Production 512: My, What A BIG Room You Have! - A Beginner's Guide to Reverb

Prod512 Logo 400pxThis month, another beginner’s guide, this time with a nod to Reverb! This is one tool that is very often misused – mainly, I think, because as radio people we seldom think in terms of subtlety. Most of the time, I hear too much ‘verb on the sound coming out of my smart speakers/radio. As we delve into the nuts and bolts of this tool, please remember that very little can go an awful long way. There are many considerations when using reverb aside from how much, including track placement, early reflection, stereo image, surface type and distance. It can get way out of hand very quickly, becoming a swirling nightmare of factors that are seemingly impossible to juggle, especially for someone new to the production world.

Let’s get on the same page with a definition. Reverb – The sound of a space. Notice it says ‘a’ space, not just space in general. The ‘a’ is critical.

No matter where you find yourself, the room you’re in or even just outside of it, has its own sonic signature. Bathrooms typically have a lot of tile and thus a lot of reflected sound. A bedroom most often has three walls, mainly covered with photos, posters or paintings and one wall with windows and usually a door opening to a bathroom or hallway. A kitchen has some tile, wooden (or plastic) cabinets, some metal appliances and windows with an opening to a dining or living room. EVERY room has a sound that is unique. Madison Square Garden has a sound signature that is different from every other arena in the world. While it might be similar to American Airlines Arena in Miami, their dimensions are different, the scoreboards are different, the large screen monitors are different…making their individual sound signatures different.

Natural reverb is the baseline. A natural sounding reverb is our goal, and until very recently, almost impossible to achieve. The road to that goal has been long, and for quite awhile, each and every attempt has produced worse results than the one preceding it.

There are a thousand different things that go into reverb. The size of the room, the size and quantity of reflective surfaces, the size and quantity of sound-absorbing surfaces, even the air pressure and humidity come into play. The math involved in calculating all of that (and more) is astronomical in scale. It’s pretty amazing that we can dial up some decent reverb in a plug-in.

There are basically FOUR types of artificial reverb available to the discerning audio engineer, beginning with:

Chamber Reverb – One of my first gigs (pre-radio) was a gofer at LA East Studios in Salt Lake City, Utah. It was originally built in the basement of a big, old, church on the West Side of the downtown district. Warner-Chappell has long since remodeled the entire building into one of the nicest recording facilities anywhere. They converted the chapel into a fantastic large-scale studio, capable of handling a fairly big orchestra. But, back in the day when I was there, the chapel served as a most amazing reverb chamber. They’d put a speaker at one end and a mic at the other and route the sound back into the mix. This was a fairly common practice in the early days of music recording. Using a real space to create the illusion of space wasn’t so much a luxury, but more a necessity. Big recording studios all over the world had rooms dedicated to making ‘artificial’ reverberation a part of their mix.

Plate Reverb – Smaller recording facilities simply didn’t have space to dedicate an entire room to it, so they had to find other means of creating the effect. The first was “plate” reverb. The plate was a massive metal plate that was suspended in a box with metal springs. They would bounce a signal directly to the plate and use pickups (like on a guitar) to capture the results. Did I mention these plates were pretty huge? Yeah, that didn’t really solve the space problem smaller studios had. Even though they didn’t have to use an entire room, they still took a lot of real estate. The EMT 140 for example is 7-feet long, 5-feet high and 18-inches wide. Not ideal. And, to be objective, the reverb they created really didn’t sound natural at all. It was better than no reverb at all and a lot of classic recordings in the '40s and '50s used the plates and created a sound of their own that endures to this day.

Spring Reverb – Somebody said, “Hey, let’s just skip the plate and just use the springs!” (Well…it coulda happened!) The idea was a hit with the guitar crowd. Finally, a reverb unit small enough that they could actually fit it inside their amplifiers; a metal box filled with springs, hit with a signal at one end and picked up on the other. It sounds even less natural than a plate, but once again they created a new sound that became the signature of the surf guitar genre. In 1963 The Chantays had a big instrumental hit with a song called Pipeline, a musical ode to surfing. Their bassist used a spring reverb on his amp that gave his instrument an annoying clicking sound with every note, but it became iconic. Weird, huh? Here they are performing it live on the Lawrence Welk Show

Digital Reverb Processor – This would seem to be the final step in the evolution of Reverb, but in fact, I divide this step into two parts. The first part is the algorithmic box, an external unit. (The plug-ins didn’t come until later.) They use filtering, delay and pitch-shifting to approximate the sound of various spaces from small bright rooms to stadiums. Lexicon™ is the name that pops immediately to mind. They were the real pioneers in the algorithmic reverb world. The second part of this stage happened when they introduced a plug-in version. They were the ONLY ones that even came close to sounding natural. Evan Brooks and Peter Gotcher, the guys who invented Pro Tools™, tried to get Lexicon™ to throw in with digidesign™ so they could sport the most respected name in reverb on their DAW, but Lexicon™ said no. Evan Brooks got a little miffed so he sat down one night and did all the math to figure out the Lexicon™ algorithm. He succeeded and then the dam broke. Before you knew it, there were plug-ins popping up everywhere and Lexicon’s stranglehold on the DAW reverb world was shattered.

This is where we are now…at least most of us.

When you pop open a reverb plug-in now, you are confronted with a bewildering array of controls. Once you play with them for awhile, you will kind of figure out what’s what, but I’ll try to explain some of them here:

Life – (Early Reflections) Adding sounds caused by reflections of the original signal, much the way sounds are reflected from the walls or ceiling. Most of these sounds come from 5 to 100 milliseconds after the original and tells the brain about the dimensions of the room.

Space – Sounds are not just reflected once, but many times, filling the space with copies of the original sound that get weaker and weaker with time. A tiled space, like a bathroom, has a lot of reflections that die slower because of the glossy surface being a better reflector. More space equals more third and fourth generation reflections.

Distance – This controls how far away the original sound is from the listener. If you’re sitting front row at a concert, distance is minimal. If you’re in the back, up in the nose-bleed seats, you’re about as far away as you can get.

Room Size – How many cubic meters the room you’re emulating really is. A room size of 8000m3 would be a room that is 20mX20mX20m, a very large room. Madison Square Garden is about 15,000m3, more than double our very large room. A typical living room might be 48m3.

Decay Time – Usually measured in seconds, this determines how quickly all the early reflections and reverb fade away.

Is your head beginning to swim? Your eyes getting blurry? Don’t worry. You’re not alone. (“Nobody told me there would be mathing!”) Here’s the good part. Now that you have a reasonably good understanding of what all these controls do, you can play around with them until you find something that sounds about right. I know that’s not terribly helpful. Sorry, not sorry. It is what it is.

Something more helpful is pointing out that most plug-ins come with a raft of presets that can get you really close to the right sound you’re looking for, including plate reverb and spring reverb settings. I know, they are not very natural sounding at all, but there is a huge demand right now for that certain “retro” sound, which these deliver perfectly.

Remember, I said “This is where we are” earlier?

The next revolution in reverb has already hit. It’s called “convolution” or “impulse” processing. It’s software based, so I’d imagine that plug-ins will come down the pipeline soon, but as of now, this is extremely high-end stuff. These systems use recordings of actual natural spaces to mathematically recreate the response of that space and apply it directly to your signal. If you were trying to make a recording sound like a concert at Madison Square Garden in New York, this software will make it really sound like the Garden…exactly. Finally, we’re getting back to a truly natural sounding reverb!

Until convolution or impulse processing becomes available to the average Joe or Jill, we are where we are and we need to be extremely critical of what we design for our sounds. This is most assuredly, a ‘less is more’ kind of thing. Ease up on the decay time. Even in a very large venue, the decay time will almost never be more than a couple of seconds. If you use more than that, you are moving beyond anything natural sounding, and while that is not a crime, it can be distracting. Distracting is bad…usually.

Comments (1)

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"Less is more" indeed!

Reverb does not make a voice bigger. It makes it farther away.
Generally, big things are farther away... but (in a normal room) a giant monster in-your-face will have less reverb than an announcer ten feet away!

If you want an intimate sound, dial the reverb down or totally out. Let the listener's office/bedroom/car acoustics provide the only reverb. It'll sound more like the talent is talking directly to the individual listener.

From a film-mixing point of view (I left radio about 15 years ago), voice reverb is used primarily to make studio replacements match location dialog. Voice-overs, unless they're the character talking from their dialog world, have little or no reverb.

Jay Rose
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