Like the above poster said, don't use samples. If you only learn how to do one thing as a producer, learn how to make sub bass patches. Its the loudest part of any song (from a decibel standpoint), so make it count.
Take a sine wave from whatever stock synth comes with your DAW. I use ableton so operator is my go to.
Zero volume decay, short release, usually 50 to 100 ms. 1 voice.
Pitch envelope of 12 semitones, with a decay time that matches your kick drum, more on that later.
Now, run it through any amp simulator and distort it, making sure your low end doesn't get crushed out but distort it enough so a simple sine wave starts producing all kinds of harmonics throughout the spectrum. This will fatten your low end and give you some character. I like to use ableton's glue compressor after that to squeeze it a little. After this whole chain, I put a hard filter on everything over 100-150hz. Now you have a fat bottom end.
Next, I'll group that chain to an instrument rack and add another instance of operator with a square or saw wave instead of a sine. I like to duplicate the original instrument and change the waveform so all my envelopes are consistent. I'll run that through a low pass filter and distort it heavily AFTER the filter to add new harmonics in the frequency spectrum that are different and have more character than sin waves. Once these frequencies are added I'll high pass them so the low end doesn't interfere with the sub (usually I'll eliminate a huge portion of the lows and low mids so I don't get any mud). I'll then throw another compressor on the end of the instrument rack so it compresses BOTH CHAINS to glue them together.
Now, as far as the kick sample goes. Find a kick that you like (sage advice
) and cut out everything below 100 to 150hz. I recommend kicks with fast attack since, in my opinion, an 808 is used similar to a marching band kick drum which is basically a slap with tons of low end.
Now adjust your pitch envelop to give it the same attack as your kick sample. You'll be able to hear when it's right as the two instruments will clash when the timing is off because they'll be momentarily out of tune.
After that you're pretty much done. I don't like side-chaining my sub bass to allow for the kick to hit because you get a pumping sound that creates a disconnect between the two sounds when it's supposed to be one instrument, which is why I filter the low end out of my kick drum.
Now it's all about drawing pitch envelopes to get the bend you want.
Another thing you can do is use a multi step pitch bend like the one in operator and make your whole sub slide to -1 semitone at a really slow rate (AFTER your initial pitch dive to simulate a drum). This will give your sub some character but if it goes too fast all your hits will be out of tune, so be careful with it.
Hope this helps.
