LM741... an 8-pin noise source
when i was in a band and we were trying to record a demo tape, we had an 8 channel mixer, and the drummer was trying to figure out why there was a noticeable background hiss. taking the cover off the mixer revealed the output was driven by a socketed 741. popping a TL071 into the socket instead cured the hiss...
Shouldn't be a problem on the output, and if properly designed pretty well throughout the entire mixer. I imagine the 741 was probably faulty?.
People here, and AG in particular, slag off 741's - but they will all have many albums recorded using mixers full of them - in a properly designed circuit they perform quite respectably.
Obviously though, now isn't the time to be using a 741 (and hasn't been for decades), as there are thousands of much superior pin compatible replacements (I'm currently used TL072's for various purposes).
I was having the same discussion with AG a fair few years back (probably about 15 or 16 years?), and at the time I was setting up a cheap PA system for a small gig my daughters band had got. As it happened, I'd been given a small amplifier, which had four input channels, and I built a pair of 1x12's with piezo tweeters, and bought some cheap Behringer mikes. Ih, I also replaced the mains transformer in the amp to a lower voltage one (and did a few minor changes), as it was designed to feed 8 ohms, and I wanted it to feed 4 ohms.
The amp used 741's in the mixer, so as an experiment I removed the 741's from one channel, and fitted 8 pin sockets - then tried a variety of different opamps, and compared that channel with the others. Not a smidgen of audible difference, and you couldn't tell which channel you were using.
Obviously it could easily be a
FAR different story for other uses, such as a preamp to record bird song out in the woods.