How to make kicks like these

[pololas]

Hello! im trying to make a kick with this attack, hold & release, but i always get a cripy and very "broken" kick, also using 3 kicks, one of them as the attack (cutting the hold and release), other as the hold (cutting attack and release) and last one as the release (cutting the attack and hold), two examples:





In the first one, I sampled that kick to try learning how to make it and I saw that is filtered about 5Khz: here it's:
http://rapidshare.com/files/311287955/kick.mp3.html

these kicks sound really good, punchy without that ugly color of kicks from sample packs. It's synthesized? it's some kicks from sample pack?

Help me!

Thanks:)