Magical Mystery Tour

Posted: 3/28/2008 1:24:55 PM

From: Alberta Canada

Joined: 1/5/2008

Even though I've seen this countless times, I only just realized that during the wizard scene in The Magical Mystery Tour by The Beatles, there is a very theremin like sound being played in the background. I'm not entirely sure, but it sounds very much like one.
Here's a link to this scene:
It's brief, but if anyone can share some insight as to whether or not this is a theremin it would be greatly apreciated.
Posted: 3/28/2008 11:55:39 PM
Brian R

From: Somerville, MA

Joined: 10/7/2005

Definitely NOT a theremin. Rather, you're hearing a couple of voltage-controlled oscillators (VCO): the one you hear directly, operating at audio frequency, putting out a sine wave; its frequency is being modified by another, sub-audio-frequency oscillator (a.k.a. "low-frequency oscillator," or LFO), also putting out a sine wave, so that the first oscillator's pitch swoops up and down smoothly.

The dead giveaway is the way that the swoops return EXACTLY to the same top and bottom pitch for a cycle or two. The creators do manipulate the degree to which the LFO is sweeping the pitch of the audio VCO, so that it's not the same upper and lower boundary pitches throughout the entire excerpt... but if you listen closely to various pairs of cycles, it's just too clean and precise for a human thereminist.

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