Connect speakers in series - how it works

You can connect speakers in series to increase impedance or simply to put multiple speakers on the same output channel. For both purposes, you should consider the overall impedance and performance of each speaker. This practical tip shows you how to connect loudspeakers in series and calculate the total impedance of the circuit as well as the performance of both loudspeakers.

Connect two speakers in series

In principle, connecting two speakers in series, i.e. building a series connection, is very simple. How to connect several speakers in series and combine a series connection with a series connection, we explain in the picture gallery.

1. A loudspeaker signal is an alternating voltage between two lines, which are usually referred to as amplifiers and loudspeakers as "+" and "-" or as "signal" (SIG) and "ground" (GND).
2. Always turn the amplifier off before connecting the speakers or tinkering with the circuit. To operate two loudspeaker series, first connect "+" of amplifier and loudspeaker A to each other.
3. Then connect "-" from speaker A to "+" from speaker B. Finally connect "-" from speaker B and "-" from amplifier.
4. Loudspeaker series connections can be implemented with jack and cinch as well as with simple loudspeaker cables. We will explain how you can solder the jack cable and RCA plug yourself in further practical tips.
5. The total impedance Ωges of the series connection is simply the sum of the input impedances ΩA and ΩB: Ωges = ΩA + ΩB.
6. The total power Pges remains unchanged. It is divided between the two partial outputs of the PA and PB speakers. PA = Pges × ΩA / Ωges and PB = Pges × ΩB / Ωges.
7. The load resistance, i.e. the total input impedance of the loudspeaker series, ideally equals the output impedance of the amplifier. So connect a 16 ohm speaker or two 8 ohm speakers to a 16 ohm amplifier.
8. If the input impedance of the loudspeakers is higher than the output impedance of the amplifier, the signal may sound a little quieter, more muffled and impulses such as the attacks of bass drums or harpsichords are less sharp. But: If the loudspeaker impedance is too low, damage to the amplifier can occur.

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Be careful never to connect - to - or + to +. Otherwise, the polarity-reversed loudspeaker diaphragms vibrate in opposite directions and may radiate less efficiently. Incidentally, the principle is not limited to two speakers. You can also daisy chain three speakers,

with four speakers or with even more. Just make absolutely sure not to short-circuit any loudspeaker, so to avoid connections at the point marked with the "X".

A combination of parallel and series connection looks like this. Here the series connection consists of a series of two parallel connections. Then 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 still corresponds to the same impedance in this circuit: Ωges = ΩA = ΩB = ΩC = ΩD.