Microphone Recording Techniques for Guitars

Recording Guitar Amplifiers

The speakers of a guitar amplifier aren’t of the hi-fi type, they have a frequency response upto only about 8 khz, if it was higher than that then the deliberate distortion that guitarists often create would be unpleasant to listen to in those higher frequencies. This means that dynamic microphones such as the Shure SM57 are ideally suited to guitar amplifiers because they don’t need to have a wide frequency response and their robust construction allows them to be put in a high sound pressure level.

In the Live recording the microphone is pointed directly at the centre of one of the speakers (or slightly off centre for a warmer sound) from a distance of about 6 inches (15cm) or from slightly further back e.g. 1-2 feet, to give a more general coverage of several speakers.

In the studio the same is true but sometimes engineers will experiment with an extra microphone at the back of the cabinet to get a more bassy response.

In addition condenser microphones such as the AKG C414 range can be used several feet away for a more overall sound of one or several cabinets fed from the same amplifier and others further away to get the ambience of the room. You will then experiment with the balance, e.q., phase and panning of these microphones in addition to adding any D.I. (direct injection) sound feed and any effects.

Recording Bass Guitar Amplifiers

The Bass guitar speaker, like a bass drum, generates high sound pressure levels so the microphones needed are much the same. The Electrovoice RE 20 and AKG D112 are best suited to being in close proximity to the bass cabinet. Like the guitar amplifier you tend to use dynamic microphones close to the speakers whereas in the studio there is more room for experimentation.

Acoustic Guitar

In a Live situation this is one of the most difficult instruments to amplify / record. Because its sound comes from all over its body it needs more general coverage. Increasingly built-in piezo bridge pickups are used, but they’re not ideal for getting a great 'warm' tone.

An electret lavalier microphone inside the body can give a more general sound but it is prone to feedback if the P.A. or monitors are very loud, alternatively a cardioid version could be used on an external clamp. A hypercardioid or cardioid condenser microphone such as the Shure SM81 pointing between the sound hole and neck of the guitar should get a good sound, though it will force the guitarist to stay by the microphone stand.

The Rode NT6 could be used with the capsule mounted on the guitar and the pre-amp’ cable looped through the guitar strap to avoid any pulling on the cable as the guitarist moves about.

Lots of Microphone placement ideas at - www.guitarists.net/lessons

Keyboard Amplifiers

Electronic keyboards have a wider frequency response than electric guitars and generally their sound is fed directly to the P.A. system so their speaker cabinets wont need to be mic’d up. If they aren't DI'd then a condenser microphone such as the Rode NT5 or a pair of them if the amplifier is stereo (and the P.A. is being run as a stereo system) can be used from about 6 inches (15cm) pointing directly at the speaker centre. A -10dB pad might be needed to avoid distortion of the microphone pre-amplifier.

In the studio a D.I. feed and/or possibly the sound from the amplifier are used. The cabinet and the room adds a different tone, particularly if a bit of valve distortion is added in the amplifier, a ‘bit’ being the operative word since keyboards generally don’t sound as good heavily distorted as electric guitars do.