Unit 32: Sequencing Systems & Techniques - Sequencing Terminology

Unit 32 - Sequencing Systems & Techniques

Sequencing Terminology

·  Cabling & Equipment

XLR cable – An XLR cable is an analogue cable which carries audio signals as continuous voltage or electrical current. It has two types of connector, a male which has 3 pins facing outwards and a female which has 3 holes to accommodate the pins. These are often used in recording to connect a microphone to an audio interface, or if in a studio with a separate recording and mixing room, to connect into a wall socket input, which connects the microphone to a channel on the mixing desk.

Jack cable – A Jack cable is similar to an XLR in that it’s an analogue cable so it carries electrical current. It has two types of connector, a TS (Tip, Sleeve) which transmits unbalanced mono signal, or TRS (Tip, Ring, Sleeve) which can transmit balanced mono or unbalanced stereo signals. A Jack cable is often used to connect a guitar to an amplifier, or an audio interface, so it can be recorded into a sequencer.

USB cable – A USB cable differs to the first two, as it’s a digital cable which carries a code signal, which is data that can be interpreted by a sequencer. For example, a MIDI keyboard can be connected to a computer via USB, and the data information passed to the sequencer from the keyboard can have any sound applied to it as it’s not an audio signal. There are two types of USB cable, USB and USB II. The USB II is a new version of USB, adapted for more modern devices, which carries data faster for devices which demand higher speeds. The two connectors are the same size, the speed is the only difference.

Fire wire cable – This another example of a data carrying cable. There are two types of fire wire cable, the 400 and 800. Again the difference between the two is that 800 is an updated version of 400, and can transport data far quicker than 400, but unlike the USB I and II, these two have different size and shape connectors.

MIDI Keyboard – A MIDI Keyboard is a device styled like a keyboard but contains no pre-set sounds like a synthesiser does. Its purpose is to send data signals to a sequencer which can read the data and apply a sound to the data from its library of sounds. This means a musician can play a melody, and hear it back as any instrument the sequencer or sound plug in can produce. MIDI keyboards can also be connected to Digital Audio Workstations which read the data and send it to another source like a synthesiser which will create the sounds of the data without human interference.

Mac – The Mac computer is hardware, which contains a sequencer like Logic which is recording software. The mac has multiple USB inputs which allow you to plug in devices like MIDI keyboards, so you can create more complex progressions using the sounds in Logic.

Audio Interface – An audio interface is used to convert electrical audio signals into digital data signals, and to convert digital data signals back into electrical audio signals. This means you can connect a guitar to it using a jack lead and it will convert the signals into digital data signals which will be carried out by USB to the sequencer meaning they can be digitally recorded. This also means that digital signals can be converted to analogue and send via the XLR output to monitors so we can hear the guitar that the sequencer has just recorded, and then hear any effects or digital equalising we do to the digital recording. 

DI Box – A Direct Injection box is used to convert an unbalanced audio signal into a balanced one. This means that when a signal is transported across an XLR cable, less of the signals high or low end frequencies are lost. Often guitars are plugged into a DI Box with a jack, and the signal is balanced before being sent via XLR to a mixing desk or amplifier.

Synthesiser – A synthesiser is different to a MIDI keyboard as it contains its own sounds, and doesn’t require a plug in or sound library to create a sound. Often a certain sound is unique to a certain synthesiser, so unlike with MIDI keyboards it maybe necessary to use more than one, when playing live or recording an album. Synthesisers use XLR or MIDI cables to connect to an audio interface and then to have the signal changed to digital so it can be read by the sequencer, similarly to the MIDI keyboard.

DAW – A digital audio workstation is similar to a sequencer in some ways. Both modern versions are computer software, and are designed to arrange audio regions to create a piece of music, but a sequencer has more limitations than a DAW.

·  MIDI recording & editing

Logic Interface – The Logic interface is the layout first seen when you open a new project in the logic sequencer. It is split into 6 areas, each for its own role. Each individual track and all the regions on that track are arranged in the area, which consists of a series of rows containing the information, and a timeline across the top which can be set to represent time in seconds or bars of the song. The right hand side of the page contains a column for media and lists. This is where the library of apple loops are found, which are pre recorded sounds that can be dragged into a project at the correct tempo and key. Also this is where the virtual instrument sounds are found, which can be applied to a virtual instrument track, so that when someone plays the MIDI keyboard they hear back the sound of their selected instrument. The top of the screen is where you find the toolbar, which is where all the shortcuts are, which allow you to perform functions like setting looping a section. On the left side of the screen is the inspector, which changes appearance depending on which track you have selected in the arrange area. For example, if you have a piano track selected in the arrange area, the inspector will show a fader for the piano and one for a similar track like an organ or rhythm guitar. Along the bottom is the transport bar and editing tabs. The transport bars contain CD player like controls such as PLAY/PAUSE, but also contain controls like a Metronome which will play a BPM click throughout the song to make sure the instruments in the track are all playing at the right tempo. The editing tabs open pop ups like a digital equaliser, which allows you to add effects like reverb to a track and change the volume balance of the tracks.

Key Commands – key commands are a combination of keys pressed simultaneously on the mac keyboard, which allow you to quickly perform functions on Logic or similar sequencers. Some frequently used examples of these are:

Cmd+Alt = This key command enables you to easily zoom in and out as you select the regions you want to view more closely. It’s very handy for if you want to cut a part out of a region, for example, cutting a kick drum out of a drum loop.

Alt+Drag = This allows you to copy a certain region or regions, and drop them further along the track. This can be very useful if you have a 2 bar drum loop that needs to run for 8 bars, as without this you’d have to insert it 4 times, but doing this you can copy and paste it once, then copy and paste both the original and the first pasted item to fill the 8 bars.

Adding Tracks – There’s an icon in the top left of the arrange area which allows you to create a new track. The two options of MIDI tracks are an instrument track or external midi track. An instrument track allows you to create a piece of music either with a MIDI keyboard or by drawing notes in on the piano timeline. These notes or keyboard sounds are data that can have sounds from the library applied to them.

MIDI Keyboard Recording - Once a virtual instrument track has been created, you can record MIDI information onto it. Once a sound is selected to use on the track, you can hear yourself playing that instrument on the MIDI keyboard. To record you press the record button in the transport bar, which gives you a metronome click of one bar in length before you start to play. For example, if your time signature is ¾ it will give you 3 beats of the first bar before the track starts to record to ensure you’re ready to play.

CAPS LOCK Keyboard – This works in the same way as the MIDI keyboard in terms of recording, but doesn’t allow as many notes in different octaves, as there aren’t enough keys on the QWERTY keyboard. Also it’s different than playing a keyboard, so pianists or keyboard players may find it difficult to use.v

Quantise – This can be done to both audio and MIDI regions, or globally, which means to apply quantise to the entire project. Quantising is setting a value like 1/8 for example, which splits a bar into 8 equal sections that a note can be moved to, eliminating human error during performance, and making all notes and percussion in time with the BPM and the rest of the track. More recently quantise has been used to give an entire song a “groove” by setting the quantise value quite low (1/4) so the track is in time, but isn’t overly quantised and still has a live band feel.

Pencil Tool – When it comes to editing in Logic one of the most useful MIDI editing tools is the pencil tool. If you’ve recorded a series of notes on the MIDI keyboard and played some wrong notes, or not held a note long enough, you can use the pencil tool in the piano roll to move these notes to either the correct pitch or to put them at the correct beat of each bar. Also the pencil tool can be used to create a melodic phrase in the piano roll, as it allows you to draw notes, copy them, change their pitch and position on the piano roll, and also all this doesn’t need quantising as it can be perfectly positioned on a beat or at the start of a bar.

·  Audio recording & editing

Blue Apple Loops – In the Logic loops library you can use either green or blue loops, green being MIDI and blue being audio. The MIDI notes can be moved and altered in the piano roll, but the audio ones are more restricted as they not MIDI information, they’re real instruments recorded and then converted to digital. This means the only editing that can be done to these is cutting out and copying sections to create variations between regions in the arrange area. You can use the scissors tool to cut out a kick or snare drum and either leave a gap or double it in the space. This can create a variation on the original loop, and make you track more interesting. One of these loops could be quantised, but they’re already in time with the BPM of your track when dropped into the arrange area so this isn’t necessary.  

Plug-Ins - Plug-ins are useful in MIDI and audio recording, as they allow you to apply a specific sound to you instrument. For example, in audio recording you can plug a guitar into your audio interface, and open a guitar amplifier plug in which will make your guitar sound like it's playing through a vintage 60s amplifier.

Microphones – There are two types of microphone, a condenser and a dynamic. There are many differences between the two microphones, and each serves its own purpose when recording different instruments or vocals.

·         Condenser – This microphone has a diaphragm with two metal plates, one positively charged and one negatively charged. The positively charged plate moves towards and away from the negatively charged back plate, which creates the signal. A condenser microphone is very sensitive, so it doesn’t need to be very near to the sound source meaning it’s good for recording the ambience of a room, or standing left and right above a drum kit to create a full effect. As the plates are electrically charged they need a power source which is either a battery or phantom power from a mixing desk. As it takes so little input to move the capacitor, it has various tiny movements that can be picked up, meaning the output signal is very detailed and accurate version of the input. For example, the recording of the guitar will sound to the human ear very similar to the guitar being played live in the room next to you.

·         Dynamic – The diaphragm of a dynamic microphone is very different to that of a condenser. It consists of a coil of wire around a magnet behind the condenser. According to the sound pressure the coil moves around the magnet, and a signal is produced in a process called electro magnetic induction. If the SPL is large there will be lots of movement around the magnet from the coiled wire, and if the SPL is smaller the movement too will be, and this means the audio signal produced has dynamic properties. However, the detail in the signal of a dynamic is less than that of a condenser as it takes more SPL to create a difference in movement, however the dynamic microphone doesn’t require phantom power. This microphone is far less sensitive than a condenser, which makes it more robust. It can be put inside a kick drum for example, and record the sound without the internal workings being broken.

Audio Interface – Although this was mentioned in section one it’s necessary to talk about it again here. An audio interface allows an analogue audio signal to be converted to digital and a digital to be converted back to analogue. The process of recording live instruments digitally is impossible without this. It has various inputs for Jack or XLR, which mean either of the for mentioned microphones can record through it, or instruments like guitars and bass which connect via Jack to be recorded and have signal converted to digital to be recorded by the sequencer. Also the conversion from digital back to analogue is important. You could for example add reverb to the digital recording in the sequencer, and want to hear it back through headphones or the monitors. The signal has to be converted back to analogue, as the headphones and monitors use analogue signals and analogue cables. If the signal couldn’t be converted back, then you could never listen to the effects of equalisation you added in the sequencer to see if you liked it or not.

·   Virtual instrument control & editing

Plug-Ins/Pre-sets– A virtual instrument is a software recreation of a real instrument, which is often run in a sequencer like logic. Logic has its own virtual instrument sounds, which can be applied to a virtual instrument track. These offer good instrument sounds, but not ones that can be altered to achieve a perfect sound for you. This is where third party plug ins can be more useful, as they allow you to not only select an instrument, but alter its EQ and effects before playing it. Plug ins come in various formats, which ensure they're compatible with the sequencer you're using them in, but if a plug in isn't compatible it can use a software wrap which acts like a universal format, meaning you can use it in any sequencer, but this is rarely necessary.

MIDI controllers - A MIDI controller is a physical piece of equipment which means it’s unnecessary to use the faders, channel strips and piano roll in Logic. They can be for example a drum pad layout, and the player can tap the different pads to produce sounds of a drum kit. This makes the recording process more creative than drawing notes on the piano roll with a pencil tool, and also the pads are velocity sensitive, meaning tapping them with varied force creates a different sound, and this ads depth and dynamics to your recording. Another example could be a fader bank for EQ and automation. This means you can perform functions more quickly without the use of the mouse on Logic.

Automation – Automation is the control of the volume of a sound or the effects on a sound, which can change throughout the length of the sound making an interesting sound. It can be done in the sequencer, but the easiest way to do it is to use a control surface like a fader bank. Using a pot on a control surface achieves an interesting sound, and once recorded once it is automatic and on the track every time it’s played without having to be done again. Automation can be applied to an entire track, or to one particular region on that track.  This is useful as the automation may become repetitive on the entire song.

External MIDI Devices – If a keyboard has a MIDI Input and Output this means it can be used to play automated progressions in a sequencer. The keyboard is connected via a digital data cable and has the automation sent to it, meaning the keyboard will play the notes sent from the sequencer automatically. Also if the keyboard has pots on it, then it can add any effect automation the sound as well. If the pot is motorised you will see this happening, for example as the automation moves the pot will move with it. In sequencers like logic there’s an option to set up an external MIDI device track, and this is how this can happen.

·  Mixing & Bouncing

Mixing – To Mix a song is to blend all the tracks you have recorded, by changing the volume, effects and equalisation of the tracks so it sounds accurately like it would as an entire band playing it (assuming the song was overdubbed, and not recorded live). There are various techniques to mix a song; most are done at the mixing desk or digitally on the sequencer. All the techniques are used sound the song sounds professional, and makes it enjoyable to listen to.

Volume Equalising – It’s important to equalise the volume of all the tracks in your song, so no individual sound is overpowering and instruments that are usually back in the mix like bass aren’t too loud or quiet, so they’re unnoticeable or overpowering. This can be done in the sequencer or the mixing desk, but if it’s done on the mixing desk you could accidentally change the signal to noise ratio of a recording.

Panning – Panning a sound is to spread it between a Left and Right speaker to create a stereo sound. Panning can be hard in one direction or more subtle, and only slightly to one side, and it can even swap between the left and right speakers. According to Sound on Sound, “sounds arrive at the left ear slightly earlier than the right”, and when it does this helps us to determine where a sound is coming from. Panning can help to add depth, or a third dimension to a recording, and it’s usually done using a pot on the mixing desk, which allows us the move the dial slightly for subtle panning or all the way in one direction for very obvious panning. An example of panning commonly used is having a recording of the left side of a drum kit and a recording of the right side of the drum kit and panning them to the correct sides to create an illusion of the drum kit being right in front of you.

Effects – Adding effects to a sound can make a sound more interesting, and often certain genres are distinguished by the effects on the instruments, for example in Heavy Metal or Rock the guitars are heavily distorted. As well as distortion there are other interesting effects like Delay, Tremolo, Echo, Phaser and Chorus. These are often applied to instruments to in recordings to create a unique sound. Adding these effects is usually done in the sequencer, as the have plug ins like guitar stacks with lots of guitar sounds that can be applied to the digital recording of the guitar. Alternatively you can take a recording of the amplifier with the guitarist using an effects pedal to create the desired sound.

Reverb – Reverb is classed as an effect, but it stands alone as an effect that is usually applied to everything in the mix. This is because rooms have unique properties, so often a live recording with room sound properties will sound different to a MIDI recording. Therefore reverb is necessary to apply to all sounds in the mix, as it creates consistency with all the sounds. The end result will be that it sounds like all the instruments on your track were recorded live in one room, with lots of echo and reverb. Reverb can be subtle and dry or very obvious, for example a recording in a small room with padded walls wouldn’t have sound bouncing around and hitting your ears long after the note was struck, where as a recording in a giant bare room like a giant church or cathedral for example would have lots of natural reverb and echo already, so this can simulated using a reverb effect in the sequencer.

Bouncing - Bouncing is turning a mono singular recording into a panned stereo one, and ties in with the left and right panning. If you record an acoustic guitar for example, it is one instrument playing one thing, so therefore is a mono recording. A way to create a stereo guitar track from this is to duplicate it so you have two versions of this same recording in your sequencer, then make one a fraction of a second later than the first and pan one hard left and the other hard right. This means that the guitar will sound fuller, and each note or chord will be sustained slightly longer and you will be able to hear a subtle sound difference in the sound from each speaker or monitor. Another way of doing this is to multi-track the recording, by playing the same thing twice, and allowing the subtle human differences to create this effect naturally, but this could have negative effects if the player doesn’t play rigidly to the metronome, otherwise errors could occur and the end result would be a sloppy sound.