Any idea what does "two-bar tangle" mean?
It's a paragraph from a fantasy novel:

The first thing I heard was the music. A hectic, two-bar tangle, played over and over again. We entered a hall so high and vast it felt like a gym, its gilded corners softened by mossy masses that had to be birds’ nests. A U-shaped table in the center of the room was lined with people. People eating, laughing, whispering to each other, stabbing at their meat. In the center of the room was the source of the awful music: a man in dirty green with a head of dark curls, holding a violin. He sawed at it savagely, in a jerky motion that looked painful.

Question

Any idea what does "two-bar tangle" mean?
It's a paragraph from a fantasy novel:

The first thing I heard was the music. A hectic, two-bar tangle, played over and over again. We entered a hall so high and vast it felt like a gym, its gilded corners softened by mossy masses that had to be birds’ nests. A U-shaped table in the center of the room was lined with people. People eating, laughing, whispering to each other, stabbing at their meat. In the center of the room was the source of the awful music: a man in dirty green with a head of dark curls, holding a violin. He sawed at it savagely, in a jerky motion that looked painful.

Answer

It's not a standard expression.  As AP suggests, it's probably a badly played piece of music which has a tune which repeats every 8 beats (4 beats in a bar).

Answer

A "tangle" is something very confused ("with no head and no tail"). 
A two-bars music is a rhythm (bars are a measure unit -- but I can't say how it works..)

Your sentence may sound as (eg.) = "a 4/4 rhythm messy music in the background"

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