I still don't understand why anyone would want to replace perfectly working ICs with essentially the same type. OK, an SA5534A is guaranteed to work below 0 degrees Celsius and has a slightly tighter noise specification, but if the noise isn't obtrusive now and if it doesn't freeze, what difference does that make?
Unisonic it appears will continue to make them: https://www.diyaudio.com/community/threads/unisonic-ne5534-une5534-and-ne5532.412174/#post-7670283
LM833 was a resounding failed attempt from NS to have something competitive with the NE5532, it is to be avoided
if you can get the 5532, theses are worlds apart.
I wonder why they used those op amps in this preamp
2x 5532
4x TL072CP
6x LM833
1x LM393
It makes not sense
Very rare Rockford Fosgate RF200
no schematics or anything only a few reviews out there
2x 5532
4x TL072CP
6x LM833
1x LM393
It makes not sense
Very rare Rockford Fosgate RF200
no schematics or anything only a few reviews out there
Attachments
30 or 40 years ago people didn't have the measuring devices to determine the qualities of op amps. The few op amps that were available were used.
Take a look at the LM393 datasheet ; it is a dual voltage comparator, a 1-bit Digital To Analog Converter. It is not an opamp. If you attempt to build linear analog amplification circuits with the LM393, you will encounter instability (oscillation) because the chip does not include frequency compensation. Voltage comparators never do.
Rockford Fosgate's designer felt that some aspect of the design required a voltage comparator (not an opamp), and chose the LM393 for that position.
I disagree with that general statement. There existed different types of op-amps for different tasks - not one size that fits all.
How can the TO assume that the different stages inside the circuit all use the same amp?
Without the context, it is impossible to judge the choice of op-amps
Audio Precision System 1 was on sale during that period which easily showed the noise difference between NE5532 and TL072.