This is a detailed measurements of the audio performance of the Pixel 4a smartphone. It was kindly purchased new by a member and drop shipped to me. It costs US $350.
Being used to my Samsung S8+, the Pixel 4a looks decidedly small:
Screen sharpness is much better than above as I left the protective film on it.
For my testing, I installed Roon client on it as you see above and played my test tones. I don't know how Roon handles the Android audio pipeline and whether everything is resampled or not. It doesn't appear to be but I don't know for sure. In contrast, I test phone dongles using my computer so bit-exact transmission is assured.
The hope with testing phone audio is that it can work stand-alone without the need for an external dongle. Let's see if the Pixel 4a gets there.
Smartphone Audio Measurements
I streamed my 24-bit, 44.1 kHz, 1 kHz test tone using Roon. This is the output at maximum volume (with no load):
Let's start with the good news. Distortion is below -100 dB which should make it inaudible for more practical purposes. Interestingly distortion dies off after third harmonic which is good perceptually. Noise floor is higher than that so results in a SINAD of 95 dB which is good for a phone:
Now the bad news: the output is only 0.3 volts. Even 1 volt would not be enough to drive high impedance headphones such as Sennheiser HD-6XXX. I like to see 2 volts output for proper performance.
Switching to 33 ohm load dropped the output further down to 0.27 volts although there, current availability matters more.
Since I had more own Samsung S8+ beside me, I thought I show its performance using identical setup:
There are more harmonics than on Pixel 4a but because the noise floor is much lower than it, the S8+ actually gets slightly better SINAD. But that is not important. What is important is that the Samsung produces nearly 1 volt.
Due to the fact that my analyzer can't control the phone, I can only run one more test which is jitter:
This is much better than dongles although they suffer from noise over USB which the internal playback does not.
Subjective Listening Tests
I started my testing with Pixel 4a using my Sennheiser HD650 headphone. As measurements predicted, there simply was not much volume there. I could still hear the fan from my computer which is not too loud. I plugged the HD650 into my Samsung S8+ and it was night and day in volume.
I then switched to AKG K371 and here, there was more volume and the experience was usable.
What is nice is that what volume there is, is absolutely clean. There is no hint of distortion.
Conclusions
The Pixel 4a has a clean DAC implementation. Unfortunately they set their sight way too low as far as output level, making the phone almost useless with any high impedance headphone. Lower impedance headphones and more efficient ones should help create a usable experience. So a mixed experience: very clean sound but not much of it.
As is, I can't recommend the Pixel 4a for its audio performance. Taking a step back from my Samsung S8+ is just not acceptable. There should be a mandate that the output voltage is at least 1 volt, if not 2 in any smartphones.
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As always, questions, comments, recommendations, etc. are welcome.
Spent today running to the store to pick up my order of canning jars. There has been a massive shortage of them for weeks now. Twice I put in an order at the local store, only to have them cancel it after accepting it. By magic, today's order worked and we now have some breathing room as we can and can some more. Spent the entire afternoon helping my wife can 14 quart jars of pears and there is much more.
Once that was done, I started a speaker measurement (which got screwed up and I have to repeat), and dehydrated more variety of tomatoes:
Yeh, pretty soon this section of the reviews will be longer than the audio portion! Your only hope of this not happening is our constant rain now killing what harvest we have left. Donating a few dollars may also occupy my mind with money and not gardening: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Being used to my Samsung S8+, the Pixel 4a looks decidedly small:
Screen sharpness is much better than above as I left the protective film on it.
For my testing, I installed Roon client on it as you see above and played my test tones. I don't know how Roon handles the Android audio pipeline and whether everything is resampled or not. It doesn't appear to be but I don't know for sure. In contrast, I test phone dongles using my computer so bit-exact transmission is assured.
The hope with testing phone audio is that it can work stand-alone without the need for an external dongle. Let's see if the Pixel 4a gets there.
Smartphone Audio Measurements
I streamed my 24-bit, 44.1 kHz, 1 kHz test tone using Roon. This is the output at maximum volume (with no load):
Let's start with the good news. Distortion is below -100 dB which should make it inaudible for more practical purposes. Interestingly distortion dies off after third harmonic which is good perceptually. Noise floor is higher than that so results in a SINAD of 95 dB which is good for a phone:
Now the bad news: the output is only 0.3 volts. Even 1 volt would not be enough to drive high impedance headphones such as Sennheiser HD-6XXX. I like to see 2 volts output for proper performance.
Switching to 33 ohm load dropped the output further down to 0.27 volts although there, current availability matters more.
Since I had more own Samsung S8+ beside me, I thought I show its performance using identical setup:
There are more harmonics than on Pixel 4a but because the noise floor is much lower than it, the S8+ actually gets slightly better SINAD. But that is not important. What is important is that the Samsung produces nearly 1 volt.
Due to the fact that my analyzer can't control the phone, I can only run one more test which is jitter:
This is much better than dongles although they suffer from noise over USB which the internal playback does not.
Subjective Listening Tests
I started my testing with Pixel 4a using my Sennheiser HD650 headphone. As measurements predicted, there simply was not much volume there. I could still hear the fan from my computer which is not too loud. I plugged the HD650 into my Samsung S8+ and it was night and day in volume.
I then switched to AKG K371 and here, there was more volume and the experience was usable.
What is nice is that what volume there is, is absolutely clean. There is no hint of distortion.
Conclusions
The Pixel 4a has a clean DAC implementation. Unfortunately they set their sight way too low as far as output level, making the phone almost useless with any high impedance headphone. Lower impedance headphones and more efficient ones should help create a usable experience. So a mixed experience: very clean sound but not much of it.
As is, I can't recommend the Pixel 4a for its audio performance. Taking a step back from my Samsung S8+ is just not acceptable. There should be a mandate that the output voltage is at least 1 volt, if not 2 in any smartphones.
------------
As always, questions, comments, recommendations, etc. are welcome.
Spent today running to the store to pick up my order of canning jars. There has been a massive shortage of them for weeks now. Twice I put in an order at the local store, only to have them cancel it after accepting it. By magic, today's order worked and we now have some breathing room as we can and can some more. Spent the entire afternoon helping my wife can 14 quart jars of pears and there is much more.
Once that was done, I started a speaker measurement (which got screwed up and I have to repeat), and dehydrated more variety of tomatoes:
Yeh, pretty soon this section of the reviews will be longer than the audio portion! Your only hope of this not happening is our constant rain now killing what harvest we have left. Donating a few dollars may also occupy my mind with money and not gardening: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/