A little bit about a good vocal recording configuration, bass frequencies, acoustic treatment in home recording studios, accessories that make the recording process easier and better.
A good vocal recording configuration
This is a setup that will give good results in a home recording situation:
- A cardioid microphone .
- A suspension shock-mount on which the mic is mounted. Shock-mounts suppress low-frequency rumble on the microphone line by absorbing and damping vibrations.
- A pop shield to protect from blasts of air, for example when singing consonants P B F.
- Keeping the microphone within 12 inches of the vocalist.
- A non reflective surface that prevents reflection of the sound into the mic, placed behind the vocalist. (The voice reflected by any surface behind the vocalist, falls on the front side of the mic which is the most sensitive part of a cardioid mic.)
Acoustic Treatment For Vocals
Microphone patterns are three dimensional. A mic picks up sound from all the sides, top and bottom. Sounds reflected from the walls, the floor and ceiling are also recorded by the mic. These secondary sound waves recorded along with the direct sound is what brings in the 'room sound' to the recordings. Room reflections result in boxy sounding recordings which do not improve significantly even with reverb addition or equalization.
Improve the acoustics in the vicinity of the microphone
If we can control the reflections around the singer and mic, it will improve the situation a lot without having to worry about acoustic treatment for the whole room.
Soft absorptive material behind the singer and to the sides is a good start. Carpet on the floor and some soft material on the ceiling can reduce the reflection from top and bottom. Remember that reflections from the wall behind the vocalist falls in the front part of the cardioid mic capsule, where the mic records the most. So absorption and diffusion of reflections from behind the vocalist is more important than what comes from in front of the vocalist (it falls on the rear of the cardioid mic, where it is almost a null.)
The bass frequencies
A room treated with reflective and diffusive material will prevent claps and such high or mid-high sounds from reflecting. But this is not enough as an indication of good sound treatment.
Overuse of acoustic foam or other acoustic treatment will absorb the high-end and upper mid-range reflections, without having any effect on the bass frequencies. This can sound worse than before with the low end booming above the reduce high end frequencies. Make sure that there is enough reflective surface so that highs and mids are not completely taken off the recording surroundings. Then take care of reducing the bass frequencies.
To reduce reflections of frequencies below 400Hz, specialized material in appropriate thickness has to be used. Rockwool slabs which are 4 inches or more thick, when appropriately placed can help reduce the low end boom considerably. Read more about Acoustics and Basstraps from Ethan Winer.
Pop Shield, Shockmount and Headphones
Pop shield prevents 'thud' sounds in the recording that usually happen from air blown into the mic while singing consonants like B P & F. Pop shields are a must when using condenser mics since they are very sensitive. When using SM58, you won't need shields, but with some dynamic mics you may need pop shields to prevent the plosive sounds from ruining your recordings.
Use pop filters instead of foam wind shields that come with some mics because the foam filters out the high frequencies from the recording. They are also not very effective in diffusing the plosive gusts of air and better not be used.
Shock mounts give a break between the condenser mic and vibrations that come up through the mic stand. Building rumble and other mechanical noises including a tapping feet can all enter the vocal recording as low frequency vibrations that do not add any relevant audio information while taking up valuable sound energy space. Inexpensive shock mounts are available even if the mic did not come with one.
Use closed headphones like the AKG K271MKII to prevent spill from headphone monitor from reaching the vocal microphone and getting recorded along with the vocals.