Comparison of several op amp combinations for CD analog output

Today, I finally repaired the CD player, the old machine, remember to buy it in 1996, CDM 12.1 struggling. So it took more than three hours to use the newly created "Dragon Edition" DAC to make a rough comparison. Due to the limited resolution of the equipment, and the long time and concentration, it may be too late to feel it. I do n’t know whether the memory and judgment are accurate. To be honest, this difference is indeed very subtle. For example, if the expressiveness of an effect is divided into 100 points, then there is a difference of 6 or 7 points, which is a very big difference. Therefore, if you are not using the same piece of music A short period of more than 20 seconds) to repeat the comparison, it is difficult to feel the difference. But since it's done, write it out for reference only, even if it's irrigation! Come to verify later when you are interested and conditions again :-)
The op amps participating in the comparison: OPA627AP, LT1115CN8, PMI's OP37GP, LM318N, RCA's CA3140, AD's OP27G. Because there are only 4 OPA627 and LM318, and the rest are only 3, so the I / V conversion part can only use these two types, and the latter buffer amplification and LFP parts are replaced with the above ones. Since it was a temporary rise, I did n’t choose the tracks intentionally. I grabbed a piece of "Foreign National Song" and Bandarid "Dream Garden" (of course, all of them are D versions), and selected "pigeon" and "Adagio in Minor" respectively. , Use different combinations to compare the effects. The following uses sound field, resolution, overtone, low frequency, vocal, localization as the comparison content.
The first one: OPA627 + LT1115. This is the most expensive combination here. Ha ha, I have been using this combination, so it sounds almost out of touch :), but since it is a comparison, let ’s talk about it: the sound field is the widest and has a good sense of layer , The sound image is between the two speakers, neither protruding nor retracting; clear positioning; highest resolution, clear details and transparent sound; good bass strength, soft and soft diffusion, there is a diffuse effect; human voice is very Magnetic, rich harmonics.
The second kind: 6 LM318. As soon as I got on the phone, I suddenly felt a refreshing feeling, and I felt that the impact of the bass has improved a lot. This may be due to the conversion rate of 318 that is as high as 70V / uS, but it is a little blunt. The high-frequency overtones are rich, the sound image is a little forward, and the human voice is more prominent, but the sound field is slightly narrower, and the sense of hierarchy is slightly lacking, but it is very subtle, almost indistinguishable, and may be an illusion; the sound image positioning is still clear and analytic The degree is still very high. Rich overtone and transparent sound.
The third kind: LM318 + OP37. The impact of the bass is weakened and the sense of diffusion is slightly stronger; the sound field is slightly narrower and the sense of layering is normal. The sound image is between the two speakers, not protruding nor retracting; the high and low frequencies are more balanced, and the overall feeling is quite satisfactory.
The fourth type: LM318 + OPA627. The sound field is basically the same as the first one. It has better impact but feels a little harder and rich in high-frequency overtones. The sound image and vocals are also a little protruding, but the layering is better and the sound line is clearer. The positioning is clear and the resolution is clear. There is no difference from the previous comparison, and the sense of depth is still excellent.
The fifth type: LM318 + CA3140. The biggest feature of this combination is that the high-frequency overtones are the most abundant, with a relatively bright radiance, and even a glitch, but in general, the feeling is still very detailed; the bass is similar to the fourth; the depth of the sound field is slightly Poor, the thickness of the human voice is a little insufficient, and it feels a bit floating in front of the speaker; the sound image is clearly positioned.
The sixth kind: LM318 + LT1115. This is a very unique kind of combination. The bass head has good strength, but it is very soft and diffused, and the thickness of the sound is relatively good. There is a feeling of convexity and depression; the other is basically the same as the fourth kind, but it seems that The sense of detail is slightly worse.
The seventh kind: LM318 + OP27. This is also a unique combination. The sound field is the narrowest; the treble is somewhat compressed, the thickness of the sound becomes thinner, the high, middle and low frequencies seem to be a pyramid shape, the resolution is slightly lower, and the bass is more diffuse; the interesting thing is that the height of the sound image is lower than other combinations About 15-20 cm.
The eighth kind: OPA627 + OP37. The sound becomes a little light, but the layering and positioning are still accurate, the bass is softer, and the other is similar to the third.
The ninth kind: OPA627 + OP27. Similar to the seventh kind, the height of the sound field is reduced, the high frequency is somewhat compressed, and the resolution is reduced, but the thickness and depth of the sound seem to be better than the seventh kind.
Tenth: OPA627 + LM318. The fourth one is basically the same, at least I can't hear it.
Eleventh: OPA627 + CA3140. Similar to the fifth, the overtone is still very rich, but the high-frequency compliance is better and more detailed; the thickness of the sound is also thicker than the fifth, and the position of the sound image is retracted, basically there is no such floating a feeling of.

From the audition, you can roughly summarize the sound characteristics of these models of op amps. My favorite combination is the sixth one, which has been used in DAC. Because this combination basically does not lose to other combinations in performance, but the cost performance is much higher.

Follow WeChat

Interesting and informative information and technical dry goods

Download Audiophile APP

Create your own personal electronic circle

Follow the audiophile class

Lock the latest course activities and technical live broadcast