Compressors/Limiters
Compression
To change the tonal qualities of a sound/even level
Limiting
Control of dynamics to prevent overloads
Primary Controls
Threshold
- Sets the point (Db) at which automatic gain reduction (GR) is triggered
Attack Time
- Determines the time taken for the unit to respond to the threshold breach. Too slow and overloads may still breakthrough. Fast attack times guarantee overloads are kept at bay.
Release Time
- Determines the time taken to return the volume to its nominal level. Setting release time to a fast response will give an audible motion to the sound, an on/off effect referred to as 'pumping' or 'breathing'
- Setting release time to a longer duration eliminates this movement/near oscillation sensation
Compression Ratio
- Determines the amount of compression that will occur
e.g. a 1:1 ratio will produce no effect
a 2:1 - for every to 2Db beyond the threshold, the compressor will only increase output by 1Db
a 10:1 - for every 10Db beyond the threshold, the compressor will only increase output by 1Db
Breach of threshold > 10:1 < resultant output increase
(Db)
Setup
Ratios of 2:1-9:1 are considered compression, as they keep level even and produce tonal adjustments
Ratios of 10:1 + are considered limiting and serve predominantly for dynamics control and overload prevention
Outstanding examples : Vintage
Monday, 14 October 2013
Sunday, 13 October 2013
DAW Recording - Re: TREHB Ch.4
DAW Recording
ADCs and DACs
ADC - Analogue-to-Digital Converter
DAC - Digital-to-Analogue Converter
Low-end units are often combined ADC/DAC interfaces, potentially with a built-in pre-amp too.
Mid Range - High-end units are usually standalone hardware, specialised and focused.
High-end units are typically outboards, superior in design and quality.
(Tip: Ultimately the quality of a signal is only as high as that which the weakest link in a signal path can afford i.e. the benefits of a chain of high end equipment will not be perceivable if the signal is ultimate converted by a cheap ADC/DAC.)
Latency
Latency should by default be kept to the absolute minimum where possible.
Acceptably low latency may be a delay of 3ms or lower.
Anything beyond 6ms is bordering futile.
Latency should be set as low as possible, but comfortable clear the point of byte dropping.
Audio Interfaces such as ADC/DACs generally use 'input buffers' to set the rate of latency.
One should avoid using any processing beyond the necessary when recording as this will only drain valuable CPU and cause hangups/dropouts, the result will be better quality audio and more tightly synced monitoring.
Some AIs may employ zero-latency monitoring, channeling a direct loop from input to output, producing accurate monitoring alongside backing track playback for timely recording.
In the absence of Z-L monitoring -
- A similar result can be achieved by connecting the interface input to an aux, bus or direct output on the A or D console to avoid recording the entire temp mix to the new track. With digital consoles there will be some latency experiences, but often only around the 2ms or less mark due to the optimised OS installed.
TO AVOID LATENCY -
- LOWER INPUT BUFFER SIZE
- USE Z-L MONITORING
- USE AN OUTBOARD CONSOLE
- AVOID THE USE OF PLUGINS
Firewire vs USB
USB 2.0 - 480kbps data transfer rate - utilises as MASTER/SLAVE configuration
- Adds system overheads, resulting in slower data flow between devises.
- May cause dropouts when recording multiple tracks
FireWire - 400kbps data transfer rate - utilises PEER to PEER configuration
- optimal path for data transfer established via communication between devices.
- superior choice for multiple track recording
Interface Card
- Very high track counts (8+) will require an IC to plug in directly to the computers PCI (peripheral component interconnect) bus.
- Pro Tools|HD utilises an IC for this purpose
Headroom and Gain Staging
Gain Staging
- Proper setting of gain at each stage of a signal path, to prevent overloads occurring at any point.
Example - Analogue Console
Input gain > EQ > Pan Amplifier > Fader buffer > Bus > Master Bus
All of these stages are points at which overload may occur, and where care should be taken to set gain properly.
Pre-fader and after-fader listen is for monitoring for overloads at different points along the signal path.
(PFL & AFL)
Channel Faders
- The level of the channel faders should always remain below the level of the subgroup and/or master faders.
- This is especially crucial for those channels with high gain structures: utilising highly active EQs and/or plugins providing additional gain.
LEAVE HEADROOM! - Generally 10Db HR, at least 6-3DB.
Headroom
A legacy of early 16 bit digital recording is a belief that a protocol of mixing as close to 0Db full scale, using all available bits, is needed for maximum resolution and to avoid noise produced by unused headroom.
While this was somewhat necessary for early 16 bit digital recording, the 24 bit DR of today and intrinsic calculation of coefficients mean that this is simply no longer the case, and it is wise to leave healthy headroom to preserve transients, avoiding clipping, and produce a cleaner, more harmonious mix.
The super-fast transients produced by the initial attack of an instrument can peak as high as 20Db, while a VU meter may read 0Db. (Peak meters are far more accurate.)
Recording too hot (approaching or meeting 0Db FS) will likely result in overloading and tonal transients being clipped, produce a dull and less than realistic sound.
Headroom Summary
- Keep all ch. faders below subgroup and master faders
- Channels with high gain structures should be lowered, rather than raising all other channels to the same level.
- Leave headroom - you can raise the level later in the mixing process.
Tips from Gannon Kashiwa of Digidesign
Causes of decreased fidelity -
- overcompressing
- too much processing to achieve a 'CD sound' too early in the process
- maxed out mixes with master chains allowing little room to work for mastering studios
Headroom -
- Recommends 3-6Db
- Issues with reaching 0Db FS include potential for inter-sample clipping, i.e. if two samples breach in to overload, an overage will be assumed and compensated for during the reconstruction of the waveform, meaning clipping applied to peaks will carry over and result in a clipped waveform even between breaches (ms) - this the reconstruction filter at work
Mixing
- mix in groups
- distribute EQ and compression across a number of stages, do not over work any one instance of either for a cleaner result.
Filtering
- Use low pass filters to cut out the unnecessary highs of sounds to avoid competition for the desired highs of other sounds.
24 bit DAWs
- calculate vol and pan coefficients as 24 bit coefficients, meaning level no longer has sonic or mathematical consequence, unlike 16 bit predecessors.
(Unity Gain = Input 0Db + Output 0 Db)
GOOD ANALOGUE PRACTICE TRANSLATES TO DIGITAL REC. PRACTICE LOGICALLY
ADCs and DACs
ADC - Analogue-to-Digital Converter
DAC - Digital-to-Analogue Converter
Low-end units are often combined ADC/DAC interfaces, potentially with a built-in pre-amp too.
Mid Range - High-end units are usually standalone hardware, specialised and focused.
High-end units are typically outboards, superior in design and quality.
(Tip: Ultimately the quality of a signal is only as high as that which the weakest link in a signal path can afford i.e. the benefits of a chain of high end equipment will not be perceivable if the signal is ultimate converted by a cheap ADC/DAC.)
Latency
Latency should by default be kept to the absolute minimum where possible.
Acceptably low latency may be a delay of 3ms or lower.
Anything beyond 6ms is bordering futile.
Latency should be set as low as possible, but comfortable clear the point of byte dropping.
Audio Interfaces such as ADC/DACs generally use 'input buffers' to set the rate of latency.
One should avoid using any processing beyond the necessary when recording as this will only drain valuable CPU and cause hangups/dropouts, the result will be better quality audio and more tightly synced monitoring.
Some AIs may employ zero-latency monitoring, channeling a direct loop from input to output, producing accurate monitoring alongside backing track playback for timely recording.
In the absence of Z-L monitoring -
- A similar result can be achieved by connecting the interface input to an aux, bus or direct output on the A or D console to avoid recording the entire temp mix to the new track. With digital consoles there will be some latency experiences, but often only around the 2ms or less mark due to the optimised OS installed.
TO AVOID LATENCY -
- LOWER INPUT BUFFER SIZE
- USE Z-L MONITORING
- USE AN OUTBOARD CONSOLE
- AVOID THE USE OF PLUGINS
Firewire vs USB
USB 2.0 - 480kbps data transfer rate - utilises as MASTER/SLAVE configuration
- Adds system overheads, resulting in slower data flow between devises.
- May cause dropouts when recording multiple tracks
FireWire - 400kbps data transfer rate - utilises PEER to PEER configuration
- optimal path for data transfer established via communication between devices.
- superior choice for multiple track recording
Interface Card
- Very high track counts (8+) will require an IC to plug in directly to the computers PCI (peripheral component interconnect) bus.
- Pro Tools|HD utilises an IC for this purpose
Headroom and Gain Staging
Gain Staging
- Proper setting of gain at each stage of a signal path, to prevent overloads occurring at any point.
Example - Analogue Console
Input gain > EQ > Pan Amplifier > Fader buffer > Bus > Master Bus
All of these stages are points at which overload may occur, and where care should be taken to set gain properly.
Pre-fader and after-fader listen is for monitoring for overloads at different points along the signal path.
(PFL & AFL)
Channel Faders
- The level of the channel faders should always remain below the level of the subgroup and/or master faders.
- This is especially crucial for those channels with high gain structures: utilising highly active EQs and/or plugins providing additional gain.
LEAVE HEADROOM! - Generally 10Db HR, at least 6-3DB.
Headroom
A legacy of early 16 bit digital recording is a belief that a protocol of mixing as close to 0Db full scale, using all available bits, is needed for maximum resolution and to avoid noise produced by unused headroom.
While this was somewhat necessary for early 16 bit digital recording, the 24 bit DR of today and intrinsic calculation of coefficients mean that this is simply no longer the case, and it is wise to leave healthy headroom to preserve transients, avoiding clipping, and produce a cleaner, more harmonious mix.
The super-fast transients produced by the initial attack of an instrument can peak as high as 20Db, while a VU meter may read 0Db. (Peak meters are far more accurate.)
Recording too hot (approaching or meeting 0Db FS) will likely result in overloading and tonal transients being clipped, produce a dull and less than realistic sound.
Headroom Summary
- Keep all ch. faders below subgroup and master faders
- Channels with high gain structures should be lowered, rather than raising all other channels to the same level.
- Leave headroom - you can raise the level later in the mixing process.
Tips from Gannon Kashiwa of Digidesign
Causes of decreased fidelity -
- overcompressing
- too much processing to achieve a 'CD sound' too early in the process
- maxed out mixes with master chains allowing little room to work for mastering studios
Headroom -
- Recommends 3-6Db
- Issues with reaching 0Db FS include potential for inter-sample clipping, i.e. if two samples breach in to overload, an overage will be assumed and compensated for during the reconstruction of the waveform, meaning clipping applied to peaks will carry over and result in a clipped waveform even between breaches (ms) - this the reconstruction filter at work
Mixing
- mix in groups
- distribute EQ and compression across a number of stages, do not over work any one instance of either for a cleaner result.
Filtering
- Use low pass filters to cut out the unnecessary highs of sounds to avoid competition for the desired highs of other sounds.
24 bit DAWs
- calculate vol and pan coefficients as 24 bit coefficients, meaning level no longer has sonic or mathematical consequence, unlike 16 bit predecessors.
(Unity Gain = Input 0Db + Output 0 Db)
GOOD ANALOGUE PRACTICE TRANSLATES TO DIGITAL REC. PRACTICE LOGICALLY
Saturday, 12 October 2013
Mic Pre-amps - TREHB Ch.3
Mic Pre-amp
- Boosts the weak output (v) of a mic up to 'line level'.
Outboard vs Modern inbuilt/DAW modules
- Outboards are considered to have superior quality, producing higher highs and lower lows, and stronger more desirable 'characters'
(Recording Tip - Preserve the transients as this is where the character of sound lies, at its genesis i.e. easy on the delay of attack.)
Vintage Mic Pres -
- Considered to have superior 'sound', or character, which can broadly put down to the iron used for the construction of transformers and inductors. Modern replacements use lighter, cheaper materials, and 'integrated circuits' i.e. complete circuits//chips
Outstanding examples
NEVE 1071/1083
The 'Neve Sound'
- Channel strip pulled from a Neve console, reconfigured for outboard use.
- Common features - Input Line + EQ
1071 - 3 Band EQ
1083 - 4 Band EQ ( 2 Mids)
Modern Mic Pres -
- Generally divisible into two groups
1. Emulation - Modelling sonic character of vintage modules
2. Transparent/Accurate
Outstanding examples
Great River
Types 1+2
Example MP-2NV (Neve 1073 model)
Manley Labs
Langevin AM$ Console channel repro (rough)
Vintech
X73 and X81 - Neve repros
Daking
52270B 4 Band Eq - Trident A Range console channel repro
Universal Audio
2-610 - 610 console channel repro
Hardy
M-1 One of the first dedicated outboard mic amps, accuracy and transparency with the ability to become aggressive if desired
Millenia Media
HV-3B
- Wide Bandwidth up to 300KHz
- Standard for recording of classical and critical acoustic music
GML
Units by George Massenburg, world-class audio design/recording engineer
GML Gear produces life-like/reference standard transparency
Grace
Transparent/True Hi-Fi
Mic Amp Setup
Primary Controls
Gain/Level/Trim
- Level of amplification
- Most mic pres amplify raw mic signal up to 60 Db (x1,000,000)
- Some as much as 80Db for low output mics i.e. ribbon mics or field audio recordings
Metering
- Overload indicators + Ladder style peak meters/Combined
Attenuator/Input Pad
- Reduction of amplitude to prevent circuits from over loading
- Buffer zone of 10-20Db, switch triggered
Phase Switch
- Switches the polarity of a signal in the case of incorrect or poor miking
- Set so as to achieve the richest lows
High Pass Filter
- attenuates/reduces low outputs in bands between 40-160hz
- this value is usually fixed in mic pre-amps, however some feature variable low cuts
(Rare) Impedance Control
- Accurate matching of mic impedance, originating in a necessity for a 600 ohm load for audio equipment to operate to spec (40s-70s)
Setup Advise
- Gain - adjust until only the loudest sections of a signal are triggering clip/overload indicator
- indicator often (but not always) triggered before overload as a precaution, so minor triggering is negligible, however consult manual. This is to achieve full bodied yet clean lows.
- Low mic pre gain may need boosting further along the signal path/chain, raising noise levels to an unacceptable degree.
Direct Injection
- Opportunity to bypass mics altogether when recording electric or electrified instruments
- Benefits include the use of fewer mics during production, resulting in less leakage in sessions involving live recording of multiple signals. Easier and faster than a mic setup.
(Plugging directly to the preamp without a DI will not cause damage, however mismatched impedance between instrument and preamp usually results in dropped highs and a dulled result.
Advantages
- DI transformers provide ground isoloation, allowing long cable runs from high impedance sources (guitars, keyboards) without the excessive loss of bandwidth.
- The extremely high impedance of DIs ensures a perfect match with any pickup to provide warmer, more natural sound.
- Allows for a 50ft cable length before the signal degrades.
Types of DI
Active
- Active DIs provide gain (some to an extent which could nullify the need for a preamp)
- Ground switch for minimising noise/hum
- Requires power source
Passive
- No gain and no power source
- Ground switch
Amplifier Emulators (Advanced DI)
- reproduces the sounds of various guitar/bass rigs
- a lesser result than a full rig/mic/pre setup
- Boosts the weak output (v) of a mic up to 'line level'.
Outboard vs Modern inbuilt/DAW modules
- Outboards are considered to have superior quality, producing higher highs and lower lows, and stronger more desirable 'characters'
(Recording Tip - Preserve the transients as this is where the character of sound lies, at its genesis i.e. easy on the delay of attack.)
Vintage Mic Pres -
- Considered to have superior 'sound', or character, which can broadly put down to the iron used for the construction of transformers and inductors. Modern replacements use lighter, cheaper materials, and 'integrated circuits' i.e. complete circuits//chips
Outstanding examples
NEVE 1071/1083
The 'Neve Sound'
- Channel strip pulled from a Neve console, reconfigured for outboard use.
- Common features - Input Line + EQ
1071 - 3 Band EQ
1083 - 4 Band EQ ( 2 Mids)
Modern Mic Pres -
- Generally divisible into two groups
1. Emulation - Modelling sonic character of vintage modules
2. Transparent/Accurate
Outstanding examples
Great River
Types 1+2
Example MP-2NV (Neve 1073 model)
Manley Labs
Langevin AM$ Console channel repro (rough)
Vintech
X73 and X81 - Neve repros
Daking
52270B 4 Band Eq - Trident A Range console channel repro
Universal Audio
2-610 - 610 console channel repro
Hardy
M-1 One of the first dedicated outboard mic amps, accuracy and transparency with the ability to become aggressive if desired
Millenia Media
HV-3B
- Wide Bandwidth up to 300KHz
- Standard for recording of classical and critical acoustic music
GML
Units by George Massenburg, world-class audio design/recording engineer
GML Gear produces life-like/reference standard transparency
Grace
Transparent/True Hi-Fi
Mic Amp Setup
Primary Controls
Gain/Level/Trim
- Level of amplification
- Most mic pres amplify raw mic signal up to 60 Db (x1,000,000)
- Some as much as 80Db for low output mics i.e. ribbon mics or field audio recordings
Metering
- Overload indicators + Ladder style peak meters/Combined
Attenuator/Input Pad
- Reduction of amplitude to prevent circuits from over loading
- Buffer zone of 10-20Db, switch triggered
Phase Switch
- Switches the polarity of a signal in the case of incorrect or poor miking
- Set so as to achieve the richest lows
High Pass Filter
- attenuates/reduces low outputs in bands between 40-160hz
- this value is usually fixed in mic pre-amps, however some feature variable low cuts
(Rare) Impedance Control
- Accurate matching of mic impedance, originating in a necessity for a 600 ohm load for audio equipment to operate to spec (40s-70s)
Setup Advise
- Gain - adjust until only the loudest sections of a signal are triggering clip/overload indicator
- indicator often (but not always) triggered before overload as a precaution, so minor triggering is negligible, however consult manual. This is to achieve full bodied yet clean lows.
- Low mic pre gain may need boosting further along the signal path/chain, raising noise levels to an unacceptable degree.
Direct Injection
- Opportunity to bypass mics altogether when recording electric or electrified instruments
- Benefits include the use of fewer mics during production, resulting in less leakage in sessions involving live recording of multiple signals. Easier and faster than a mic setup.
(Plugging directly to the preamp without a DI will not cause damage, however mismatched impedance between instrument and preamp usually results in dropped highs and a dulled result.
Advantages
- DI transformers provide ground isoloation, allowing long cable runs from high impedance sources (guitars, keyboards) without the excessive loss of bandwidth.
- The extremely high impedance of DIs ensures a perfect match with any pickup to provide warmer, more natural sound.
- Allows for a 50ft cable length before the signal degrades.
Types of DI
Active
- Active DIs provide gain (some to an extent which could nullify the need for a preamp)
- Ground switch for minimising noise/hum
- Requires power source
Passive
- No gain and no power source
- Ground switch
Amplifier Emulators (Advanced DI)
- reproduces the sounds of various guitar/bass rigs
- a lesser result than a full rig/mic/pre setup
Monday, 7 October 2013
Studio - Day 1 - 7/10/2013
Mike - Assistant Producer/Engineer
Dan Swift - Producer/Tutor
Spill - interference from other sources of vibration i.e. hearing drums on bass track
Terms Encountered -
Auxiliary sends -
Dynamic Mic - For warmth of tone (re: guitar)
Overheads (Mics)
Under snare mics
Room Mics - Natural stereo spread
Phasing (-) - Product of multiple mics capturing one sound, resulting in mutual cancellation, reverse competing signals to eliminate phenomenon
DI (Direct Injection) - Compensates for modal? issues i.e. frequency bias
Concept of track efficiency (Vintage method) - record bass and tambourine with one mic to two channels, high pass to isolate tamb., low pass to isolate bass.
'57' Mic - traditional mic for the capture of snare hits, present highs and mids, use a high pass/low cut to eliminate kick spill
Close mics - modern recording technique pioneered in the recording of rock music 1980s
'D12' AKG? - appropriate for kick capture
D112 - kick capture - 'clicky and subby'
AD converter - Analogue to Digital - use ethernet for headphone monitor module - communication between control room and capture room
Screen off Bass to reduce inference/cross-play between drums and bass
When recording two elements in close proximity (singer/guitar) direct mics at an angle away from the direct path of the competing element.
BOOKING STUDIO TIME -
Mike - Monday/Tuesday 4-6 surplus hours
Tips for vocal capture and treatment - Mic>EQ(Corrective)>Compressor>EQ(Creative)>
Slapback delay - John Lennon solo style vocal effect.
UPCOMING TOPICS - Signal Paths & Gain Structures
Subscribe to:
Posts (Atom)