Since vivo introduced independent DAC in vivo X1, Hi Fi mobile phones have begun to rise. Since then, several successive vivo mobile phones have used independent Hi Fi chips. At the same time, consumers are beginning to be confused by these imperceptible chip models: DAC, ADC and DSP, operational amplifier and ear amplifier, codec and independent DAC. In addition, the combination scheme of Hi Fi chips is unique. What are the differences between different Hi Fi chips of the same manufacturer with different functions. What are the differences between Hi Fi chips with different functions or the same functions from different manufacturers? Today, let's start with a simple talk about DAC ADC、DSP、codec、 What are the six terms of operational amplifier and ear amplifier.

ADC and DAC DSP

ADC is an analog to digital signal encoding chip, such as TLV320ADC, and DAC is a digital to analog signal decoding chip, such as ES9028. The former is generally used for recording while the latter is generally used for decoding audio. The intermediate digital signal processing is operated by DSP. The analog signal is input from ADC, coded into digital signal, sent to DSP for calculation and processing, and finally sent to DAC to decode the digital signal into analog signal and output.

Operational amplifier and ear amplifier

Ear amplifiers are the names of a class of products, not chip types. An earphone may have multiple operational amplifier chips, such as OPA1612 and OPA2604. In addition, there are also classifications between op amp chips, some of which are only used for external amplifiers rather than headphones, such as the TFA9890 of NXP. Some only work on headphones and not on external amplifiers, such as Maxim's MAX97220. The OPA1612 and OPA2604 are two op amp chips that can simultaneously work on headphones and amplifiers.

Codec and independent DAC

We always thought that codec must be integrated in the SoC, while independent DAC is external to the SoC, so it is wrong to think that codec and independent DAC can be well identified through the position arrangement between chips.

Codec can also be independent of SoC. For example, the codecs of Samsung and Apple phones are generally independent of SoC, which can also be regarded as independent audio chips. In other words, the WCD9335 codec of Samsung S7 (Snapdragon 820) is also an independent audio chip, but its decoding effect is not as good as that of a chip like CS4398. Similarly, vivo Xplay5 has two decoding chips: WCD9335 codec and CS4398 DAC. Why is codec not as good as independent DAC?

Codec integrates ADC, DAC and other audio related modules at the same time. For example, AK4961 integrates ADC, DAC and amp functions at the same time. It is a complete audio scheme. It should be more powerful than an independent DAC that only knows decoding and cannot be used independently, right? The problem is concentration. With more codec integration functions, there will be more things to take into account. The amount of computation will naturally be allocated and scheduled by various functional modules, and the decoding efficiency and effect will naturally be inferior to that of independent DAC.

In the past few years, it seems that the Hi Fi scheme with three independent chips is more popular, such as vivo Xshot, TLV320ADC+CS4398+MAX97220。 Since the emergence of SABRE9018Q2C and ES9118, which are highly integrated with operational amplifier chips, the industry seems to have begun to pay attention to this new Hi Fi solution. The biggest advantage of this is that it can save the internal space of the mobile phone, and at the same time, it can continue to satisfy the consumers' desire to stack materials on the Hi Fi circuit. The integration is between the codec and the independent DAC, giving consideration to the decoding effect and efficiency.

Finally, let's take a look at the mainstream Hi Fi chips of independent DAC, DAC integrated with operational amplifier chip and codec in the market, as well as the corresponding models?

Stand alone DAC series

Horizontal comparison of mainstream independent DAC

ES9018K2M：vivo X3、vivo Xplay3S、vivo X5Max、 Xiaomi Note standard version, Meizu MX4 Pro and Meizu PRO 5, Blue Devil MOS1 max, TCL Dongdong Gun 2, Gigaset ME and Gigaset ME pro

SABRE9018C2M：LG V10、 Lenovo Lemon X3 and Xiaomi Note top configuration

ES9018AQ2M: Geek Out V2 portable decoding ear amplifier all-in-one machine can be used with smart phones. Generally, it is best to find a mobile phone with high USB output power. If the power is too low, this portable all-in-one machine cannot be carried. Due to the high power consumption and heat, it is not recommended to use it with mobile phones for a long time, and the sound quality is not as good as that of computers.

ES9028Q2M: vivo X6Plus, vivo Xplay5 Ultimate

ES9028C2M: LG G5 B&O Hi Fi module

AK4490： ZTE Tianji 7

AK4375: nubia Z9 Max, nubia Z9 Max Elite and nubia My Prague, vivo X5ProV, vivo Y27, vivo X6 and vivo X6S, Gigaset ME pure

CS4398：vivo X1、vivo Xplay、vivo Xshot、vivo X5、vivo X5F、vivo X5Pro、vivo Xplay5、vivo X6S Plus

Many readers may wonder what suffixes like C2M and Q2M mean for ES90xx chips? In fact, it means that the packaging mode of the chip is different. C2M is the smallest of the three packaging specifications, K2M is between C2M and Q2M, and Q2M is the largest of the three packaging specifications. According to the comprehensive comparison of the above ESS DAC chip parameters, the ES9028C2M used by the LG G5 B&O Hi Fi module is relatively the best. However, similar to Geek Out V2, an independent decoding ear amplifier, LG's Hi Fi module also has problems of high heating and high power consumption.

DAC chip integrated with operational amplifier chip

Integrate the horizontal comparison of operational amplifier chip DAC

AK4376： Representative models are nubia Z11 and vivo X7

ES9118： No specific model

SABRE9018Q2C： No specific model

Codec series

Horizontal comparison of mainstream codecs

338S1285： iPhone 6s

338S1201： iPhone 6 Plus

338S1117： iPhone 5

Lucky CS47L91： Samsung S7 (Exynos 8890)

CS43L36： Meizu PRO 6

WM5102： Samsung S4, Meizu MX3, Lenovo K860i

WCD9335： Samsung S7 (Snapdragon 820)

AK4961: nubia Z7 and nubia Z9

summary

There are many mobile phones using these chips, but their power supply scale and the number of operational amplifiers are far from the listening range, so their voice cannot be compared. For the simplest example, the ES9018K2M on the mobile phone is actually a miniature version of ES9018, which is customized for mobile devices. The former is dual channel, and the latter is 8-channel. ES9018 is far superior to ES9018K2M in terms of dynamic range, signal to noise ratio and other parameters. For example, HIFIMAN 901 uses two ES9018 DACs. At the same time, HIFIMAN 901 uses professional operational amplifier chips with more advanced models than Hi Fi mobile phones, including two OPA2107 chips and two OPA627 chips.

As shown in the figure above, from ES9018K2M to ES9028Q2M/C2M, the distance is gradually shortened in key indicators compared with ES9018S. On the other hand, the new chip ES9038PRO continues to make breakthroughs in key indicators, and DNR and THD+N rise to new heights.

On the other hand, back to the three mainstream chip solutions of the Hi Fi mobile phone, the independent DAC and the DAC integrated with the operational amplifier chip will generally have better sound quality performance than the codec solution. Among them, the DAC integrated with the operational amplifier chip, which will save more space inside the body, will become the mainstream solution in the future, and will be used in the Hi Fi mobile phone.

Finally, in a short time, the Hi Fi chip with better performance and higher comprehensive level generally performs worse in terms of endurance and heating, which is also an unavoidable technical bottleneck, just as the power consumption and heating of mobile phones will also increase when 4K video is recorded and decoded. Better sound quality and better picture quality must pay a price.