If you’re new to the art of recording music through a DAW program, it can be pretty tough trying to wrap your head around the multitude of settings and plugins that the world of recording software has granted us. From subtle EQ curve manipulation to endless post-mix polish, recording music from a computer gives pretty much anyone willing to learn the power to create a professional mix that would have taken hundreds of thousands of dollars worth of equipment to achieve only a couple of decades ago. Today, we’re going to focus on one of the more common and well-known effects used in recording – reverb. There are essentially six main types of reverb settings used on most DAW programs: predelay, room size, reverb time, color, damping and a setting for wet / dry mix. Let’s take a closer look at each of them individually, along with a couple of other common examples.  

 

Predelay

The predelay determines how far the sound source is from the walls of the room. This has the effect of creating depth, and long predelays of fifty to sixty five milliseconds are often used to wash vocals and make them fit better in a mix. Sound travels at one thousand feet per second through air, so a fifty millisecond predelay gives the effect of placing a sound source fifty feet away from the opposite wall of a room. This sounds pretty huge, but it is not unusual for concerts to take place in large concert halls or auditoriums that are considerably larger than fifty feet in length.

 

Room Size

Quite simply and as one would expect, room size determines the size of the room that is being simulated. To create a huge spatial effect on a mix element, select a large room size. To keep things tight and close, select a smaller room size.

We're treading into pretty subjective territory here. Large room sizes could be used to create ethereal effects on vocals, strings, and in fact on various mix elements. I myself have used artificial large room reverbs to create an artificial orchestra that was multi-tracked across over a hundred tracks by a single violinist to simulate the feel of a huge orchestra in an auditorium. Small room sizes would be used to give a more natural feel on a mix element whereas large room sizes give an impression of space and power.

 

Damping

Damping can be used to simulate coverings on walls and objects in a room that absorb or diffuse sound. For example, it stands to reason that the smooth tiled wall at the local swimming baths will reflect sound more efficiently than a wallpapered stud partition that you would find in a house.

It seems unlikely to me that an engineer working on a studio multitrack mixdown of a song would worry about checking up on the reflective index of cement walls or wooden panels and trying to set a reverb to match on his tracks, he would be more inclined to manipulate the damping control until he found the sound he liked, but this kind of idea may be more important for an engineer wishing to create sound effects with a view to realism, for example in effects for radio or television.

 

Color

It stands to reason that not all surfaces or objects will necessarily reflect sound equally at all frequencies. The color control on the reverb unit or plugin can adjust the frequency spectrum of the reflections being simulated. Alternatively, the output of the reverb unit could be patched through an equalizer before being returned through the mixing desk. Using lower frequency values for color will generate a “warmer" feeling reverb, while using higher frequency values will generate a “brighter" feel.

 

Wet And Dry Mix

It stands to reason that when standing in any acoustic space, one will hear sound waves directly from the source as well as reflections from the ambient surroundings. The levels of these can be adjusted in an electronic reverb by changing the wet and dry mix. In an anechoic chamber, one will hear the dry source almost exclusively as there are close to zero reflections, whereas in a large wood paneled hall, one would hear a lot of reflected sound.

Elements in a mix, especially things like overdriven guitars, have a habit of swallowing up reverb, which can be compensated for by making the reverb wetter. In modern music production, the level of wet reverb will typically be considerably lower than the dry signal, as the reverb tends to be more often used to add spaciousness to a mix than purely as a special effect. One thing to watch for when setting these levels is that the mix settings don't cause the sample to clip.

 

Reverb Time

The Reverb time, or RT60 of a room is a measure of the length of time, usually in milliseconds, from when the initial sound reflections are set up to when they are attenuated by sixty decibels. This is simulated in a digital reverb and can be anywhere between close to zero and infinity. This is of course not possible in a real room, where the reverb time will be dependent on how big the room is and how reflective the walls are. It is common practice in modern production to have reverbs that can be large but are tightly gated in terms of the time domain to give a spatial effect which is still kept tight and controlled. This is particularly noticeable on percussive instruments like snare drums. Properly controlled reverb times are instrumental in keeping a mix tempo based, and stopping it from sounding sloppy and wet.

 

Plate Reverb

In the days before the era of the electronic reverb, plate reverbs were used to simulate spatial sounds in music. Listening to music recorded in the seventies, it is obvious that a lot of the engineers who tuned these devices were immensely skilled in using them.

Commercial plate units use piezoelectric pickups or accelerometers attached to a metal plate which is bolted onto a frame. These are basically contact mic / pickups that pick up vibrations in the plate set up by a driver that carries the dry sound to the plate, as seen below.

The level of reverb on a plate is set by having the dry signal on one tape return and the wet signal on another. The levels can be adjusted using faders on the mixer. Tuning plate reverbs is accomplished by adjusting the lugs that hold the plate in place so they are all equally tensioned. It is important in doing this to listen for flutter echoes or beats, which are similar to the sound modulation set up by playing two slightly out of tune guitar strings simultaneously, and eliminating them. Improperly tuned plate reverbs can give an unpleasant and unnatural metallic sound.

 

Timing A Delay

In order to time a delay to land on the quarter beat, there is a very simple equation that can be employed. Simply divide sixty thousand by the beats per minute of the song and you have, in a 4/4 time signature, the number of milliseconds in every quarter beat. If you want an eighth beat delay, simply divide this number by two, for a half beat delay multiply by two. For a sixteenth beat, a full beat, or anything else, apply the same principles, very simple math.

If you don't know the beats per minute tempo of the song because it hasn't been tracked to a click, then it's time to either download a tap plugin or get the stop watch out and do some counting, but generally speaking, delay is more effective in recordings that have been tracked accurately to a metronome.