magates, most low-end muddiness problems are between maybe 150 -300Hz (possibly starting a little lower), while the rumble you're talking about is from about 80Hz down. The two issues aren't necessarily connected, in other words.
Sometimes cloudiness problems have to do with the reverb rather than the direct sound. My instinct would be to try filtering the reverb send, especially on bass drums - if that's how you have it set up in your mixes (i.e. you're not using a convolution processor in-line).
Sometimes cloudiness problems have to do with the reverb rather than the direct sound. My instinct would be to try filtering the reverb send, especially on bass drums - if that's how you have it set up in your mixes (i.e. you're not using a convolution processor in-line).