I hope you just mean you won't accept criticism on them because they are now old. And if you mean that overall, then you won't improve if you don't accept it. And even if they are old, you should still be open to criticism because some habits you still have may still be repeated until somebody shines the light on you.
You still have a long way to go. You may not want to just be overpowering things to try to get a "phat" sound, as half the time people butcher tracks due to this. It's too all over the spectrum and it's not very pleasant to listen to. You need serious EQ work in order for a heavy track to work. And in your case, I wouldn't even have made this a heavy track.
Not a bad attempt, but you still have pretty much that random feeling. Change instruments every now and then, never keep the same ones all throughout, and even if you can't do it (like if a band was playing), then something has to clearly change within enough time of the song, or else it gets boring pretty fast. This both applies to sound of instruments used, as well as the actual melody, if there even is one (I can't really notice one because stuff is reused way too much). If you don't, then your melodies become harmonic, and then the song becomes way in the background with nothing up front. This is only OK if you are doing an instrumental that requires vocals, and even there, you usually have solos to keep the song from being boring.
I'll tell you right now, Studying theory will only do one thing: Teach you terms used to describe actions in music. That's all it does. It's not as useful as people claim it to be. I've seen and know people who went to Music Theory and came out with nothing way too often. It's a good thing to know, but it is far from important to making music, so if you do study it, don't rely on it and don't think it will improve your music, because it won't. Yes, I've studied it, but I don't rely on it, I only studied it for the curiosity.
The best way to learn is to listen to what people say when they give hard critique. As well as listen to other songs of all genres. The more you appreciate other people's music, the more you will learn what is the good sound that will please the most people overall.
SO please, take my advice, and don't be afraid to get shot in the face, because this is how it is supposed to be in the artistic world. Those that don't die, move forward.
