This page is for those who don't fully understand how to connect their speakers to their amplifiers to present a safe load to the amplifier. Most people want to connect their speakers in the lowest possible safe load to get the most power from their amplifiers. There will be some speaker/amplifier combinations that will not allow full power to be produced safely. In those instances, there will be two choices. The speakers could be connected to present a load that is unsafe (for example, a 1 ohm load for an amp only capable of driving 2 ohms minimum). This would get more power from the amp but it's also likely to cost the owner $200+ to repair the amp. The better option is to connect the speakers to present a lighter_than_minimum load. The amp won't produce full power and the system won't produce as much SPL as it would with the correct load but it's also going to allow the amp to operate safely and reliably.Series Connection:
We described series speaker connections on a previous page. This page will explain how the impedance changes when speakers are connected in series. In a series connection you simply connect the positive terminal of speaker 'A' to positive terminal of the amplifier. Then you connect the negative terminal of speaker 'A' to the positive terminal of speaker 'B'. Lastly connect the negative terminal of speaker 'B' to the negative terminal of the amplifier. If both of the speakers have an impedance of 4 ohms, the total impedance will be 8 ohms. In a series connection, you simply add the individual impedances. If there were three 4 ohm speakers in series, the total impedance will be 12 ohms.
Parallel Connection:
The impedance change with a parallel speaker connection is only slightly more complicated than the series connection. When speakers are connected in parallel, the impedance is reduced. This means that, given the same output voltage, the current demand on the amplifier will be increased. If all speakers have the same impedance, the total impedance is the impedance of a single speaker divided by the total number of speakers. If you have two 4 ohm speakers connected in parallel, the total impedance is 4/2 or 2 ohms. As you can see in the diagram below, all of the positive speaker connections are connected and then connected to the positive terminal of the amplifier. The same is done with all of the negative connections. You must be careful when paralleling speakers onto an amplifier. The impedance can quickly fall below safe levels. This is especially true when connecting speakers in parallel onto a bridged amplifier.
This is a series/parallel connection (below). Connecting individual woofers in a series configuration is not common in car audio. This is a lot more common in musical instrument (guitar and bass guitar) speaker cabinets.
In the diagrams below, you can see the relative current flow from the amplifier's outputs (indicated by the red arrows) into various loads. At the bottom, you can see that 2 ohm mono (two 4 ohm speakers bridged) is the same as 1 ohm stereo (four 4 ohm speakers per channel).
The image below shows the DVC speaker wired to both channels of a stereo amplifier. Each channel of the amplifier drives a 4 ohm load.
This image shows the DVC driver with both voice coils wired in parallel. This presents a 2 ohm mono load to the amplifier which may damage most amplifiers.
This image shows the two 4 ohm voice coils wired in series. This will present a 8 ohm mono load to the amplifier.
This diagram shows 3 DVC woofers with dual 6 ohm voice coils. The coils of each speaker are wired in series (which makes each speaker a 12 ohm speaker) and then all of the drivers are wired in parallel for a total of a 4 ohm load.
This diagram shows 2 DVC woofers with dual 2 ohm voice coils. The coils of each speaker are wired in parallel (which makes each speaker a 1 ohm speaker) and then all of the drivers are wired in parallel for a total of a .5 ohm load. You can calculate for more speakers by changing the input.
This is the wiring diagram for woofers with dual 4 ohm voice coils. This will give you a 4 ohm load. The voice coils of each individual speakers are wired in series. This gives each speaker an 8 ohm impedance. Wiring them in parallel will present the amp with a 4 ohm load.
This is the wiring diagram for woofers with dual 2 ohm voice coils. This will give you a 2 ohm load. The voice coils of each individual speakers are wired in series. This gives each speaker an 4 ohm impedance. Wiring them in parallel will present the amp with a 2 ohm load. You can calculate for more speakers by entering the number of speakers in the correct field.
This diagram is a wiring diagram for 3 DVC drivers with dual 6 ohm coils. All of the voice coils are wired in parallel for a 1 ohm load. Class D and high current class AB amplifiers are probably the only amplifiers that can handle this load. Make sure that your amplifier can handle this load if you use this wiring configuration.
This diagram shows 2 DVC speakers with the voice coils wired in parallel. Each voice coil has an impedance of 4 ohms which results in a 2 ohm impedance for each speaker. One speaker is connected to each channel of the amplifier. This is a 2 ohm stereo load.
For those who don't quite understand why too many speakers will damage an amplifier, maybe this will help.
OK, let's say that we have a water pump which is powered by an electric motor. This pump is designed to do whatever is necessary to keep the pressure constant (within the green range on the gauge). It is also designed to operate with a maximum of only two valves open at a time. In this first diagram, you can see that one valve is open and the RPMs are easily in the green. This is like a 2 ohm stable amplifier with a 4 ohm load. The motor RPMs are low and the system isn't stressed.
Calculating series resistance is as simple as it gets. All you do is add the resistance of the individual components. If you have two 4 ohm speakers in series... Total resistance = R1 + R2 +R3... Total resistance = 4 + 4 Total resistance = 8 ohms for 2 series connected 4 ohm speakers. Calculating Parallel Resistance: Calculating parallel resistance is a little more involved but still fairly easy. There are 3 methods. Method #1: If all of the resistances are equal (all 4 ohm speakers or all 8 ohm speakers...), simply divide the impedance of a single speaker by the total number of speakers. Total resistance = 4/2 (4 ohms speakers divided by the number of speakers) Total resistance = 2 Method #2: This one says that the sum of the reciprocal of the individual resistances is equal to the reciprocal of the total impedance. Well, I know that that sounds complicated but look at the following formula and you'll see that it ain't so bad. Let's do the calculations for two 4 ohm speakers in parallel. 1/(total resistance) = (1/R1) + (1/R2) + (1/R3)... 1/(total resistance) = 1/4 + 1/4 1/(total resistance) = .25 + .25 1/(total resistance) = .5 Total resistance = 2 ohms Method #3: This method is most useful for calculating the parallel resistance of 2 components. It can be used for more than two components at a time but the formula becomes convoluted and much more difficult. This method uses the product of the individual resistances divided by the sum of the resistances. Like this... Total resistance = (R1*R2)/(R1+R2) Total resistance = (4*4)/(4+4) Total resistance = 16/8 Total resistance = 2 As you can see, all 3 methods result in the same answer.  Total parallel resistance = (R1*R2)/(R1+R2) Total parallel resistance = (4*8)/(4+8) Total parallel resistance = 32/12 Total parallel resistance = 2.67 ohms Total parallel plus Series: Total resistance = R1 + R2 Total resistance = 4 + 2.67 Total resistance = 6.67 ohms total Click HERE to make this calculator fill this window. |
| You should remember: 1.In a series circuit, the current flow decreases and the impedance increases. 2.In a parallel circuit, the current flow increases and the impedance decreases. |
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