View Single Post
Old 16th January 2020
  #21
Lives for gear
 
JohnRoberts's Avatar
 

Quote:
Originally Posted by tINY View Post

No treatise on slew-rate, gain, and frequency?


No.... There is only a weak association between slew rate and GBW as decompensated op amps with smaller dominant pole capacitors exhibit both higher slew rate and higher HF open loop gain, of course with less stability margin.
Quote:
It can make for some interesting distortions....
Slew rate was more of a concern back in the old days, but since the 70s jelly bean op amps have been faster than audio so not much of a concern.

In fact experiencing slew rate limiting distortion is arguably a design flaw. Dr. Marshall Leach (RIP) wrote an AES paper on the subject decades ago. If an input signal/gain stage is properly bandwidth limited, it can not be made to slew limit with valid input signals...

Since the unwashed audiophools still insisted on slew rate specs, some amplifier designers had to defeat the input bandwidth limiting just to make max slew rate measurements, then restored it.
Quote:


-tINY
[edit] if you want to know what gross slew rate limiting sounds like, dust off an old delta modulation delay line and run the clock frequency too low... [/edit]

JR

Last edited by JohnRoberts; 17th January 2020 at 01:18 AM..