Let's Talk About Space
by Phil Gates

For years as guitarists, we've used the reverbs on our amps without even thinking. We've just been turning up the reverb knob to taste, not really knowing, or caring about room size, density, early reflections, etc. We just had it on the amp. No problem!

Then when guitar pedal and rack effect processors came out, we used to find a preset we liked, and went with that. "Oh I used patch 23 on that" we used to say. Not knowing what was involved. It just sounded cool, and that was good enough.

Now in the studio, we have to pay much more attention to detail when it comes to reverb. There are so many settings, and subtleties that we now need to know these options, and what they sound like, to use these tools to better our mixes.

Reverb is basically a way to artificially create an acoustic environment for a sound source. More easily said, reverb let's you make a source sound like it's in a room, a club, a church, or a canyon.

There are a few terms we need to get accustomed to when dealing with reverbs. Some are fairly self-explanatory, some not. This month's column will be to explain, with text and audio, what these terms mean literally, and aurally.

• Original signal
• Early Reflection
• Room Size
• Room Shape
• Pre-delay
• Reverb Time
• Density
• High Cut
• Wet/Dry

Original signal
This would be the original signal that you want to put the reverb effect onto. (i.e. the vocal track or guitar track, etc.)

Example 1 Original Audio

Room Size
Room Size is the size of the room. Is the room a 10'X10' room, 30'x30', or larger. Remember, this includes the ceiling and floor.

Example 2 Small Room Size

Example 3 Large Room Size

Room Shape
Room Shape has to do with the shape of the room. As we all know, not all rooms are square. Changing the shape of a room can have a big affect on the sound reverberated in it. Being able to control this aspect is a big plus.

Example 4 Three Sided Room

Example 5 Seven Sided Room

Early Reflection
When you make a sound in a room there are many reflections of that sound bouncing off of every surface in the room. Some will hit one surface and come back to you, others will bounce off of many surfaces before getting back to you. Imagine a pool table. If you hit the ball straight on against one side, it'll come right back to you. If you hit the ball towards a corner, it will hit one or two, maybe three sides before coming back to you, if at all. This is the same for reverb. The first sounds that come straight back to you are the early reflections.

Pre-delay
Pre-delay is the amount of time between the original signal and those early reflections. A lower setting for this will give the source a non-directional aspect. More pre-delay will give an initial shape and distance to the reverb. Too much will sound like an echo before the reverb happens.

Example 6 Low Pre-delay Time

Example 7 High Pre-delay Time

Reverb Time
Reverb Time is commonly known as the time it takes for a reverberated signal to drop by 60dB. Smaller times will represent room acoustics, (1-4 seconds), and longer times will represent bigger rooms. A 60'x60' room may have a Reverb time of 8 seconds or more. Reverb Time can also be explained as how long will you hear the reverb after the initial source is played. Your garage would have a shorter Reverb time than a gymnasium.

Example 8 Small Reverb Time

Example 9 High Reverb Time

Density
Reverb Density. Easily explained this is the clarity of the reverb. A picture that has more dots per square inch will be more clear to the eye, than a picture with less density, or less dots per square inch. Sometimes you want it clearer, sometimes less.

High Cut
Normal things in a room like carpet, drapes, furniture cushions, etc, will give the effect of fewer highs, and more lows. High Cut can be used as a reverb EQ, to trim the highs. This will recreate this natural phenomenon. High Cut is good to use to contour the reverb for the type of musical material as well. For a rock song, maybe there's not much need to cut the highs, but on a ballad to keep the track sounding nice and warm, cutting the highs on the reverb can keep the track sounding warm, and less brittle.

Example 10 High Cut Not on (Bright Sound)

Example 11 High Cut set to 2500Hz (Darker Sound)

Wet/Dry
This is the mix of the source sound, and the reverb.

Example 12 Less Wet More Dry Sound

Example 13 Very Wet Reverb Mix

Ways to use reverb can vary extremely. However reverbs, as all DSP, can chew up your processor capabilities. So you need to use reverb wisely. By this I mean, if you place a reverb on the Snare, another on each tom, another on the piano, another on each of the guitars (four guitar tracks), another on each back up vocal (4 part harmony), another on the lead guitar, and yet another on the lead vocals, that's 15 instances of the reverb effect. That's going to jam most home computer systems so that they won't play. There's just no DSP power after that in your computer.

Now if you place one on the snare, one on all of the toms, one on all of the back up guitars, one on all of the backup vocals, one for lead guitar, and one for lead vox, well, at least your down to six from fifteen. Sometimes to save even more DSP, I'll print or bounce a track with the reverb, then use that instead of the original track with a reverb assigned. I always have the original, but this can be more efficient. Creating Aux tracks and assigning reverb sends from individual tracks helps a lot.

Reverb is definitely a spice to be used to taste. Sometimes all you need is one, sometimes, as we saw earlier, six. It's up to you. Understanding these terms and how they sound and affect your original source, as well as your mix, can only help you in your quest for better mixes.

Play with your reverb for a day. Save the cool ones as presets. Have Fun!

Phil Gates

http://www.philgates.com
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