The difference in both cost and complexity between a budget reverb unit and a top-flight studio model is enormous -- but this doesn't necessarily mean we should assume that low-cost reverb units are little more than toys. If a heavyweight Lexicon reverb costs as much as a small car, exactly what kind of result can you expect from a reverb unit that costs about the same as a bargain basement mountain bike? The only way to find the truth is to get a few reverb units together and compare them -- and what I've recently discovered is that a good many budget reverbs are capable of producing far more natural results than their presets might lead you to believe.
In recent years, effects units have increased in audio bandwidth from around 12kHz to the current norm of 20kHz -- but you don't need anything like a 20kHz bandwidth to create a decent reverb. Analyse a real-life concert hall, and you'll find that little is going on above 5kHz -- and even in a live room with stone or tiled surfaces, the reflected sound is noticeably warmer than the original dry sound. This is borne out when you check the parameter values relating to some of the classic Lexicon reverb patches -- only the obviously unnatural reverbs have very wide bandwidths.
Plug in any budget reverb, and you'll probably find the designers have tried to impress you by creating long, bright, spacious effects where the early reflections fly around like shrapnel. This is fine where you want such an effect, but real rooms, halls and plates just don't behave like this. Early reflections don't sound like ripping cloth and reverb tails don't sound like escaping steam -- and even if the effect is artistically pleasing sometimes, it can really mess up the sound you're trying to process unless you really know what you're doing. Vocals become unintelligible and harsh, drums sound as though they're accompanied by a hail of arrows slamming into a wooden door, and guitars just become edgy and cluttered. Switch to a more natural-sounding reverb, and the original voice or instrument appears in its own three-dimensional, virtual space, with the reverb playing more of a supporting role. I suppose it's rather like lighting a theatrical scene -- you could use a hard white spotlight that looks like the inside of Mr Spielberg's fridge, but if you're after a natural effect, then a softer, warmer light will work better.
It's all very well knowing what a natural reverb sounds like, but how do you coax that from your own effects unit? I decided to spend a few hours experimenting with my Alesis Midiverb 4, and I came up with quite a few interesting patches that were worryingly similar to those produced by far more expensive units. I'm not going to say that you can make your budget unit sound like a Lexicon PCM90 -- that would be raising unfair expectations (in my opinion, Lexicon still have a clear lead in this area) -- but it's often possible to come far closer than some budget reverb presets suggest. The idea behind this article is to dissect some of the more popular reverb types, and see how the key parameters can be adjusted to optimise them. Although I used a Midiverb 4, the same techniques can be applied to virtually any programmable effects unit with a fair degree of success.
Plates are often considered to be very bright because of the mechanical properties of sheet metal, but in reality, it is usually necessary to add a lot of EQ to a real plate reverb's output to subdue its metallic overtones, and make the sound warmer and less cutting. Plates also produce a very dense reverberation because of their small physical size (the reflections build up in complexity very quickly), and for the same reason, there are no really well-defined early reflections. The reverb time of a typical plate is usually around three to four seconds, though a shorter decay time can be obtained when necessary by applying subtle mechanical damping.
To emulate a warm plate with my Midiverb 4, I chose a basic plate algorithm, with a decay time of 2.7 seconds, low-frequency damping at 100Hz and high-frequency damping at 10kHz. Density and diffusion were set to maximum, and no pre-delay was used. Most importantly, the low-pass filter was set to 5kHz and Swirl was set to around 10. Swirl is a little like putting chorus on the reverb -- if your effects unit doesn't have it, you can add a little gentle chorus before the reverb, or miss it out altogether. Note that the values given aren't exact, as the Midiverb 4 parameters increment in rather weird steps.
If you have a machine with very little parameter editing (such as a Lexicon Alex), you can feed your reverb returns through a pair of mixer channels and use the EQ to roll off a little top end. Listen to the reverb as you adjust the EQ, and try to get to the point where the roughness created by the individual reflections just disappears. This particular patch works well with percussion, piano and acoustic guitar, though it is by no means limited to these. Try using the same parameter values with Room rather than Plate algorithms -- sometimes you can get a surprisingly good alternative result.
The drum room has similar characteristics to a plate, except that it is based on the Real Room algorithm, and is slightly brighter. Once again, set the Diffusion and Density parameters at maximum, and use no pre-delay. This time, the reverb time is 3.0 seconds and the high-pass filter should be set to 7kHz, with the high-frequency damping at around 5.5kHz. If you have a low-frequency damping parameter, this can be set to around 300Hz, but it doesn't matter too much if you don't have one. If Swirl is available, this can be set to suit your taste somewhere between 25 and 75%. The result is a warm but quite articulate room effect, with a 'woody' sound eminently suitable for drums and percussion.
This is a good room for choral recitals, and has a medium decay time of 2.5 seconds to prevent the sound from becoming too spread out. A pre-delay of 20 milliseconds helps introduce a sense of room size, but the first reflection level is kept at zero. I usually find that with pre-delay values of less than 20 milliseconds, having an audible first reflection just makes the sound phasey and unnatural. Density and Diffusion are back up to full on this setting, but the low-pass filter is right down at 3kHz to keep the room warm. High-frequency damping is set at around 6kHz, and Swirl is again optional. The result is a very convincing hall effect, which can be used to underpin choral vocals or backing vocals without overpowering them. If you listen carefully, you can hear the sound bouncing off the wood panelling and plaster alcoves!
Take the previous patch, extend the reverb time to 4 seconds, increase the low-pass filter to 6kHz, drop the high-frequency damping to 4.5kHz, and you have a typical concert hall patch, which is great on classical sounds, pad synths, string pads and solo acoustic instruments. Swirl can be added for more shimmer, and the decay time can be increased further for New Age music. This is a very useful stock patch, which can be quickly tweaked to suit a number of requirements.
Yet another refinement of the basic hall patch is to brighten it up even more for use with pop vocals. Even though this is quite a bright reverb, the low-pass filter is still only set at 7kHz, and the high-frequency damping is at 6.5kHz. Pre-delay can be varied from nothing up to about 80 milliseconds, but the first reflection level should be kept down to zero. Reducing the Density and Diffusion parameters to between 50 and 75% makes the early reflections more discernible, adding interest to vocal sounds. Swirl is optional up to 50%, and, like the other patches where low-frequency damping isn't mentioned, none is necessary, unless you feel the reverb tail is getting a little boomy. Personally, I find rolling some bottom end off the reverb return channels is usually more effective in curing this.
My final patch is based on a Plate algorithm, and has a short decay time combined with a bright decay and a prominent first reflection to create a slight thickening effect. The decay time is around 1.6 seconds, with maximum Diffusion and Density settings, while the low-pass filter is right up at 10kHz to keep the first reflection fairly bright. The high-frequency damping is set at 4kHz to stop the reverb tail from being over-bright, and a pre-delay of between 12 and 50 milliseconds may be used, depending on how obvious a doubling effect you want. The low-frequency damping is set at 100Hz, though a little low end roll-off on the reverb returns will do just as nicely. This patch creates a small room sound, but with an enhanced sense of space. It is reasonably lively, and useful for vocal thickening or adding depth to solo instruments.
The outcome of this brief spell of research is that a great many preset reverb patches are too bright to be useful, and only end up confusing a mix. Even a modest reverb unit sounds more natural with a little top end rolled off, and if you have access to low-pass filter and high-frequency damping parameters, you can make vast improvements to existing patches very easily. The brightest patch I've described in this article has a low-pass filter frequency of 10kHz -- so remember that you don't need a 'DC-to-light' frequency response to get realistic-sounding reverbs!
With very cheap effects units, using the desk EQ rather than the patch parameters can help the overall sound quality, because any top cut applied after the effect will also reduce the noise produced by the unit. It also pays to take a set of parameters and apply them to a different algorithm to see what happens -- for example, a room patch can smooth out a plate patch, while an ambience patch might make a hall patch less dominating.
Another important thing I've learned is that if you have a decent reverb unit, there are very few parameters you really need to change in order to get close to the sound you're after. In most cases, you just need to pick the basic algorithm, set a suitable decay time, and then juggle with the high-frequency damping and the low-pass filter. Everything else is pretty much secondary, though you'll probably want to adjust the pre-delay as well.
My experiences have shown me how good budget reverb units can sound; the big names definitely have the edge on overall quality, realism and flexibility, but the little guys aren't nearly so far behind as the huge price differential might have you believe. As in so many areas of life, the law of diminishing returns holds true -- in this case, the law of diminishing effects returns!
This patch is designed to provide an intimate 'club' feel, with a fairly short decay time. It works well with jazzy vocals, but can be used to place just about any instrument in a smallish, live environment. Here, the decay time is around 1.7 seconds, with both the Diffusion and Density set to 75%. There should be no pre-delay, the low-pass filter should be set right down at 3.5kHz, and the high-frequency damping should be at 6kHz. The basic reverb algorithm should ideally be some kind of room; I used the Midiverb 4's Real Room with just a hint of Swirl.
If you're new to the world of effects processors and reverbs, and are unfamiliar with some of the terms employed in this article (early reflection, plate, high-frequency damping, pre-delay, etc) check out Paul White's article 'All About Reverb' from the September 1993 edition of SOS. Back copies of this issue are available from SOS priced at £2.50 per copy, plus £1.25 UK postage, £5 overseas.
This is a short ambience setting, similar to the Vocal Ambience patch (see separate box), except that the decay time is pulled right back to 1 second and the Diffusion and Density should both be down at 30% to add more coloration. Both the low-pass filter and the high-frequency damping are set to 5kHz, and Swirl can be added up to 50%. As a rule, adding Swirl (or chorus) on the input is OK for most sounds, but may produce an obvious chorus effect when used with piano or similar instruments. If the modulation becomes noticeable, reduce the amount or remove it altogether.