RE­VER­BER­A­TIONS PART ONE

ROB LONG APOL­O­GISES FOR THE DE­LAY IN GET­TING THIS STORY TO YOU…

Australian Guitar - - Home Recording -

This will be a two-part ar­ti­cle: part one dis­cusses the fun­da­men­tals of dif­fer­ent re­verb types, while part two will serve as an in-depth work­shop on us­age.

Af­ter EQ and com­pres­sion, re­verb is prob­a­bly the most used ef­fect in record­ings. Like all pro­cess­ing ap­pli­ca­tions, though, there are many vari­ables, and pro­duc­ing a great re­sult re­quires a good un­der­stand­ing of the pos­si­bil­i­ties, and dis­cre­tion in choos­ing the most ap­pro­pri­ate type of re­verb for the ap­pli­ca­tion.

Reach­ing for a generic re­verb as a ‘tal­ent en­hancer’ to pla­cate a vo­cal­ist is quite of­ten the first thing that hap­pens af­ter the artist hears their vo­cals back through the mon­i­tors. It’s of­ten a re­ac­tion to hear­ing them­selves raw and recorded cleanly, with­out the usual bounce and rum­ble that they're used to hear­ing through PA speak­ers at gigs or in re­hearsals. Vol­ume, re­flec­tions and the blend­ing of au­dio sig­nals gen­er­ally mask im­per­fec­tions, and of­ten give an ‘en­hanced’ im­pres­sion of the ac­tual per­for­mance.

In de­fence of the con­fronted per­former, it’s im­por­tant to re­alise that this is tra­di­tion­ally how live mu­sic is heard, both by the mu­si­cians and their au­di­ence – in a live space which has in­her­ent re­flec­tive prop­er­ties and re­ver­ber­a­tion char­ac­ter­is­tics. Thus, the dry, clin­i­cal sound of the raw stu­dio track – un­en­hanced and naked – is un­nat­u­ral and con­fus­ing to the ear, and makes many peo­ple feel in­se­cure about their abil­i­ties.

But of course, re­verb is not just about repli­cat­ing nat­u­ral spa­ces, mak­ing peo­ple feel com­fort­able or mask­ing is­sues. It’s also used as a creative tool to cre­ate at­mos­phere, give a larger-than-life sound to a recorded part, lengthen note de­cay times, dis­tin­guish one sound from another, and to com­bine sound sources like sonic glue.

Let’s look at the most com­mon types of re­verb. Re­verbs can be bro­ken into two main cat­e­gories: nat­u­rally oc­cur­ring and man­u­fac­tured. The nat­u­rally oc­cur­ring types re­fer to re­ver­ber­a­tion heard in spa­ces or rooms. The most com­mon man­u­fac­tured types come from phys­i­cal de­vices – the spring re­verb and the plate re­verb. WEL­COME TO MY CHAM­BER

One of the ear­li­est and sim­plest ways of cre­at­ing re­verb af­ter the fact was to play a sound source back through a loud­speaker placed in a re­ver­ber­a­tion ‘cham­ber’, then rere­cord the re­sult­ing sound back to tape. These cham­bers could be ei­ther a specif­i­cally de­signed re­flec­tive space, or an ex­ist­ing, adapted space. Vari­a­tions could be made by us­ing dif­fer­ent ma­te­ri­als on the sur­faces, dif­fer­ent sized rooms, and by vary­ing the dis­tance from the mic to the loud­speaker.

Cham­bers built be­low Abbey Road Stu­dios were used by The Bea­tles for vo­cal ef­fects. John Bon­ham got the drum sound on Led Zep­pelin’s “When The Levee Breaks” by set­ting up at the base of a stairwell, while mics were placed at var­i­ous points above him. HAIL THE HALL

Hall re­verbs sim­u­late the sound of real, ex­ist­ing halls of var­i­ous shapes and sizes. There’s usu­ally a clus­ter of ini­tial re­flec­tions fol­lowed by a long de­cay time of be­tween 1.2 and three sec­onds, with a high fre­quency roll-off over time. Many fa­mous con­cert halls around the globe have been sam­pled for use in dig­i­tal re­verb units and plug­ins – these types of re­verb can add am­bi­ence and depth to a mix, sus­tain notes, and cre­ate a sense of depth and ‘majesty’. Overuse or mis­use on

un­suit­able sources can cre­ate mud and boom, and gen­er­ally wash out a mix.

ROOM SER­VICE

Room re­verbs, as the name sug­gests, are cre­ated to sim­u­late the sound of var­i­ous types and sizes of rooms, tak­ing into con­sid­er­a­tion the sur­face ma­te­ri­als as well. The smaller rooms mean faster de­cay times and less boom. Room re­verbs are gen­er­ally used to put a very dry sig­nal into a more 'live' space. It’s of­ten the case that in a smaller bud­get stu­dio, it’s eas­ier to cre­ate one dry, non-re­flec­tive, multi-pur­pose record­ing space then ap­ply an ef­fect to that sig­nal later. Other­wise, ev­ery­thing you record will es­sen­tially sound the same. You can add re­verb to a dry track, but you can’t take it off a wet track.

Small room re­verbs can also be used as a kind of slap­back echo: try us­ing a short de­cay, then dial in a lit­tle bit of pre-de­lay to get a quick re­flec­tion. Over­do­ing short re­verbs can make a record­ing sound like the mics were too far away from the in­stru­ments, though, and work neg­a­tively on clar­ity and fo­cus.

FILL UP YOUR PLATE

A plate re­verb is lit­er­ally a steel plate sus­pended un­der ten­sion by springs in the cor­ners where the plate at­taches to the outer shell or frame. The plate vi­brates via a sig­nal from a trans­ducer, and the vi­bra­tion is sensed else­where on the plate with a con­tact mi­cro­phone. Tap­ping a large me­tal plate and plac­ing your ear in close prox­im­ity will give you some idea of the way this works.

Plate re­verbs don’t add the same kind of depth and ‘dis­tance’ to sounds as hall re­verbs. They tend to al­most merge with the source to re­in­force it, rather than throw it into a space. Thus, they can make vo­cals sound fat and lush, while mak­ing a snare more pow­er­ful and adding char­ac­ter.

SPRING IS IN THE AIR!

Like plate re­verbs, spring re­verbs work by send­ing a small sig­nal through a spring in­side a cas­ing. The sig­nal is re­flected back and forth through the springs with a de­lay de­ter­mined by each spring’s di­am­e­ter, wire gauge and length. The mov­ing mag­nets of the out­put trans­ducer gen­er­ate an al­ter­nat­ing mag­netic field, which in­duces an elec­tri­cal sig­nal in the out­put trans­ducer coil.

Spring re­verbs are com­mon in tra­di­tional gui­tar amps, and most gui­tarists will be fa­mil­iar with the rau­cous sound the springs make just from lift­ing or mov­ing the amp while it’s pow­ered up. They're gen­er­ally used across elec­tric gui­tars or key­boards to add char­ac­ter.

RE­VERSE RE­VERBS

As the name sug­gests, these re­verbs cre­ate the sound of a re­verb that starts with the de­cay and fin­ishes with the ini­tial at­tack. Thus, it starts qui­etly and pro­gres­sively gets louder. Back in the day, the only way to do this was by cut­ting the sec­tion of tape with the re­ver­ber­ated sound on it, then flip­ping it and splic­ing it back in. Of course, when dig­i­tal re­verbs came in, it could be done with the flick of a but­ton, and the ef­fect was very fash­ion­able for a time. It’s worth a look if you’re chas­ing some­thing a lit­tle dif­fer­ent for ef­fect.

SHUT THE GATE!

Gated re­verbs are cre­ated by in­sert­ing a noise gate in the chain af­ter the re­verb, in or­der to abruptly cut off the re­verb’s tail. This was very pop­u­lar in the '80s – it would be placed over snare drums to fat­ten the tone and add colour. The re­verb de­cay time and the gate thresh­old were ad­justed to suit the song’s tempo so that the de­cay didn’t con­tinue across the next beat.

THE CONVOLUTION REVO­LU­TION

This is a maths-heavy, digi­tised re­verb that uses sam­ples, or im­pulse re­sponses (IR) of real-life acous­tic spa­ces. An im­pulse re­sponse, in this case, is a rep­re­sen­ta­tion of how a sig­nal changes when go­ing through an acous­tic en­vi­ron­ment. Convolution re­verbs are rel­a­tively new, due to

their com­plex­ity. They are able to ac­cu­rately sim­u­late re­verb and sound very nat­u­ral. That be­ing said, they can be a lit­tle heavy on a com­puter’s pro­ces­sor.

AL­GO­RITH­MIC

This is a dig­i­tal re­verb that cre­ates echoes us­ing math­e­mat­i­cal al­go­rithms to sim­u­late the de­lays that oc­cur in re­verb. Syn­the­sis­ing the echoes rather than us­ing ac­tual sam­ples, like a convolution re­verb, is much eas­ier on the pro­ces­sor. The trade-off is that they rarely sound as nat­u­ral as a convolution re­verb, so it's best to use a convolution re­verb for the most im­por­tant parts, and then an al­go­rith­mic re­verb for less ex­posed sounds.

Here’s list of typ­i­cal pa­ram­e­ters to check out: Us­ing pre-de­lay is a great way to put a tiny space be­tween the source and the re­verb, so that the at­tack of the notes is not swamped out. De­cay lit­er­ally con­trols the length of the re­verb. Dif­fu­sion refers to the amount of time is takes for the re­verb to con­vert from early re­flec­tions into full re­ver­ber­a­tion. Mix is used like a bal­ance con­trol to switch be­tween the dry sig­nal and a re­ver­ber­ated wet sig­nal. If you’re us­ing the re­verb on an aux­il­iary buss, this would be set to full wet. If it’s been in­serted di­rectly over a chan­nel, it’s pretty much a vol­ume con­trol for the amount of re­verb you want. LPF (low pass fil­ter) will roll off the high fre­quen­cies at a cho­sen point as time passes. This is used to shape the tone of the de­cay. HF Cut con­trols which fre­quency be­gins to drop off first dur­ing the de­cay phase

KEEP BOUNC­ING OFF THE WALLS

In the next is­sue, we’ll look at ap­ply­ing and tweak­ing re­verbs in a typ­i­cal mix sit­u­a­tion, as well as some DIY ap­proaches to cham­ber re­verbs and re-amp­ing for ef­fect.

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