Microphones Explained

Microphones Explained Brought to you by: guitar.com

Just Press Play Logo Gif 99900This is the first in a series of columns on recording the guitar and recording in general. I'll share numerous tips with you, as well as interesting stories from my career as they relate to the process of recording guitar. The Recording the Guitar column will cover recording in detail and will help you achieve the best possible tone and recordings, whether youre working in a home or pro recording studio.

 

A few years ago, I started writing a series of books on recording techniques with author Craig Anderton. The series will include recording the guitar, bass, drums, percussion, keyboards, vocals, horns, strings, mixing, and much more!  The series will begin to be released in 2003. You might consider this Guitar.com column a prelude or teaser to those books.

 

Most of you have at least basic knowledge regarding recording the guitar but I must start from the beginning as to make sure there are no loose ends.

 

Instant gratification


Set up your amp, plug in the guitar and power up the amp.

If using stomp box effects, or rack set up, set the effects to taste.

 

Mic the amp


Plug the mic into a mic pre amp on the recorder mixer. If using a computer based recorder, plug the mic into the mic input Analog to Digital converter.

Assign the mixer module that relates to the mic input to a recorder track.

EQ the signal.

Compress if needed.

Add outboard effects on the mixer if wanting to use during recording or simply for monitoring.

 

Simple, right? Yes it is regarding the basic set up, but there are so many considerations that need explanation. After many years of recording experience, I have learned that no matter what education I have gathered along the way, around the corner lurk new discoveries!

 

When recording, always remember rule #1 there are no rules when recording just guidelines! The following story is amusing as well as educational, and it proves rule #1.

 

John Lennon Invents Distortion

A few years ago, my good friend Steve Lukather was talking with George Martin and George told him that the intro distorted lead guitar sound on the BEATLES song REVOLUTION was generated on the console recorded direct! John Lennon wanted to gang a few mixer modules together and slam the gain to maximum on each module to the point of distortion!

 

The block diagram would look something like this:

  Guitar plugged into a direct box.

  Direct box output plugged into mixer module X mic pre amp input.

  Mixer module X output patched into mixer module Y mic pre amp input.

  Mixer module Y output patched into mixer module Z mic pre amp input.

  Mixer module Z output patched into a recorder track.

  Note the odds are good the mic pre amp and line fader level controls were all set to maximum level.

 

We have all heard the result major distortion without a guitar amp in an era that did not have stomp boxes! (OK, note that somewhere in the early 60s Travis Wamac recorded the song Scratchy. The odds are good he used the first fuzz tone design).

 

In that area in England, the studio techs wore lab coats (you gotta love that). Supposedly, the techs were freaking out when John wanted to try this set up! Thanks to John, this was the beginning of total disregard using gear! 

 

The bottom line is no rules so always experiment as long as you are sure the experiment is not dangerous to you or your gear.

 

Basic Mic Designs

Let's start with mic designs. There are three basic mic designs: dynamic, ribbon, and condenser. Here are the basic charisterics for each:

 

Dynamic: The common choice for miking a guitar amp since such a design can accept loud volume levels without damaging the capsule (microphone diaphragm). The industry favorite is the Shure SM 57, especially for loud level stuff. Over the years I have tried others but, to date, I still like this mic for loud/full blown distorted sounds. Note this mic also works well for low- and mid-level amp levels. By the way, my older SM 57s (early 1970) sound better than a bunch I bought about 8 years ago.

 

Ribbon: My experience with this design style is not as good as dynamic mics per the application. Note I have only tested a few in the past since the result was not what I was looking for. In this era, however, manufacturers have come out with many new designs which I have not tested. If you wish to try such a mic design, check the specs and make sure it can handle high-level SPL (sound pressure level), meaning it can be used with high volume guitar amps.

 

Condenser: A condenser mic may be a good choice for a clean guitar (non distorted) tone if you want a hi-fi sound, meaning a wide frequency response. Try this type of mic for country, jazz, or rhythm guitar playing such as R&B, pop and more basically any style that is being played through the amp from a low to normal listening level, or without distortion.

 

In general, most condenser mics are fairly bright sounding, meaning they reproduce the upper frequencies in a big way. For distortion applications such as hard rock, etc., this type of mic may make the distortion sound shrill, whereas most smooth sounding dynamic mics will not accelerate these upper frequencies. There are some condenser mics that do not accelerate the upper frequencies and provide more of a sweet mid-range sound, such as the Neuman U47, U49, U67 and others. In any case, the mics frequency characteristics will be very obvious when listening over the studio monitor speakers. 

 

Important: It is a bad idea to use a condenser mic on any sound source you would not put your ear next to. If youre using a condenser mic on a loud guitar amp (or any loud signal source) the diaphragm may be damaged! Considering that condenser mics are often quite expensive, youll want to be very cautious about placing them too close to a loud signal source.

 

OK, I said no rules: If you like the sound of a condenser mic for loud guitar amp sounds, if possible, dedicate the mic to this kind of application since the mic will most likely not sound good afterwards for sensitive applications such as vocals, etc., after the SPL (sound pressure level) abuse.

 

So if using a condenser mic for a loud sound source, its best to use the mic pad switch as to not overload the mic electronics. Typically, the mic pad switch is 10 dB. Some offer a -20 dB setting as well. If more than one is setting available, experiment with both settings. The odds are good if the guitar amp is 100 watts or more, -20 dB would be the logical setting. In any case, experiment with the pad settings after we get into setting mic levels on the recording mixer.  

 

Mic Roll Offs

Condenser mics (and others) might offer a bottom end roll off (attenuation of low frequencies probably around 120 cycles). In most cases, we will not use this roll off when miking guitar amps since the frequency curve is very steep. Some mics offer a top end roll off (attenuation of high frequencies). Again, we will not use this feature in this case.

 

The roll off mode may be labeled M or V. M means music and no roll off is in play. V stands for voice and the bottom end would surely be rolled off. There are other modes on some mics such as M1 and M2, V1 and V2, etc. Its best to check the mic spec sheet to see what the frequency curves show. I have always set the mic to the flat position (no frequency attenuation) to get the full spectrum the mic has to offer. EQ shaping will be performed later, when we get into EQing the guitar mic.

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