The vivo X7Plus has been released for some time, and its main functions are performance, selfie, endurance and Hi Fi mentioned today. We have seen the special evaluation of its endurance before, and today we will talk about some experiences of Hi Fi. Since vivo X1, the three series of mobile phones, vivo X, Xshot and Xplay, have basically used Hi Fi chips. The audio solution has successively cooperated with Cirrus Logic, Ti, ESS, AKM and other chip manufacturers. In the era of Hi Fi 1.0, vivo brought ES9018K2M decoding chip and OPA2604 operational amplifier chip to support vivo Xplay3S. In the era of Hi Fi 2.0, in addition to the ES9018K2M, the vivo X5Max also introduced a two-stage amplification scheme: the primary operational amplifier SABRE ES9601 and the secondary operational amplifier OPA1612. At the same time, YAMAHA YSS-205X digital surround sound signal processing chip is introduced to realize portable karaoke experience.
In the era of Hi Fi 3.0, the flagship version of vivo Xplay5 first enhanced the two-stage amplification circuit, introduced three OPA1612, and then used two ES9028 DACs to act on the left and right channels for independent audio decoding. What new attempts will be made for the vivo mobile phones after Hi Fi 3.0? In the past 16 years, with the integration of operational amplifier chips such as ES9118 and SABRE9018Q2C, DACs have come to the fore. The mobile phone industry has begun to find that this Hi Fi solution can save more space inside the body than the previous independent DAC solution. At the same time, this DAC integrated with the operational amplifier chip has no decline in decoding and amplifying signal effects.
The AK4376 on the vivo X7Plus is a DAC integrated with an operational amplifier chip. Why did you choose AKM instead of the chip of your old partner ESS? Looking at the Hi Fi scheme used by vivo's X series mobile phones in recent generations, the AK4375 is used by vivo X5ProV, vivo X6 and vivo X6S. So we have accumulated some experience in driving AKM's new Hi Fi solution vivo.
Difference between AK4375 and AK4376
AK4375 is the predecessor of AK4376. Is the latter an upgraded version of the former? It's not that simple. Let's first look at the following chip parameter comparison:
Previous Popular science articles The author has roughly divided mobile phone decoding chips into three categories: independent DAC, DAC integrated with operational amplifier chip and codec. Readers who do not understand these three concepts can review this article. Among them, AK4490 and AK4375 belong to independent DACs, AK4376 belong to DACs integrated with operational amplifier chips, and AK4961 is codec.
AK4961： This codec integrates ADC, DAC and Class G amplifiers at the same time. ZTE Tianji 7, nubia Z7 and nubia Z9 all use this chip. Key audio indicators are similar to AK4375.
AK4490： Both PCM and DSD encoded audio files can be hard decoded by this DAC, which is one of ZTE Tianji 7's Hi Fi chips. In the horizontal comparison of the above four chips, the total harmonic distortion of the AK4490 is the lowest, and the individual performance is the best.
AK4375： The key audio indicators are similar to those of AK4961, but they are only responsible for implementing DAC functions and cannot operate independently. Many mobile phones of nubia and vivo use this independent DAC. Unfortunately, this chip does not support DSD encoded audio.
AK4376： Compared with AK4375, the total harmonic distortion and signal-to-noise ratio have been greatly improved, and the signal-to-noise ratio is also the highest among the four chips. Compared with AK4375, in addition to integrating class G operational amplifier chips, it also increases the sampling speed to 384kHz.
How about the performance of AK4376 hard indicators compared with similar chips from ESS and Cirrus Logic?
In particular, the red background color indicates that three DACs integrate the operational amplifier chip. At the same time, we introduced three other independent DACs that Vivo often uses for horizontal evaluation. From the table above, it can be seen that the biggest difference between AK4376 and the other five DACs is the total harmonic distortion.
vivo XE680
Vivo original earphones range from the entry-level XE100 (earplug), to the mid-level XE600 and XE600i (in ear), to the flagship XE800 (in ear rotatable). Generally, the vivo X, Xshot and Xplay series phones will choose to deliver XE600i randomly. The XE600i has also been in service for many years. At the time of the release of vivo X7 and vivo X7Plus, vivo finally updated its mid-range headphone product line and launched the XE680, the latter of which is equipped with this headphone as standard. The XE680 adopts a semi in ear earplug design, which is popular recently. Similar representatives include Apple EarPods and LeEco digital headphones (CDLA, USB Type-C). It is a pity that this engineering machine is not provided with earphones, so a Sony earphone is used for subjective hearing test: MDR-XB90EX。
Subjective auditory perception test
High, medium and low tri band songs can be divided as follows:
High frequency: symphony, piano music, string music, electronic music
Mid frequency: baritone, mezzo soprano, soprano
Low frequency: rock, pop, dance music
According to the above classification and some industry metrics, the author summarizes them into the following table and finds the corresponding tracks for testing:
The test results are shown in the following figure:
In the above part of the test results, three mobile phones that the author has previously experienced are added to the vivo Xplay5 standard version, vivo Xshot and vivo X6Plus for horizontal comparison. On the whole, the voice of vivo X7Plus is similar to that of vivo X6Plus, which is cooler than that of vivo Xshot and vivo Xplay5 standard version, which is warmer than that of vivo Xshot and vivo Xplay5 standard version, especially when compared with the voice of vivo Xshot, which is obviously warmer. I prefer the latter, but many consumers should prefer a cooler performance.
The dynamic range of vivo X7Plus is not wide. Let's take Sister Cai Qin's ferry as an example:
The treble part feels suppressed, and the midrange and bass parts are not prominent. Fortunately, the dental sound is obvious when singing "draw out", and the overall dynamic range is not as rich as that of several previous models of vivo that use ESS and Cirrus Logic decoding chip solutions. Although the voice part is mediocre, the details of background drumming are in place and can grasp the ear nerve.
The vivo X7Plus has properly enhanced the performance of the bass part of the vivo mobile phone compared with the past, and the resulting chemical reaction is good, perhaps thanks to the integration of the amp module in the AK4376. Both All About That Bass and the Bass part of the California Hotel have a sense of low frequency, and the drums of drum poetry have a feeling of beating the heart. And Drum Poetry has a certain diving ability.
The low frequency performance is excellent, but the adjustment of the medium and high frequency is a little more plain water. Although the voice is still relatively durable, it is a little backward compared with the vivo Xplay5 standard version and vivo Xshot. There is no broken sound in the songs of zither and flute. The control is good, but the high-frequency suppression can be clearly felt.
Compared with the standard version of vivo Xplay5, it has its own advantages in terms of analytical power. The latter performs better in One I Love and ferries, while vivo X7Plus performs better in A Thunsand Years.
summary
I heard that vivo has focused on the performance of the low-frequency part on the two flagship models of the vivo Xplay5 series, but I didn't feel any difference from the previous models. Until vivo X7Plus, we had a long lost sense of low frequency and low potential, which proved that vivo has begun to cater to the mainstream tastes of Chinese people. Of course, the price is to make the performance of the medium and high frequency go backwards. However, with the further cooperation between AKM and vivo, these problems should be solved well in the future.
The standard version of vivo Xplay5 symbolizes the peak of the cooperation between vivo and Cirrus Logic platform for many years. The potential of CS4398 has basically been exhausted. The flagship version of vivo Xplay5, supported by dual DAC and three op amp chips, has made a lot of progress compared with the vivo X6Plus when the ES9028 was first used, and it has been adjusted more carefully, but there is still room for progress. Compared with Cirrus Logic and ESS, AKM and vivo have cooperated for a short time, and there are not many high-quality products, but vivo X7Plus is a commendable work. I still remember that the Hi Fi switch of the vivo X6 could not be opened and closed manually. It can be seen that the adjustment was not mature at that time. After water testing several products, we came to the AK4376 platform of vivo X7Plus, which not only supports CUE song selection and manual opening/closing of Hi Fi mode, but also kills common lossless audio formats other than DSD coding. The unusual 44.1kHz/32bit WAV format tracks and 192kHz/24bit sample rate tracks can also be well compatible.
As shown in the above table, combined with the full text experiment conclusion, compared with the AK4375 of the independent DAC, the AK4376 integrated with amp is obviously not just an upgraded version from the perspective of parameters or actual decoding performance. The decoding ability, audio format compatibility and sound quality performance have obviously risen to a higher level. Of course, from the perspective of Vivo's three different Hi Fi platforms, ESS and Cirrus Logic still have advantages. However, with the longer cooperation between AKM and Vivo, this gap can be narrowed.
