I'm a big fan of the song "Sweet Mountain" by American Spring from 1972, which features some captivating synthesizer textures.

I wanted to ask some experts how they think a certain layer of the track was synthesized. I know a Moog Modular was being employed by The Beach Boys heavily around this time. There are also photos of Brian Wilson with his American Spring collaborator, David Sandler, where Brian is at the helm of an Arp Odyssey. I'm guessing either Brian Wilson and/or engineer Steve Desper played the synthesizer parts on this track.

Here's the audio: https://willcmusic.com/sweet-mountain

Track 1: Here, I used AI stem extraction to extract the song's instrumental for about 20 seconds.

The particular sound I am referring to is the kind of sparkly pad that swells. To help you identify it, it fades out and disappears at 13 seconds. I am not referring to the oboe type sound or the shorter staccato stabs, but the swirly pad that sustains.

Track 2 is the full original song recording in its entirety for greater context.

Does any body know how a sound like this is generated? I can't tell if it's a rapid arpeggio, or a held Bb (?) note sent through certain effects.

Any thoughts or insight would be massively appreciated. I think it's a beautiful, ethereal sound, and I'd love to have a stab at recreating it or something similar.

Thank you in advance!

 

It's a fast arpeggio, I think based on church organ like sound.
To me is similar to Interstellar ost (go to 1:00 about):

 

I really like the old vst K700 for sounds like this, but its only 32bit.. try this adjust to your taste
https://plugins4free.com/plugin/1357/

 

The Interstellar track is a spectacular example to help illustrate that it is indeed an organ technique. I really appreciate you sharing! I think the ambience of it on the Sweet Mountain track is pretty ethereal - the reverb, the appear-and-disappear in the mix changing dynamics of the pad. All very cool stuff!

 

That sparkly pad in "Sweet Mountain" is indeed mesmerizing! It sounds like a combination of sustained notes with some modulation for that ethereal feel.

 

That sparkly pad could be a sustained note with modulation, maybe using a phaser or slight chorus to give it that shimmering effect. Definitely fits the ethereal vibe of the track!