I have a circuit with a Darlington emitter follower used as a buffer between a common emitter amplifier and a low resistance load (speaker). i wanted to know if this arrangement could alone (with the corect values ofcourse) amplify an input from a microphone and give output at the speaker. could this arrangement be used for applications such as mobile phone speakers? if i have an overall voltage gain of say, about 170? would this be enough to drive a speaker of less than 1watt power?
A single common emitter will probably be not enough to supply sufficient (170×) gain. A Darlington emitter follower will only decrease that gain further (approx. 0.9×), so the quick answer is no.
Depending on your exact circuit, the voltage gain may be fairly easy to solve/increase. So show us the circuit.
As far as I know, Darlington emitter followers only operate in one direction—no AC. Microphones and speakers need current flowing in both directions. If you only have one single-sided follower, it isn't going to work. I think that you might do better with an op amp or two.
Darlington configuration is normally used between the pre amplifier stage and the output ( power ) stage is used to get a large amount of amperes ( current ) and acts as an insulator being with unity voltage gain so the signal comes from the pre amplifier maintains its strength on arriving the power amplifier means we have amplification to both voltage and current so the last power amplifier can voltage-amplify the high current signal to a level that enables operating the speaker with maximum power transfer from the power output amplifier to the speaker using matching between them.