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Google Pixel 4a Smartphone Audio Review

amirm

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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:

Google Pixel 4a Smartphone Audio DAC Review Meaurements.jpg


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):
Pixel 4a Headphone Output Audio Measurements.png


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:

best smartphone headphone audio review.png


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:

Samsung S8+ Headphone Output Jitter Audio Measurements.png


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:

Pixel 4a Headphone Output Jitter Audio Measurements.png


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:

More Tomatoes Dehydrating.jpg


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/
 

Blumlein 88

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This has been a constant with Google phones. They limit the output to a quarter volt or so. I have no idea why. I've had a couple generations of them and now this test of the 4a.

I use a discontinued Creative Aurvana on the ear headphone with my cellphones. Fortunately it is very efficient and even this low output is enough to drive it to dangerous levels. This earphone sounds pretty nice too though lacking deep bass it has enough. Otherwise I'd have been very bothered by Google having such low output.

It does make it less useful to play over a car radio or hook up to someone's fixed rig using the 3.5 mm jack with such low output.
 

Jimbob54

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Pretty sure roon goes out via usual android resampling etc. Doesn't really matter given that low output. Just get a dongle and uapp for music on this phone.
 

Blumlein 88

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Ah this must be why my by Huawei phone can't drive my JBL boombox to very high levels .

Disappointing, I'd like to see more phones measured . Though I guess it's only worth doing if they have a headphone socket.
While not my choice, what we need is more bluetooth via cellphone measurements. It would be applicable to lots more people.
 

pavuol

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Caution, Amir shows schizophrenic tendencies:
- he gets anemic phone and he prays for more juice!
- he gets hell of a juicy tomatoes and he dehydrates them! :p

Anyway, google maybe aims for some upcoming EU/US guidelines for hearing protection by aplying fixed power limiter.. ;)
 

bobbooo

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Thanks so much for this @amirm , especially your S8+ measurement, as that uses the same audio chip as the still popular S9, S10, Note8 and Note9 series, so is very useful for a lot of users. Roon on Android is not bit-perfect and does go through the Android audio mixer which resamples though as far as I've read. Measurements I've seen elsewhere seem to show even less distortion than you measured, so maybe that's the cause. Could you measure your S8+ output using Neutron Player? As that bypasses the Android mixer and so could reveal even better performance.
 
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Thomas savage

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While not my choice, what we need is more bluetooth via cellphone measurements. It would be applicable to lots more people.
Yea that's especially true now the headphone jack is becoming a thing for history to enjoy only .

The problem is there's so many different standards of Bluetooth, for example my JBL boombox had crappy Bluetooth and is obviously worse sounding comparatively to my DAC that uses the HD Bluetooth standard. Hence why I connect with a lead if I can when using it . *Crappy as in weird annoying distortion around HF area . Only really a issue if I'm sat next to it , mostly I use it at work and would not really notice as I'm not in the same room .

So even if your phone can send a half decent Bluetooth signal the receiving end might screw it up so just by testing the phone we are non the wiser.
 

3125b

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The limited output level is a thing that i ran into with my letest phone as well.
The more-or-less-solution I found is playing something, then pausing the playback via cable remote and then starting it from the lock screen that automatically turns on when using the cable remote. It's the wierdest thing and fairly annoying, but it does work to get useable output levels.
Also I noticed that the new phones, like most PC onboard soundchips these days, have load impedance sensing now.
The wonders of mass-market consumer electronics. Too smart for their own good.

Earlier devices I had in the past did not have that limitation, I think it might be down to gouvernment regulation.
My old iPad Pro 9.7 can comfortably drive my K702 and T90 no problem - the headphone output is fairly powerful.
 

Jimbob54

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Yea that's especially true now the headphone jack is becoming a thing for history to enjoy only .

The problem is there's so many different standards of Bluetooth, for example my JBL boombox had crappy Bluetooth and is obviously worse sounding comparatively to my DAC that uses the HD Bluetooth standard. Hence why I connect with a lead if I can when using it . *Crappy as in weird annoying distortion around HF area . Only really a issue if I'm sat next to it , mostly I use it at work and would not really notice as I'm not in the same room .

So even if your phone can send a half decent Bluetooth signal the receiving end might screw it up so just by testing the phone we are non the wiser.

Yes, think there is only any mileage in testing the end of the bluetooth chain that has the amps and transducers attached- anything else is simply beaming whatever codec is used rather than impacting on the end result. Which would mean dismantling the device- so we are back in a similar argument about testing the components in active speakers- unrealistic
 

Jimbob54

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The limited output level is a thing that i ran into with my letest phone as well.
The more-or-less-solution I found is playing something, then pausing the playback via cable remote and then starting it from the lock screen that automatically turns on when using the cable remote. It's the wierdest thing and fairly annoying, but it does work to get useable output levels.
Also I noticed that the new phones, like most PC onboard soundchips these days, have load impedance sensing now.
The wonders of mass-market consumer electronics. Too smart for their own good.

Earlier devices I had in the past did not have that limitation, I think it might be down to gouvernment regulation.
My old iPad Pro 9.7 can comfortably drive my K702 and T90 no problem - the headphone output is fairly powerful.

Depending on what your source is , on Android USB Audio player pro circumvents the output levels imposed by android- even for internal chips, not just dongle DACs- worth a free trial and only $6 or so . Supports Tidal and Qobuz as well as local files .
 

YSC

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IMO that's decent enough performance to use for a phone, and TBH, we use phones or DAP on the go and in office etc. where the option of headphone like HD650 is almost ridiculous... for IEMs it seems decent enough no?
 

Matias

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I don't know but for me this is kind of irrelevant as one can get a supposedly good measuring dongle like TempoTec Sonata HD (to be measured by Amir sometime) for 30usd which should measure a lot better than the phone's DAC.
 

Vini darko

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I have the first lg google nexus 5. It's laughably anemic too. Currently being used as a streamer via usb where it works very well.
 

Jimbob54

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I don't know but for me this is kind of irrelevant as one can get a supposedly good measuring dongle like TempoTec Sonata HD (to be measured by Amir sometime) for 30usd which should measure a lot better than the phone's DAC.
See the Hidizs S8 review. Same device
 
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