The operational amplifier is a very widely used linear integrated circuit. And there are many types. In terms of application, they can not only amplify weak signals, but also be used as inverters and voltage followers, and can add and subtract electrical signals, so they are called operational amplifiers. Not only is it widely used in other places, it is also used most in audio. For example, in addition to some discrete components and tubes used in preamplifiers, buffers, and headphone amplifiers, most of them use integrated operational amplifiers. Sometimes it is also used in voltage stabilizing circuits to produce high-precision voltage stabilizing filter circuits. Due to their different internal structures, various op amps produce different distortion components, so their timbre characteristics also have certain differences. Originally, what we were pursuing was high fidelity. The op amp should have the lowest distortion, be able to truly restore the music, and be the best if it had no personality. However, due to the need to cooperate with other audio components such as digital audio sources, power amplifier tubes, etc., if it is too dry or cold, it can be paired with an op amp with a delicate and warm tone, while if it is too feminine or soft, it can be paired with a colder, brighter tone. The operational amplifier can cooperate with the whole machine to achieve the best effect by learning from each other's strengths. Therefore, it does not mean that the more expensive the op amp is, the better the effect will be. The matching is very important, and the best in terms of listening is the goal. If it is used in a low-voltage analog filter circuit, it is also necessary to choose a type of op amp with good low-voltage operating performance. There are no fewer than five or six hundred types of op amps on the market. There are more than 300 types with GBW bandwidths above 5M, with the highest reaching 300MHZ. There are hundreds of types with conversion rates above 5V/us, up to 3000V/us. The above-mentioned ones have been very popular among audio enthusiasts. In fact, there are a large number of high-quality products that are not well-known to everyone to choose from. You do not need to be limited to the above-mentioned ones. The packaging of an op amp model can also be divided into gold seal, ceramic seal and plastic seal. Generally speaking, the quality of gold seal and ceramic seal is better, and the quality of plastic seal is slightly worse. Driven by profit, everything has fakes, and op amps are no exception. There are many fakes on the market. If you want to pick up good products at a low price, you need to be discerning. Those who are not very good at it should pay attention when buying. , I would rather spend an extra dollar or a few cents than buy from a reputable merchant.
Low-end operational amplifier JRC4558. This kind of op amp is most commonly used in low-end machines. It is now considered super bad because its sound is too bright and has a strong burr feeling, so it is the worst type of op amp compared to other audio amplifiers. However, it is still widely used in our country, and many power amplifiers worth four or five hundred yuan still choose to use it, because considering the cost issue and the actual effect, there is no need to choose an op amp with a quality higher than 5532. For some computer active speakers, its ability to cope is more than enough
Op Amp King 5532. If anyone has not heard of its name, then he or she is not an audiophile. The NE5532, known as the king of op amps back then, is one of the four famous op amps along with LM833, LF353, and CA3240, but now only 5532 is used the most. 5532 is now mainly produced in Taiwan, the United States and PHILIPS, and also in Japan. The best ones are the American products with the big S logo. Authentic products on the market cost more than 8 yuan. Since SIGNE was acquired by PHILIPS, the 5532 trademarks produced use the PHILIPS trademark. The quality is equivalent to the original product and only costs 4 yuan. -5 yuan. The quality of the products produced in Taiwan is slightly worse, and the price is also the cheapest. You can buy it for two or three yuan. The package of NE5532 is the same as that of 4558, both are DIP8-pin dual operational amplifiers. The inside of 5532 is JFET (junction field effect tube structure). The sound characteristics are generally warm and delicate, with strong driving force, but the treble is slightly rough and the bass is slightly rough. Fat. In the past, many people thought it had a slightly "bold smell", but now there are many that are more bold than it, and relatively speaking, it is not so prominent. The voltage adaptability range of 5532 is very wide, and it can work normally from plus and minus 3V to plus and minus 20V. Although it is an older op amp model, it is still considered the most cost-effective op amp for audio. It is a civilian op amp and is used by many mid-range and low-end power amplifiers. However, there are too many fake NE5532 or non-audio industrial products. Since the pin function of 5532 is the same as that of 4558, some unscrupulous merchants also erase the letters of 4558 and print the word 5532 as 5532. Generally, the appearance is rough. The printing is easy to erase and can be discerned by those with a little experience. It is said that 8mA current heating is the authentic audio 5532. NE5532 also has two brothers, NE5534 and NE5535. 5534 is a single op amp. Since it separates the single op amp, there is no mutual influence between the dual op amps, so the tone is not only soft, warm and delicate, but also has better music. taste. Its voltage adaptability range is also very wide, and it can maintain good working condition with voltages as low as plus or minus 5V. Because the famous American BGW-150 power amplifier used 5534 as voltage excitation, it deliberately made the positive power supply voltage 0.7V higher, forcing its output tube to work in a more perfect Class A state, further improving the sound quality, so now it is generally believed that if The sound quality will be better if the positive supply is 0.7V higher. The pin functions of 5534 are similar, and the price is similar to 5532.
The NE5535 is an upgraded product of the 5532. It is characterized by a simpler internal circuit and a fully complementary output stage. The conversion rate is higher than 5532. However, one disadvantage is that the noise is large, the frequency band is not wide enough, and the performance when working at low voltage is not good enough, so the effect when used for analog filtering is not as good as 5532. However, when used as a linear amplifier circuit when the operating voltage is greater than or equal to 15V, the music taste will be better than that of 5532, so its price is two or three yuan more expensive than 5532, and its pin functions are the same as 5532.
Dual op amp AD827. This is a newer product of AD Company. It was originally designed for video circuits, so its gain bandwidth reaches 50MHZ and SR reaches 300V/us. Like EL2244, it is the top voltage feedback dual op amp on the market. Goods, ordinary op amps are hard to come by. Its high-frequency operation is crystal clear, and its low-frequency bounce is superior. Its performance indicators and actual listening experience are better than many other similar products. The sound quality is described by some as impeccable. And it still has excellent performance under the power supply of plus and minus 5V. But its price is also slightly expensive, more than 30 yuan. The pin functions are the same as 5532.
Dual op amp OP249. This op amp is a product of the American PMI company. The manufacturer claims that it is used to replace op amps such as OP215 and LT1057. LT1057 is a type of op amp with large dynamics, high resolution, and cool and clear tone. It is very suitable when paired with Toshiba's warm-color famous tubes. suitable. The OP249 is different from it. Its input stage uses JFET. Its main feature is that it is neutral and has no personality. The sound is balanced, natural and accurate, so it embodies the true meaning of HIFI. The plastic package is only 15 yuan, and the ceramic package is more than 30 yuan, which has a high cost performance. However, if you have a strong preference for timbre, you may not like it very much.
Dual operational amplifiers OP275 and OP285: They are also products of PMI. The internal circuit adopts a dual-stage and JFET-type hybrid structure. Its timbre is very individual, with low noise, clear sound contours, high resolution, and smooth sound. The mid-frequency has the soft and moist characteristics of a tube amp, and the human voice is close to it. The price is affordable and the performance is stable. Suitable for rubbing CDs, decoders or amplifiers with thin and rough sounds. Their packaging form and pin functions are also the same as 5532. The current market price of OP275 is 10 yuan and OP285 is 15 yuan.
Top operational amplifier OPA627. BB Company's OPA627 is the most high-end operational amplifier so far. It also uses a field-effect tube input method. The tone is warm and charming, but its price is simply scary. With such an expensive operational amplifier, whether the performance can reach this price is a matter of opinion. However, Enthusiasts who have heard of OPA627 agree that AD827, LT1057, etc. are simply incomparable.
Bile-flavored operational amplifiers OPA604 and OPA2604. These two operational amplifiers are products of Burr Brown Company, OPA604 is a single operational amplifier, and OPA2604 is a dual operational amplifier. They are all special operational amplifiers designed specifically for audio. Their tone is mellow, round, neutral to warm, and bold. They are known as the operational amplifiers with the best tube tone. The price at that time was not low, but it was still chosen by many audio enthusiasts as an upgrade machine. Now the prices of these two op amps are relatively reasonable, OPA604 is 25 yuan, and OPA2604 is more than 40 yuan. It is a good choice for enthusiasts to use for gaming.
If you want to buy, it is usually Taobao. If the quantity is large, you can directly find an agent or contact the manufacturer.