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| OK audio gurus: What are the highly regarded FET-input op amps these days? |
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| cvanc:
This question is triggered by a repair I recently did where the originals, while still available, were stupid expensive. It occurred to me that a more modern & higher performing part must exist at a lower price - a win-win scenario if ever there was one. Due to the circuit specifics it needs to be FET input, and also unity gain stable. I have not kept track of this category since the LF411/LF412 were considered the good stuff. Surely there's something better by now? Thanks. |
| floobydust:
It's not that simple, you have to consider what the op-amp is seeing and doing. Line driver? Tone controls? DAC reconstruction filter? The better FET-input op-amps are expensive because they are laser-trimmed and prices can be crazy. I would recommend OPA2134 or OPA134 and if you have money the OPA627 or OPA637. But $40-57 each :o Careful swapping in a higher bandwidth part, they can oscillate in "old" circuit designs and not all parts are unity-gain stable. |
| Zero999:
--- Quote from: cvanc on December 06, 2018, 05:37:55 pm ---This question is triggered by a repair I recently did where the originals, while still available, were stupid expensive. It occurred to me that a more modern & higher performing part must exist at a lower price - a win-win scenario if ever there was one. Due to the circuit specifics it needs to be FET input, and also unity gain stable. I have not kept track of this category since the LF411/LF412 were considered the good stuff. Surely there's something better by now? Thanks. --- End quote --- Just replace the original op-amp with one with a similar specification, if it's not possible to find an exact replacement. Old op-amps such as the LF412 and TL072 are more than good enough for 99% of audio applications. Replacing the part with a more modern device could risk messing it up and ruining the performance so lose, lose. Newer so-called audiophile op-amps have a higher bandwidth, than the traditional ones, so are more sensitive to board layout and can easily oscillate. If a circuit isn't designed for such a high bandwidth op-amp, then blinding replacing the op-amp with a faster one is asking for trouble. |
| SiliconWizard:
Some references come to mind: OPA2134 OPA2604 OPA1652 |
| Conrad Hoffman:
A lot of new parts are only available in SMT, which can limit you unless you use adapter boards. The TI OPA164x series looks interesting. |
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