Car Audio Speakers On Axis!

All speakers have an optimum listening angle. Most domestic speakers have an on-axis angle of 45° from the centre. This is the range over which the tweeters perform at a similar sound level. When the listener is not sitting in this range, they can experience a drop-off in high frequencies. Some specific car speakers use specific designs to broaden the listening angle and achieve over 55°.

This drop-off can be quite significant, with some tweeters losing some 6dBA (an awful lot!) in the off-axis range. This increases depending on how far off-centre the listener is.

In a car, it is not unusual to be faced with a 90° angle between a speaker’s centre and the listener’s ear, particularly when tweeters are mounted on the dashboard facing upwards or even firing across the dash. The effect is far more dramatic in the high-frequency ranges, as that is where a good deal of detail and directional information lies.

Consequently, dramatic improvements in the stereo image are possible and, in some cases, absolutely necessary for fans of Hi-fi when having a car upgrade carried out in their cars. Issue X of Driving Sounds Magazine carries an article about a Hyundai i20 N (https://www.drivingsounds.co.uk/articles/archive/issue-10/hyundai-hi-fi). This car is owned by Mark Holterman, who is a confirmed home hi-fi fanatic. He has lived and worked and played home Hi-fi for the majority of his adult life.

Having finally been persuaded that Hi-fi can be achieved in a car, Mark had installed an Audison Prima/Hertz Mille Pro package. He liked it, but it is fair to say he didn’t love it, as the imaging was not good enough to satisfy his acutely trained ear.

As his installer was the very able and accommodating FOUR MASTER, Source Sounds in Sheffield, he felt entirely comfortable ringing proprietor, Paul Ellis, to discuss his disappointment. Paul had already expressed his concern that the standard tweeter mounting positions may not enable Mark to achieve the result he desired. Mark had decided not to go to the additional expense of having the tweeters placed on-axis, as he was working to a very specific budget. Fortunately, Paul was easily able to convince Mark that the extra expense was justified and worth every penny!

Placing tweeters on-axis often requires them to be installed in the vehicle’s A-pillar or in the triangular piece of plastic covering the workings of the wing mirrors. This is a complex job and can be very time-consuming. The usual technique is to cut a hole in the existing A-pillar or mirror cover, create a “pod” from resin or another hard compound for the tweeter to sit in, and glue it in.

The process requires a lot of rubbing down or smoothing, and of course, the finished pod needs to be integrated into the vehicle as seamlessly as possible. Integration is generally done by covering the pod in a matching material or something of a similar colour with a nice finish. Alcantara or alternative faux suede material is often used as it provides a very smart finish. However, any blemishes will show through, so the smoothing has to be spot on.

In Mark’s case, the mirror covers were chosen as the perfect space for his tweeters. Mark was keen that he could return his vehicle to stock if he ever sold it. Paul kindly ordered replacement mirror covers for Mark to stash away for such an occasion.

We are happy to report that Mark is absolutely delighted with the result both aesthetically and sonically, and he drove away a happy Hi-fi fan!

On-axis listening in a car can be challenging and will add to your bill, but it is well worth it if Hi-fi quality is your aim. Ask your local FOUR MASTER to quote you: https://www.fourmasterscaraudio.co.uk/four-masters

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