Mixing : Volume controls part 1 - Faders

Volume faders control the volume of each sound in the mix, including effects.

David Gibson comes up with a very useful and detailed description about what all the studio equipment does and how does it affect our sounds in his book "The art of Mixing Second Edition"

Faders

Volume faders control the volume of each sound in the mix, including effects.

The level set for each sound is based on it's relationship to the rest of the tracks in the mix. When volume is mapped out as a function of front to back, you can place any sound or effect up front, in the background or anywhere in between by using the faders.

However, the level that you set a sound in the mix is not based solely on the Vader. If the level of the faders was the only thing that affected the volume of a sound in a mix, you could mix without even listening. You could simply look at where the faders are set on the console. There is more to it than that.

When you set volume relationships in a mix, you use apparent volumes to decide on the relative balance - not just the voltage of the signal going through the fader. The apparent volume of a sound in a mix is based on two main things, fader levels and waveform, and another minor one, the Fletcher / Munson Curve (See the "Fletcher/Munson Curve section below). First, the level of the fader does affect the volume of the sound. Change the level of the fader and the sound gets louder or softer.

Fader Level

When you raise a fader on a mixing board, you are raising the voltage of the signal being sent to the amp, which sends more power to the speakers, which increases the sound pressure level (SPL) in the air that your ears hear. Therefore, when you turn up a fader, of course the sound does get louder.

The decibel (dB) is used to measure the amplitude of the signal at each stage of this circuit. In fact, there are very specific relationships between voltage, wattage, and sound pressure level. Decibels are the main variables that affect the apparent volume of a sound. However, there is another important factor: The waveform of the sound.

Waveform (or Harmonic Structure)

The waveform, or harmonic structure, of a sound can make a big difference as to how loud we perceive a sound to be. For example a chainsaw will sound louder than a flute, even if they are exactly at the same level on the VU meters. This is because the chainsaw has harmonics in the sound that are irritating - or exciting, depending on your perspective. These odd harmonics are dissonant to our psyche, which makes them seem louder to us. Therefore, a sound, even if they are at the exact same volume in the mix. A minor factor contributing to the apparent volume of a sound is the Fletcher / Munson Curve.

The Fletcher / Munson Curve

The biggest problem with the human hearing process is that we don't hear all frequencies at the same volume - specially those at low volumes. (Fletcher and Munson did a study that shows just how screwed up our ears are.) This is why there are loudness buttons on stereos - to boost the lows and highs. You are supposed to turn them on while listening at low volumes. However, most people like extra lows and highs, so they leave the switch on all the time.  The main point here is that you should check your mixes at all volumes all of the time because you won't be hearing ass and tremble as much as you should. Also, whenever you do a fade at the end of a song, the bass and treble will drop out first. Technically, your ears give you the flattest frequency response at around 85 decibels.

Apparent volume is, therefore, a combination of decibel level, waveform, and the Fletcher / Munson Curve. But relax. Your brain has all it figured out. Most people has it all figured out. Most people have no trouble telling whether one sound is louder than another (although most of us need to learn to hear smaller and smaller decibel differences). Your brain quickly calculates all of the parameters and comes up with the apparent volume. All you have to do is listen to the overall apparent energy coming from each sound in the mix. It is apparent volume that you use to set volume relationships in the mix. You don't look at the faders; you listen for the relative volumes.

You can read more about the most important things you need to know about mixing, in Dave Gibson's book "The Art of Mixing 2nd Edition" A visual guide to recording engineer and production.

Mixing : Functions of Studio equipment according to David Gibson

Get the most of your studio equipment knowing the functions of all of the different devices

Dave Gibson brings a comprehensive guide to understanding functions of studio equipment in his book "The art of Mixing" according to him studio equipment can be broken down in the following categories.

To simplify all of the functions of a huge variety of studio equipment, I have broken down all of the functions of studio equipment into categories based on the function of each piece in the recording studio.

1. Sound Creators : all instruments, accosting to electric, voice to synths
2. Sound Routers : mixing boards, patch bays, splitters
3. Storage Devices : recorders, tape players, sequencers, samplers
4. Sound transducers : miss, pickups, headphones speakers
5. Sound manipulators : processing and effects.

Effects rack

Sound creators range from acoustic to electric instruments, from voice to synthesizers.

Sound creators

Sound routers route sound from one place to another. Mixing boards route the signal to four places: the multitrack, the monitor speakers, cue headphones (for the band out in the studio), and the effects (so we can have a good time). Patch bays are just the back of effects - the back of the mic panels, the back of the multitrack (inputs / outputs), the back of the console (ins / outs) and the back of the effects (ins / outs) - located next to each other so we can use short cables to connect them.

Sound routers

Storage devices store sound or MIDI information and play it back. Tape players store digital or analog sound; sequencers store MIDI information. Some storage devices can be used to edit the sound while it is stored.

Storage devices

Sound transducers take one form of energy and change it into another. Microphones take mechanical energy, or sound waves and change it into electrical energy. Speakers take electrical energy and change it into mechanical energy, or sound waves. Likewise pickups on guitars take the movement of the strings and change it to electrical energy.

Sound transducers

You can read more about the functions of studio equipment and the most important things you need to know about mixing, in Dave Gibson's book "The Art of Mixing 2nd Edition" A visual guide to recording engineer and production.

House Music Production : Synthetic percussion

Zaps, clicks and glitches are the bongos of the tech age, and an essential beat element in minimal and electro.

Synthetic percussion has been steadily rising in popularity to the point where it has become a staple ingredient of minimal and electro grooves. Synth-derived hits are used to spice up the rhythm in place of tradicional acoustic and ethnic percussion with zaps, clicks and glitches taking the places of congas, bongos and shakers, introducing detail and rhythm to the groove.

When choosing percussive synth sounds it can be helpful to think in terms of the tonal qualities (in terms of size, shape and frequency) of traditional percussive instruments and use similar sounds for similar purposes. Clicks, high frequency metallic noises, for example, are ideal substitutes for hi-hats; thick, chunky, snappy noises are good snare replacements; and hits with a recognizable pitch can be used instead of toms, bongos and congas.

The most obvious synthetic percussion is that offered on drum machines like the 808 and 909, where the drum sounds are synthesized versions of their real-life cousins, each sound offering a tonal and frequency approximation of the acoustic original. These machines are tweak able, with may of the sounds editable using front panel controls. Toms can be tuned and hat decay times altered, giving producers the tool to fit individual sounds into the mix. This tweak ability accounts for the multiple variations of percussive sounds in vintage beatbox sample collections.

Old-school percussion remains popular today. But house producers have widened their sonic palette to make use of many other sounds  - often used sparsely and picked solely for the way they work in the groove.

Sound Sources

The beauty of synthetic percussion is that the source material can be almost anything, from a vinyl click to a sampled burst of digital feedback.

Sample CDs are a great source of ready-made noises (often in percussive 'hits' folders). Once loaded into a sampler these hits can be sculpted to fit the track's beat using filters envelopes and any number of effects.

Synthetic percussion is also easy to create from scratch. Any analogue synth can be used as a source. For more complex textures such as atonal or metallic sounds, use frequency modulation (FM synthesis), ring modulation, cross modulation or phase distortion techniques. These techniques sound good when used with basic sine waves as the sound source. For subtle sounds spread the tuning between the two oscillators by a few semitones. For more extreme effects detune two by several octaves. Swapping the carrier and modulation modulators around will change the tone dramatically. Digital FM and wavetable synthesis can also create unusual textures.

For more sophisticated sounds try drum synthesizers such as the Waldorf Attack, Elektron Machinedrum or Sonic Charge's micro tonic. These offer a number of drum models specifically designed to create kicks, snares and cymbals. They also have advanced programming functions.

Glitched effects

Some effects are perfect for processing glitch percussion. These include bit-crushers, ring modulators, frequency-shifters, multi-band distortion and FFT-based ('Fast Fourier Transform') filter effects

With bit-crushers, changing the sample-rate value will introduce atonal harmonics to the sound, while lowering the bit-depth will make it more chunky and abrupt.

DestroyFX make an essential series of freeware plugins including Buffer Overide while Audio Damage have the reasonably priced Replicant, Automaton and Big-Seq. These can transform a tiny splinter of sound into something wildly different.

Tip / White noise can be used on it's own or as an extra layer of a percussive sound. Use hi-hats and low-pass filters to shave off unnecessary frequencies around the sound.

Tip / Use reverb to position a sound in the groove. Keep it up-front and snappy with early reflections. Use a long reverb for occasional dramatic hits.

Tip / Distortion transforms thin, weak hits into thick strikes madden with character.

Tip / Any short, simple sine wave blip can be mutated into a lo-fi computerized percussion noise with the help of a bit-crusher. Lower the sampling frequency to introduce tonality.

Reduce the bit length to add noise.

Tip / Up the expression by automating a few parameters in a percussive line over time. Try changing a sound's amp attack / decay, filter cutoff and oscillator pitch.

Tip / Create a hooky, highly personalized beat by introducing a distinctive hit or sound effect into a straight rhythmic pattern. Use the hit sparingly - once in eight bars is often enough.

You can read about the kick drum with more detail in Sample Magic's book "The secrets of house music production".

House Music Production : Cymbals and percussion

The spice of the rhythmic snack: cymbals and percussion bring flavor to the groove

Crash

Crash cymbals are used like sonic energy bursts to emphasize key points in a track, or to soften transitions into new sections of a song, like the breakdown or chorus.

Crashes can be live samples or synthesized. They contain mostly high-end frequencies and are therefore easily produced on a synth with a white noise oscillator and high-pass filter. Crashes usually sit on the first beat of a new bar and can be repeated every 16, 32 or 64 bars, when new parts come in and out. The classic crash trick is to reverse the sound so that it creeps in slowly. Position it so the suck finishes just as the first beat of the next bar drops. Crashes sound great in wide stereo. Use a stereo widener with delays and reverb to give them additional depth and character.

Ride

The acoustic ride cymbal has to distinctive tones depending on where it is hit. Striking the edge gives a smooth, jazzy sound with a long decay, while tapping the central belt produces a shorter, defined pitch in the form of a metallic 'klang'. the controls of the ride on an analogue beat box are designed to produce one or other of these tones. When programming, ride patterns can take the part usually assigned to the closed hat (1/8ths or 1/16ths), or they can cut across the groove like cowbells. Melodic deep house and jazzy house make use of loosely-programmed lines to give a relaxed, a lazy feel to the beat. A long, sustained ride sound with a simple 8th note downbeat pattern is also prime material for pairing with heavy side chain impression for classic sucking effects.

Percussion

Don't underestimate the power of the less significant percussive sounds. When used right, they can become the focus of a groove. In some styles they are essential.

Every drum machine has its variation of toms, usually offered at a high, medium and low pitches. These are based on a deep, warm sample that can be tuned to the key of the track. If they are tuned low enough, synthetic toms can be programmed to play the baseline. This type of programming is common in both minimal and deep house.

The sounds of Brazil and Africa are both excellent sources for drum and percussion loops, specially hand drums like congas and bongos. Latin and disco house often feature conga and bongo loops, bringing an irresistible live, funky feel to the beat, while fallen tradition rhythms have enjoyed a decent resurgence among tribal producers.

Original percussive patterns can be analyzed and recreated using Midi programming. Note that when bongos and congas are played by percussionists the sounds vary according to the hype of hit made by the palm, generating a variety of open slapped and muted hits. Load up the different sound variants into a sampler and use velocity changes and mute groups for a more realistic feel. When programming percussive parts it can also be useful to tap them in live.

Easier than generating an authentic loop with Midi is using a live percussion loop. These can be sourced from any number of sample collections or old records. The important thing when using a loop in this way is to maintain as much control over it as you can to ensure it sits comfortably in the groove you've got rolling. You can do this in a number of ways.

The first method is the 'old-school' way, cutting up different hits using scissors in the arrange page and then nudging the cut samples back and forth until they are in time with the groove. It's tedious but can be very effective. A second method is to leave the loop as a single Wav and then re-groove it using realtime tools such as Logic's Grooveshifter

The third -and most powerful- option is to use tools that intelligently chop a loop into it's constituent parts and then map these parts to different sample zones. This allows you to totally change a loop's construction and alter its groove to fit the track. Rex files are ideal for this. 

Overview: What is?

Conga:  Tall, narrow Cuban drum with African origins, typically played in sets of two. Each drum can be played with five different strokes - including open, slap and touch.

Bongos: Pair of single-headed, open-ended drums attached to each other, played by striking drumheads with fingers and palms. Produce relatively high-pitched sounds.

Cowbell: Hand-held percussive instrument. Brings definition when struck along with snare. Popular in Latin house. 

Claves: Pair of short, traditionally wooden, sticks that produce a bright clicking noise. Used in Afro-Cuban music.

Tom (or tom-tom): Tunable drum commonly used in Western music most frequently during drum fills. Modern drum kits typically feature three different toms.

You can read about the kick drum with more detail in Sample Magic's book "The secrets of house music production".

House Music Production : Hi-hats

The cracking, sizzling, slurping, body-rocking hi-hat is the third sound in the beat maker trilogy.

Hi-hats are the third essential component for building the groove. They can be used to reinforce any element of the rhythm and are the primary tool for increasing the pace and excitement of your rhythm track.

Most drum machines have two types of hi-hat - open and closed (OH and CH). The terms refers to the two different ways an acoustic drummer strikes the hi-hat cymbals in their kit. Closed hats are short and tight because the drummer closes the hats with their foot pedal, while open hats are played with the foot pedal released and have a longer sustain. They are often played on the off-beat earning them the nickname 'disco slurps' for the sucking sound they make.

Mute groups

Because a drummer only has one hi-hat set in their kit, a closed and an open hat can't be played at the same time. Instead, when an open hat is playing and the drummer puts their foot back on the hi-hat pedal, the open had is ended, the sustain 'choked' as the two cymbals return together. This 'choking' style was emulated by early drum machine sequencers, which restricted open and closed hi-hats to one note polyphony so that only one or the other could be triggered at any one time. This shaped the sequenced sounds of the TR-808 and 909 rhythm boxes, adding a sense of realism to their beats.

Software samplers and drum machines like Battery use 'mute groups' to determine how many notes can be triggered simultaneously. To emulate the classic choking style, assign all hi-hats to their own mute group and restrict polyphony to one.

Top hats for style

The style of house you're making will influence your choice of the hi-hat sound. Classic and retro choices come from the vintage E-mu, Linn and Roland (particularly 909) drum machines. In main room and deep house these are often layered with hats sampled from disco records. The same sampled hats find their way into funky and Latin productions too.

Away from the sampled vinyl and classic drum machines, hats can be created using synthesis. Of increasing popularity are entirely synthesized white noise hats, favored by minimal and techno producers.

These white-noise hats are very easy to make using most soft synths. All you need is a white noise oscillator as the source (FM synthesis works just as well.) The amp envelope is all important in shaping the dynamics and requires at least two different settings to re-produce open and closed versions. Since white noise occupies the full frequency spectrum, it is essential to use a combination of filters (both hi and low-pass) to shave off high and low frequencies to help the hats sit in the mix.

Electro-house and bassline/fidget producers use a range of sources, from drum machine hits to sampled hats from rock and even old rave classics. Their inherent filth comes from liberal doses of distortion, compression and reverb created space. Look for impulse responses on the net, or try an algorithmic reverb with modulation parameters to really mess with the sound.

Sculpting hi-hats

Hi-hats are supporting rhythmic instruments that must work effectively alongside - and not overshadow - the kick and snare. After selecting the right sound the important part is shaping the hat so it works in, and fits with, the groove. Attention to detail here is paramount, and beat programmers use a mix of sampler amp settings, compressors and transient shapers to shape their hats in the same way a sculptor would stone: cutting and chiseling the sound until it sits perfectly in the groove.

In the mix - transient shapers

The dynamics of a hi-hat can be further refined using a transient shaper or envelope plugin. When the attack is increased, the front 'edge' becomes harder and more defined - great for adding definition to a groove. If the sound is too biting ease back on the attack. The tail can also be manipulated for shorter or longer tails. A long compressed-to-the-max sucking tail can be great in lo-fi electro beats.

In the mix - de-essing

When pressing vinyl it is essential to ensure sibilant hi-hat frequencies don't distort at the cutting stage. Hi-hat sibilance (that nasssty sss sound) occurs in the upper mid-range, around the 5-6khz region and beyond. An effective way to tame it is to use a de-esser to dynamically lower the volume of problem frequency bands.

Tip / An echo or delay effect on a hi-hat can increase the pace of a track and introduce an extra element of rhythm. Use a 1/16 note setting for speed or 1/8 note triplet setting for dub rhythms. Ping pong delays are also nice. Roll away the high end of any returns.

Tip / Flangers and phasers introduce movement into linear hi-hat patterns by sweeping through the frequency range. For subtle changes keep the mix value low and sweep the LFO across an 8 or 16-bar cycle. Automate the wet mix level and bring it up slowly when the track needs more intensity.

Tip / Lock the frequency of a phaser so it resonates at a fixed pitch. Tune the resonant frequency to the key of the track, choosing either the route note or one that's in harmony.

Tip / If you're after ultra-wide hats send them through a frequency shifter. Look for the offset parameter: this is the key to stereo width enhancement. Keep the frequency range below 1-10Hz for sublime panning. At settings below 1Hz the sweeping motion of the frequency shifting becomes more noticeable.

Tip / Hats and shakers occupy the same high frequency area. When using both in a track be careful that they don't clash. You can do this using programming to ensure one supports the other rhythmically, rather than playing the same line. Separate them further by using a mix of panning, EQ (cut one and boost the other in the same area) and reverb (pushing one further back in the mix by using a little more reverb on it).

Tip / For a heavily compressed nu-rave / electro-style disco slurp, sidechain a long dirty open hat with the kick drum so that it gives nice syncopated off-beat-breaths. Use a very slow release so that you never hear the start of the hat. Get even dirtier by adding bit-crusher or distortion. Long white noise hats are great candidates for this too.

Tip / It's always tempting to reach for an exciter to add high-end to the hats. But beware: excited hats can sound brutal on a club system. If you use one, be subtle.


You can read about the kick drum with more detail in Sample Magic's book "The secrets of house music production".

House Music Production: Snares and Claps

The second weapon in the beat armory is a snappy companion to the kick.

After the kick, the next element in a house groove is the snare drum. It's main function is to provide a counterpoint to the steady pound of the kick, typically sounding on the second and fourth beats of the bar. It's not essential for a house track to have a snare: a clap is occasionally used instead. What follows applies to both.

The snare sits in the mid-range of the frequency spectrum. It is commonly blended with other percussive sounds, including claps, sticks, clicks, hi-hts and other percussion to create the requisite snap, crackle and pop.

Many snare sounds in house are delivered from drum machines and synthesizers, which are then processed with effects including distortion, compression, bit crusher and reverb. Sampled acoustic snares are often layered with them for added character.

Sonically, synthesized snares have two tonal elements. The first is a sharp attack transient that contains high and mid-range frequencies usually made from white or pink noise. The second, which forms the body of the sound, is a low pitched sine or triangle wave with a recognizable pitch and a longer sustain. This can be doubles with another oscillator an octave or so able for a more complex body knock.

This combined noise / sine oscillator model was used to create the snare sounds on analogue drum machines including the Roland TR-808 (thwat) and TR-909 (cluck).

Choosing the right sound

Thanks to the diversity of influences permeating house music there's no right or wrong choice for the raw snare sound.

Classic choices include drum machines, specially the snappy 909 and deep-tuned LinnDrumm. The latter is a favorite with electro-house producers looking to add a wonky layer or synthetic bite to the mix.

Bassline, electro, and nu-rave producers look to old rave records and classic hip-hop breaks for snare samples. There are fed through overdrive unites, bit-crushers and compressors for added grit and filth.

Funky, deep, tribal and Latin house tracks feature more organic snares and claps from disco and rare-grooved records, or targeted sample collections. Such samples often feature hi-hats, which add to their character.

Newer choices, in minimal and progressive house, include tight DSP-derived sounds and white-noise generated hits.

Snares are frequently layered for a thicker sound. The timing between hits can be loosened by triggering each layer a title before or after the beat. This gives the groove a more relaxed feel.

Sometimes clap samples come with lead-in noise to give them a sucking quality. Don't cut this noise: just trigger the sample a little before the main hit so that the noise anticipates the snare like the funk records of old.

As with kicks, the secret to a successful layered snare is choosing sounds that complement each other rather than fight. An example of a successful combo might be a fat LinnDrum snare filling out the bottom end, a live disco hit with low-end removed supplying the highs, and a stereo clap that anticipates the beat to add a sheen of mid-range polish and depth.

Tip / If your sampler offers a loop stage, like Battery, it can be used to add extra crack to a clap. The impact stage of a clap features a series of impulses before the main body of sound hits. Set the sampler loop points around the impact portion and restrict the count to around three cycles. If there is a loop tuning parameter experiment with this too.

Who snares wins

1. The snare supplies the rhythm section's snap, crackle and pop. Choose one that complements the kick.
2. Drum machines provide solid sample choices, but layer them with other samples for bigger more unique sounds.
3. Snares are ripe for all kinds of processing treatments, from compression to bit-crushing. Delay layered samples for great stereo sounds.
4. In progressive and minimal styles snares are often mixed so low that they become almost inaudible - their role is to supply a little extra bite to kicks two and four. 

You can read about the kick drum with more detail in Sample Magic's book "The secrets of house music production".

House Music Production: All about the Kick Drum

In house the kick drum is king. How do you get it right?

In terms of defining characteristics, in house music and it's derivatives the kick drum is king. It is the single most important part of the rhythm section, on which everything else is built. Get the kick right and the rest will follow. Get it wrong and your track stands little chance of being played in a club, let it alone being bought by discerning DJs.

With thousands of kicks to choose from, what are the factors you need to consider when choosing - or building - your kick? Please check out these awesome tips from the book "The secrets of house music production"

Depth, length and vibe

The depth and length of a kick should be directly related to the bassline, as the pair work hand-in-hand to power the track. They also overlap in their respective frequencies, so it's vital they produce the maximum amount of energy together and not fight for space. They say opposites attract, and that's definitively true when mixing kick and bass. Picture the two as you can choose them, thinking about where each sits in the frequency spectrum, if they sit in the same sonic place they will rub against each other uncomfortably. Neither will shine and you'll struggle to make them gel. As a general rule, a higher, short kick (a classic disco kick) will work well with a booming deep bassline, while a higher bassline will site nicely alongside a longer, deep kick drum (like the Roland TR-808 kick). As the relationship between the two will probably alter during the mixing process, be prepared to make minor adjustments to each as you go to ensure that they continue to work well together.

Tip / if you use a kick from a drum machine / sample you can easily tune it to the key of the track and adjust the amp envelope to get the right length.

Getting the right sound

Each house sub-genre makes use of kicks with distinct character traits. Because of various seminal recordings certain types of kick have become associated with different styles. Selecting the kind of kick popular in the genre you're producing is a good starting point when writting as it sets a basic vibe that can help focus subsequent production decisions.

Classic / funky / deep houseClassic

deep and funky house producers use 909-style kicks that are often layered with samples from disco tracks. This pairing gives the beat the best of both worlds - the power of the 909 and the live party vibe of a disco beat. If you get the disco kick from an old record you'll end up with layered hi-hats in the mix, along with some vinyl infused vintage reverb. This all adds to end clarity and spatiality to the kick, helping it cut through the mix.

Electro and jackin' house

The kind of kicks used in electro tracks vary, Some tae inspiration from the 80s with chunky E-mu Drumulator or LinnDrumm-style kicks laced with sub reinforcement to power the low end. Others take a more minimal tech tip, using analogue 808-style kicks topped with a disco or electronic high-hat for definition. A third variant - that has found fans in the nu-rave and nu-disco arena - is to use rough and ready live kick samples from funk or even rock records. Tracks from the 70s and 80s offer a wealth of possibilities.

The emphasis throughout is on the slightly dirty warmth that only vinyl gives. Whatever direction you choose, there are plenty of excellent samples to choose from.

Minimal house

Minimal is all about simplicity and producers tend to lean towards analogue and synthetic generated kicks. The quintessential minimal kick is based on the Roland TR-808 bass drum, but thanks to the flexibility of software such as Logic's ultrabeat and Waldorf's Attack drum synthesizer, you can create more interesting variations than the 808 ever could.

Progressive / tech-house

The closer prog house gets to trance, the more reliance there is on the 909 which more than 20 years on, remains the quintessential trance drum machine.

Tricks for kicks

1. A club track fails or succeeds on the basis of it's low-end energy. The two inhabitants of this area of the frequency spectrum are the kick drum and bassline.
2. The key to a great dance track is getting these two elements to work together. A booming sub-bass kick will clash with a similarly subby bassline.
3. The classic Roland TR-909 kick drum is a great place to start. It has enjoyed so central a place in house music precisely because it works so well in dance tracks.

You can read about the kick drum with more detail in Sample Magic's book The secrets of house music production.