On 01/03/2020 09:46, Jan Panteltje wrote:
> On a sunny day (Sun, 1 Mar 2020 08:56:41 +0000) it happened The Natural
> Philosopher  wrote in :
>
>> Bifet is not bad but there exists today an opamp that is low enough
>> noise to match the very best discrete circuit that I used to design back
>> in the 70s .
>
> Oh, sure
> I am not uptodate on what the latest and greatest is (ask in
sci.electronics.design if you need to know)
> but bought a few TCL274 quad opamps a few month ago as sort of universal
opamp for projects, specs:
>
>   Trimmed Offset Voltage:  TLC279 . . . 900 µV Max at 25°C,
>            VDD = 5 V
>   Input Offset Voltage Drift . . . Typically 0.1 µV/Month, Including the
First 30 Days
>   Wide Range of Supply Voltages Over
>   Specified Temperature Range:
>         0°C to 70°C . . . 3 V to 16 V
>         ­ 40°C to 85°C . . . 4 V to 16 V
>         ­ 55°C to 125°C . . . 4 V to 16 V
>   Single-Supply Operation
>   Common-Mode Input Voltage Range  Extends Below the Negative Rail (C-Suffix
and I-Suffix Versions)
>   Low Noise . . . Typically 25 nV/Hz  at f = 1 kHz
>   Output Voltage Range Includes Negative Rail
>   High Input Impedance . . . 10^12 Ohm Typ
>   ESD-Protection Circuitry
>   Designed-In Latch-Up Immunity desription
>
> Much better than the LM324 :-)
>

Try the LM833.

https://www.onsemi.com/pub/Collateral/LM833-D.PDF

At typical phono cartridge/MC microphone source impedances, that's
around 4nV per root hertz

  Noise performance of Bifets like TL074 only beats that when running
from very high source impedances.

I used to try and get close to 2nV/root Hertz when designing phono inputs.


>
>> I think unity gain on CMOS is a lot more than 1Mhz tho.
>
> Oh yes, and there is,  after the CD4000 series,  the 74HC4000 series.
>
> The TCL274 has a gain of 1 at about 1 MHz, but I typicaly use these things
for measurement equipment design.
> Not done much audio lately, apart from funny little things like this:
>    http://panteltje.com/panteltje/pic/audio_pic/
> These days you can get a decent PWM 80W audio amp for next to nothing from
ebay...
>
>


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