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.

Dynamic Range, Crosstalk, and Stepped Response Additional Data
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  • brusselwilson - Sunday, December 08, 2013 - link

    Is sample variation an issue of relevance for smartphone audio systems? Reply
  • cheinonen - Sunday, December 08, 2013 - link

    No more than it would be with anything else I would think. For the Nexus 5 I tested two different samples (one from Brian, one from a friend of mine) and both exhibited this issue. So you might see small variations, as you would with any display or anything else, but nothing major I wouldn't think. Reply
  • vailr - Sunday, December 08, 2013 - link

    Another factor to consider: certain cell companies can enable enhanced audio quality for cell phone calls, but only on selected cell phone models. The IPhone 5 has that ability, as I recall. Not sure about the specifics, but I believe that both ends of the cell call must be using supported phones, as well as: the cell provider must enable that feature. That would enable cell calls to have better voice quality than land line calls, via increased audio frequency response. Reply
  • shenkey - Sunday, December 08, 2013 - link

    Could we also get Windows Phone devices included in the test. Lumia 920 and 1520 should fit in the range. Reply
  • cheinonen - Sunday, December 08, 2013 - link

    I'll add whatever I can when I get a chance. This first run has taken almost all my time up since the week of Thanksgiving. Reply
  • hopfenspergerj - Sunday, December 08, 2013 - link

    It's not useful to measure noise/dynamic range at the highest volume setting. You have to measure at one of the lowest settings to determine whether the phone truncates bits, whether the noise floor does not decrease with the volume setting, etc.

    I have an htc dna and it is completely, totally, utterly useless for playing music with sensitive IEMs; I suspect many android phones with "-90db" thd+n measurements are similarly bad in practice.
    Reply
  • hopfenspergerj - Sunday, December 08, 2013 - link

    Not to mention poor shielding on the dna causes the phone to output chirping and static and other loud extraneous noises whenever it transmits data. Reply
  • cheinonen - Sunday, December 08, 2013 - link

    We have stepped output level charts as well that measure this, they just aren't included here right now. I can start to pull those out for current and future tests if we want to use them. Reply
  • evonitzer - Monday, December 09, 2013 - link

    I saw that one graph included when you compared the Nexus 5 and G2 at different levels and I think it should be in all the reviews. I always run my IEM's in the lower half of the volume range so I am quite interested in how they perform. As others have said, excellent work! Reply
  • DoctorG - Tuesday, December 10, 2013 - link

    Same here -- I always run my good IEM's below half volume at least (usually more like a third.) No point in having good headphones & music if the volume is turned up so loud it hurts....

    BTW Great job Chris! I have always wanted more in-depth reviews about smartphone audio quality. It's very important to me, but so far there haven't been any reliable/objective tests available. Thanks! Just a thought, but maybe it would be possible to test against a pro-quality amp/DAC? When I use my GNex, the quality is obviously very different from my audio interface that I use with ProTools. It'd be interesting to see just how much of that is measurable...
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