If you started with Recording Electric Guitar: Part I, you may be anxiously awaiting this section. But let me remind you what I already stated in Part I:
"there is no easy or simple recipe for recording guitar...."
Sure you can take the minimalist approach and shove an SM57 into the cone, but your sound may not record like it sounds in an open room, to your ears. Miking a cab IS NOT like your ear which can perceive a hell of a lot of information. And sonically speaking, the single SM57 technique is very limiting.
So let’s explore some of the most common mics you can employ in tracking guitars so you can start to craft your recorded sound.
MICROPHONES
There are generally three types of mics employed in recording guitars: Dynamic, Ribbon, and Condenser. And each of them has their specific purpose.
Dynamic Mics - Generally speaking, Dynamics are used to record loud sources. They also have a limited frequency range. That said, you can record loud sources with a Ribbon or Condenser mic as well, but they have limits on the amount of dBs they can handle. Blowing an expensive vintage condenser capsule on a guitar screeching out 125dB of sound is a costly mistake.
The SM57 is a dynamic mic. It has been used in live and studio applications to record everything under the sun. And at around $100, it is a must-own for any guitarist if you don’t already own a similar mic like a Sennheiser e609 or it’s more expensive brother the e906. You don’t need an e906, the e609 has the same capsule.
Even more expensive dynamics are the ElectoVoice RE20 and Shure SM7b. Of course each of these mics are slightly different, so you may prefer one over the other.
Another type of dynamic mic you should employ are those commonly used to mic drums. Many engineers like to use the Sennheiser 421 (less expensive Shure Beta 56 or Lewitt DPT 340 TT) commonly used on tom toms or the AKG D12 or D112 kick mics (less expensive CAD D12) because they provide a more rich low-mid and bass response.
I recommend you employ both an SM57 or an e609, and a wider range 421 or D12 style mic to handle the dynamic mic part of the equation.
Ribbon Mics - There are a few Ribbon mics commonly employed in recording guitar. This is because Ribbon mics are generally good at producing the warm characteristics of the drum mics we listed above, but also a very realistic and natural capture of the sound source. And they are extremely fragile which is mainly why they are not very popular.
Here is a great review on Ribbon microphones for guitarists: https://youtu.be/CDyH-J9LHOk
Ribbon mics are also 5-10x more expensive that Dynamics. But if you have the wallet for one, here are a few recommendations: Royer R121 and the Beyer Dynamic M160.
A more palatable version of a guitar ribbon mic that is making a name for itself is the SE Electonics Voodoo VR1 ($400) or the slightly larger VR2 ($500).
Condenser Mics - When it comes to mics that produce a full range of sound, compared to Dynamics that are somewhat limited, nothing beats a Condenser. Thankfully, we also don’t have to purchase super-expensive condensers to record Guitar but if you have the money, the sky is the limit.
There are basically two types of Condenser mics used to record guitar: Large Diaphragm, typically those you see used to capture singers, and Small Diaphragm, which look like a shotgun shell or pencil.
The larger the diaphragm, the wider the frequency spectrum it can capture. That said, the smaller diaphragm Condensers have the ability to produce more detail, and are generally good with acoustic instruments, but not as commonly used in the Electric Guitar world as the ones we are considering.
Here are some large condensers I prefer:
Large Condenser - The AKG C214 ($400), which has the same capsule as the much more expensive C414, is a large diaphragm Condenser. It is an industry standard for studio recording and is used on a number of instruments, including vocals and guitar. The Lewitt LCT 440 Pure ($300) is also a comparable, less expensive option.
Honorable Mention - Before we close this section we need to include a microphone platform that is truly a life-saver for the Home Studio Guitarist. The Slate Digital ML-2 is a very affordable ($150) small diaphragm “condenser” that is extremely flexible.
It comes with software that allows you to emulate a family of classic instrument mics including Dynamics, Ribbons, and Condensers. I use these mics myself and can say they are an excellent choice because they allow you to basically switch microphones, post recording, to determine the best mic for the sound capture.
The ML-2 provides emulations of the most popular instrument microphones, 18 in all, and is capable of operating in both dynamic and normal condenser modes. And at the price point, it’s hard to pass-up. Plus, try to find one used on eBay, they don’t get sold hardly ever, which to me is a good sign they are highly coveted.
MIC PLACEMENT
Again, with placement of mics on a speaker, the options are somewhat endless. What I am going to recommend below is a fairly safe version of many different miking techniques out there. I employ this method primarily because it captures two of the most musical areas of the speaker which I will explain below.
There are four primary parts of the speaker you can target: Center Dust Cap, Dust Cap Edge, Mid-Cone, Cone Edge. Each of these locations are used as guide points for placing mics. But they are also important reference points when considering tone you want to capture.
From a technical standpoint, the further away you get from the center of a speaker, the less high frequency information will be available. Some of this has to do with how the sound waves are broadcasted from the cone, and I am not a physics student.
But it is also the result of how vibration resonates in the cone itself. Guitar speakers don’t just piston in and out, they vibrate (Speaker Geeks: Tone Is in the Cone - Premier Guitar), and it is this vibration in the main body of the cone that produces the warmer tones we experience when miking this area.
Simply put, waves emanating from the center of a speaker are much brighter than those coming from the body. Additionally, the further your mic is positioned away from the grill, the less detail you are going to capture. Keep this in mind as you develop your miking strategies.
Dust Cap Center - Typically, if you aim a mic directly into the center dome of the cone, which is really just a dust cap for the speaker components behind it, you will capture the most high-end parts of the sound source. If your mic is dead center, right against the grill, chances are it’s going to be dominated by high frequency information which can lead to unmanageable or ugly distortion. For my sound, I generally stay away from Dust Cap Center miking, but it is frequently used by many engineers.
Dust Cap Edge - Where the dust cap meets the paper cone itself, there is a glue joint that is pretty obvious to find. Aiming a mic at this location, close to the grill, will grab the rich, but somewhat tamed, high-end information from the center and some of the rich tone generated by the cone.
For the Dust Cap Edge I recommend a dynamic SM57 or e609. I employ my Large Condenser C214 there as well. The Dynamic and Condenser will each capture a different picture from the same spot. And together they are very musical.
That said, if you only have one of these mics, you may lack some richness from the speaker, but it’s not the end of the world. The Condenser is going to pickup a lot of the dynamic of the sound, which is ironically where the Dynamic mic tends to fall short because of its limited range. But if I only had two mics to record, it would be these two.
Mid-Cone - I find the most tonal part of the speaker is located in this section. Granted, you lose some high-end air as you venture away from the center, but what you gain is a very manageable and tonal version of your speaker.
My preference when recording Mid-Cone, however is also aimed-at canceling-out the frequencies I am already capturing with the Dust Cap Edge mics. To do this I angle my small condensers and point them directly at the Mid-Cone at around 55 degrees from the direct center.
Here you can see both mics are positioned on the left edge of the Dust Cap and angled approximately 110 degrees apart.
One of my ML-2 small condensers (left in the picture above) is running the Royer 121 ribbon mic emulation. It points across the Dust Cap to the center of the Mid-Cone on the other side. Because of the angle, the condenser will pickup few frequencies from the center, but since it is crossing nearly half of the speaker to get there, this allows it to pickup a lot more frequencies than the second condenser.
My second ML-2 small condenser (right in the picture above) is emulating the Sennheiser 421. It points directly at the Mid-Cone. It does not cross the center. Again cancelling-out any high frequency information from the center due to the angle.
Cone Edge - Like the dead Center, I usually stay away from the Cone Edge where the paper is glued to the speaker frame. This area of the driver provides very little musical information. It is usually quite dead and very dampened as compared to the Mid-Cone just a few inches away.
OTHER MIC POSITIONS
If you are up for experimentation, you may want to try some of these techniques.
Large Condenser at Distance - Between 1-4 feet from the front of the cabinet you may find you get a very natural capture with a Large Condenser.
Large Condenser Behind Cabinet - If you are running an open back cabinet, place a Large Condenser inside or just outside the back of the cabinet. This will capture frequencies the front mics don’t and may be a nice addition to your mix.
GAIN STAGING
Before you hit the record button, be mindful of the gain being applied to each microphone on your Digital Audio Converter. On my Scarlett this is easy to manage since there is a light surrounding each input gain dial that will flash Green when the gain is at a safe level, Yellow when the gain is nearly clipping above 0dB, and Red when clipping is occurring.
Clipping is not necessarily a bad thing post tracking, but it should be totally avoided during tracking. When a sound source clips the pre-amp and rises over 0dB, distortion - not the good kind - and high frequency clicking will be very audible. And there is no fix for it. The track will be unusable.
To prevent clipping your input, play the hardest or most aggressive section you are expecting to record. Starting at 0, increase the input gain until you see a Yellow ring on your pre-amp, then back-off the gain until it is Green again. This will ensure you stay ~15dB under 0dB.
PHASE CANCELLATION
When employing more than one microphone, you must be mindful of phase cancellation. This occurs when waveforms from the same audio source conflict with each other, and by their nature, cancel parts of each other out. Many times this is caused by microphones that are not spaced equally from the source.
Even if your microphones are spaced identically, phase cancellation still occurs. So it is important to identify the degree of cancellation you are dealing with and determine how you are going to proceed.
First, solo the 1st & 2nd mic tracks and flip the polarity of the 1st mic. In Logic Pro you can do this with a Gain plugin. What you hear is the parts of the two tracks that are being cancelled. When you flip polarity back, you hear the net result of the two tracks together, minus what is being cancelled. Now do this for the 1st & 3rd tracks, the 1st & 4th, the 2nd & 3rd, the 2nd & 4th, the 3rd & 4th.
When you reverse polarity between any of these track pairs and the result appears to be stronger or more musical than the tracks in their natural state, you can either leave them as is, sometimes it can be quite musical, or attempt to fix it on the grid.
Many times phase cancellation can be fixed by simply nudging the region forward or back a few milliseconds in order to line-up the waves. In the picture below, notice the waves of the first track appear to be nearly a mirror opposite of the waves in the second. When the wave in the first track rises above the median, the wave in the second falls below its median.
This misalignment is exactly what causes phase cancellation. To fix this, simply move the second region until it lines-up perfectly with the first. If you need to zoom in or out to verify you have synchronicity between the two waves, by all means do it. The more exact you can be in this process the better.
Now check the track you edited against all the other tracks again. Do you have an acceptable level of cancellation? If not, validate each of your tracks are aligned appropriately. Continue to do this until you have achieved an aggregate tone that is acceptable.
In the next and final section we will discuss the gear you need beyond mics to record guitar and some post production techniques that most Engineers employ after the tracking is complete.
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