Using two 8 ohm speakers the total resistance is given by the formula;
RT = R1 + R2
RT = 8 + 8
RT = 16 ohms
For loudspeakers in series;
Just add the values of all the resistances together;
Rt = R1 + R2 + R3.
Using two 8 ohm speakers the total resistance is given by the formula;
1/RT = 1/R1 + 1/R2
1/RT = 1/8 + 1/8 =2/8
Turn fraction upside down to get
RT = Rt = 8/2 = 4 ohms
From the previous Diagrams you will see that for two 8 Ohm speakers In parallel, the total resistance is half of the value of one speaker 4 Ohms.
For 2 16 Ohm speakers in parallel;
The total resistance is half of 16. And thus = 8 Ohms
If you use 3 speakers of equal value then total resistance will be a third of the resistance of one speaker.
3 x 8 Ohm speakers; Total R = 8/3 Ohms.
For different value speakers use the formula provided above.
For two speakers of different value in parallel;
1/Rt = I/16 + 1/8 = 1/16 + 2/16 = 3/16
Rt thus = 16/3 Ohms = 5.3 Ohms
For three speakers of different value in parallel;
using 16 Ohm 8 Ohm and 4 Ohm
1/Rtt = 1/R1 + 1/R2 + 1/R3
Rt = 1/16 + 1/8 + 1/4
as 2/16 = 1/8 and 4/16 = 1/4
RT= 1/16 + 2/16 + 4/16
1/Rt = 7/16
Rt = 16/7 = 2.3 Ohms
For speakers in parallel the total resistance is roughly half of the lowest resistance speaker.
Warning! You can blow your amplifier up by running it into too low a speaker resistance.