Remember when you were young?

I found a couple of old tapes I made back in 1989 and 1990 on a tascam 4-track cassette machine. I also had an 8-bit Ibanez reverb rack and a little Mesa Boogie practice amp. As an exercise in futility, I figured I'd try loading them into Sonar and play around with them. Since they are 4-track tapes and I could only find a stereo cassette player, I had to transfer tracks 1 and 2 forwards, then flip the tape and transfer tracks 3 and 4 backwards. Then in Sonar, I reversed 3 and 4 (back to forwards) and synchronized the lot of them using a magnifying glass and some silk thread. Then I tempo mapped and tossed in some drums and bass. 
 
At this point, the guitars are all set in stone. I can't back them off any. But how can I get better clarity between the kick and the bass? Any other suggestions are welcome. 
 
https://soundcloud.com/wardcheese/what-it-was

I've done similar experiments, although in my case I had the luxury of 4-track open-reel tapes and was able to track down my old 3340S and borrow it back temporarily. Results were mixed. In most cases, I just stole my original melodies and chord progressions and re-recorded the whole thing.
 
Surgical EQ, like Wookie says, is the first stop. One trick is to clone a track that has multiple instruments on it and separate them using equalization. It doesn't have to be just HP on one and LP on the other. Complementary EQ with multiple bands can isolate instruments that might at first seem inextricably intertwined. I have managed to separate individual drums from a full drum track, generate MIDI from them and then reconstitute the whole thing using samples.
 
I prefer a dynamic EQ for these things, as it can be much more transparent. Set gain reduction on the fundamental for the snare, for example, and you can greatly reduce it without affecting other things on the track. The ringing and the decay from the snares will be partly masked, so you may only need to attenuate the first couple of milliseconds.
 
If the track is drums + bass, a fast-acting compressor with a filtered sidechain can be used to hide the kick. Fast attack, fast release, and dial in the sidechain filter to the kick's fundamental. This will attenuate the initial kick hit but only sacrifice a small portion of the bass' attack, which probably won't be noticed after you've replaced the original kick with samples.
 
Try a gate, multi-band gate or multi-band compressor on the over-reverbed guitar. I once pulled this off with surprising ease and efficacy using a plugin from Wave Arts called Multidynamics5. If I were doing it today, I'd probably go for Meldaproductions' MMultibandDynamics plugin. It's a do-all multi-band gate/comp/expander. Wait for it to go on sale, though, as it's kinda spendy at $185. 
 
Noise reduction is best handled by an audio editor, not EQ. I use Adobe Audition 3 for this, which works quite well as long as you have some lead-in to provide a snippit of pure noise as a reference.
 
Have fun!
 
 

If you have X2, you have R-Mix, and you can try Noel Barthwick's methods for resurrecting old tracks.
 
I have tried stuff like this, and I'm with bitflipper: In the end I re-recorded.

I get the consensus, that to re-record would be ideal, but it doesn't really work in my situation. In the 30+ years since I recorded these my body has fallen apart and I really can't do much of anything on the guitar anymore. My hands just don't work. That's why these old recordings have meaning for me. I don't have any illusions that I'll be able to make them sound like much more than they are, but I'd like to get them to a point where I can listen to them. 
 
A lot of my reasons for getting Sonar was thinking I could try building music in little bricks instead of playing through entire tracks at once. These old tapes are sort of a side-job, a fringe project. I reckon this one is as good as it will get now. 
 
Thanks again, all. 

Ward,
I have found BBE sonic maximizer to be very helpful in clarifying old recordings. I have always been impressed by how much you can boost the bass with BBE.
 
Here is an example of an unbelievably muddy recording (drenched in reverb as it was) that was cleaned up using BBE. Unfortunately, I can't find the before version. http://www.soundclick.com/player/single_player.cfm?songid=5265795&q=hi&newref=1  BTW, this is an honest to God CAKEWALK 1.0 project.
 
Cheers,
Bert