General Advice

We recommend that you choose an amplifier that can deliver the loudspeaker's program power rating. For example, the Koala 12m requires an amplifier that can deliver 600 watts per channel into 8 ohms. Loudspeakers are most often damaged when amplifiers are driven into clipping. More powerful amplifiers are less likely to be driven into clipping because they have more headroom.

Switch mode or transformers?

These days you have the choice of amplifiers with a conventional transformer power supply or a switch mode power supply. The best thing about switch mode amplifiers is how little they weigh. On the down side they do need more regular cleaning to prevent overheating and are more expensive. Some of the cheaper switch mode amplifiers also have a problem with sustained power delivery. This results in them sounding gutless when the bass kicks in.

Our advice would be; if you are touring and can afford it get an amplifier with a switch mode power supply, if you are going to install the amplifier, save yourself the money and get one with a conventional transformer power supply.

RMS, Peak and Program Power

There are different power ratings for a loudspeaker. These are continuous, program and peak. The power handling is what a loudspeaker can take before it overheats and becomes damaged.

Continuous power is the maximum power a loudspeaker can take when it gets the worst possible signal. Here you get maximum heating of the voice coil. Something like white noise played at full volume for an extended time is likely to distroy tweeters and a low frequency sine wave will destroy bass drivers. It is unusual for a loudspeaker to ever receive a signal this demanding.

Program power is a lot more useful to us. This is the maximum power a loudspeaker can take when receiving a signal that approximates a real world program signal such as music.

Peak power is the maximum power the loudspeaker can take over a very short time (under 1/10 of a second).

Continuous power is also often referred to as RMS power or AES power. Although RMS, AES and Continuous power are similar there are different specifications of how they are measured.

Amplifier Gain

Gain is the difference in input signal level and output signal level. It is measured in Decibels (dB). If you know the amplifier gain and the level of the input signal and enjoy maths you can calculate the output power of the amplifier.

Gain becomes useful when setting up Limiters to protect your loudspeakers. If you limit the signal level going into the amplifier you also limit the output power going from the amplifier. We have calculated the correct Limiter settings for use with Traction Sound loudspeakers.

Different Loads

If you attach two loudspeakers to the same side of an amplifier you effectively half the ohms seen by the amplifier. Most amplifiers will put out nearly twice as much power if you do this. This means that a amplifier that can deliver 600 watts per channel into 8 ohms will therefor deliver around 1000 watts per channel into 4 ohms. Different amps do perform differently so do check the amps specification.

Minimum load

It is important not to connect too many loudspeakers to one side of an amplifier. This will cause the ohms being driven to fall below what the amplifier can handle which will damage the amplifier. Most modern touring amplifiers can take a minimum load of 2 ohms while many older amplifiers and install amplifiers only go down to 4 ohms.