Yeah, I started using 2 mic's on the guitar cabinet also. I like the close up mic (3 or 4 inches away) from the speaker. Not to close (mashed in there) I don't like :x
But you get the point...
Then I use a different mic (like say an Audix OM series or whatever) just a different mic, even condensor.
Put the other mic about 5 feet away from the cabinet.
I run one of the mic's through an API and the other to the Great River. If you have a Seb, well that's just as good.
IMO-the mic further away gets the great big room sound, which for some reason is always "really BIG" sounding after tracking. I like

I use both methods depending on the sound I'm looking for.
If you have a good sounding room, than a LDC (in addition to a dyn up close) out a few feet or more from the cab gives you a much more "broadband" sound. But, for some mixes where there are multiple gtrs, this can quickly become "too much information".

Here's an alternative to try.

Instead of a LDC in the room, try a ribbon mic. And in exchange for the "ever-present" sm57, try either a Beyer M88 or a Sennheiser 421. The 421 is one of the most over-looked gtr mics ever. Sad

My .02

Chris

There is the ever-present SM57 on a stand in my room. I might never hook it up but its ALWAYS ready...

Lately, my go to mic on guitars has been an LDC. ADK A51 model V. Its been modded a bit and you have to keep a tight rein on the amp levels,(no pad on the mic.....er yet...), but these things are really guitar oriented in their natural frequency response...and they'll take a load of spl's....For around a bill on ebay, this is a very underrated mic and has been an extremely good find for the gits.

I still use the Unidyne III a lot...on closed back cabs its the shizits...Because of the sensitivity and tone of the LDC I can use it as a room mic too in this context....It still sounds really good up close and personal, and those tracks are huge and intimate both...

Try one if you can....I aint lyin.............

I'll second Guy's favorite config. It's a great technique for capturing the "force" of the push of air from the cone and then the room mic picks up the "air" movement in the room which can be really valuable in mixdown.

Like Dave said, an LDC for the room mic is a solid choice.

Sometimes if you angle the close mic about 30 degree's (horizontally) on the cone you can keep more of the bass freq's coming off the cone as well as some of the higher mid freq harmonics. Depends on the mic though.

Hey Chris, how far back do you put the 421 away from the speaker?
I gotta get one for guitar after what you said in the last post.

Check Blevins Audio online Guy. Sometimes you can score used 421's and 441's at killer prices.