Speaker ports on a LG home theatre HT806TH

What to consider when connecting Speakers to Amplifiers


Connecting speakers to Amplifies is assumed to be a very easy task, but it’s actually one of the hardest things to do. In this post I will highlight the most overlooked features and therefore mistakes that people do when connecting speakers to Amplifiers, Hi-Fis, Home Theatres and Radios. Some of the features are straightforward ignored and some mistakes maybe you did not know you were making. The first important feature is:-

Polarity Matters a lot

Connecting speakers to amplifiers in the opposite polarity can damage the speakers. Normally when speakers are connected the correct way, a low frequency signal (bass) makes the speaker cone move forwards. Connecting the speaker wrongly has the opposite effect, the cone will move backwards. If this happens when playing heavy bass music, the part that holds the voice coil, hits the bottom of the speaker with such great force that the speaker gets damaged. In the featured image you can see the polarities clearly marked + and -. Connect + terminal of speaker to the + port and likewise for the – terminal and port.

On the same point if you have multiple speakers to a music system and one of the speakers is connected on with opposite polarity, bass cancellation will happen. You see a speaker produces waves and waves have toughs and crests. When a crest and a trough meet at a point, the result will be no sound at that particular point. Stereo speaker systems complement each other by increasing the overall volume and listening experience, but if one speaker is connected in the opposite side, the experience is not that good.


Impedance matching is very important

Always match the Impedance of the speaker to the Output Amplifier Impedance

Every electronic load has a resistance and so do speakers. Speakers usually have an impedance value printed at the bottom on the Magnet. Impedance can be loosely translated to Resistance only this time we are using AC voltages for calculations. All electronic products have the impedance printed at the back, where you connect the speakers. If it’s labeled 4Ω then connect a 4Ω speaker. If its labeled 8Ohms and you connect a 4Ohms speaker then you risk damaging your amplifier. The character Ω stands for Ohms, the SI unit for resistance

Impedance matching without Power Matching is useless

Connect speakers that can handle what your amp is producing. You cannot connect a 4Ω   2 Watts Speaker to an amplifier that has an output impedance of 4Ω but produces 100 Watts. This will damage the speaker instantly if you play anything at the average Volume level.

Use the Right speaker for the right port

In the featured image you can see the output ports of an LG HT806TH Home theatre. The major reason Home theatres get damaged is because innocent Kenyans connect the wrong type of speaker to the ports. Connect the subwoofer to the subwoofer port only and the other speakers to their respective ports. All speakers are labeled. I usually encounter some clients connecting more speakers to a speaker port and this brings me to my last point.

Connect one speaker to one port only

Most domestic sound systems should be connected to only one speaker per port. If you usually connect more than one speaker per port then put away some money to buy another music system in the near future. However professional audio equipment can allow more than one speaker for each port but calculations beyond the scope of this post are usually done by professionals.

  • eliffio

    Hello. If the amplifier outputs 25W and the speaker can take up to 150W, would that be any problem? According to your post the inverse will damage the speaker. Thanks in advance!