How to achieve a certain 60's voice effect?

I’m not hearing anything other than vocal technique? I don’t hear effects at all. The layering of the female voices and the trumpets in the girls walk by song I’ve always thought was clever though.
It was easy... you set up the microphone, hit the record button and SING IT THAT WAY! The Twist was recorded in 1960. About the only effect that people were using at the time was reverb, which in many cases was an empty room with a speaker and a microphone! You had EQ, compression and volume, and the talent of the musicians to work with. Chubby Checker's Twist was done in a small studio in Philly. A lot of their success was tied to the fact that Dick Clark and American Bandstand were located in Philly originally.

The Andy Williams record has his vocal doubled, including him doing harmonies. It shows how good some of those old singers were. Williams was a major artist for Columbia records, so he would have been working in the best studios in California, with the best studio musicians of the time.

People today are so ingrained to think of stuff in terms of plug-ins and effects that they miss the obvious.
The Andy Williams
I think he's a great singer. I love his smoothie songs because they are so musically good. I actually remember watching his show in the 60s when I was a little boy. I never really understood it, but hey, it was television. I seem to have a memory of a bear being on the show and not being at all freaked out by it !
Or maybe I just dreamed it.
People today are so ingrained to think of stuff in terms of plug-ins and effects that they miss the obvious.
I was reading an interesting interview with Paul McCartney the other day from an 80s article on bass players and when asked about how he compared the sounds he was getting during the 60s with the current day, he said that he preferred the old effects and methods because they weren't pristine but "more fuck-uppable" as he put it. That has pretty much always been my approach to recording. Rather than search the internet for the sampled sound of a cat, I'd rather go find a real cat and try and get a recording of one myself. I wanted a cat miaowing for years and whenever I heard them, I didn't have my Zoom H1. But one day last year, outside my flat, a cat was miaowing in terror because of a bigger cat. Before I went to help the cat, I got a load of great miaows. Then just as I got outside to help the cat, it went off together with the one I thought was the aggressor !
But I'm forever messing with sounds. With digitalia, one can still do many of all those old analog things without running into the digital red. And one still finds new ways of doing "old" things like recording a banjo and then re-amping it through a fuzz pedal on a light setting and running it simultaneously through the tremolo on a Line 6 amp, lightly.
I'm also reminded of something George Martin said. I can't remember if it was in the 80s or 90s {my guess is early 80s as it might be in a book on record producers that I had at the time}, but he was talking about sounds and effects pedals and he said words to the effect of "Back in the 60s, we created. Nowadays, people select." Which sort of fits in with Paul's statement.