll know that a peak of -0dBFS is not all that uncommon now. This chart at NPR shows the average and peak levels for the most popular songs over the past thirty years. Two decades ago testing for -0dBFS might not have been important but it is now. So lets look at this image from the Nexus 5 again.
Now for comparison, we will look at the LG G2.
This looks much better. However the LG G2 is still putting out 0.546528% THD+N into the left channel while only outputting 0.003338% into the right channel. So there is still some imbalance going on here. So why is the issue so much less on the G2 than on the Nexus 5?
The key to this is looking at the scale on the graphs here. While the Nexus 5 peaks are up close to 1.3-1.4V, the G2 has peaks that don't even reach 700mV. Looking at the actual numbers the G2 has a Vrms level of 475.3 mVrms while the Nexus 5 checks in at 843.6 mVrms for the left channel and 982 mVrms for the right channel. The G2 is placing far less stress on its headphone amplifier and keeping it from the output levels that cause this excessive clipping in the Nexus 5.
To look in more detail, we have THD+N Ratio charts for the stepped level sweep that we looked at earlier. First, lets look at the Nexus 5.
We see that the first three volume levels, 15-13, have THD+N distortion over 0.3% for the left ear, while they are below 0.01% for the right ear. From level 12 and below the THD+N levels are practically equal. Now to see how this data on the G2 looks.
We see the first volume step has 0.55% THD+N or so for the left ear, but the right ear is down at a similar level to level 14 on the Nexus 5. The next step drops it to 0.03% which is way, way below where it is on the Nexus 5 at that point. By step 13 they are equal.
The conclusion I pull from this is that both the G2 and the Nexus 5 have the exact same flaw right now. However, the G2 has attempted to hide it by reducing the maximum output level of their headphone amplifier. The Nexus 5 can play louder, but only with far more distortion. Given this I would expect there to be an update to the Nexus 5 at some point that lowers the maximum headphone level to something closer to the G2.
However this doesn't mean that the Nexus 5 is certainly worse to use with headphones. The top 3 settings are ones I would avoid due to the left channel issue, but I might avoid the top 1-2 settings on the G2 as well. If we consider 1% THD+N to be the maximum allowable level, that leaves 8 volume steps on the Nexus 5 that are usable. The G2 has 9 steps that are available to you, and 10 if you consider 0.03% THD+N in one ear to be OK (it probably is).
In the end, the G2 won't play as loud as the Nexus 5 will, but you don't want to play that loud anyway. It has more usable volume steps than the Nexus 5, and otherwise very similar numbers. I'll be interested to see if either of them make further changes to their maximum output levels to remove this issue.
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sonci - Friday, December 13, 2013 - link
Thanks Anandtech,Nice for doing these reviews, one of my top reasons for choosing a smartphone is audio quality, and im not talking about the voice of my wife, but the music reproduced through earbuds.
Please keep going testing at full volume not only for those who use them with an external integrated, but because that's the right way, if manufactures bost the volume and allow clipping than thats a flaw, also if a phone measure good at full volume than its super good at low volumes, you also can measure them at a specific sound pressure levels, though the difference should be small, but anyway these are not reviews for the casual listener,
and Yes unfourtunately iphones sound very good.
I also would be interested in measuring some old and new mp3 players, though in that case its different to be objective, because for a n audio player SQ is a major selling point, but I dont see Lumia selling more than Galaxie because of better SQ.
If you cant find any old mp3 player, we are crazy enough to send them to you, hoping to have them back once tested.
Thanks
Mokona512 - Saturday, December 14, 2013 - link
Can you do a comparison of smartphones and dedicated mp3 players?for example my sandisk sansa running rockbox firmare gives much better audio quality than my smartphone, especially when driving my akg k240.
cb474 - Saturday, December 14, 2013 - link
I appreciate the sophistication and thoroughness of this review. But I have to say that I have never had a smartphone where I've thought, boy this audio quality is unacceptable. Especially with earbuds or plugged into an external system. Unless you're an audiophile, they all seem pretty good to me.Speakers on smartphones are obviously another story.
But to me the real issue is call quality, including earpiece volume, sound quality of the mic (for one's caller), and especially noise cancellation. Anandtech, thankfully, covers noise cancellation in its reviews with a meaningful babble track test. But I wish there were still much more focus on call quality. There are real differences when it comes to call quality, even amongst flagship phones, and this is an area in which, on a daily basis, I experience frustration. It's amazing how much the "phone" functionality of something that is after all phone is ignored.
kevmitch - Sunday, December 15, 2013 - link
I agree. Excellent article. I hope to see more like it and on the subject.I wouldn't mind the "sensational" scales so much if they were at least used consistently. It was difficult to compare for example the THD FFT responses by tabbing between them in browser windows because the scales aren't the same.
While the max volume should really be set correctly, it would nevertheless be interesting to see the THD FFT for what SHOULD have been the max volume (i.e., a step or two below the G2). I have to say I'm a lot less excited about getting a Nexus 5 now - the Galaxy 4 looks much more appealing in spite of the significant price increase. These results even had me consider getting an iPhone for about half a second.
vang024 - Monday, December 16, 2013 - link
Sorry, but shouldn't you be using lower impedance headphones? The grado is rated at 32 ohms and the K 701 is rated at 64 ohms. The grado might be ok for portable electronics use but the K 701 is more difficult to drive than the 64ohms it is rated at. Not only that, but they are both open headphones which leaks tons of sound and not prefer for anybody using a portable electronic as their music source.I think you have to inform the reader the difference between a closed and open headphones(assume they don't know the difference). I see people purchasing a HD600/650 or an AKG Q702 and complains about the sound leakage when these headphones are design to do so. Most of the time people will purchase headphones like a B&W P5/P7, KEF M500, Bose, or Beats for portable use because they are closed design with low impedance. I would say those are targeted for smartphone users.
I am not saying you shouldn't test smartphone devices with higher impedance headphones, but The Grado and AKGs are not designed for the average joe who don't know much about headphone technologies.
bogdan.anghel - Thursday, December 19, 2013 - link
i listen to a lot of music on headphones, i own a S3, and i want to upgrade to S4 and everywhere i see a review the audio quality and power is very bad. should i go with the HTC One? audio and design is very important to me. (i love the S4 but in terms of audio and design, it's crappy) do any of you guys test or compare those 2 on the same headphones?manveruppd - Friday, December 20, 2013 - link
It's great to see you pushing the boundaries of phone reviewing by testing things that noone else bothers to, and with a scientific precision no one else can match, but i do have a couple of suggestions:firstly, how about also testing the quality of the built in speakers, rather than just the headphone amp? after all, sound qquality in calls is an important consideration when buying a phone. as for the loudspeaker, while i agree that noone except annoying teenagers would listen to music through their phone's loudspeaker, a lot of people use the speakerphone function on their phones regularly, so it's a legitimate area of testing.
secondly, i wonder if it's fair to test all phones with a set of ear buds designed for one phone? if i were a manufacturer i would make sure to bundle a set of buds that sound good driven by the headphone amp i built into my phone, and i would expect it not to do as well with a higher impendance pair of headphones,for example. so to test on apple buds is probably not quite fair on other devices. i would simply pick 3 pairs of headphones, one each of high, low, and medium impendance, made by some reputable audio brand rather than by the manufacturrer of one of the tested devices.
good job though, looking forward to future review
synaesthetic - Thursday, December 26, 2013 - link
output impedance please!seshraj - Wednesday, January 1, 2014 - link
Thanks for another wonderful post.One suggestion to include one Xperia smartphone in your list to test. I personally use an discontinued model Arc S for close to 3 years now and have always been pleased with the bravia audio quality and output, sunlight visibility and camera. I am not a techie or a heavy user of a smartphone; but amazed with the audio quality of this device. I am sure the newer models like Xperia Z would have a more upgraded and better sound quality.
jcazes - Tuesday, January 7, 2014 - link
Can anyone comment on how these deficiencies translate to A2DP streaming over bluetooth? I have an LG G2 and am looking at finding something with Apt-X / aptX support (or cooking it in via a custom ROM, if possible). If the phone can't output audio properly over any channel then I don't want to waste my time.