Why is there four plugs on the back of speakers?

With four plug you will have a jumper from on plug to the other. (e.g. Positive to positive and negative to negative.) This is for single connection (two wires.) If you use two connections (four wires) you take out the jumpers. the bottom pair is normally for the bass and the top for treble. This is to make the speakers clearer, and sound better. As for louder,? I don't know some people think it does some don't. With better clarity of sound, you do get the feeling of it being louder.

It is for Bi-wiring and/or Bi-amping - methods commonly used within the audiophile community - let me explain

First a lesson on basic speaker design.

Speakers usually require a single speaker wire with a positive and a negative conductor to make sound. This wire is usually connected to the appropriate channel of your amp or receiver whether it is left, right, center etc..

The speaker wire terminals connect internally to the speaker's crossover which will separate the bass frequencies to the woofer (bass driver) and the tweeter (the high frequencies). some speakers add a third driver called a mid-range which also has the appropriate frequencies fed to it (think vocals - horns - most of what you hear in music).

For simplicity, I will focus on the traditional 2 way speaker with a woofer or bass driver and a tweeter for the higher frequencies.

A better speaker will sometimes have 2 sets of binding posts allowing you to connect 2 sets of speaker wires (4 conductors) to it from the amp or receiver. When you do this, you should remove the jumpers that connect the binding posts so that you don't damage the amplifier. This is known as Bi-wiring.

The upper set of binding posts will usually connect direct to the internal crossover that will strip the bass and send only the mids and highs to the tweeter. The lower set of terminals will strip out the mid and high frequencies and send only the bass to the woofer or bass driver.

If you remover the jumper and connect you speaker wire direct to the upper, you will hear only the smaller driver work so there will be no bass. conversely, connecting the the lower set of binding posts will make only the woofer work so you will hear only bass with not mids or highs.

The purpose of this is not to make your speaker louder but to make it sound clearer or better.

This is better explained here:

http://www2.audioquest.com/wp-content/uploads/2012/02/UndrstndgBiWr.pdf


Audioquest wires are more expensive than wires most are familiar with but there is an inherent science behind the design. There are other speaker wire manufacturers that make similar claims of improved performance which fundamentally is true but I will not go into which speaker wire is better and why a $50/foot speaker wire is better than a $5/foot speaker wire. Is it really $45 better? You be the judge.

Bi-amping will yield even greater performance gains in clarity and efficiency but you will need to have 4 separate amp channels 2 to drive the highs and 2 to drive the lows. This can get expensive and is usually not worth the expense unless you have speakers that are quite expensive with equipment that is equally as refined. Remember that a chain is only as strong as the weakest link. If you own an inexpensive set of speakers connected to an average system don't bother. If you can't tell the difference between a cassette recording and a CD, don't bother. If you still listen to your music on an 8 track - why are you still reading this?

To put this in perspective spending thousands of dollars to make a Prius faster is just not money well spent.

This is a fascinating topic if you really enjoy listening to quality music and you should put the power of Google to use educating yourself. You may need a second job to support you new habit though.

Good luck.