Demonstration of Distortion

An interesting situation occurred at Car and Home Stereo recently that I would like to share. It highlighted a phenomenon that is quite counter intuitive and led to some interesting discussions.

We have a demonstration Land Rover Discovery that has a simple, high quality audio system installed that is tuned to perfectly suit the interior acoustics. We always encourage our customers to sit in and experience it as it shows what can really be done with car audio. The amplifier that powers the system is the magnificent Audison 5.1K which develops a true 1650 Watts.

There is one pair of component Hertz Mille Legend speakers in the front doors and a Hertz Mille subwoofer in the rear.

A customer recently auditioned the system and we spent a good hour playing different types of music with a view to producing something similar in his car. He was completely blown away with the sound, couldn’t believe the clarity and how the sub blended perfectly with the whole system. And then he said ‘I love it, but it’s not very loud is it?’. In fact he reckoned his standard Ford system was louder!

Now I know just how loud our system is and the odd thing is that the cleaner the sound the less we perceive volume. Since we had some time I decided to run a little proof experiment with my customer’s car.

As part of our equipment set we have an industry standard spectrum analyser which is also equipped with an SPL meter. It was a simple task to set this up in the Discovery first and then the Ford to compare. As expected our Discovery hit 126dB easily, the Ford however struggled to hit 110dB. In real world terms this equates to a perceived doubling of power (a true doubling is 3dB but we don’t really hear it that way). The next test was the distortion level. By plugging an oscilloscope into the amplifier output we can measure the clipping levels. Unsurprisingly the Discovery registered less than 5 percent distortion at full volume as this was how it was set up. However the Ford reached 5 percent at a little over half volume and climbed to over 25 percent.

There is no arguing with the figures so what is going on? Simply that the higher  distortion levels were being registered as unpleasantly loud and our brains are trying to get us to turn it down! Distortion is the quickest way to destroy a speaker or indeed your hearing.

At Car an Home Stereo we value our customers and hope to be providing high quality audio systems for many years. A distorted sound system will very quickly do serious harm to our hearing and that is why we only choose the best equipment and like to carefully set these up to give the best possible sound. Brands such as JL Audio, Audison, Hertz and Dynamat may not be the cheapest but certainly are amongst the best. The fact that when installed correctly they can deliver an amazing sound makes them excellent value for money.

As to my customer with the Ford, he now has a fabulous system based around a JL Audio amp and speakers with a Rainbow active sub. He loves to play it loud and I know it will give him years of pleasure without doing any harm.

If you want to experience the Discovery sound system or would like to discuss how we can improve your car please all us on 01625 432707.

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