HTC One M8 Audio Testing

Looking at the numbers for the HTC One M8 there are a few things that stand out. The first is the output power of around 1.2 Vrms for all loads. This is a lot of power for a smartphone and should be able to drive almost any set of headphones you would use with it. There is more distortion on the 15 Ohm load but as there are 95 mW at max volume, you should be able to step the volume down a bit and reduce the THD+N.

We also see that crosstalk gets better as we have an easier load to drive. The lower (more negative) the crosstalk is, the less noise is leaking from one channel into the other. This is also the test most subject to error when using the USB automation of the phones. On the HTC One M8, USB testing results in a crosstalk level of -0.01 dB. If you are using your HTC One M8 for music you are best to not have it connected over USB while listening.

  15 Ohm 33 Ohm 150 Ohm 330 Ohm
Dynamic Range 91.791 dB 92.074 dB 91.690 dB 92.008 dB
THD+N 0.3365% 0.0152% 0.0103% 0.0101%
Crosstalk (L) -58.032 dB -64.780 dB -77.688 dB -83.656 dB
Crosstalk (R) -57.950 dB -64.329 dB -77.194 dB -83.240 dB
Output Power 95.55 mW 47.63 mW 11.14 mW 5.116 mW
Output Voltage 1.197 Vrms 1.254 Vrms 1.293 vRMS 1.299 Vrms
Relative Level (20Hz - 20kHz) ±0.664 dB ±0.664 dB ±0.665 dB ±0.665 dB

For some of the other results, I am going to pull in some charts that help to explain it better.

Relative level shows it is flat until the 20 kHz tone. Since most people can’t even hear this, the fall off there isn’t a large deal. The fall-off at 20Hz, which most earbuds cannot produce to a reasonable level, is much more slight and not audible. Unless you are playing back music for your puppy with the HTC One M8, this result is fine but it could be better.

THD+N is below 0.03% until just after 2 kHz when it begins a slow rise up past 0.2% at 20 kHz. This winds up being a good number but I am unsure what causes the rise in THD+N as the frequency increases.

The FFT spectrum for the 997 Hz test tone shows all artifacts below -80dB compared to the fundamental. The second and third harmonics are the largest, and those drop off by -10dB by the 4th and 5th.

This graph compares the frequency response to the BoomSound feature to having it disabled. As we saw earlier the regular frequency response is flat with a steep fall close to 20 kHz. Looking at BoomSound we see a steep roll-off below 30 Hz, a peak of almost +5dB around 60 Hz, a -5 dB section between 200 Hz and 500 Hz, and then a steep rise in the treble past 2 kHz.

Since I didn’t do the subjective listening, I would expect this to sound harsh in the treble, with the midrange being washed out by that dip in the middle. What we have is a high-end and a low-end that is +10 dB compared to the midrange. So these will sound twice as loud to you as the midrange. Using the interactive chart of music instruments by frequency you can find here, you can see what instruments this will obscure.

Comparing the THD+N ratio of BoomSound On to Off shows far more noise and distortion as well. If you want boomy bass, a harsh top-end, and no midrange, then use BoomSound. A better choice is to find headphones that suit your listening preferences more.

The HTC One M8 has good looking numbers, but putting them into better perspective requires more phone testing. As it is I see nothing that stands out as being a problem, unless you leave BoomSound on.


Smartphone Testing and Changes Samsung Galaxy S5 Audio Testing
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  • lessthanjoey - Monday, June 2, 2014 - link

    Wait, what? What about these imperfections is even audible?
  • zShowtimez - Friday, June 6, 2014 - link

    Plug your phone into a decent mid to high end speaker set up. Its so easy to hear the difference. It's part of the reason i went with my htc one over a galaxy s4

    Similar issue with onboard audio vs a discreet card imo
  • Streamlined - Monday, June 2, 2014 - link

    Well, it's official. According to hard data and not just opinion, the HTC One kicks the Galaxy S5's butt. If there is one group in the tech world that purchases inferior hardware due to marketing hype, it's Samsung fans.
  • hero4hire - Tuesday, June 3, 2014 - link

    But just Samsung fans... No other group in the entire world. Nope. Just the Samsung fans. Not a single purchase is bought elsewhere due to hype. Previous comment is not baiting. There is only HTC and Samsung and the best marketing in history is the most beloved and most popular Samsung company. It's official that nobody would try to invoke some other company to compare to the best marketing that is Samsung. No arguments here, Streamlined is 100% wanting to keep us focused on HTC & Samsung.
  • theduckofdeath - Wednesday, June 4, 2014 - link

    Yup, because the camera in the HTC phone is a technical marvel. :)
  • Jimster480 - Tuesday, June 10, 2014 - link

    It actually is. Wait until you take a picture in an almost dark room and it comes out perfect. Or if you are in a pitch black area and you take a picture with the flash and it is 100% clear. or you take a picture in a low light resturant and its clean. Or a pic at a concert and its got mid range lighting at best and its clear aswell! I have found the camera to be great in almost all lighting scenarios. Now it doesn't take as beautiful pictures as my EVO 4G LTE did in bright lighting, but its pretty close, and considering how many other scenarios the camera is useful in, the pro's far outweigh the cons.
  • theduckofdeath - Wednesday, June 11, 2014 - link

    It's an extremely limited camera, made for one of the least common usage scenarios. For everything else, it's far below average.
  • The1Metallian - Friday, June 6, 2014 - link

    I have a GS3 and I'm ready for an upgrade. I would buy the HTC M8 in a heartbeat, but the camera broke the deal. I don't expect the camera to be DSLR quality but at least up to par with any other smartphone in the market. I want to know that wherever I am I will be able to take a good picture if needed. The Sony Experia Z2 won't be subsidized by any provider. What am I left with? (don't say iPhone) If the LG G3 doesn't deliver when released, I'm getting the GS5. Samsung competitors need to get a clue
  • Jimster480 - Tuesday, June 10, 2014 - link

    The camera is actually not bad at all. I'm not sure why everyone hates on it, but it takes great pictures in basically every lighting. And the quality is more than enough for any type of social sharing...
  • gevorg - Tuesday, June 3, 2014 - link

    What about jitter?

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