Karaoke is a very popular leisure activity in many parts of the world today especially Asia. A basic karaoke system consists of a karaoke amplifier, wired or wireless handheld microphone(s), speaker(s) and video equipment. When purchasing a karaoke system, it is most important to ensure that all the audio equipment in the system share similar performance characteristics in order to obtain the best possible sound.

Many users have experienced unwelcome distortion in their karaoke systems even though they may have been using a high quality wireless microphone. This phenomenon is often due to the incorrect matching of the karaoke system's amplifier input to the microphone output. The dynamic ranges of many karaoke amplifiers are simply not able to handle the maximum output levels of a microphone; therefore, they will overload and distort the audio signal. No matter how you adjust the main volume, this distortion cannot be corrected.

So how should users select a karaoke amplifier? First of all, the main function of the karaoke amplifier is to convert the acoustic signal picked up from the microphone into an electrical signal which is amplified, mixed with other music sources and/or sound effects and then sent to the speakers. Users need to understand that it is very important that the input sensitivity of the amplifier precisely matches the sensitivity of the microphone. Whether the amplifier's circuitry is based on a traditional design or the latest digital technology, it would still fail to deliver the optimal sound effect if the sensitivities do not match.

Since the microphone and speaker are acoustic electronic products, their features, standards and measurement units are different from the general karaoke amplifier, which is an audio electronic product. Many karaoke amplifiers on the market have been designed and made with a poor understanding of microphone performance features. Manufacturers often disregard the output characteristics of microphones when determining the optimal gain level of their karaoke amplifiers and therefore continue to design them with an optimal gain level that is set too high, thus causing the dynamic range to be too narrow. Because of this design, these amplifiers cannot handle the larger SPL (sound pressure levels) of many singers so they can easily become overloaded, causing distortion. This overload could be avoided if karaoke amplifiers were designed from the beginning to match the output characteristics of microphones.

How is the output of a microphone determined? Generally we place the microphone in a room where it is isolated from any type of sound (an anechoic chamber) and use a sound frequency of 1 KHz at 94dB as a standard SPL to measure the microphone's output. This output is measured in mV or converted into dBV as a measurement of the microphone's sensitivity. For example, both MIPRO wired and wireless microphones are set up to a basic sensitivity of -52 dBV/Pa (0dB=1V/Pa, 1 KHz). This means that this microphone will put out approximately 2.5 mV signal strength at 94dB SPL. In point of fact, any singer's sound pressure level is considerably higher than the test standard SPL of 94dB. For example, an average of approximately 120 dB SPL with an output signal strength of about 50 mV is common. When performers sing loudly, the signal strength could well be over 500 mV, meaning the microphone must be able to withstand 140 dB SPL at a minimum. The sensitivity of a MIPRO dynamic microphone is comparable to such models as the Shure Beta 58A=-51.5 dBV/Pa (2.7 mV) and the Sennheiser E945=-54 dBV/Pa(2.0 mV) and is designed to handle these high SPL levels. The MIPRO wireless microphone's sensitivity is equal to 0dB, meaning the receiver's output signal strength equals the transmitter's input signal strength. Therefore, a MIPRO wireless dynamic system is designed to provide the same sensitivity as a wired dynamic microphone and users do not need to re-adjust the input volume of the karaoke amplifier to obtain their ideal sound.

To avoid overloading karaoke amplifiers with a high gain design, MIPRO has designed their new MR-801a and MR-823D model receivers with a sensitivity control on the rear panel. Switching this control to -6dB lowers the sensitivity level by half and effectively doubles the input dynamic range, enabling these amplifiers to handle the higher SPL levels of the microphones used in karaoke performances without distortion.

In short, users would be wise to carefully match the input sensitivity of their karaoke amplifier to the output sensitivity of the microphone that will be used with the system, thereby avoiding annoying distortion and obtaining the best possible performance out of their karaoke system.