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Which Op Amps Are the Best?

An operational amplifier, or op amp, is a component designed to increase the strength of a wide range of electronic signals. Though even the most basic, inexpensive op is adequate for audio use, manufacturers have developed specialty devices with very low noise and distortion. These qualities are important in professional environments such as recording studios; the noise from many pieces of equipment adds up, so the components in them must be as quiet as possible.

Op Amp
- Looking at it as an electronic ̶0;building block,̶1; an op is a circuit having two inputs and an output. One input inverts, turning positive signals into negative ones, and vice versa; the other is non-inverting. When current flows through a resistor connecting the inverting input to the output, the op increases the voltage of weak input signals. This basic quality makes them indispensable in amplifiers, mixers and other types of audio equipment. As with other electronic components, op amps are not perfect devices but contribute noise and distortion to the signals that pass through them. Careful designs minimize these problems, though some op amps are better than others.
LM4562
- As of the time of publication, the LM4562 op is one of the best audio components available. At prices that range between $3 and $4, the LM4562 is relatively expensive compared to similar devices. It has very low noise and a gain bandwidth product, or GBP of 55MHz, which indicates its capacity for amplification and high frequency response. For example, if a circuit using the LM4562 has a signal gain factor of 100, or 20dB, the op amp̵7;s bandwidth is 55,000,000 / 100 or 550 KHz.
LM5532
- The LM5532 is a lower-cost high fidelity op amp; in production quantities this component sells for about $.50. Its gain bandwidth product is 10Mhz, so its high-frequency range is limited unless circuits limit its amplification to a factor of about 10. Likewise, its total harmonic distortion, or THD of 0.002 percent is not quite as good as the LM4562̵7;s 0.00003 percent. The LM5532 does, however, represent an improvement over op amps such as the TL082, with 0.02 THD and 4MHz GBP. When kept to modest amplification levels, the LM5532 has noise figures similar to the LM4562.
LM833
- The LM833 op has distortion figures similar to the LM5532 and has a 12MHz GBP, 20 percent better than the LM5532̵7;s. At a moderate gain of 20dB, the performance of the LM5532 and LM833 are similar; at 60dB, the LM833 has slightly lower noise.

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