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Reverb for Beginners

by admin on August 3, 2009

Reverb can make a world of difference to your tracks...
Wonderful thing, this reverb. It's the reason we all sound better singing in the bathroom than any other room in the house.The fact is that each environment affects the sound of any noise made within it. Different spaces have their own acoustic signature, and the natural reverb or ambience in a tiled bathroom can enhance the sound of even the most tone-deaf Ronan Keating wannabe.

Now, it may not be the sound of your bathroom, but natural reverb is sometimes used in recordings. With an orchestral recording in a concert hall, for instance, that hall's natural acoustic is an essential and integral part of the overall sound. Likewise, a channel or two is usually set aside for ambient room mics when recording drum kits.

Recording the room reverb with an instrument, however, means you're stuck with it, and committed to using that room sound in the mix, which severely limits the creative options. So, in the majority of studio situations, instruments and voices are recorded with close mics, excluding just about all but the direct sound. Artificial reverb is then added at the mix stage to enhance the sounds and build a coherent overall sound, in terms of stereo width and front-to-back perspective.

Why use reverb?
In the context of making recordings, reverb in the mix helps to create the overall three-dimensional sound picture. Generally, the more reverb added, the further away a sound may appear, and that can help place it in context with the other sounds in the track.

Instruments recorded using close miking and instruments that have been DI'd have a lack of ambience that can sound quite unnatural. Adding reverb gives them a sense of space and smoothes out the sound, blurring the edges and helping to layer them together.
Effectively, it enables sounds that were not recorded at the same time in the same room to blend together into a cohesive overall sound. In this respect, it could even be said that reverb is the glue that holds a production together.

Used in a less subtle fashion, reverb can also be relied upon for the odd special effect, although whether we really want to hear those huge '80s-style exploding snare sounds again is open to question!

How do we get reverb?

The ubiquitous digital reverb unit is the main source of artificial reverb in most studios these days. It is compact and versatile with plenty of control over parameters, but prior to its invention reverb was generated in other ways.
An early method of creating reverb was to use a chamber - a small room lined with tiles or other reflective surfaces and housing a speaker and microphone.

The sound to be affected was sent to the speaker with the resultant sound captured by the microphone and brought back to the mixing desk. Variations were obtained by changing mic and speaker positioning. This is an approach that can still be applied if a room with a suitable ambience is available - lift shafts, stairwells and tiled bathrooms can all be put to good use in the right circumstances.

The reverb plate offers an electro-mechanical approach to creating reverb. Plates are large sheets of metal suspended under tension with transducers attached, and the vibration of the plate produces the reverb, with damping applied to vary the sound. With a sound of its own, distinct from the sound of a miked room, plate reverb has become a familiar sound in popular music over several decades, and all digital reverb units usually contain simulations of plates as standard.

There have been other ways to produce reverb, too. Spring reverb works in a similar way to a plate, but using a spring instead of the sheet metal. Spring reverbs are mainly found built into guitar amps, but there have been standalone models made for studio use. The sonic character of a spring reverb is of limited use in music production, however.

Some reverb units can be used as true stereo in/stereo out units, but mono in/stereo out is usually the way to go - generally how it is in nature, with any mono sound source generating reverb in all directions.

Reverb is usually added to the mix via an auxiliary send, so that one reverb can be used on as many mixer channels as desired, with the aux send pot on any particular channel sending a portion of the sound from that channel to the reverb unit. The aux send should be of the post-fade variety, so that any adjustment of the channel fader is reflected in the level sent to the reverb. The aux send is connected to the reverb unit's input, and the reverb unit's outputs are connected either to a dedicated stereo return on the mixing desk or to two spare channels.

As the reverb is stereo, the pan pots on the two channels can be panned apart, with the actual amount of panning used being a matter of taste - extreme panning could leave the reverb a little too exposed (this might sound good in stereo) but decreasing the panning width could help mono compatibility. The reverb unit should be set so that the output is reverb-only. (The global wet/dry mix should be set to 100% wet.)

An alternative way of connecting a reverb unit, although not common practice, is to use it in-line to add a touch of overall reverb to a finished track. To do this, the correct balance between the original signal and the reverb must be adjusted using the unit's wet/dry mix control.

Reverb types
Reverb units usually contain a large number of different-sounding presets that can be further edited to suit your specific needs. The types of reverbs you will find in most digital units are defined by a small number of categories - usually hall, room, plate, ambience, gated and reverse. There are likely to be a number of reverbs in each of these categories, each with different parameter settings and a descriptive name relating to its characteristic sound or likely use - for example, vocal plate, thin plate, bright room, drum room, and so on.

Hall reverbs simulate the acoustics found in large spaces such as a typical concert hall. The reverb density tends to build up over time and there will be a long reverb tail. A hall reverb can be useful when trying to put some front-to-back perspective into a mix, as it can help to make sounds appear to be further away.

A room reverb recreates the sound of a room in all its different guises and is suitable as a good all-round reverb for instruments.
Plate simulates the previously mentioned electro-mechanical plates - generally, the sound would be distinctive and quite coloured. The plate sound has long been a staple sound in music production, and is a good choice to use on vocals and drums.
Ambience programs are not found on all reverb units, but are intended to give sounds a sense of space, without actually colouring the sound. They can be used to put some 'air' around close-miked sounds.

Gated reverb was originally created by taking the ambience from a live room and using a noise gate to cut it off abruptly so it stopped dead rather than decaying over time. In a digital reverb unit this effect is created electronically and the exact length of the reverb before it cuts out can be precisely set. Gated reverb tends to be used mainly on percussive sounds and can sound quite aggressive. Reverse reverb is really reverb with a reversed envelope applied to it so that it builds up in level after the original sound and then cuts out.

Digital reverb units invariably have plenty of parameters to edit - some more so than others - but there are a select few main parameters that can really make a difference when adjusted.
Predelay is effectively the time between the direct sound and the first of the reverb reflections - very useful in that it can be used to put a bit of separation between the body of reverb and the dry sound. This has the effect of adding more space to vocals without making them sound further away or swamped by the reverb.

Reverb time, sometimes known as decay time, sets the length of time before the tail of a reverb dissipates into silence. Long decay times can work well on some sustained sounds, but overuse can clutter up a track by filling all the gaps with reverb.
Take note of the song's tempo when adjusting the decay time. A shorter time might be more appropriate for more uptempo compositions, whereas a vocal in a ballad could be enhanced by a longer decay.

High frequency damping adjusts the rate of decay of the high frequencies relative to the rest. There may also be some overall EQ adjustments for rolling off the top or bottom end of the reverb that can help the reverb sit in the mix, without having to use the desk EQ. Less top end on the reverb can make a sound appear less obviously reverbed, yet still give it a sense of space.
Other adjustable parameters found on many units relate to the level of early reflections in the sound and the density and diffusion of the reverb. Percussive material generally benefits from a reverb with little or no early reflections as these can often sound quite distinct and confuse the issue.

Using reverb
There are no rules governing how many different reverbs you can use in a track. One reverb could be used on everything to give all instruments the sense of being in the same space, or a different reverb can be used for each instrument or group of instruments - a typical example being to use one on drums, one for vocals and one to treat all the other instruments - with typical settings being a short and bright reverb for the drums and a longer warmer one for the vocals.

At the same time, if you're using several different reverbs in the track it's possible to use more than one reverb on a particular sound - the lead vocal, for example - where a reverb with a short decay could be layered up with one with a longer decay for effect. When using several reverbs, be careful not to clutter up the whole track. In other words, don't get bogged down in making minute parameter adjustments and lose track of the big picture.

It's all too easy to swamp a track with reverb - add too much and it can soon fill up all the space in the track, making it sound muddy, losing definition and making sounds seem distant. Piling on too much reverb is a common beginner's mistake, as is spending disproportionate amounts of time editing parameters. Just because digital reverbs have loads of parameters to edit, it doesn't necessarily follow that they have to be adjusted every time a new preset is selected. While soloing a track and listening to it with reverb will let you hear the minute details, once bedded into a track one reverb can sound remarkably similar to the next one. That's not to say that time shouldn't be spent finding the right reverb for the job, but bear in mind that it's the amount of reverb used in a track that is the most crucial of factors in your use of the effect.

Although digital reverbs often have EQ parameters to edit, using mixing desk EQ on the reverb returns can pay dividends. Turning down the high frequency can not only soften the reverb and help it sit in the track, but it will also help to keep in check.

Rolling off the bottom end will help to clean up any murkiness or muddiness in the track, leaving more space for kick drums and basses, instruments that, incidentally, work well with little or no reverb. Using a bright-sounding reverb on a voice that is naturally sibilant will more than likely exaggerate the sibilance. If you like the natural sound of the voice and don't want to de-ess the dry sound, try de-essing the send to the reverb unit. And for special effects, connecting any outboard processor between the aux send output and the input of the reverb unit will, in fact, affect the sound of the reverb. Try a fuzzbox or some radical EQ for a unique sonic flavour.

Mix and match
The contrast between different reverbs can be used for dramatic effect and to give added interest to sections of a song. Consider the possibility of using one reverb on a sound for a song's verse, then switching to another reverb for the chorus to give it a lift. Most digital reverbs are equipped with MIDI, so it's a relatively simple procedure to switch programs or parameter settings mid-track with a sequencer.

Adding a touch of reverb to a dry sound is the usual way of going about things, but just using the reverb without the dry sound can create a nice ethereal sound that can add interest to a track, working particularly well on backing vocals and keyboard pads. Simply take the dry sound out of the main buss routing to achieve this.
Reverb sounds with a bit of movement in them can be created by adding a touch of flanging or chorus. Many dedicated reverb units now have this optional modulation as standard, and if you are using reverb from a multi-effects unit, the reverb can usually be combined with all manner of effects - a touch of pitch-shifting, perhaps?

All the advice so far has been for using reverb in the mix, but it can also be used at an earlier stage in the recording process. When taking samples, we often have to truncate the end to get rid of any unwanted sound, but run the risk of abruptly cutting short any ambience in doing so. This ambience can be replaced using a digital reverb. After shaping the envelope of the tail end of the sample run it through the reverb unit and resample the whole sound with its new reverb tail.

The acoustics of reverb

The human brain is adept at estimating exactly what environment it's in purely from the sound of the reverb in that environment - anyone wearing a blindfold and clapping their hands would have a pretty good idea of the size of the room/space they were standing in purely from hearing the reverb.
Reverb is a complex phenomenon created by sound reflecting off the walls, ceiling and floor reaching the listener's ear over a period of time. The results are dependent on the size and shape of the space and the materials it contains or is made from, including any soft furnishings such as curtains and carpets.

Any sound in a room - a hand clap, for example - will generate sound waves in all directions at, oddly enough, the speed of sound. The original hand clap sound will travel a direct path to reach the listener first, followed quickly by sound that has been reflected off the walls and various surfaces in the room. The larger the space, the longer the first of these reflections takes to reach the listener, and it's this delay that gives us an immediate clue to the size of the room.

These early reflections may be heard as distinct echoes. As these reflections hit the various surfaces they generate yet more reflections so that the number of reflections arriving at the listener increases over time. This occurs so rapidly that we hear them blurred together, perceived not as individual reflections, but as an overall wash of reverb.

Sound energy is diminished as it travels through the air or is absorbed by the surfaces in a room, so as the reflections increase in number, subsequent ones have less energy and the reverb decays down to silence, the reverb tail tending to be longer for larger acoustic spaces.
Another factor is that the spectral content of the reflections changes as different frequencies are absorbed or reflected by different surfaces. In effect, the reverb tail lasts for different durations at different frequencies, the higher frequencies tending to die away quicker than the lower ones.

The designers of digital reverbs take account of all these natural mechanisms when creating their programs, and usually provide adjustable parameters that simulate them. Using these, we can create the illusion of any acoustic environment as well as a few that have little or no basis in reality.

Digital reverb round-up
Anyone wanting to buy a hardware digital reverb unit for the first time doesn't have to spend vast amounts of money to get hold of a good-sounding unit. Take a look at the selection below, all of which you can pick up for less than $999.

Lexicon MPX100 ($400)
Lexicon is, without a doubt, the prestige name in reverb. The sub-$400 MPX100 is the most cost-effective way to get some of that Lexicon sound with its smooth and detailed reverbs. A multi-effects processor, the MPX100 has 256 programs onboard, 240 of which are factory presets with the remaining 16 allocated as user memory locations.
Effects are either single effects or dual effects, which combine, say, flanging or chorus with either reverb or delay. Editing is very basic, yet effective. A single rotary knob tweaks the sound by adjusting a combination of the most critical parameters for a particular program simultaneously. For example, the 'liveness' of a reverb is changed by the decay time, EQ and early reflections being adjusted at once by a turn of the knob. MIDI control of front panel functions is also possible.

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Anyone with more than $500  to spend on a Lexicon would find more sophistication in the company's newer MPX500 unit. Shop around and you could also find the earlier MPX1 at under $999, which offers more editability and parameters to tweak.

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TC Electronic M-One ($500)
TC's new budget M-One might be a multi FX unit, but the emphasis is fixed firmly on its reverb capabilities. Types of reverb featured include hall, room, spring, live, ambience and two different plates. The M-One boasts two effects engines that can be configured in six routing options covering parallel and serial routings as well as a dual-mono mode that sets the unit up to act like two separate mono processors.

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Roland SRV-3030 $500
The SRV-3030 is Roland's 24-bit dedicated reverb processor. Featuring 100 factory programs and a further 100 user memory locations, the 3030 uses two reverb engines to create its effects, with additional processing available in the form of an effects block for modulation and 3D-style spatial movement via implementation of Roland's proprietary RSS system.

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Great depth of editing is available in the SRV-3030, but a three-tier system is in place so that you can dip into it on a level that suits, with three main parameters available on dedicated front panel knobs at all times. Two unique features set the SRV-3030 apart from its rivals. Dynamic Separation allows two different reverbs to be applied to different elements of the same sound source. This is set with a user-programmed template on the basis of dynamic level, frequency or note density. Thus, a drum loop could be treated so that there were different reverbs added to the kick and the snare. The other unique feature is that the SRV-3030 has onboard samples of various instruments that can be used to audition the reverb sounds.
Zoom represent the budget end of the effects market, especially as their RFX300 can be picked up for under $150. The RFX1000 is a more sophisticated unit, but can still be had for $200 if you shop around. A multi-effects unit, in the sense that it covers a full range of effects (there's even a vocoder onboard), the RFX1000 has 33 program types, each with 11 different variations of the program.

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11 of the 33 programs are reverbs, so with all the variations there are effectively 121 different-sounding reverbs to choose from, covering a whole range of applications. Editing couldn't be simpler - there's only one parameter per program to adjust, and for the reverbs that parameter is reverb time. There's no MIDI, but the more costly RFX2000 has that, if desired.

Sony's reverbs, it's probably fair to say, have never really achieved the high profile of their competitors' products, but are, in fact, classy performers that deserve more attention.

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Reverbs (including halls, rooms and plates) are available to cover most eventualities, and with the unit's four jack outputs it can be configured to work as two separate stereo processors, which happily sets it apart from most of the other processors in this price bracket.

Lexicon -
TC Electronic -
Alesis -
Yamaha -
Roland -
Zoom -

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