I've recently bought myself an electro–acoustic guitar and it sounds really loud, clean and crisp when I play it. Yet when I record it on my Fostex XR7, through my instrument mic, the sound is noticeably decreased on tape. I want to record the acoustic exactly as I hear it when I play it. When you hear acoustic guitars on commercial CDs they sound great — Paul McCartney is a fine example of this. How can I achieve the same kind of loudness from my acoustic?
Mark Blow
Assistant Editor Sam Inglis replies: Acoustic guitars are hard to record well, and are one of those instruments that really reveal inadequacies in the microphone, mic preamp, recorder, the room in which it is being played, and often in the instrument itself. To be honest, then, it's hardly surprising that you can't achieve the same sound as Paul McCartney with budget gear at home. Paul McCartney's guitars will be recorded through high‑end microphones, preamps and compressors to high‑quality analogue or digital recorders. They will also be expensive guitars, probably played in special acoustically designed rooms. To start at the beginning, then...
Neumann's KM 184 — a classic choice for miking‑up acoustic guitar.So‑called electro‑acoustic guitars are usually designed specifically to sound good when amplified over a PA system. The design compromises involved in making a guitar that amplifies easily without feedback mean that many such guitars sound rather 'dead' when played unamplified, compared to a good dreadnought or jumbo instrument. However, you say that yours sounds good when you play it, so it ought to be possible to record it reasonably well.
Acoustic guitars won't come over very well unless you use a good condenser mic; many professional engineers would prefer a small–diaphragm model such as a Neumann KM184, although you can get excellent results with much cheaper mics such as those made by Rode, AKG, Audio‑Technica, CAD and so on. If you're using a dynamic mic you will inevitably lose much of the sparkle and clarity that a good condenser mic will capture.
Mic placement is very important. The usual default is to point the mic at roughly the spot where the neck joins the body (rather than directly at the sound hole), from a distance of around 12 inches, but you should experiment with different placements.
What kind of room are you recording in? Since you'll have to place the mic at some distance from the guitar, you'll inevitably pick up a lot of the 'room sound'. If you're playing the guitar in a boxy or dull‑sounding room, this will make the recording sound boxy or dull. Experiment with recording the guitar in different rooms. Tiled bathrooms can be good if you want a bright, zingy sound.
The Fostex XR7, like all cassette four–tracks, has inexpensive preamps, and records to ordinary cassette tapes. A complex sound like an acoustic guitar, which has a wide dynamic range and frequency spectrum, is frankly never going to come back exactly as you hear it when you play it. We normally try to avoid recommending that readers solve their problems by buying equipment, but the honest truth is that you'll never achieve your goal unless you have a decent condenser mic, a good preamp and a better‑quality recorder. You should be able to get an acceptable sound within the context of a cassette four–track recording, but it'll never sound like Paul McCartney.
Many recorded acoustic guitars that you hear will have been compressed at some stage. If you're finding that you can't get the acoustic loud enough, compression should help. You can either do this by putting a compressor in the signal chain between preamp and recorder or as an insert at mixdown.
If you want a sound that's louder and cuts through more, try blending some of the sound from the built‑in pickup with the signal you've recorded through the mic. On its own, this signal will not sound very natural, but it can help add force and body to a 'weedy' miked sound.