Amplifiers, more than just amplification(an overview on output impedance)

A lot of my friends ask me why do amplify something as easy to drive, at one time the M50s and now, even more ridiculous, the Objective 2 with the Triple-fi 10s. There are a few reasons. I will go through them to tell you why as simply as I can.

In general:

1.To increase sound quality by increasing control over the audio signal to the headphones/ earpiece.

2.Bypass Ipod/Iphone internal volume control which alters tonal balance and adds distortion to the music(because of lack of control over audio signal.)

Short overview:

A audio signal is in the form of AC current which is highly dependent on many factors, of which I will talk about only 1 for this article, output impedance.

Output impedance in an AC circuit determines how linearly the the circuit will deliver power no matter the load.

This is true with most power regulation circuits where capacitors are added to reduce output impedance, giving more linear power. This also applies in audio signals, since they are also AC currents. Generally 0 ohm output impedance is highly desirable in audio.

To audio 0 ohm output impedance provides the following benefits.

Reduced distortion no matter the load(ear bud/headphone).

Flat frequency response no matter the load.(no emphasis on bass or treble)

Uniform power delivery into different loads so that the right amount of power can fulfill the music's frequency requirement.

Of course, this a extremely short explanation of the benefits of a low output impedance. Couple that with the overall better performance of the external amplifier, this forms my reason why amplifiers are more than just amplification.

Some reference material I used:

Power supplys

The advantages of the "0 ohm" headphone amplifier.

Great article by Nwavguy about output impedance.

Wiki article on impedance.