How many phone manufacturers really care about audio and show off their audio chipset in the phone specification sheet? Not many. Among the list of few who do mention this detail does not have the names of the big shots like Samsung, NOKIA(Microsoft) and Apple. Apple, did not even bother putting a high-res audio chipset in their latest iteration of the iPhone.
There is this quite unknown (at least for me) phone manufacturing company called Vivo which has been making some good quality phones with excellent, customised user interfaces and flagship killing hardware that will beat just about any smartphone on the market. Speaking of flagship killers, the market has been flooded with such smartphones recently by manufacturers like Meizu, Xiomi, Oppo, Micromax and the list can go on. Among all these flagship killing smartphones these guys make, Vivo stands with heads held up high! That is because of the fantastic choice of audio chipset that can deliver superior sound as compared to most smartphones.
Vivo X5Max comes with Snapdragon 615 64 bit SoC with Adreno 405 GPU and has all the 4G circuitry required for high speed communication. We won’t talk much about the non-audio hardware rather focus on the intricate details of the audio block in Vivo X5Max.
HiFi 2.0 standard
According to the specifications, x5 Max is the first phone with HiFi 2.0 standard.
HiFi 2.0 Standard features high resolution 24 bit audio for SoC that are used in mobile devices. When it comes to mobile devices, one of the important feature is AMR (Adaptive Multi-rate) audio which changes the sampling rate and encoding scheme depending on the audio. It is especially used for voice calls and AMR helps compress the audio greatly. Since, HiFi is a proprietary standard made by Tensilica, the latest iteration of the standard features a low gate count, which means there is lesser digital circuitry to do the same amount work it was doing in the version 1 of the standard. That also means, the audio chipset working on the HiFi 2.0 standard will consume much lower power.
There are so many audio codecs available today and whenever there is a new audio chipset which claims to have the ability to provide better performance, there is a big hurdle to overcome. The hurdle to port all the codecs for the new chipset. This is because every chipset has different memory addressing schemes, or there might be a different set of assembly instructions for code execution and so on. Fortunately, the new kind of marketing adopted by semiconductor companies has pushed pre-ported codecs to be released with the software development tools. So, the guys at Vivo possibly did not have to port any codecs to work with the new standard because Tensilica should have already provided it.
I can go on talking about the HiFi 2.0 standard because there are so many improvements and additions to the feature set that will make any audiophile drool all over the datasheet.
The actual standard specific functions are handled by a dedicated surround sound chip from Yamaha, namely YSS-205X. There was not much information available regarding this chip, but from what I could find, YSS-205X has very low latency audio processing design which minimizes delay in audio playback.
The actual chipset
Vivo x5 Max comes with a massive ES9018 32 bit audio DAC that has 8 output channels to drive 7.1 channel system. The chip can be programmed to use only 2 channels for stereo mode. There are a bunch of audio processing blocks inside the chip which allow very basic digital filtering. The datasheet also has a few code samples in case you are interested in that. Based on the filters provided inside the chip you can have digital audio effects added to your audio without actually putting any load on the Snapdragon SoC. Nevertheless, the task of handling HiFi standard will be upon the SoC which includes proper handling of codecs.
The analog section of the ES9018 is quite interesting. It claims to have -120dB THD+N when the conditions are near ideal. Whereas, the noise produced by the digital circuitry goes through a series of noise reduction techniques and ends up at a value of -60dBFs which is quite good.
Looking at the level linearity error we can see that there is 0.3dB error when the signal level is -126dB below full scale voltage. To dumb it down, -126dB below full scale voltage with 0.3dB error is almost perfect performance!
Since, we are dealing with digital audio chipset here, audio is encoded in PCM (Pulse code modulation) format. There is something known as pre-emphasis and de-emphasis. While encoding analog audio in digital format, pre-emphasis is done to boost the high frequency parts of the signal to achieve better signal to noise ratio, and the reverse is done while converting coded audio back to analog form. This process introduces inherent errors and distortions in the signal. ES9018 has de-emphasis error of 0.2dB which is not the best, but definitely above average. The best de-emphasis value I have seen was 0.004 dB on a Burr Brown PCM1794 24bit DAC.
The bad thing about this chip is that it can only go up to a maximum sampling rate of 48kHz which is quite sad in comparison to all the beautiful specifications we have just seen. 48kHz is enough for mobile devices, but having a higher sampling rate would have clearly made it a true HD-audio DAC. Even so, with these features, ES9018 is an inexpensive DAC for all the goodies it has to offer.
You can have the best DAC in the world, but everything depends on the way you implement the further analog sections that actually drive the speakers. Apparently, Vivo engineers did take care of that as well by using high performance operational amplifiers, specifically Texas Instruments OPA1612 and ESSTech ES9601. Apart from that, having a good power source to power up the audio circuitry is just as important has having above average, high performance audio chips.
Speaking of power supplies, Vivo x5 Max comes with DC-DC converters and a low drop out linear regulator which provides clean DC power to the analog sections of the audio circuitry.
Second to that, the operational amplifiers used in the design have high CMRR and PSRR. CMRR is a number which tells how well the amplifier can reject a signal that is common to the two input lines being fed to it, whereas PSRR tells us how well the operational amplifier can perform without being affected by fluctuations in power supply. Since, both the specifications are good enough, there is lesser chance of the audio being affected by issues such as external electrical noise or power fluctuations that might happen because you turned on some heavy app on the phone.
Meanwhile, CMRR and PSRR are not the only specifications to look out for in an opamp. Things like intermodulation distortion and THD also apply here. OPA1612 and ES9601 are one of the highest performance opamps on the market, check out their data sheets if you do not want to take my work for it. The OPA1612 has a total distortion of 0.000015%, which is next to nothing! While, the inherent noise is mere 1.1 nV/rtHz (nV = nano volts). I have been a regular user of Texas instruments analog chips and they do indeed produce some of the best analog chips on the market.
While having a good power supply, the best operational amplifier and a nice little audio DAC, your sound can still be distorted to some level if your board design is bad! A few images on the internet of the Vivo x5 Max PCB show a neat little design with proper ground plane spread across the area of audio section confirming a good board design. Having ground plane is important to avoid current loops forming that can introduce distortions in the audio. I won’t go too much into the engineering details, but rather just say that it is all good and worth giving a try.
Vivo X5Max is truly a phone for audiophiles with high performance ES9018 DAC, TI OPA1612 and ES9601 Operational amps to give above average audio experience on an affordable, flagship killing smartphone.
The only other phone that has a similar design is Meizu MX4 which has the advanced version of ES9018, namely ES9018K2M DAC. It also happens to have OPA1612 opamp in it.
We tend to use different apps to have better audio performance, but in this case you would not need one. All thanks to the fantastic dedicated audio hardware! I wish this was there inside more smartphones on the market.
Vivo X5 Max is truly a phone for audiophiles with high performance ES9018 DAC, TI OPA1612 and ES9601 Operational amps to give above average audio experience on an affordable, flagship killing smartphone.
Reader Rating13 Votes90
Thin body and light weight
ES9018 high performance audio DAC
OPA1612 and ES9601 high performance opamp
Very low distortion
Good power design for reduced distortion and noise