New ultralow noise, high BW op-amp from ADI

[jan.didden]

just had a quick think about what kinds of instruments in a recording would have a huge slew rate, since it implies that the waveform won't go smoothly from base to peak if the frequency is kept constant at 20kHz and amplitude is some constant arbitary level.

Electric guitars came to mind. If they're heavily clipped, the slew rate could be extremely high. Now the question becomes, how high and can I hear it?

I've looked over the datahsheets for the OPA637, AD8620 and AD843 again and the slew rate is still the only thing glaring out at me.

There's also possibility for me being able to hear that difference because I listen to lots of rock and have been (possibly) overly interested in the sound of guitar distortion for half a decade or so. If you were listening to classical music, slew rates might be less of an issue given than classical instruments aren't designed to have rocketing slew rates into clipping; they'll be closer to the sinewave example, which means a lower slew rate for a given SPL compared to a nearly squarewave clipped guitar at the same SPL. Which seems to at least roughly agree with tradition given that lots of people who like valve amps like their smoother sound, and valves have low slew rates compared to opamps like the AD843.

There have been some studies of slew rate with real-world music, and I never seen it above 5V/uSec. For a full swing (say 80V pk-pk) 20kHz signal that about it anyway.

There is also the possibility that your preference for opamps is based on other things than audio reproduction. In fact, many studies have documented that expectations, paid price, peer opinion, the "newness" of things, shape, color, in general play a larger role than just sound quality.

Without a properly conducted blind test there is no reliable, repeatable way to determine what it really is.

Jan Didden

 

[eeka chu]

Without a properly conducted blind test there is no reliable, repeatable way to determine what it really is.

Which is what's weird because I found the more expensive one less interesting (I didn't pay for any of them), I didn't know the specs of the components until after I'd decided which order I liked them in, and being OP amps they all look pretty much the same.

I'm definitly interested in absolute blind testing though given what passes for testing on a lot of audio sites.

I might test it out on some friends and family to see what they hear. Always knew there was a use for 'em.... 😀

I love your signature quote