The conductor Stokowski (who was the conductor of Disney’s Fantasia) was a pioneer of orchestral recording.  This was not without its problems:

Stokowski was moving more and more toward what is recognized as his most significant achievement – the broadening of popular interest in serious music.  He developed a firm conviction that radio, recordings, and films would inevitably be the most effective instruments in bringing aesthetic understanding into everyone’s life.  It explains his immediate acceptance of a broadcasting series on NBC in 1932, which made Stokowski a household name.  It also gave rise to an embarrassing incident that spurred him to acquire a more solid technical background.

I was told by Bill Thomas, formerly of Young and Rubicam’s radio department, that before the series began, NBC officials gave Stokowski the grand tour of the original Fifth Avenue studios.  Pausing before a control room, Stokowski observed a man manipulating a panel with a row of dials and galvanometers. 

“Who’s that?” Stokowski asked.

“He’s the engineer who controls the sound.”

“Do you propose to have one on my programs?” Stokowski demanded.

“Oh, yes.  He’s necessary on all programs.”

“Not on mine.  No one controls Stokowski’s sounds but Stokowski.”  And he marched off.

This put the NBC into a real quandary.  They patiently explained the facts of broadcasting to Stokowski but to no avail.  He remained adamant.  Faced with a crisis, they gave in and reluctantly built at huge cost a portable glass-enclosed control room for him to operate.

As Stokowski rehearsed, he practiced on the dials while the program staff suffered.  He would wave his hands and then suddenly reach down to twist a knob, often the wrong way and invariably too much or too little, for he was unable to gauge the blended sounds as heard in the control room.  Inevitably, the first broadcast was a sonic disaster. 

For the next broadcast a bright engineer had an inspiration.  “Let’s use two control cubicles,” he suggested, “a well-screened functioning one, and a disconnected play-toy for the conductor.” They built another, and the scheme worked just fine.

No one knows just who tipped off Stokowski, but about the third rehearsal, he strode right past the glass monster and never looked at it again.

Chasins, Abram (1979) Leopold Stokowski: A Profile.  London: Robert Hale, p.133-134.