Mobile phones can also switch to operational amplifiers via MOD vivo Xplay | Ainuo Mobile - 上海419贵族宝贝-上海后花园1314-上海品茶网-阿拉爱上海

For a long time, the "grinder" (also known as the MOD machine, or modification) of the walkman is a kind of play that enthusiasts enjoy talking about. and vivo Xplay The "three core combination" of CS4398+CS8422+OPA2604 and the large internal space of the phone make it possible to MOD. The following is our transformation of the operational amplifier.

Dismantling the phone will lose the warranty qualification, and changing the chip may also damage the phone. Children at home should not imitate it.

The object of our operation this time is OPA2604, the operational amplifier chip of Xplay. Of course, the first thing to do is to disassemble the machine body. Here we will briefly explain the disassembly process.

Disassembly, replacement, transportation and release process

Xplay uses the "three-stage" design, and the screws ▼ are not visible on the phone shell

In fact, its screws are hidden under the white plastic shell. We use a crowbar (nail can also be used) to gently remove the white plastic shell, and be careful not to use too much force, otherwise it is easy to damage the buckle ▼

Close up of the top of the fuselage after disassembly, with six screws ▼

There are also seven screws ▼ at the bottom

Before disassembling the metal back shell, remember to take out the card slot ▼

After six pieces on the metal shell, we can remove the rear shell, as shown in the figure, push ▼ to the left

The back shell was successfully disassembled. Although the battery capacity of Xplay reached 3400mAh, the whole battery does not appear exaggerated due to the large body area ▼

Disassembled metal shell ▼

Before disassembly, first cut off the power supply. There is a small sticker at the power pin, and you should first open ▼

Cut off power ▼

Next, unscrew the four screws at the bottom of the body to take out the speaker ▼ at the bottom

There are seven screws on the top. After unscrewing, the plastic shell can be taken out, and the L-type motherboard can be seen ▼

Before disassembling the mainboard, pay attention to unplugging the necessary flat cable ▼

The protagonist of our transformation, the AD8620BRZ, is a two-way high-precision JFET input amplifier with ultra-low offset voltage and drift, extremely low input voltage and current noise, extremely low input bias current and broadband characteristics. Tone is delicate and sweet ▼

The following are the main features of the AD8620BRZ:

Low noise: 6 nV/√ Hz

Low offset voltage: 100 µ V (maximum)

Low input bias current: 10 pA (maximum)

0.01% fast setup time: 600 ns

Low distortion

Unit gain stability

No inversion

Dual power supply: ± 5 V~± 13 V

Price: about 100 yuan

The original operational amplifier OPA2604AU of Xplay is a two-way FET input, low distortion operational amplifier, which is characterized by mellow voice, mellow tone, warm neutral, strong gall flavor, and is commonly used in mills. The OPA2604AU is located between the motherboard near Samsung memory chip and 3.5mm interface ▼

Main characteristics of OPA2604AU:

Low distortion: 0.0003% (1kHz)

Low noise: 10nV/Hz

High voltage swing rate: 25V/ms

Wide gain bandwidth: 20MHZ

Stable unit gain

Wide power supply voltage range: ± 4.5~± 24V

Can drive 600 Ω load

Price: about 30 yuan

CS4398 digital to analog converter, as this article is only the process of replacing the operational amplifier, it does not put too many features of other chips ▼

From the perspective of power supply requirements, OPA2604AU has higher requirements for power supply, which can be better used only when the voltage is ± 15V or above. There is even a saying that "from the perspective of music taste, ± 12V power supply is the best, and from the perspective of dynamic sound field, ± 20V power supply is the best". The OPA2604AU itself is more used for mobile phones, so it is difficult to use it on walkman players or even mobile phones. The internal circuit of Xplay is ± 5.8V boost circuit, which is difficult to meet the requirements of OPA2604AU. Because of this, we also had the idea of replacing the Xplay op amp, replacing the Xplay op amp with the AD8620BRZ, known as the "emperor of op amp", to ensure that it works better under low voltage. Of course, after the operation amplifier is changed, the sound orientation will be different from the original, which also has a lot to do with personal listening orientation and headphone collocation.

Effect of replacing AD8620BRZ ▼

matters needing attention:

1. Once again, disassembling the mobile phone will lose its warranty qualification.

2. Pay attention to the direction when welding, transporting and placing.

3. Not all op amps are suitable. The first thing needed is a two-way amplifier with SOIC-8 packaging. If it is purchased from Taobao, it needs to be noted that it is a chip op amp. Of course, the working voltage also needs to meet the requirements of the phone itself.

Hearing sense behind MOD

Audience equipment: Xplay original, Xplay "AD8620BRZ version"

Comparison headset: UE10, VSD1

In view of the sound distortion caused by SRS, BBE, etc., the following test turns off all sound effects and only turns on Hi Fi mode.

Of course, there is no difference between the MOD machine and the ordinary Xplay in appearance ▼

As we happen to have two Xplays, we can directly compare the difference in sound between the original Xplay and the AD8620BRZ. The first impression of the Xplay after replacing the op amp is that the high-frequency extension is better and the low-frequency diving is more flexible. The improvement of sound separation is also obvious, and the voice is extremely penetrating. After the AD8620BRZ was replaced, the sound dynamics of Xplay has made a lot of progress. This high-quality low-frequency diving elasticity is also hard to feel on mobile phones in the past. On the whole, the sound style of the Xplay replaced with the operational amplifier is more high-quality, and the sound is relatively loud, which has a certain impact on its hearing endurance. Therefore, more consideration should be given to this aspect when matching earphones.

Since Xplay has not yet gone through a long enough process of "warming up" and its voice has not yet been shaped, the comparison with other high-quality walkman players is not available for the time being. I will share it with you again when I have the opportunity.

As digital players, we have always been committed to exploring the residual value of our products, but the playing method like MOD mobile phone is still relatively rare in the past. And the mobile phone design with high audio quality such as vivo also provides us with MOD machine space like high-end walkman. Although the sound improvement is not a qualitative leap, and even has some drawbacks, I believe many enthusiasts will be happy to make an attempt in this regard.

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