Audio Recording

This is a beginner tutorial on controlling bleeding in multi-track recording by implementing proper isolation techniques. As a background, bleeding is a serious issue in recording where undesired audio are captured during recording.

To better understand bleeding and how it can seriously affects your multi-track recording project, say for example you are recording a band. You decide to place the band in a single room and then you place a microphone on the vocalist, one microphone on the guitar amp and one microphone on the bass amp. The drum also needs at least 4 microphones. All in all there are around 7 microphones in a single room.

If your objective is multi-track recording, you will be assigning each of these tracks in your DAW (recording) software. Since you are recording using 7 microphones, you need to create or insert 7 tracks in your DAW. If you are using Reaper, then you will simply insert 7 tracks to capture or record the band live as they perform; for example:

Can you guess what will happen next? Yes, there will be extreme bleeding. As they start playing; the drum sound will go into the vocalist microphone, or the guitar amplifier sound will go into the drum microphones, vice versa. In all microphones; there will be serious bleeding of sound.

Effects of Bleeding during Mixing and How to Control It

Supposing you are done recording the band and then you start mixing your multi-track project. This is where serious problem will start to occur. First, the track is not an accurate representative of the instrument recorded because it substantially contains recorded audio of other instruments. Second, since the track is not an accurate recording, applying EQ, compression and other effects can be less effective or even futile with extreme bleeding. Finally, your mix sounds dull and confusing since tracks does not seemed isolated properly in the mix.

This is why bleeding needs to be controlled during the tracking or recording process. How? Different record producers and engineers have different approach in controlling bleeding during recording. Let’s discuss the two common methods.

First Method: Record Drums first with a click track

In this method, you need two rooms; the drums are isolated and first recorded. Since timing is very difficult for the rest of the band members; the record producer will decide on the BPM (beats per minute); then formulate a click track primarily for the drummer. The drummer will be placed alone in a single room with microphones aiming at the drum kit. The guitarist, bassist and the vocalist can be placed in another room with audio output feed to the drummer headphones and vice versa.

So the first aim of the producer is to record the drums clean. The rest of the band members will just play live as a reference for the drummer. After recording the drums are cleanly recorded (without serious bleeding), the rest of the instruments can be recorded one at a time. The vocals will be recorded last. And take note that recording them one at a time prevents bleeding since they are not playing together in a single room.

Second method: Record Guitars, Bass and Drums Together in Isolation

In this method, you need 4 rooms. The drummer is not alone in the room but with the guitarist and the bass player. However:

1.) The guitar amplifiers are placed in a different/isolated room with microphones on it. A headphone output would be provided to the guitarist, bassist and drummer. The output audio contains the rough mix of all live instruments.

2.) The bass guitar amplifiers are also placed in a different room with its microphone.

3.) The vocalist would be placed in a vocal booth but the vocal is not yet recorded and will be used as a guide vocal for the rest of the instruments to be recorded.

When the recording starts, the record producer and the engineer would be able to record guitars, bass and drums together while still getting very clean recording without any bleeding.

This method is primarily important for those bands that are reluctant to play one at time. The record producer should decide if bands would be best if recorded together or one at a time. In most cases, particularly those bands in the rock, alternative and grunge genre, they are recorded together because they seem to play with more energy with that setup. As usual, the vocals or any overdubs (guitars or vocals) can be recorded last.