Electronic – Common emitter amplifier

There are a number of things wrong here

1. There are no component designators in the schematic. This makes it hard to talk about, so I'll be more brief than otherwise.

2. You should use junction dots at all points where nets connect. The four lines crossing left of the transistor is ambiguous.

3. A quick calculation of the bias point not taking base current into account results in 1.3 mA thru the transistor, so your claim of 1.26 mA is plausible. However, this should tell you there is no way you're going to get anywhere near 1 W of output power. Even looking at the transistor as a perfect switch, the collector swing will be from 6.6 to 24 volts, for a swing of 17.4 volts. However all this is at a impedance of 8 kΩ. 17.4 Vpp sine wave is 6.15 V RMS. At the best case power transfer, the load is 8 kΩ so the voltage is half that, or 3.1 V RMS into 8 kΩ, which comes out to 1.2 mW. That's less power (although at a different voltaqe) than the MP3 player is likely putting out.

4. The frequency response is a mess. The gain of the amp only 2.7 at low frequencies. This starts going up 3 dB/octave at about 50 Hz, but the high end is unpredictable because it relies on properties of the transistor you don't know. Then the cap in series with the speaker forms another high pass filter, but this also allows the speaker to load the output heavily probably having a reverse effect for part of the range.

5. I can't even begin to guess what the 12 kΩ resistor accross the speaker is supposed to do. It makes no sense whatsoever.

I thought common collector amplifier is immune to loading effects

A CC is not immune to loading since it has a low, but non-zero, output impedance.

The small signal output impedance of a CC amplifier is roughly:

\$\dfrac{V_T}{I_E} + \dfrac{R_{tb}}{\beta + 1}\$

where

\$V_T \approx 25mV \$ (assuming room temperature)

and \$R_{tb}\$ is the equivalent AC resistance connected to the base.

For example, if \$I_E = 1mA\$, the output impedance is at least 25 ohms.

So, while the output impedance of a CC amplifier is much lower than a CE amplifier, it is not immune to loading effects.