The electric guitar is a compelling musical instrument with a complex, ear-arresting and immediately recognizable sonic signature that has continuously evolved, on record or in concert, since someone attached an electro-magnetic transducer to a big, hollow archtop acoustic guitar more than 75 years ago, during the Big Band era.
The tonal variations produced by an electric guitar, an amplifier, and a chain of stomp-box or rackmount effects processors are endless, and with the advent of the DAW and its many software-amp, speaker-cabinet and effects-modeling accoutrements, so are the options available for recording it. Since most commercial studio engineering techniques and tricks for recording the electric guitar apply to the project and home studio recording environment, let's turn on the gear, fire up the amp and get going.
Tuning Up
Before recording, make sure that the guitar is in tune, with a fresh set of strings, and that you check the tuning regularly. New strings always produce a brighter sound and better sustain. If the instrument has been properly set up, string and fret buzz should be minimal; while this type of noise is much less obvious when playing through heavily- distorted or overdriven amplifier settings, it can be very distracting when using clean settings or recording directly.
A can or bottle of fretboard lubricant will eliminate most squeaks and other noises related to fingering and sliding along the strings, and offer the player prolonged comfort and navigating ease while performing. Keep some handy in your studio.
Amps Are People, Too
Let's face it: Big, high-powered guitar amplifiers full of sizzling tubes capable of frying an omelet are fun, and the sound of an electric guitar playing through one has been pervasive in popular music since the 1960's. They're sometimes very loud as well, and sustaining the volume levels required whilst attaining those majestic, exotic or extreme guitar tones for any appreciable length of playing time in one's house or apartment without interruption from family, neighbors or the police is generally impossible. Don't fret over it. We'll discuss a variety of solutions for the volume problem later on.
Let's discuss the signal path of a tube amplifier, connected to or built into a speaker cabinet, after it's been turned on and warmed up (1 or 2 minutes minimum), the guitar has been plugged in, and the amp has been switched from Standby mode.
A typical modern guitar tube amp has both a preamp stage and a master power amp output stage. The preamp section will be supplied with a set of smaller tubes (frequently 12AX7 or the lower-gain/lower noise 12AU7), and the power amp section has a set of large tubes (EL34, EL84, 6L6, etc.). The preamp controls input gain and typically provides treble, midrange and bass tone controls.
The tone controls compensate for and complement the somewhat lifeless and mostly midrange-y character of the average guitar pickup. The gain control, often designed with a pull-boost, basically excites and heats the preamp tubes, which along with judicious use of both the amp and the guitar's tone controls will begin to produce much of the sonic seasoning and flavor that guitarists and their fans crave as it flows from the speakers.
Many guitar amplifier preamps are also equipped with a Presence control, which often works in tandem with the treble control, boosting frequencies beyond the treble control range, and reducing or increasing negative feedback from the output transformer in the power amp section.
Negative feedback controls the accuracy of the output stage's reaction to the signal coming from the preamp stage, and reduces distortion at the point where it's fed back into the signal chain. Too much negative feedback causes a sluggish amp response with insufficient attack, while too little negative feedback produces an exaggerated and harsh upper midrange response with an overly aggressive pick-attack sound. The Presence control is thus a useful contributor to the overall tone production of the amp.
The master volume control in the power amp section generally controls the output level of the amp, and it can also affect the sound and apparent frequency response of the amp as well; turning it up to 10 (or 11) won't necessarily produce the best tone.
Remember, all of the operative amplifier controls and principles we've discussed above have been fanatically and lovingly recreated by software plug-in developers, so that programming an amp sound on the computer is just like adjusting the knobs of the real thing, often resulting in uncannily realistic simulations.
Taming the Beast
There is a group of products available today, known collectively as Power Soaks (the name of the original model designed and manufactured by guitarist/inventor Tom Scholz) that help deliver high-gain amplifier tones at low speaker-playback volumes.
Basically, Power Soaks are in-line devices that attenuate the signal from a full-out, saturated tube amplifier, preserving the tone and sustain while vastly reducing the bone-crushing volume. That signal flows from the attenuator to a speaker cabinet, which is then miked, reproducing the sound at a very manageable volume level. A Power Soak is like a second master volume control, absorbing the full power of the amp and converting that power into heat (these units get very hot!) while passing only a small portion of that power to the speaker. While there is an inherent loss of the natural non-linear speaker distortion associated with screaming guitar amps, and the pleasing sizzle and cabinet "thump" that results,
the trade-off is obvious.
Speaker simulators are switchable filter sets designed to reproduce the EQ curves of a variety of speaker cabinet configurations (with varying degrees of success). The subsequent coloration is meant to replicate typical speaker sound and behavior, softening the harsh upper-midrange edges associated with amplifier distortion. Speaker simulator boxes are designed with direct guitar-amp recording in mind, and are intended to remove the speaker cabinet and microphone link from the signal chain.
There is also a large selection of direct recording preamps available for purchasing, which are usually equipped with speaker simulators and varying degrees of tone control. Low-wattage practice or direct-recording amplifiers provide another viable studio alternative, serving up a variety of clean and overdriven tones at manageably low volumes.
Portable speaker chambers represent another viable solution. These units are thick, reinforced wooden boxes outfitted with both interior and exterior insulation, housing a built-in speaker and an adjustable microphone stand, along with speaker and microphone cable connectors. Think of a miniature portable iso-booth. They're used professionally in the studio and on stage, preventing unwanted leakage and greatly diminishing stage noise, with excellent results.
Last and not necessarily least, consider the ever-popular closet and sound blanket trick. This involves a speaker cabinet, a closet or large cupboard, and at least a pair of the thick, padded blankets normally used professionally for sound insulation or by moving companies (quilts and regular bedding blankets are ineffective). You'll lose some speaker "air" and room interaction, but you'll be able to crank the amp and avoid unwanted noise complaints. Assuming the blankets are properly placed, the volume level should seem no louder than that of a distant stereo system blaring at someone's party.
Miking the Cabinet
Guitar speakers typically exhibit a peak frequency response of between 5 and 6kHz, and sound brightest at the center. Because the top end of the speaker's reproduction is limited, the harsh upper harmonics of amplifier distortion are essentially removed, and what's left sounds pleasing and musical. Open-backed cabinets offer both front and rear miking opportunities for a nice blend, with increased low-end "thump" and "chug" emanating from damped low-string rhythm parts.
Good results are usually achieved using a dynamic instrument microphone placed 6-8" from the speaker, off-center. If more low-end is needed, move the microphone closer in (2-5") for increased cardioid proximity effect. Use your ears or a set of headphones to find the "sweet spot" of the speaker. Consider miking the guitar itself with a small-diaphragm condenser in the area of the picking hand aimed toward the bridge, for extra string texture in the track.
Large-diaphragm condenser microphones set to cardioid or omni mode work better for ambient purposes at distances of 2-3' or farther, introducing more room sound and coloration.
Ribbon microphones , which are also (usually) dynamic, have become a popular alternative for guitar-cabinet recording in either close or distant miking situations. They combine good, detailed sonic reproduction with the capacity to withstand intense levels of sound pressure (a characteristic of their dynamic brethren, as well).
Ribbon mics exhibit a figure-of-eight pickup pattern. One useful close-mike application for achieving heavy rock sounds involves a ribbon mic (or large-diaphragm condenser set to a figure-of-eight pattern) aimed toward the center of the speaker, with a cardioid dynamic mic angled next to it at roughly 90°, aimed off-center, with the capsules almost touching.
Record the mics on separate tracks, and with proper balancing the sound should be powerful and frequency-rich.
When using multiple microphones, always remember to check for phase cancellation, and keep in mind that a 2-8kHz boost is probably all that's necessary at mixdown for enhanced electric guitar presence within a track. A small amount of delay (1ms = 12") on an ambient mic track will increase the perceived ambient distance of the microphone without actually moving the mic. This trick works well when blending close and ambient microphone tracks during recording or mixing.
Re-amping is another increasingly common production technique, often used at the mixdown stage. This process involves a dedicated re-amping device, which takes a line-level feed from a mixing console or DAW interface and converts that signal's level and impedance to one that a guitar amplifier is able to accept. That signal is usually a separate "dry" (unamplified and unprocessed) guitar track recorded using an active 500kOhm direct box placed between the guitar and the amp.
Direct boxes (some of which have tubes as well) are generally useful for recording the clean, natural sound of the guitar itself, for use in rhythm or lead tracks, as an alternative to using clean settings on an amp.
Though the guitar is played through an amplifier which is often miked and recorded, the engineer or producer may later decide to use a different amplifier tone that's better suited to the character and timbre of the song, while preserving all the nuance and inflection of the original performance embedded in the direct track.
The re-amp device allows the dry track to be sent to an amplifier again and properly miked and re-recorded for use as the final track.
Many people "re-amp" direct guitar tracks recorded to a DAW using amp-modeling software , with good results. Plug-ins are wonderfully suited to the virtual recording environment, allowing for fast access to a plethora of modeling amplifier and speaker cabinet combinations, hence tones, effectively replacing a roomful of amps, cabs and microphones.
Programming the virtual amplifier is the same as tweaking the knobs on the real thing, and the same is true for programming software dynamics and effects processors in relation to their hardware equivalents. As the realism and sophistication of modeling technology continue to develop, so does the viability of virtual re-amping as a production technique.
One last note concerning the use of compression: Be careful. Compression occurs naturally in overdriven tube amplifiers, and overly-compressed clean settings or direct guitar tracks can sound harsh, with an exaggerated picking sound. We hope that having read this article, you'll approach the process of recording the electric guitar with a new insight and fresh ears, and wish you the best in your quest for the ultimate tone.
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