"Arny Krueger"
"Phil Allison"
PSRRs are typically in the 120dB region.
** Really?
On what planet is that ???
Earth in 2007-2008.
** Completely false that is it a *** TYPICAL *** figure !!!!!!!!
Modern pro-audio gear is CHOCK full of them.
Yes, but most modern gear is low end and/or based on legacy designs.
** Irrelevant, ridiculous DRIVEL
Ignoring the performance of SOTA equipment that is on the market and
generally available is deceptive.
** Got even the faintest idea what the word ** TYPICAL ** means ??
Need a dictionary ????
On balance, why one *needs* 120 dB power supply rejection when $0.25 and
0.50 cent regulator chips produce DC power with just a few millivolts of
noise on it, makes this discussion kinda moot.
** The figures quoted in op-amp spec tabes for PSRRs are VERY
MISLEADING - as they quote only the DC test result. You have to find a
maker HONEST enough to publish a graph of PSRR over the full frequency
range, like Natsemi do for their LF351 - which is near identical to TI's
TL071.
http://cache.national.com/ds/LF/LF351.pdf
Notice how the table figure for PSRR falls at * 20 dB per decade * from
about 10 Hz up !!!!!!!!!!!
The range near 10 kHz is important for audio circuits and you can see the
*ACTUAL* PSRR is a mere *40 dB* for the negative supply rail.
Perfectly possible for negative supply rail regulator noise to inject itself
into the op-amp at a noticeable level.
Smart audio designers use local R/C filtering on the DC rails to eliminate
the problem.
Obviously not congenital, masturbating dopes like Graham Stevenson who
cannot even read a data sheet.
...... Phil