Submitted by thewhippinpost on Tue, 02/01/2007 - 13:11.

There are some frequencies in the mix that are basically redundant and do nothing more than steal speaker-power - If we can reclaim this resource-hog, the speaker can concentrate all of its energies onto the important frequencies, and thereby give us more headroom, ie... more volume!

Here's the basic premise: Most loudspeakers can't reproduce certain frequencies. Nevertheless, if the frequencies are present, the speaker is still obligated to try, resulting in wasted bandwidth and (ultimately), a lower overall mix-volume.

Kill Bass Rumble

Apply a high-pass shelf filter to remove frequencies below 40 Hz - Oppinions seem to vary on numbers of between 30 - 50 Hz; 30 Hz is rather low but PA systems can generally still kick out "meaningful" energy at this level, so if you're specifically mixing for a club environment, then you might consider it.

Mid and High-Frequency Range

This is really just added as an addendum for your considered judgement...

Some instruments may emit frequencies which are not essential to the mix. For instance, you might have an instrument(s) occupying the mid-range which has a low-end that is not heard in the mix, but nevertheless - as above - is still using-up energy which cuts into your "bass-space". Similarly with the higher-frequency elements of your track too.

Try to be objective. Stand-back from your music and take a break for a few days, then re-listen to it with fresh ears. I know, as a musician, we get to love hearing an instrument's full dynamic sound-palette when we're at the composing stage - We get used to hearing it played alone. Naturally, we want to reproduce that sound but in the context of the mix, some of those frequencies will necessarily be "blurred" by other instruments and not needed. It can be tough "letting-go" but the process is much easier if you put some distance between the composing, and final mixing stage.

In these instances, consider applying a shelving filter to remove frequencies that just don't contribute anything to the mix.