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Indeed bias cancellation is a hidden evil in recent (and not so recent) audio opamps. It is simply omitted from the specs, and in the neat and ideal noise calculations with resistive generator impedances.

Thanks for spotting that for the OPA210. And like I said, even ignoring bias compensation it only gains you a mere 0.6dB SNR as compared with the 5534 in MM SNR.

And that is something in favour for the 5534 and 5532 still - no bias compensation. And still available in 8-pin DIL packages. I just wish that they had the comprehensive set of performance graphs of more recent devices.

Sorry to hear of what ever has caused the beach bum from quitting the beach. Following a five month chest infection that needed kick ass antibiotics to kill, I'm luckily back to firing on all cylinders.

Craig

------ Original Message ------

From "Richard Lee via " <ricardo_lee@...>

To [email protected]

Date 09/04/2025 05:00:30

Subject Re: [MicBuilders] FET OPAs for mikes

On Tue, Apr 8, 2025 at 01:21 AM, Craig Sawyers wrote:

And the only bipolar opamp to beat the NE5534 is the OPA210. 2.2nV/rootHz at 1kHz, an amazing 2.5nV/rootHz at 10Hz, and crucially for MM cartridges current noise of 400fA/rootHz (same as for the NE5534). It is just better in all respects than the Neanderthal NE5534

Thanks for these suggestions Craig.

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OPA210 has EVIL input bias current cancelling.? The damning evidence is its +/- input bias current spec.? These invariably have much higher noise for stuff with different impedances on each input pin like single OPA RIAA preamps.? You may remember us looking at the ???? preamps with Steve Sells and finding significant improvement replacing OP27 or OP37 with 5534 on their RIAA

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It's more than a decade since I last looked at this seriously

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Wayne (and NWavGuy IIRC) measured NJM 2068, sadly Unobtainium today, quieter than LM 4562 so env < 2.5nV/rtHz @ 1kHz and inv good enough in to beat 5534.? Of course da Jurassic NJM topology (dating back to Raytheon 4136 ie much older than 5534) can't give 1 ppzillion THD like more modern stuff but good enough for an old beach bum like me.

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BTW, I hope you are not suffering various health issues like me which may mean I need to give up the beach