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Recording Mythology, Pt. 6 / Signal Flow and Musical EQ


Due to request, I’m going to go into more depth concerning the use of musical EQing. Using the example set forth earlier, I’ll begin by outlining the process of equalisation in preparation for the recording of a lone acoustic guitar. In order to get a good idea of how to get the best recorded sound, it will be necessary to do a bit of experimenting, and having a good, strong signal to work with is of the utmost importance. Let’s review this.

The first thing that we’ll want to do is power up our equipment. Then tune our instrument. After about 30 minutes, once things have warmed up and stabilised, lower the volume on everything and then put the headphones on. Let’s say we’re going to record an acoustic guitar over which we’ll record vocals later. That’s right. We are only wanting to record one track at a time. If this is going to be difficult to do, I suggest that time be well spent in practicing this technique because it is necessary. If we record the vocals and the guitar in the same pass, the presence of the guitar may override the vocals, and there’s no way to remedy this if it is all recorded on the same track. Learn to keep up with the vocals in your head while you lay down the guitar track first.

Position the microphone in front of the guitar; a good place to start is to point the mic toward the sixteenth fret, about five inches away from the fingerboard. It will become apparent that minute adjustments either toward or away from the guitar body will render surprisingly different results. If you are recording using a Digital Audio Workstation, or DAW, the process is quite straightforward: turn up the gain on the mic preamp, watching the LED meter while strumming vigorously. If no signal is present, make sure that you haven’t inadvertently pressed the mute switch. If your unit doesn’t have a metered level display, then you will want to turn the knob to the ‘zero’ position, which represents unity, (no gain or no reduction) but never beyond. Now, raise the channel gain 3/4 of the way to unity on the channel you are going to be recording on. If recording digitally, this level should never go into the red. Acoustic guitars, unlike their electric counterparts, sound like crap when they distort, and digital distortion never sounds pleasing. Then, slowly turn up the volume on your headphones.

Many of you may be recording through a series of ‘old school’ modular units. (Digital recordists: forgive me if I tend to lean toward this style of recording, as it is the process that I am most familiar with, having done it for over thirty years.) This sort of approach requires a bit more explaining, however, as each unit usually comes with its own battery of gain controls. This quality is precisely why I enjoy the format, as it lends more in the way of, well, control, and this is what recording is all about. In this case, using the strumming approach outlined above, the preamp is adjusted to a gain just below clipping, or redline. This will insure that our signal is as strong as possible before routing it to the next unit in our chain, which is, more often than not, the mixer. Most stand-alone mixers have preamps built into each channel, but in modestly priced units, I generally find that these pres are of inferior quality, and quite noisy. These primarilyonly add gain, but if your unit has a unity, or ‘0’ setting, this is where you will want to set it. If you are employing inserts and/or send and return jacks to include other processors, all of the gain adjustments should also be set to unity. Next, you’ll want to raise the slider up on the mixer channel that your mic is plugged into until the meter begins to tell you that your signal is present. Raise this level either to unity, or to a threshold of just below redline, whichever comes first, again while strumming vigorously.

By strumming in this manner, you will be setting your level to a threshold that we are not likely to go beyond. You can always tweak the gain if you are going to play at a softer volume, but if you are the type who gets caught up in the emotion of playing, you probably tend to start out at one level and then end up strumming harder as you progress through the song. This is a bad habit thatmany players exhibit, and is something that takes time to overcome. It is worth the effort.

Last, you’ll want to slowly turn up the volume on our headphones. I always have the volume of my headphones cranked all the way up, which is unity, and turn the Master volume down to a pleasing level. We don’t want to be turning up the channel gain if the headphone volume is the culprit! At this stage, you should begin to hear your instrument through the headphones. If not, lower the channel slider and make sure that a mute switch hasn’t been pressed. I can’t begin to relate the times I’ve set my ears ablaze by releasing a mute swith which had accidentally been pressed while my signal was as loud as hell. It hurts.

If you elect to record the instrument wet while you record, that is, with effects, extreme caution is advised: a little goes a long way. I would suggest nothing more than a little reverb. Reverb tends to muddy up an acoustic very quickly, especially when additional instruments are to be recorded. (Most engineers frown on this style of recording. Effects are usually added in post-production but many budget recording devices do not offer this option.) If your equipment is the sort that doesn’t offer on-board effects, or, if insert points or an effects loop isn’t an option, an inline outboard unit will be necessary, placed in the signal path between the mic preamp and the mixer. (If this is the case, the gain level on the effects unit will be the second one which you’ll want to adjust immediately after adjusting the preamp gain, keeping in mind that the signal should never be turned up beyond unity, initially.)

Now, tune up again. After you hold the guitar neck for a while, especially in cooler environs, it will expand and the strings will go sharp. I find it advantageous to tune the low E a cent or two flat, as when it is fretted, it goes a bit sharp due to the pressure exerted on it.
After we achieve a good, clear signal, we’ll want to play around with the EQ levels to get a good idea of how each slide pot will affect the sound when the freqs are either cut or boosted. If we start at the bottom of the audio spectrum using a 31 band EQ, (which, incidentally is the only one which I have found is musically useful for serious sound contouring), we’ll find that the first slider controls the 20 Hz range. Strum your instrument (you needn’t play a chord) and slide both channels all the way up to boost the frequency, then slide them down completely to cut it. You’ll probably hear or “feel” a faint rumble if anything at all. This frequency is useless for recording our acoustic so we’ll want to “kill” it completely before we record by pulling the slider all the way down. But for now just return it to the “zero” position.


Cutting useless frequencies will actually serve two purposes: Vibrations in the lower freq range will only add muddiness to the recorded sound and we are wanting to keep this to a minimum, but more importantly, it takes a great deal of energy to reproduce these frequencies. If we have extraneous vibrations here, we are forcing our amplifier and our monitors to work harder to reproduce unnecessary sounds and this leaves less energy to share in the reproduction of all of the other frequencies that will be useful when recording other instruments (such as bass guitar) on other tracks, so don’t just turn these frequencies down, kill them.

Proceed up the frequency range using the sliders in the same fashion. Soon, we will begin to enter the range of the sub-harmonics of the guitar. There will be a big difference heard when these frequencies are boosted or cut completely. Make a note of “ugly” or interesting freqs and then move on to the next, moving each slider back to zero before moving on. Move the sliders slowly, and don’t monitor through the headphones too loudly as some of these freqs will make a huge difference in volume, and we don’t want to do any damage. As we get into the fundamental frequency range, this will begin to manifest. Some fundamentals add body and some will sound downright nasty when boosted. Make a note of all of these. By the time we move into the upper-harmonics, we’ll see where boost can be advantageous in adding presence. This type of boosting is generally unnecessary in our present application, but, depending on the mic, or if we were recording tracks containing an electric bass, drums and a couple of electric guitars, presence is an invaluable asset in allowing the acoustic to be heard amidst the din of the other instruments.

Finally at around 12.5 kHz, we will begin to lose most of our musical tones and enter the world of noise and hiss. I usually begin to “roll off” these frequencies and everything beyond 16kHz, I’ll kill completely. This is an area where, if these frequencies are accentuated, especially on multi-track recordings, they become audible. I refer to different frequencies with various adjectives: thud, boom, boxy, crash, hash, sparkle, tinkle.. you get the idea. It’s all largely subjective, but it helps me go for what I’m after and disregard of the rest. I’ll reset my EQ every time I record. I like starting out with a clean slate for a variety of reasons, and I won’t limit these types of reconfigurations to my acoustic guitar. I’ll constantly readjust the tone of my electric guitar and even my vocals.

I have a friend who is emphatic about leaving his electric guitar amplifier controls set in one position. I can’t figure out his logic. He has several guitars, and each one is a completely different piece of wood with pickups of different values. Every guitar, electric or acoustic, displays a different range of frequencies so what works for one will not necessarily bring out the best in another. It pays to experiment. Variety is the spice of life, as they say.

After we complete our experimentation, we may choose to boost or cut various frequencies, but we don’t want to overdo any of them. Sit back, close your eyes, and hear how the guitar sounds through the headphones. If there’s something that you don’t like, change it. After you have what seems to be an acceptable EQ curve, hit record on your unit and play a bit of something. Rewind and then remove the headphones, mute the mic, and play the track back through your monitors. Is this the way you want the guitar to sound? If not, mute the monitors, put your headphones back on and re-engage the mic and try to find the culprit frequency. This is going to take some time, but if you aren’t willing to learn to go through all of the labor, you’d be better off driving a truck, but with patience, your hard work will be rewarded.

If you, like I, are constantly recording stereo tracks, then it will be necessary two employ a dual channel, or stereo EQ which will have two banks of controls, one for the left and one for the right channel. These units may serve double-duty during post-production in programme equalisation.

After our EQ is satisfactorily adjusted, we’ll want to move on to the next piece of equipment which I mentioned in the last installment, the compressor. As I said, if the DAW doesn’t have the compression/gate option included, and an outboard unit is necessary, a unit such as the Alesis 3630 is both cheap and effective and will render treatment of the entire room largely unnecessary. Now a lot of negativity has been generated concerning the use of compression, most greatly unfounded, but unless you are a very consistent strummer or picker, there are times that you will either strum more or less vigorously, if only for effect, or you will ease in on the mic. Both actions are sorely apparent in a recording situation, and since we are wanting to record at a level approaching redline (especially for those of you who, like me, are die-hard analogue tape fanatics) you do not willingly want to record at levels much lower. On the other hand, if you record digitally, you simply can not go into the red zone. Digital distortion, unlike the more forgiving tape saturation (which sometimes sounds good ) sounds utterly horrible and you will have to chunk the track if you exceed the limit. This is where compression is an invaluable tool. It is just like having an engineer in the control booth “riding” the slider. And it is more efficient (the compressor doesn’t have to learn the song first in order to anticipate loud passages), not to mention that an engineer costs a lot more. Generally, this unit will be employed in the signal chain after the equaliser. A compressor can effectively lower the level of the louder passages and the expander will gently raise the level of the softer portions of the music depending on the attack, release and threshold adjustments. This way, the overall volume of the recording remains consistent but the depth is largely unaffected. Who wants to have their listener constantly turning the volume of their stereo or mp3 player up and down in order to hear everything? When a compressor is properly employed, the affect is invisible yet completely effective. We’ll get into the “dialing in” of the unit in part 7.

Meanwhile, practice using the EQ as outlined above, but on your vocals, instead. And don’t forget to keep notes.

Johnny Nowhere is a self-made songwriter, composer, musician, engineer, producer, publisher and no warranty is expressed or implied.


About Johnny Nowhere

Johnny Nowhere is a songwriter/composer and owner of Hell Paving Company, music publisher. Johnny doesn't really exist outside of the music industry and Facebook. He is simply a figment of my imagination.

One response »

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