There are two front speakers - Front left (FL) and Front right (FR). If you want to replace only one of these two, it is a novel idea and hardly anybody will venture.
How a speaker works:
Inside a speaker, there are two magnets. Electromagnet is mobile and placed in front of a permanent magnet which is fixed to the enclosure of magnet. As pulses of electricity pass through the coil of the electromagnet, the direction of its magnetic field rapidly changes. This means that it is in turn attracted to and repelled from the permanent magnet, vibrating back and forth. The electromagnet in turn is attached to a cone made of a flexible material which amplifies these vibrations, pumping sound waves into the surrounding air and towards your ears.
Speaker specifications:
Frequency response:
Mentioned in a range say, 50Hz-20KHz. While human ear can hear from 20Hz-20KHz, the lower end called bass frequency and below 30Hz it is less heard but more felt.
Bass = 10 Hz to 100 Hz, Mid Bass = 100 Hz to 300 Hz, Low Mid = 300 Hz to 600 Hz, Midrange = 600 Hz to 1.2 kHz, High Mid = 1.2 kHz to 2.4 kHz, Low Treble = 2.4 kHz to 4.8 kHz, Mid Treble = 4.8 kHz to 9.6 kHz, High Treble = 9.6 kHz to 20 kHz.
Power Handling:
Specified in Watts (W), the power handling specification of a speaker indicates how much power a speaker can withstand without causing any damage. Speakers usually come with two power ratings - RMS or continuous, and Peak.
The RMS rating defines the continuous power a speaker can handle without getting destroyed, whereas the Peak power rating implies the maximum amount of power a speaker can bear in an instant. This peak rating, however, is of no use in practical application.
Impedance:
This is resistance of speaker measured in ohms normally from 4-8 ohms. Lower impedance speakers is unsafe to connect an amplifier not designed for it. 4 ohm speaker should not be fed into an amp that specifies a minimum 8-ohm limit.
Sensitivity:
Measured in dB indicates loudness of the speaker. Higher sensitivity signifies the speaker is louder. Average range is 87dB-90dB.
Signal-to-Noise Ratio (SNR):
Also measured in dB indicates how much noise is there in the output sound that we hear of a device in relation to the signal level. So if a speaker has 120dB of Signal-to-Noise Ratio, it means that that the level of the audio signal is 120dB higher than the level of the noise. The higher the number, the better it is.
Do you think it is possible to replace one front speaker and expect better sound stage. Speaker and amplifier should match together for which people spend a lot.