First of all, thanks for pointing out the obvious.
Written word... I'm not sure if this statement is accompanied by rolling eyes or not
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I don't know exactly how that "peculiar 4-track/distant mic" do sound.
Yes you do, it sounds like this.
If I place a microphone a few feet (for example) from a sound source, it will not capture a lot in the way of transient information and it may (depending on the reflectivity of the room) capture secondary signal. It will also capture more of the sound of the room due to the influence of the room on the source and because of the increase in preamp gain compared to what is needed for a mic that is closer to the source at the same level. The result will be a sound that comes across as distant, indistinct, roomy and soft edged. This is neither intrinsically bad nor good. It depends on what you want to capture.
Prominent room noise or a sense of distance can be due to the stuff mentioned above, but can also be attributed to over compression as well as EQ and reverb settings at mix time.
But if you're referring to that early 90's "lo-fi" sound, I'd love to emulate that, though I don't know exactly what attributed to that. Cheap mic maybe, the amp hiss maybe. You also mentioned room noise. I don't know but here's my set-up. I'm open for any suggestion to improve it (or keep it for that "noise" effect).
I don't know if you have achieved a particular lo-fi 90's effect that you would like to represent. Since it is something you would love to emulate, you must know what it sounds like. Does your recording sound like that to you? You need to be the judge of whether or not your recorded audio is captured how you want it to be captured and presented how you want it to be presented. If you are getting what you want, don't let anyone steer you away from it. My opinions are based on my sensibilities, my preferences and what I am hearing in my room. Your sensibilities are more important because it is your art, not anybody else's.
Tips for improving... depends on what you think of the sound of these recordings and where you want to go. A day or two of just pure experimenting can go a long way. Get your amp sounding good to you in the room, stick the microphone against the grill, right in the centre of the cap. Record something and then listen back to it. Take note of characteristics that you are hearing and what you like or don't like about it. Move the microphone back an inch and record something else. Move it back another inch, and so on. Now put the microphone back on the grill, but put it off to the edge of the cap and do the same sort of experimenting. Do the same thing in the middle of the cone and then again on the cone edge. Then, move the microphone to the middle of the room. Then move it to the other side of the room. You can also repeat all of the above, pointing your microphone at an angle to your speaker rather than straight on (assuming all the above was done straight on).
After spending a few hours doing this, you should be forming some opinions of your microphone and your amp and what sounds good to you. Keep all these things in mind or keep some notes to give you a starting point when you want to work on a song.
You can do the same stuff while experimenting with your vocals.
I like your tunes by the way!