Speaker Wiring and Connection Options
Connecting your speakers up to the amplifiers seems pretty simple but there is more too it than just that. Phasing, wiring configurations and even the type of crossover you use can have an effect on the sound. We will look at various important areas of this oft-neglected field.
Most of you know about connecting speakers in phase. Most speakers and amplifiers are marked with + and – signs to indicate the right connections. While speakers are not polarised (they will work connected in either direction), all speakers in a system need to be connected so that they operate in phase. This means that each individual driver (usually the woofer) is moving in and out at the same time. It is easy to hear an out of phase stereo system, there is a “hollow” in the middle where the bass is lacking, but in surround sound system it can be harder to tell; you have to make sure the rears are in phase with each other and that all the front speakers are too, plus ensure the front and rear are as well. Using the colour coding on speaker wires (one side usually has a mark or line) will help.
The + and – marks do actually have meaning other than just a guide to connecting the speakers the right way. It also means that the system sound produce a positive sound pressure wave (driver moves outward) which corresponds to the same positive pressure when the track was recorded, that is a positive pressure onto the microphone. Sometimes the recording is out of phase in this respect, it may still sound fine but try swapping the speaker leads around on both sides (with the amp off of course!) and you may just hear an improvement.
Bi-wiring is the use of two sets of speaker leads for each channel. The speakers must be so designed and suitable ones have two terminals on the back of each speaker. Usually a metal plate or wire is used to connect them together. What is happening inside the speaker is that one pair of terminals is for the high frequencies (mid / tweeter) and the other for the low frequencies (the woofer).
You first remove the shorting connections and then connect two sets of leads to the same terminals on the amplifier and connect one to each of the pair of terminals on the speaker. There are often wiring instructions supplied with the speakers to show exactly how to do it, otherwise if you are not sure contact the manufacturer or importer for advice.
As to whether this actually makes a difference is not so clear-cut. It shouldn’t make things worse so it may be worth a try if your system is suitable. By using different types of wire for each frequency, the various frequencies supposedly can travel optimally through the wire and experience less distortion. Generally it is advocated to use different types of wire for each, usually thicker wire for the woofer and finer, higher grade wire for the mid / tweeter connection. Another advantage is that the actual electrical connection of each driver’s crossover network to the other is much further apart (at the amplifier), hence there is much less chance of interference between the two. No scientific testing has been done in this area as far as I am aware, some people claim improvements, other don’t. But it certainly won’t do any harm!
This is similar to bi-wiring in terms of the dual sets of speaker wire and the dual connections on the speaker itself, however at the other end, two amplifiers are involved. One amplifier is used for the high frequencies and the other for low frequencies. By using a higher power amp with good current delivery for the woofer and perhaps a smaller, more refined amplifier for the tweeter / midrange, a marked improvement can be had. Each amplifier can be selected for it best characteristics in the intended frequency range.
Often however, the same type of amplifier is used for each range. This simplifies things when setting the volume control as the highs and lows must be balance to obtain the correct sound; so with the same amps, the volume level is the same for each. Different amps can result in different tonal qualities but sometimes this can desirable if you are trying to alter the sound for a reason.
Another option with bi-amping is the use of active crossovers. An active crossover acts like a normal crossover inside a speaker but is in fact located before the amplifiers and uses powered circuitry to control the frequency filtering and levels. They are usually more accurate than normal passive crossovers and tend not to introduce as many problematic artefacts into the audio signal such as phase shifting. They also can cover much wider frequency ranges and are much more flexible.
When using active crossovers, it is usual for the speaker’s crossover to be bypassed. Of course an amplifier is required for each speaker driver (or set depending on the configuration). This type of set up can give you top-class sound however the down side is higher equipment costs and more complexity and difficulty in setting up the system. It is generally only recommend for the more experienced hifi enthusiast.
As you can see, speakers and their wiring can become quite a complicated issue with many options but I hope we have explained some of these options available to you. It is always important whichever way you have the wiring configured to use the best possible wiring to suit your system. A general rule of thumb is to spend about 10% of the system cost on the cables and wiring and this will usually give you excellent results.
Written by Leon Gross, originally published in Audio & Video Lifestyle magazine.
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