repaired a small satellite speaker (3" 8ohm) with a 4 ohm speaker but not on purpose just wasn't paying attention when I ordered speaker so what affect will that have? also why is there a capacitor in there? its a 47uf/100v. what does it do? thanks
Replacing a speaker with something different will likely not sound good at all as a 4ohm speaker will play louder than an 8ohm speaker will so if there is a tweeter also in the same box the two will no longer play at the same level.
The capasitor you see is probably part of the crossover and again specific to that speaker.
It is never wise to replace drivers with anything other then exactly what was designed to be in there in the first place.