Today’s post is all about mic technique for guitar cabs. When it comes to recording guitar, I still think that real amps sound better than digital amp sims, although new units like Axe FX are quickly closing that gap. Knowing how to mic a guitar cab is still an essential skill to have as an engineer, especially if you want to break out of the home studio and have the chops to work with a variety of artists and genres. Here are some tips for improving your mic technique on guitars.
I’ve experimented with many mics and combinations, but at least 80% of the guitar recording I do is still with a single Sm57 on the cab. When you add more mics, you add phase problems, and if you’re not careful the guitar sound will become a smeary mess. To get things going with a 57, grab a flashlight and shine it through the grill so that you can see the speakers. Start by placing the mic on-axis, pointed at the spot where the cone meets the dust cap, between 0-1″ away. Now go listen. If the sound is too ‘fizzy’, move the mic sideways, further away from the center. If the sound is too dark or boxy, move it more towards the center. Check for low end response and move the mic back from the cab if you notice too much low-end ‘boom’ on low notes and palm muting. After a few adjustments, you should have a pretty good guitar sound.
There are cases when a single 57 just isn’t capturing what you need. This is when you should try adding another mic. One popular combination is the SM57 paired with a ribbon mic to help fill out the low-end and midrange. As I mentioned earlier, you need to watch out for phase issues when using multiple mics, and luckily it’s not too difficult to accomplish. Place your 2nd mic beside your 57 or on a different speaker (I personally prefer to mic the same speaker), and create a new track in your DAW. Record your guitar player hitting a quick “chckk” sound (think X’s on a tab sheet), and zoom in on the waveforms as far as you can. You’ll be able see when the sound hits each mic. If one track is earlier or later than the other, compensate by moving the mic closer or further from the cab. It may take a few tries, but eventually you’ll have the sound hitting each mic at the same time, and voila, you’re in phase. You can repeat this process for additional mics, but in my experience, it’s not necessary. If the tone’s not right, fix the problem by trying a different guitar, amp, cab, or mic before adding another one.
A Different Approach to Multiple Mics
There’s another way to get the most out of having multiple mics on a cab. Set up 2 or 3 mics and have them all ready-to-go in your DAW. Rather than recording all the mics for each track, audition each mic on a part-by-part basis and choose the one that suits the section best. For example, a you may choose the darker tone of the ribbon mic for a thick rhythm track, and then switch to the 57 for the lead. Now you’ve got a variety of clear and distinct tones that will help you shape the overall guitar sound of your track, and switching between them only takes a mouse click.
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