Optimizing Sound for Reverb
The terms “wet” and “dry” are used in audio to denote a sound with a reverberant (“wet”) sound or a sound relatively free of reverberation (“dry”). The use of effects like reverb are powerful tools for storytelling and conveying a sense of time and place through audio. In literal terms, reverb creates a sense of space by mimicking acoustic reflections, or sound waves bouncing off surfaces. A large indoor space with hard walls reflects sound with a series of long intervals and trails off slowly. A small room with soft surfaces typically reflects sound at short intervals, while dampening reflections at high frequencies and trailing off quickly. Our minds detect these patterns when listening to a recording and recreate a scene of the physical space to match the acoustics.
In addition, we associate various reverb sounds with certain genres of music and can evoke a certain mood through the use of reverb. Popular music trends for reverb changed every decade or so, swinging back and forth between extremely heavy to dry. One only need to think back to the from the ultra-dry sound of Fleetwood Mac and Queen in the ’70s, to the heavy non-linear reverb sound of Bob Clearmountain and Phil Collins in the ’80s, the delayed reverb sound of the Nirvana and the Pixies in the ’90s, the shorter, subtle reverb tails the Eminem and Beyoncé in the ’00s, and to the heavy reverb sounds used by Adele and Mumford & Sons in the 2010s.
Regardless of how you intend to use reverb, the method of creating it has remained mostly unchanged since the widespread adoption of digital reverb generators in the late 1980s. The process typically involves recording sound in a dry, isolated environment, then adding a reverb effect using a digital effect in realtime or in postproduction. This said, there exists a growing number of experimental recording artists that advocate for capturing the final sound result directly to the recording without using external effects. This might involve recording in a warehouse, a bathroom, or another acoustical environment to achieve their desired sound without resorting to digital effects. Capturing the final effect directly to the recording works in this manner wonders when used properly. We’ll briefly address how to achieve such effects, and also explain how it may be inconvenient for certain types of content.
The first step is to create a recording with the least amount of bleed from the acoustical environment as possible. Recording studios are typically equipped with vocal recording booths that deliberately dampen acoustical reflections in the environment. Recording a dry sound can be done easily in a recording studio, but is typically more difficult to achieve when recording in a home, apartment, or office. Fortunately, recording in close proximity to a microphone can offer a tremendous amount of acoustical isolation.
We discussed this in our last post, but recording close to the microphone creates an extreme imbalance between incident sound waves, or waves originating directly from the sound source, to reflected sound waves, or sound bouncing off reflective surfaces. The greater the difference between the incident and reflected sound waves, the more “dry” the resulting recording. For vocals and voiceover, try setting up a microphone in the center of the largest room available, preferably over a rug or carpet, and keep your mouth within five inches of the microphone. The further away from walls and other reflective surfaces, the greater the isolation from the environment, and thus the drier the sound.
For music recording, this can be slightly more difficult depending on the instrument used, but electric guitar and bass amps sound excellent with microphones up close to the speaker drivers. For amps, place the center of the microphone element just above where the speaker cone meets the dust cap.
Instruments with large surface areas like pianos, guitars, and violins can be tricky to record closely since different parts of the instrument contribute different tones to the overall sound of the instrument. For example, piano hammers make a tapping sound when striking strings, but the wood sounding board resonates a with midrange tone. For instruments like these, listen to your microphone while wearing headphones and move it around the room. Keep the mic close enough to isolate the instrument while capturing as balanced of a sound possible.
Adding reverb can be done easily in just about every popular DAW and mixing console. Unfortunately, the specific steps to doing so vary drastically depending on your particular setup, but the overall concept remains the same. Reverb can be added as an insert, placed directly in line with the incoming signal from any audio feed. This is the easiest method, and most computer plug-ins offer a wet-dry mix knob that varies the balance between the reverb sound and the unaffected dry sound. Using this method, you can quickly get started shaping the tone of the combined dry and wet signal, balancing between the two to taste.
A more common method of adding reverb uses an aux send, wherein the dry signal is “sent” physically or virtually to the reverb generator, and the output of the effect gets “returned” to a separate channel in the DAW on mixing board. The concept can be difficult to comprehend at first, the benefits allow for more careful fine-tuning. Having control over the aux return with the reverb allows for customized EQ, delays, and other creative effects. As a bonus, you can use the same instance of a reverb plugin or reverb unit for multiple audio channels rather than copy/pasting the same plugin to multiple channels in DAW, for instance. We’ll cover how to set up aux sends in detail in a future post.
Recording Reverb to “Tape”
A growing number of creative recording artists enjoy capturing reverb sounds live from their acoustic environment or from electronics like amp spring reverbs. This method makes a lot of sense both artistically and in terms of postproduction workflow. Capturing the perfect sound on the microphone without having to adjust it, later on, can save loads of time on the back end. The practice typically involves placing a microphone in a live space with a sound source (say, a vocalist, guitar amp, or piano) while someone moves a microphone around and listens with headphones, finding the perfect balance between the acoustic environment and the instrument. This offers a large amount of control and precision in process, and uses natural acoustics rather than relying on reverb units or software.
The drawbacks are many, however, as this requires a lot of trust in one’s own ability to gauge the right amount of reverb for the application. Our brains interpret reverb in headphones much differently than speakers, making it difficult to anticipate what the listener hears without using a reference playback system. Moreover, capturing sound on location often limits isolation between multiple instruments in the same space, for example, and might not always be practical. Lastly, reverb captured in the mic may not offer flexibility in postproduction unless the reverberant “ambient” mics are captured separately and can be re-mixed later. For highly nuanced and specialty audio recordings, it makes sense to capture natural acoustics live into the microphone. For high volume audio productions, however, we recommend recording dry and adding reverb digitally.
Use reverb judiciously, as too much can sound distracting or unskillful. A poorly-mixed, reverb-heavy sound can be terribly off-putting and turn off your audience in a heartbeat. For vocals, reverb often subtracts from the clarity and intelligibility that makes a diction clear and easy to understand. Even worse, reverb might sound more pronounced on some listening devices than others, with headphones tending to make reverb sound more pronounced than speaker systems. For this reason, make it a point to reference your audio different playback systems whenever you can.
Some distribution media like broadcast television and radio can make reverb sound more pronounced as well. Broadcast stations typically add dynamic range compression to even out the differences between the loudest and quietest parts of the audio feed, and it’s likely that web streaming sites like YouTube and Periscope do the same. Ideally, you could monitor the signal through your distribution media’s effects, but this isn’t always an option.
We find it best to mix reverberation slightly quieter than what “feels” right, expecting some broadcast media or listening environment to make the reverb more pronounced. A recording with too much reverb can be unbearable, whereas a record with too little reverb rarely raises an eyebrow. When in doubt about whether or not to use reverb on vocals, always opt for a completely dry recording. For instruments, especially electric guitars, keyboards, or direct line (DI) feeds from instruments, opt for a subtle amount of reverb to make the instrument sound more “natural”.
Lastly, effect templates and audio presets get a bad rap, yet offer time-saving workflows where production throughput trumps artistic creativity. If your production is known for its artistic creativity and attention to detail, then, by all means, use whichever method you wish. If you’re under the crunch of the clock, then use reverb presets and blend the wet-dry ratio to taste.
We hope this gets you started with reverb, feel free to share any experiences or links to your work. Leave a comment and follow us on social media.