Strangled Power Kills Car Amplifiers!

Strangled Power Kills Car Amplifiers! – How? – Read on.

Power station

In a previous blog (, we looked at the importance of power rating. We don’t have enough room here for a ground-up review but suffice to say, we were specifically focussing on matching like for like power ratings. We have also blogged about distortion and the damage it can cause to all components in an audio system and why ( This time, we want to connect power to distortion and how these are affected by the purity of the 12 Volt supply to a system.

Unlike power output, supply power is not really a criteria a customer would concern themselves with as specialist installers are the best place to buy an audio system and they know what they are doing. However, we do like to furnish those with a stomach for science with interesting scientific facts which may help to navigate the mire of misinformation which commonly oozes out of marketing departments.


When reading amplifier specifications, a supply voltage figure must be quoted or everything else is meaningless. It would be natural to assume that the input voltage would always be quoted as 12 Volts, that being the rating of your car battery. However, the charging components of a car are more likely to output something like 14.5 Volts as you want it to actually charge the battery whilst you drive along. This fact should be ringing small bells now as in short, supply power can determine possible output power! So, no problem, we reduce the voltage when for instance we are listening with the engine turned off but all is well as it won’t need to be as loud anyway due to the lack of road and engine noise will it? – Mostly true yes. The problem arises when supply power is reduced at high levels through other limiting factors. These limiting factors can be poor quality cable, dodgy connections or anything else which may introduce resistance to electron flow through the power cable to your amplifier. But all this means is that the maximum level output will be reduced doesn’t it? – That would be most sensible and some high-end amplifiers are actually intelligent enough to monitor the condition of their own power supply and reduce gain accordingly. However, this ability is presently quite expensive and difficult to achieve. An amplifier’s purpose is to take what appears at its input and make it bigger. It operates at the limits of its capability, which is much reduced when not supplied with the right amount of volts. Not only is the ability to reach the required output level compromised but in trying its hardest to achieve it, massive amounts of distortion or “hard clipping” are introduced and a huge amount of current (Amperes) are drawn in an effort to maintain the required power (Power = Current X Volts therefore if Volts are reduced, Current must increase proportionally for the same power to be realised – sorry but that had to be said!). At the highest levels, you may not hear the distortion before something burns! This is usually some component within the speaker you are driving and as a result, the product is mistakenly replaced and the same thing happens all over again.

Burnt speaker

If you were to read our previous blogs regarding power matching of amplifiers to speakers, you could be lulled into thinking that simply ensuring that your speakers exceed the power rating of your amplifier will keep you safe but, this is not true and FOUR MASTERS frequently see subwoofers, which are rated far higher than the amplifier driving them, fried to a crisp as a result of poor power wiring which has reduced the operating voltage of the amplifying devices in an amplifier that has in turn, introduced lots of highly destructive distortion!

A specialist installer will have an in-depth knowledge of this topic and will ensure that all wiring is carried out with the utmost care to ensure that you are able to enjoy the full potential of your chosen amplifier and the speakers connected to it.

Our advice? – Visit a FOUR MASTER and get a better job done!

Visit FOUR MASTERS: 0800 652 5125

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Content Provided By: Driving Sounds Magazine –