Opinions: On op amp replacement

[Martin Czech]

> 
> Why not use the Philips NE 5534 instead? It has one third the noise of the TL071 (4 nV/Hz). The slew rate is the same (13 V/us). It also has a higher output drive capability. Can drive headphones directly!
> The NE 5532 is a dual verision in a standard 8 pin package. Same spec except the slew rate for some reason is a little lower (9 V/us).
> 

Be carefull.  

The 5532 has quite high input leakage and bias currents, also offset
voltages. Replacing a TL071 with one 5534 won't work in applications with
high signal impedance, eg. filter cap buffer, integrator.  You introduce
a lot of offset (very temp dependend and source resistance dependend)
and leakage in your circuit. The 553x series is for standard audio signal
path, ie.  no leakage and no offset requierement. Then you can benefit
from it's high bandwidth and low nois like you pointed out.

m.c.