The best-sounding ones are Signetics, made in the USA, with date codes from 8701 to 9048.
There are none left on ebay. I bought them all from hifi-szjxic 😎
There are none left on ebay. I bought them all from hifi-szjxic 😎
Those old ones needs copius amounts of snake-oil and heavy lead solder when soldered as otherwise they will not bring out the sound well....
Old chips are like old wine—the longer they sit, the better they get. You just need faith! 🤣🤣
Anecdotal story.
Designed a split riaa phono some time in the mid 80s. Signetics 5534s all over. Took a lot of effort till it became acceptable: inverting stages, matching impedances seen by both inputs, dc coupling, individual regulators or nicd batteries for each opamp. One day something happened and one blew up. The replacement came from Ti. A very different sound, the previous voicing effort was wasted. No bass, no prat, maybe a little more extended highs but generally unacceptable.
Despite some good qualities, not really tempted to try these chips again, just not enough HF resolution compared to what is available today. Differences between inverting/non inverting tolologies also seem less obvious with modern chips.
Designed a split riaa phono some time in the mid 80s. Signetics 5534s all over. Took a lot of effort till it became acceptable: inverting stages, matching impedances seen by both inputs, dc coupling, individual regulators or nicd batteries for each opamp. One day something happened and one blew up. The replacement came from Ti. A very different sound, the previous voicing effort was wasted. No bass, no prat, maybe a little more extended highs but generally unacceptable.
Despite some good qualities, not really tempted to try these chips again, just not enough HF resolution compared to what is available today. Differences between inverting/non inverting tolologies also seem less obvious with modern chips.