Connect speakers in parallel - how it works

You can easily connect speakers in parallel to adjust impedance, or simply to feed multiple speakers with the same signal. In both cases, you should keep an eye on the overall impedance and performance of the speakers. In this practical tip, we explain how to connect speakers in parallel and how to calculate the resulting impedance and power.

How to connect speakers in parallel

How to connect speakers in parallel can be explained with simple graphics and a few words. In the picture gallery we show you further circuit diagrams and a circuit to combine parallel and series connection of loudspeakers.

1. The two lines on amplifiers and loudspeakers are usually referred to as "+" and "-" or as "Signal" (SIG) and "Ground" (GND). In fact, the speaker signal is the AC voltage between the two.
2. Connect the same pole from several loudspeakers to an amplifier connection: + from the amplifier to + from two loudspeakers and - from the amplifier to - from two loudspeakers. So the speakers are connected in parallel.
3. The easiest way to connect loudspeakers in parallel is with classic loudspeaker lines. But you can also connect speakers in parallel with a jack and cinch. We explain speaker connections and their advantages as well as the assignment of jack in further practical tips.
4. If you connect loudspeakers in parallel, the amplifier power Pges is divided between both loudspeakers to PA and PB. However, the overall performance does not change.
5. The total impedance Ωges results from the input impedances ΩA and ΩB of the two loudspeakers: Ωges = 1 / (1 / ΩA + 1 / ΩB) + 1 / (1 / ΩC + 1 / ΩD).
6. The formula is somewhat transformed: Ωges = ΩA × ΩB / (ΩA + ΩB). Two parallel-connected loudspeakers have only half the impedance.
7. The performance of the respective speakers is PA = Pges × Ωges / ΩA and PB = Pges × Ωges / ΩB.
8. It is optimal if the total input impedance of the loudspeakers and the output impedance of the amplifier are identical. The loudspeaker input impedance may also be higher. In the worst case, the signal sounds a little quieter, duller and the attacks are less sharp. But: If the speaker impedance is too low, damage to the amplifier can occur.
9. Since most amplifiers require 4, 8, or 16 ohms, you should try to create this input impedance. For example, two parallel 16-ohm speakers result in an input impedance of 8 ohms.
10. Warning: the total impedance is never higher than that of the loudspeaker with the lowest impedance. If you connect a 1 megohm speaker and a 2 ohm speaker in parallel, the input impedance remains about 2 ohms. The performance of the 1 mega-ohm speaker is almost zero.
11. Of course, you don't have to limit yourself to two parallel speakers. You can also use the formulas to calculate the values ​​for even more speakers.

In further practical tips, we explain what you should pay attention to when buying loudspeakers, what role the cross-section of the loudspeaker cable plays and how you solder the jack cable and cinch plug yourself.

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In the drawing, one line goes from a main line to each speaker. Alternatively, you can route one line to one speaker and from there another to the other speaker. Both connection methods are equivalent.

The third option is to run both speakers with their own cable in the same amplifier connection.

You can also combine parallel and series connection. Then two loudspeakers connected in parallel are connected in series. The total impedance is the sum of the two loudspeakers connected in parallel, i.e. Ωges = 1 / (1 / ΩA + 1 / ΩB) + 1 / (1 / ΩC + 1 / ΩD). If speakers A to D have the same impedance, i.e. ΩA = ΩB = ΩC = ΩD, the total impedance Ωges in this circuit still corresponds to the same impedance: Ωges = ΩA = ΩB = ΩC = ΩD