What is SPL?

We Like Loud!

The EMMA Sound Pressure League is made for those kinds of competitors who are (also) interested in the maximum level of volume in their cars – not forgetting about a safe installation and a neat looking appearance.

To guarantee similar conditions and fairness to all competitors, the amount of subwoofers will be regulated in the following terms in most categories

  • All speakers with a diameter equal to or larger than 8” (20 cm) / 6”x9” are calculated as woofers.
  • It is defined, that one 25cm=10” woofer will be counted as one woofer. Since not all people have 10” woofers installed, the following calculation key will be used for transferring the different woofer sizes into the above classes.
  • In the case that a subwoofer of a size not listed below or a different shape is installed, the circumference will be measured (as per drawing) and the woofer will be classified according to the table.


Number of woofers Size of woofer Classification Circumference(No longer than)
1x 25cm =10” Equals 1 woofer 78,5cm
1x 30cm = 12” Equals 2 woofer 94,2cm
3x 20cm = 8” / 6”x9” Equals 2 woofer 62,8cm (per 8”)
1x 38cm =15” Equals 3 woofers 119,3cm
1x 46cm =18” Equals 4 woofers 144,4cm