ricardo said:
abbey road d enfer said:
Indeed it is, but there are arguments for BiFET opamps, especially with the existence of much better than TL0, such as OPA134.
As OPA134 has more than 6dB extra voltage noise than 5534, this should hide any fader noise modulation
The point is that with OPA134, there would be NO noise modulation, all the more in regard of the increased steady noise. It's a little similar to the debate over class-B VCA-s vs. class-A. Although class-A VCA's produced more constant noise at moderate gain, they didn't exhibit the noise vs. gain variation of class-B, which was deemed unacceptable by euphonists. The debate is moot today, since classA VCA's are an extinct species, to my knowledge. And anyway, digital mixing has made it pointless.
I haven't done the detailed sums but you probably need something like OPA627, AD745 to improve on 5534 for this application.
At the time, there were not much practical choices, so experimentation was limited. In fact, I don't remember having had ANY choice; I guess AD743 would have bettered the 5534, but its cost was prohibitive - probably didn't exist at the time.