Currently, the op chip used on AIYIMA A04 & A07 is NE5532. Although NE5532 performs well, many audiophiles still want to improve the sound quality by replacing the OP chip.

Here we recommend some replaceable OP chips.

NE5532: The resolution is average, the high frequency is relatively dry, and the low frequency is relatively muddy and fat.

OP275: Better resolution, low frequency and sound field than NE5532

EL2244: The timbre is neutral, the sound field is relatively wide, the high frequency is okay, and the mid-frequency music tastes poor. Some people say that the resolution is very high. In fact, it is because the low-frequency volume is less, the mid-frequency is thin, and the high-frequency is prominent. It is more difficult to use well.

LT1057: The two ends extend well, and the speed, dynamics and resolution are also quite good, but it is a cool tone.

AD827: The extension is very good, the resolution is high, the high frequency is gorgeous, the intermediate frequency is pure and thick, the low frequency dive and the strength are good, the sound field expands forward and backward, the speed is good, the dynamics are good, and it feels very exciting. It feels refreshing. But after listening for a long time, I found many problems. 1 Although the three-frequency band, the sound field is very wide, the momentum is strong, and the opening is wide, but the structure is a bit loose and not tight enough. 2 The vocal part is average, sometimes large In the dynamic state, the vocals are submerged by the soundtrack. 3 It is not detailed enough, which is more than passion but not tender enough.

OPA2604: It feels like an upgraded version of NE5532, with great improvements in all aspects, good resolution, better musical taste, courageous, solid sound bottom and a bit rigid, and the overall quality is very good.

DY649: Compared with OPA2604, the resolution is better. The high frequency part is slender and soft and rich in overtones. The sound bottom is not thicker than OPA2604. It has a clear and detailed feeling. The music picture is very clear. The vocal part is round and transparent, and sweet. The sweet feeling, human voice (especially female voice) is its strong point.

DY639: The overallity is slightly weaker than DY649, but it has the characteristics of tube amplifier.

DY669: Not too different from OPA2604, pure and thick voice.

AD712: The resolving power is very good, the sound is clear and without coloration, a very transparent feeling, the sound bottom is detailed, and the low frequency is slightly less.

AIYIMA Audio