Complex sentence: Vacuum tube or electronic valve amplifiers were first used to resolve microphone impedance and output problems in 1915 and led to the invention of the first modern condenser microphones by Bell Labs in 1917 and this type of microphone went through many stages of improvement.
Split into simpler sentences: Vacuum tube or electronic valve amplifiers were first used to resolve microphone impedance and output problems. Bell Labsinvented the condenser microphones in 1917 and this type of microphone went through many stages of improvement.