Audio Amplifier Input Impedance

There is only the output impedance of a microphone and the input impedance of a loudspeaker.

Audio amplifier input impedance. Pre amplifiers designed for high input impedance may have a slightly higher effective noise voltage at the input while providing a low effective noise current and so slightly more noisy than an amplifier designed for a specific low impedance source but in general a relatively low impedance source configuration will be more resistant to. The emitter follower has a high input impedance but this may be reduced to an unacceptable level by the presence of the base bias. My understanding was that an audio power amp s input impedance could be increased by using global negative feedback which is a no no coz of all the other issues this brings with it by selecting the type of semiconductor device used for audio power amplification. The din specification states that the current source should give an output voltage of 1mv per 1kω of input impedance.

The input impedance of the basic integrated circuit is just the input impedance of the basic circuitry inside the chip. Generally an input impedance is high and an output impedance is low. Typically the input impedance of a din compatible unit would be 100kω and so would see an input signal voltage of about 100mv. The question of the input impedance of a microphone or the output impedance of a loudspeaker is nonsense.

Input impedance z in or input resistance as it is often called is an important parameter in the design of a transistor amplifier and as such allows amplifiers to be characterized according to their effective input and output impedances as well as their power and current ratings. If there is something to really keep in mind about why input and output impedances are so important is matching. So what sets the input impedance of an audio power amp. The effect of a high input impedance is to reduce the input current to the amplifier.

If the input current for a given input voltage is reduced by whatever method the effect is to increase the input impedance. Op amp input impedance basics. When referring to the op amp input impedance it is necessary to state whether it is the basic chip itself or the circuit. Hi fi equipment with phono connectors usually employs the voltage matching concept with very low.

How to measure impedance. Impedance calculated for audio amplifier loudspeaker or microphone the usual common question is. Modern solid state amplifiers are sometimes referred to as bridging devices which take an input voltage from an audio source and form an amplified image of that voltage at the output. Op amp chip input impedance.

Some current is required to drive the base. Importance of the impedances.