Only if your amplifier is capable of driving a 4 ohm speaker. Some have a switch on the back to select 4 or 8ohm speakers. Details should either be printed some where on the back of the amp or the instruction manual
Yes, you can safely use a 4 ohm amp with one 8 ohm speaker, but you will not achieve full power. The 4 ohm amp is designed to supply a certain voltage into a 4 ohm speaker. Supplying that same voltage to an 8 ohm speaker will result in half the power, or -3dB. For maximum power, use a 4 ohm speaker, or two 8 ohm speakers in parallel.
You cannot make a 16 ohm speaker into an 8 ohm speaker. You would need to replace the voice coil. You can, however, put two 16 ohm speakers in parallel, and the equivalent impedance would be 8 ohms. The only remaining issue is frequency response, and that's a factor of speaker and enclosure design, so best is to use the exact speaker as originally designed.
You can, but the available power will only be about half of rated, and the frequency response will be slightly different. Better would be to connect two 8 ohm speakers in parallel, making an equivalent 4 ohm speaker.
If wired in parallel then 4 ohms.
You need to match the speaker with the amplifier. Better or worse is not the question. The question is dynamic range and the possibility of overloading the amplifier. If the amplifier is rated 4 ohms, use a 4 ohm speaker. Same for 8 ohms. Do not "mix and match".
Yes It all in how there wired up
Yes, but you won't get rated pwer. Best is to match the speaker to the amplifier.
Of course! As long as your amp's minimum impedance is 4 ohms or lower.
The impedance of the speaker does not determine its quality. Assuming that your amplifier can drive the 4 ohm speaker, you will notice that this speaker is louder than the 8 ohm one.
Study ohms law to get your head around it.
Four 8 ohm speakers wired in parallel would give an effective 2 ohm load.
Yes, you can use an 8-ohm 400-watt speaker with a 4-ohm 350-watt amplifier to play bass. The speaker will receive less power from the amp, resulting in lower volume, but it won't damage the speaker or the amplifier. Just ensure that the overall impedance of your setup matches the amplifier's specifications to prevent any potential issues.