This is a common problem, to which I think there are two most-used solutions. You don't mention any mic other than the Shure SM58. Are you not also recording the acoustic guitar part? If you are trying to record ONLY the voice while playing the guitar, then option 2) is your best bet, though you will not be able to eliminate the guitar completely. If you are using two or more mics and recording the guitar as well as voice, then there are two options as I see it.

1) One way is to keep the mics pointed as much toward their sources as possible and embrace the fact that you are going to get bleed into the other tracks. That can make mixing a little tricky if you need to do a lot of processing to a track, but can be done successfully to get a nice natural balance. Keep the SM58 as close to your mouth as possible without getting popping sounds. You could use a pencil condenser (with a cardioid mic pattern) pointed at the 12th fret on the guitar as one part of a stereo pair on guitar, or point it a little more twoard the sound hole if it's the only mic. Make sure to place it ABOVE the guitar and pointing somewhat down at the 12th fret. That will minimize the bleed from the voice.

2) The other way is to use 2 mics that have a figure-of-eight pattern. You place the mics so that the null point of each mic is pointed toward the other source. The null point on a figure-of-eight mic is the sides where very little sound is picked up. So you point the null point of the vocal mic at the guitar and the null point of the guitar mic at the voice. It's surprising how little of the guitar you can end up with in the vocal track (and vice versa) when you use this method. There's no way to absolutely block the sound of the guitar in the vocal track, however.

Hope this helps. Have fun!

Rob

You are absolutely using the best microphone to use for your situation. Nothing else is going to give you better results than a 58. What you are picking up is all part of the deal. Improper level setting can create problems in its own right. This is what you may be currently experiencing. Acoustic music is acoustic music and it's that acoustic interaction & that magic that you get while doing both simultaneously that is so important to preserve. This is not a detriment. It just requires some treatment.

Many of us frequently utilized 2 microphones on the guitar while simultaneously having another microphone on the singer/player. And quite frequently 2 57's are used on the guitar while utilizing a 58 on the vocal. Sometimes the guitar is taken via a direct. When it's taken via a direct, then the guitar picked up by your vocal microphone can be even more important in creating a musical blend. So, it's all good. Acoustic music is not computer music and can't really be treated as such. You're not the Beatles, yet. But getting a good recording with a couple of 57 and/or 58's is a prerequisite for being a good engineer. You'll hear plenty of that here. Dazzling results will only be achieved through your talents and not your equipment. Yorty got the right stuff perhaps, in both ways.

Keep asking the right questions and you'll keep getting the right answers
Mx. Remy Ann David

M first question is, why is isolation so important to you? If you are just using tools like compression and eq, then isolation isn't that big a deal. If the tracks have the energy that you want don't obsess over a little bleed. However, if you want to use pitch correction on the vocal, then isolation helps a lot. But you have to give up a lot for it - it means new mics and a lot of twitchy mic placement issues. You have to be very careful of your position as a guitarist/vocalist. And of course you never get perfect isolation. Hence a lot of people just go for Remy's "let it bleed" approach. It's really the best from a pure sound point of view.

However, if you decide to go the figure 8 - placement approach, [[url=http://[/URL]="http://www.youtube…"]here[/]="http://www.youtube…"]here[/] is a YouTube to give you the idea. There are several other similar YouTubes that you can check out as well.

Just a thought here. I know this makes things a little convoluted but, you can do a scratch track singing and playing at the same time, then track just the guitar and finally the vocals on separate tracks. You'll get the separation you want but you'll be able to keep the feel that you want as well.

All good advice, and I've done all in just the past few months, if not days.

I typically record acoustic w/ 2 pencil condensers (no 57s here, Remy - though the 57s might work better in the OP's dilemma) & vocal w/ whatever mic is right (often a 58 or 421).
Sometimes, it's all together, sometimes separate.
Depends on the song and the sound of the artist/group.
Nothing wrong w/ ambience or bleed or organics - unless it's just plain wrong for the song.
Personally, I favor performance over isolation, so keep w/ what allows you to give the best performance.

I often cite Wilco's Sky Blue Sky as an example for Remy's cries for technique & simplicity.
Recorded almost exclusively w/ 57s and all live in the same room.
Some gobos were used and the drum OHs and lead vox got different mics. But almost all 57s.
(I believe I read this in TapeOp? - checking on reference)
It's also my example for myself when I record/mix. The clarity, energy, and sonics of that album amaze me everytime I listen to it.
*Especially* on my studio monitors.

hueseph's suggestion is very nice if you feel you MUST have separation.
A little tricky w/ someone not experienced w/ recording, overdubs & headphones - but a good workaround.

I've recorded in this manner many times before and never really had a problem with bleed. It is there, don't get me wrong, but it's not a problem. I delete the guitar tracks which were recorded at the same time as the voice and re-track stereo acoustic guitars and hard pan them. Once that is done, the bleed on the vocal track is limited in its audibility. From there all you do is automate the track volume so that in-between the vocal phrases the track volume goes to -∞, and you'll be hard pressed to notice any bleed at all since it only comes in with the vocals which are much much louder than...