Whenever I see someone playing an organ they’re always constantly playing with knobs and switches and things. What are all of those things they’re adjusting all the time?
They’re called stops, and they switch which voices (i.e., pipes) the sound is coming from at any given moment. The organist can also change this by playing on a different keyboard (known as a manual), but each manual has its own set of stops. Some organs have buttons directly under the manuals that allow the player to set up certain preset selections of stops and switch to all of them with one push.
Organs are amazing instruments.
^ And that’s where “pulling out all the stops” comes from.
This gets into a lot of detail about this specific organ, but it covers the basics of how organs work.
I didn’t rewatch the video, but IIRC, that was mentioned in it.
A rock/jazz* organ like a Hammond B-3/C-3/L-100/etc will have drawbars that you can pull in and out on them to shape the sound. That’s what the sliders here are that the hand is reaching for:
*OK - they were not originally made for these genres, but these are the ones most associate them with.
There are also buttons on this type of organ where you can turn vibrato on and off, toggle percussion (little clicking sounds when you hit a key) and shape its quality, and turn the Leslie speaker on and off and set its speed.
Oh, and those inverted colored keys on the left side of the keyboard are presets.
And of course, the reason that Bach had twenty children was because his organ didn’t have enough stops.
Ninjaed by 19 days!