Increase total Speaker Impedance Question

If you combine four speakers by connecting two in parallel and two in series, you will end up with the total impedance equaling the impedance of a single speaker. You can see this by using this calculator and selecting "2 series and 2 parallel" and entering the correct impedance values. If you added a series resistor to increase impedance, it would have to be a power resistor able to dissipate the wasted power it would use in heat, and it would affect the sound. Hope that this helps!

Good comments by Bill, as always.

I'll add that connecting speakers in series will usually result in poor sonics unless the speakers are identical models. The voltage and power put out by the amplifier will divide up between series connected speakers based on the relation between their impedances. If the two speakers are identical the voltage and power put out by the amplifier at any instant of time will divide up equally between them. If they are not identical models, the relation between their impedances will almost always be significantly different at different frequencies, resulting in the voltage and power put out by the amplifier dividing up between them differently at different frequencies, resulting in arbitrary frequency response irregularities in each speaker, as you found.

Regards,
-- Al

In my response above I was assuming that the four speakers each have identical impedance values. Thanks to Al for kindly confirming my input, as I consider him to be the true authority on any technical issues.