29/09/2025 5:28 am
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When it comes to audio circuits, I’ve seen many people emphasize the importance of choosing the right op-amp, since it can significantly affect noise, distortion, and overall sound quality.
What factors should be considered when selecting an op-amp specifically for audio applications? For example, how important are parameters like slew rate, input noise, bandwidth, or THD+N (Total Harmonic Distortion + Noise)?
Are there certain op-amp families that are generally preferred for high-quality audio, and how do they compare to using general-purpose op-amps?
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30/09/2025 5:29 am
For audio, the main things to look at in an op-amp are noise, slew rate, bandwidth, and THD+N. Low noise is important in preamp stages, a decent slew rate keeps transients clean, enough bandwidth avoids roll-off in the audio range, and low THD+N keeps the sound transparent.
That’s why audio circuits usually use parts like the NE5532/5534, OPA2134, TL072, or LM4562/LME49720. They’re designed for low distortion and good sound quality.
You can use general-purpose chips like LM358 or 741, but they’re noisier and distort more, so they’re not ideal for hi-fi. For anything beyond hobby-level, an audio-grade op-amp is the safer choice.
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07/10/2025 7:00 am
For audio op-amps, the big four are noise, slew rate, bandwidth/loop gain, and THD+N—matched to your source impedance and supply rails.
Low‑impedance line stages favor low voltage‑noise bipolars like NE5532/5534, LM4562/LME49720, or OPA1612; high‑impedance sources and filters prefer JFET inputs like OPA2134 or OPA1642/1656. Aim for a slew rate of at least 3–5 V/µs (10–20 V/µs gives margin) and enough GBW to leave healthy loop gain at 20 kHz; then verify THD+N at your actual level and load.
Check unity‑gain stability, output drive into 600 Ω/cables, and headroom—many classics assume ±12–15 V, while parts like OPA1656/OPA1688 excel at 5 V. Good layout, modest resistor values, and solid decoupling matter as much as the chip.
General‑purpose parts like LM358/741 will work, but their higher noise, limited slew rate, and distortion usually cap hi‑fi transparency.
