If you are building or upgrading your own speaker cabinet, then there are lots of useful parts in this section to help get good results. Once you have selected a design there are a number of good quality bass drivers and tweeters, together with a range of crossovers. You will always need to use a crossover if you are fitting a compression driver or tweeter with a voice coil. You will also need to select the crossover point carefully to ensure that the drivers are working within their safe operating range. If you are just making a bass cabinet, then a low pass filter can be fitted instead of a crossover, this will exclude the high frequencies and improve cabinet performance.