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I wonder if it could be Laurel and Hardy? Thought beyond that, I don't have a clue.
Here's a list of some shorts. "Below Zero" matches only the bass violin part, but almost nothing else.
http://laurelandhardycentral.com/sound.htm
I would have recognized them as Laurel And Hardy had they been them, and it wasn't them.
Bump. Also, "Laurie" has an American accent, but "Fry" might have a British accent of some kind. The two were more or less equal but my recollection of my impression is that "Laurie" had slightly higher status in their relationship. Both of these details are the inverse of Laurel & Hardy.
Edited by randomsurferBump. "Laurie" doesn't so much play "Zoom zoom" with the orchestra out of stupidity, more like arrogance. Plus it's the only record he has. He and the conductor get in a bit of an argument.
- Conductor: We play Beethoven's 5th Symphony! note"Laurie:" Well I play "Zoom Zoom!"
Also I guess "Laurie's" accent is sort of Mid-Atlantic; definitely not British, but he pronounces Zoom sort of partway between "zoom" and "zuhm."
Edited by randomsurferBased on the IMDB description, no. It was a bass and not a violin, and there wasn't a plan/scheme to get on the radio. Thanks for the suggestion though.
EDIT: Though it may well have been Clark & McCullough, having seen one of their intros on Youtube. Clark is wearing drawn on glasses all right! Based solely on the title it may have been "Music Fiends," but I can't find a summary anywhere online let alone a copy to view.
EDIT #2: Hey, I was wrong! it is "Fits in a Fiddle" after all! Thank you.
Edited by randomsurfer

A short subject from the 1930s starring a comedy duo who look a little bit like Fry And Laurie. The Laurie-type wears drawn-on glasses (much like how Groucho Marx wore a painted-on moustache). "Laurie" is a street musician who plays a bass violin and sings a song which goes "Zoom, zoom, / Zoom, zoom, / [something something] melody!" while playing along on the bass. He gets hired off the street to play in an orchestra which is missing its bass player. But "Laurie" can't really play, he has a record player hidden in the back of the bass and mimes along while playing a recording of someone playing the bass. When it comes time to rehearse, while everyone else in the orchestra is playing whatever piece they're supposed to be playing, he plays "Zoom zoom." Meanwhile the "Fry" character has some adventure of his own in the orchestra hall but I don't remember what.
Edited by randomsurfer