How to find mob spawners easily without mods or x-ray in minecraft 1.7.4?

I'm trying to find a mob spawners underground but it takes slot of time to find one. Is there a faster way to find them?

CAS

I would mine from any level between 20 to 60. Look for caves. Caves usually expose them more easily.

Robby

You can dig a low level strip mine and hit f5 to 3rd person and itll show caves above u

Denver