Amplification and loss

[Kevin Weddle]

Is loss in amplifiers any indication of design? Could you design a good amplifier with a lot of loss? A resistor causes loss, but no distortion. Many times I have had to reduce a signal after amplifying it. Is this a design problem?

 

[audioguru2]

An amplifier has gain, not loss. You can reduce the gain with negative feedback or reduce the input and output with a volume control at the input.

If you need to reduce a signal after amplifying it then the input level is too high or the amplifier's gain is too high.

If your amplifier causes distortion then it has a design problem.

 

[Kevin Weddle]

But shouldn't loss, as in the way of resistors be avoided. Of course discrete component circuits use them, but isn't it because of the necessity to complete the design. It's a way of interfacing circuit sections and is a concession in a design.

 

[audioguru2]

It is desirable for an audio amplifier to have extremely low distortion. Then it has a very high open-loop gain and uses plenty of negative feedback to reduce the gain to a useable amount and the negative feedback reduces the already fairly low distortion.

If you attenuate a signal so that an audio amplifier can have a high gain without much negative feedback then its distortion will be much higher.

If an audio amplifier needs to have a high gain like for a microphone then a low distortion preamp amplifies the signal so that a very low distortion power amplifier can be used.