How do you wire Loudspeakers?

Answer 1

The "Plus" (+) of the speaker cabinet is wired to the Plus side of the amplifier. Most speakers have red (+) and black (-) terminals. The Negative wire (also known as "minus", "-", Common, or COM) goes to the the other connector. Red and black should be quite common to you if you've ever jump started your car.

That's how you hook it up. Easy - right? But that's notall you need to know. You need to know the "impedance" or "ohms" of the speaker. You also need to know the minimum rated impedance of the amplifier or receiver. [I am assuming transistor amplifiers only for this discussion.] If the speaker impedance is higher than the minimum rated impedance of the amplifier than you are OK. If it is lower, than the minimum of the amplifier you could risk blowing up your amplifier. More modern units will have overcurrent protection circuitry. That doesn't necessarily make them better sounding units though.

If you are trying to connect more than one speaker to your amp, you are opening another can of worms. It's not an easy subject to approach without diagrams. On most amplifiers, the speakers will be in parallel which means that the impedance is cut in half. So, two sets of 8 ohm speakers, both on and in parallel, will be seen by your amplifier as a single 4 ohm load. Many amps still have an 8 ohm minimum rating - 4 ohms would blow the amp or cause it to go into protect mode. These days, most speakers are rated at 6 ohms. This is less resistance to the amplifier which causes it to put out more current and thus the speaker sounds "louder" than an 8 ohm. This is a marketing trick. When doiung an A/B comparison between two pairs of speakers, most consumers would choose the ones that are louder.

Two 6 ohms speakers in parallel would be 3 ohms - that is even lower than an amp with a minimum rating of 4 ohms could go. Rarely will you ever see a consumer receiver that would go as low as a 2 ohm minimum but this is now fairly common in the PRO SOUND world (amps used for PA systems).

Some manufacturers have gotten around this issue by wiring two sets of speakers in series and the impedances add together (8+8=16ohms). This is done internally on the amp and instead of + to + and - to -, the configuration is more "tail to head" like when installing flashlight batteries. The best way to tell is to read your owner's manual. Don't have one? Put the model number in a search engine and most manufacturers have a pdf file online.

Another way to tell is to hook a pair of speakers to your "A" or "main" receiver outputs. Now, without a second pair of speakers connected, turn your speaker switch to A+B. If you still hear the speakers, it is a parallel connection. If the speakers cut out then you have a series connection. It's exactly like how your dual cell flashlight wouldn't light with just one battery in it - you aren't completing the circuit.

Just remember, you won't blow up a transistor amp with "too many" ohms - just not enough. Zero ohms is a "dead short" - like placing a screwdriver across the terminals. If impedance (resistance to electric current) is zero, then the amp want to try and put out infinate current (which it can't).

Now, many speakers (especially with dual woofers) are four ohms. Certain Thiel and Cerwin-Vega models come to mind. I recently had a customer that had two sets of C-V 4 ohm speakers. In parallel, a two ohm load! He asked the sales monkey at Best Buy if the amplifier he was buying would work on his speakers. The idiot said "sure". Well, it shuts off when the volume knob gets to 10:00. Hopefully you will listen to engineers - and not sales monkeys...