Filtering bass lines is an old technique that has been used for a long time in hip hop production. It was popularized by Pete Rock in the early 90's, whose bass-heavy sound was highly sought after and copied by many. What do I mean by filtering? Basically, you're looking to isolate and therefore amplify the lower frequencies (bass) of a sample. It's a fairly easy process, you can do it with almost any audio editor, sampler/sequencer. For this tutorial, I used Sony Acid. Step 1: Duplicate the main sample. The main sample on track 1 is played a second time on track 2. Step 2: Isolate low frequencies. On track 2, with a parametric EQ plug-in, turn up the lows; turn down the highs and mids. Step 3: Amplify high frequencies. On track 1, again with EQ, slightly turn up the highs. You have to do the opposite of the previous step to create a contrast between lower and higher frequencies in order to avoid any muddiness caused by the increased bass. Once you're done with step 3, you should have a full, dynamic sound. Final Words: Alternatively, you can use this technique to create a standalone bass line, used in coordination with another sample or other sounds. In that case, only Step 2 is necessary. One word of caution: this technique is pretty much useless if the main sample has no or very little bass, you may have the best EQ plug-in on the market, it won't be able to boost anything if it has no substance to work with.