Introduction to Music Production: Compare and contrast an algorithmic and convolution reverb. Demonstrate the difference and the important features in both types of reverb

Introduction to Music Production:

“Hi Everybody, how is going on?

My name is Matt, Italian 34 years old, based in Italy. I am a vocalist, a new producer and

I have worked as production assistant for a English company as well based in London, booking agency and production management company for quality bands and artists.

This lesson is for week 5 of Introduction

To Music Production at Coursera.org

We are going to learn an algorithmic and convolution reverb and demonstrate the difference and the important features in both types of reverb.

...........Let's go...

Compare and contrast an algorithmic and convolution reverb. Demonstrate the difference and the important features in both types of reverb.

Advantage and disadvantage: difference and the important features in both types of reverb.

Convolution reverb

Algorithmic Reverb

Space Designer Mono/Stereo Output Configuration Parameters

• Dry slider: Sets the level of the non-effect (dry) signal. Set this to a value of 0 (mute) if

Space Designer is inserted in a bus channel, or when using modeling impulse responses

such as speaker simulations.

• Rev(erb) slider: Adjusts the output level of the effect (wet) signal.

• GoldVerb can be automated easily
• Algorithmic reverbs use math formula
• Few parameters to control the reverb
• Normal amount CPU power
• Great response
• Easy to find a good reverb
• Useful whit sample libraries that already have some room recorded in
• Not recommended using algorithmic reverb on your solo instruments

• Space Designer cannot be fully automated
• Convolution reverbs use real sound samples
• Great feature to import a real sound captured from your studio by impulse responses with Impulse Response Utility
• So much parameters to control the reverb
• Really Creative reverb in Synthesized IR mode and amazing Sorround effects.
• Slow response
• Really hard to manage all parameters and understand how does it works very well
• Need to study all parameters between to get a full control of it.
• More realistic sense of space back
• Good sound on instruments on dry environment
• experimental approach on Synthetic sound but really complex parameter's chain

Introduction

• Initial Delay slider and field: Sets the time between the original signal and the diffuse

reverb tail. If you’re going for a natural-sounding, harmonic reverb, the transition

between the early reflections and the reverb tail should be as smooth and seamless as

possible. Set the Initial Delay parameter so that it is as long as possible, without a

noticeable gap between the early reflections and the reverb tail.

• Spread slider and field: Controls the stereo image of the reverb. At 0%, the effect

generates a monaural reverb. At 200%, the stereo base is artificially expanded.

• High Cut knob and field: Frequencies above the set value are filtered from the reverb

signal. Uneven or absorbent surfaces—wallpaper, wood paneling, carpets, and so

on–tend to reflect lower frequencies better than higher frequencies. The High Cut filter

mimics this effect. If you set the High Cut filter so that it is wide open (maximum value),

the reverb will sound as if it is reflecting off stone or glass.

• Density knob and field: Controls the density of the diffuse reverb tail. Ordinarily you

want the signal to be as dense as possible. In rare instances, however, a high Density

value can color the sound, which you can fix by reducing the Density knob value.

Conversely, if you select a Density value that is too low, the reverb tail will sound grainy.

• Reverb Time knob and field: Time it takes for the reverb level to drop by 60 dB—often

indicated as RT60. Most natural rooms have a reverb time somewhere in the range of

1 to 3 seconds. This time is reduced by absorbent surfaces, such as carpet and curtains,

and soft or dense furnishings, such as sofas, armchairs, cupboards, and tables. Large

empty halls or churches have reverb times of up to 8 seconds, with some cavernous

or cathedral-like venues extending beyond that.

• Diffusion slider and field (Extended Parameters area): Sets the diffusion of the reverb tail.

High Diffusion values represent a regular density, with few alterations in level, times,

and panorama position over the course of the diffuse reverb signal. Low Diffusion

values result in the reflection density becoming irregular and grainy. This also affects

the stereo spectrum. As with Density, find the best balance for the signal.

Space Designer Surround Output Configuration Parameters

• C(enter) slider: Adjusts the output level of the center channel independently of other

surround channels.

• Bal(ance) slider: Sets the level balance between the front (L-C-R) and rear (Ls-Rs) channels.

• In 7.1 ITU surround: the balance pivots around the Lm-Rm speakers, taking the

surround angles into account.

• With 7.1 SDDS surround: the Lc-Rc speakers are considered front speakers.

• Rev(erb) slider: Adjusts the output level of the effect (wet) signal for all channels.

• Dry slider: Sets the overall level of the non-effect signal for all channels. Set this to a value of 0 (mute) when using Space Designer as a bus effect in an aux channel strip.

Use the Send knob of each bussed channel strip to control the wet/dry balance.

Reverb is really important component of most modern mixes because it give us a the sense of a space. Now we are going to look at two separate kind of categories of reverb plug ins. The first one is an algorithmic reverb, and that creates a reverb from some kind of formula, and a convolution reverb which is actually a recording of real space applied to the sound that you are currently using in the DAW.

Space Designer Convolution Reverb

Space Designer generates reverb by convolving, or combining, an audio signal with an

impulse response (IR) reverb sample. An impulse response is a recording of a room’s

reverb characteristics—or, to be more precise, a recording of all reflections in a given

room, following an initial signal spike. The actual impulse response file is a standard audio

file.

Conclusion

Envelope and EQ

parameters

Impulse response

parameters

Global parameters

Important: To convolve audio in real time, Space Designer must first calculate any parameter adjustments to the impulse response.

This requires a moment or two, following parameter edits, and is indicated by a blue progress bar. During this parameter edit processing time you can continue to adjust the parameter. When calculation starts, the blue bar is replaced by a red bar, advising you that calculation is taking place.

Filter parameters

Global parameters :

Lower Section

Working in Space Designer’s IR Sample Mode

In IR Sample mode, Space Designer loads and uses an impulse response recording of an

acoustic environment. This is convolved with the incoming audio signal to place it in the

acoustic space provided by the IR.

To activate IR Sample mode : Click the IR Sample button in the circular area to the left of the main display, and then

select the desired impulse response file from any folder

In Synthesized IR mode, Space Designer generates a synthesized impulse response based

on the values of the Length, envelope, Filter, EQ, and Spread parameters. To switch to

this mode, click the Synthesized IR button in the Impulse Response Parameters section.

Parameter bar

Impulse Response Parameters :

The “sample rate” slider determines the sample rate of an impulse response.

• Input slider: Determines how Space Designer processes a stereo or surround input

signal. For more information, see Using Space Designer’s Input Slider.

• Latency Compensation button: Switches Space Designer’s internal latency compensation

feature on or off. See Using Space Designer’s Latency Compensation Feature.

• Orig: Space Designer uses the current project sample rate. When loading an impulse response, Space Designer automatically converts the sample rate of the impulse response to match the current project sample rate, if necessary. For example, this allows you to load a 44.1 kHz impulse response into a project running at 96 kHz, and viceversa.

• /2, /4, /8: These settings are half-divisions of the preceding value one-half, one-quarter,

one-eighth. For example:

• If the project sample rate is 96 kHz, the options will be 48 kHz, 24 kHz, and 12 kHz.

• IR Sample button and IR Sample menu: Click the IR Sample button to switch to IR Sample

mode. In IR Sample mode, an impulse response sample is used to generate reverberation.

Click the down arrow next to the IR Sample button to open the IR Sample pop-up

menu, in which you can load and manipulate impulse response samples, and record

and edit impulse responses with Impulse Response Utility.

• “sample rate” slider and “preserve length” button: The “sample rate” slider determines

the sample rate of the loaded impulse response. Activate the “preserve length” button

to preserve the length of the impulse response when changing the sample rate.

• Length field: Adjusts the length of the impulse response. See Setting Impulse Response

Lengths in Space Designer.

• Synthesized IR button: Click to activate Synthesized IR mode. A new synthesized impulse

response is generated. This is derived from the values of the Length, envelope, Filter,

EQ, and Spread parameters

• Predelay slider and field: Determines the amount of time between the start of the original

signal and the arrival of the early reflections. Extremely short Predelay settings can

color the sound and make it difficult to pinpoint the position of the signal source. Overly

long Predelay settings can be perceived as an unnatural echo and can divorce the

original signal from its early reflections, leaving an audible gap between them.

The optimum Predelay setting depends on the type of input signal—or more precisely,

the envelope of the input signal. Percussive signals generally require shorter predelays

than signals where the attack fades in gradually. A good working method is to use the

longest possible Predelay value before you start to hear undesirable side effects, such

as an audible echo. When you reach this point, reduce the Predelay setting slightly.

• Room Shape slider and field: Defines the geometric form of the room. The numeric value

(3 to 7) represents the number of corners in the room. The graphic display visually

represents this setting.

• Room Size slider and field: Determines the dimensions of the room. The numeric value

indicates the length of the room’s walls—the distance between two corners.

• Stereo Base slider and field: Defines the distance between the two virtual microphones

that are used to capture the signal in the simulated room.

Note: Spacing the microphones slightly farther apart than the distance between two

human ears generally delivers the best, and most realistic, results. This parameter is

available only in stereo instances of the effect.

Chapter

Hey Guys,

Thanks for watching my presentation .

Writing this lesson went pretty well.

But It was so hard to cover all details and explain better this lesson because Reverb is a huge field.

The material wasn’t new to me but I needed to write slides to make sure I used all the terms correctly.

I was able to use a demo version of Prize which made slides and editing fairly easy, though it did take

a while to figure out.

I think I covered all details during the lesson and I hope you found it useful.

“I worked hard on this and I would love to know if I got everything right.

Is there anything I missed or could have explained better?

What do you think of the slides?

Thank you for watching and critiquing.”

All the best, see you on the next lesson.....

Matt

Changing the sample rate upward increases—or changing it downward decreases the frequency response (and length) of

the impulse response, and to a degree the overall sound quality of the reverb. Upward sample rate changes are of benefit

only if the original IR sample actually contains higher frequencies. When you are reducing the sample rate, use your ears to

decide if the sonic quality meets your needs. Note: Natural room surfaces except concrete and tiles—tend to have minimal

reflections in the higher frequency ranges, making the half-rate and full-rate IRs sound almost identical.

When you select half the sample rate, the impulse response becomes twice as long. The highest frequency that can be

reverberated will be halved. This results in a behavior that is much like doubling every dimension of a virtual room multiplying

a room’s volume by eight. Another benefit of reducing the sample rate is that processing requirements drop

significantly, making half–sample rate settings useful for large, open spaces.

Activating the “preserve length” button preserves the length of the impulse response

when the sample rate is changed. Manipulating these two parameters as you see fit can

lead to interesting results.

The lower sample rates can also be used for interesting tempo, pitch, and retro-digital

sounding effects.

If you are running Space Designer in a project that uses a higher sample rate than the impulse response, you may also want

to reduce the impulse response sample rate. Make sure the “preserve length” function is enabled. This cuts CPU power

consumption without compromising reverb quality. There is no loss in reverb quality, because the impulse response does

not benefit from the higher project sample rate. You can make similar adjustments while running in Synthesized IR mode.

Most typical reverb sounds don’t feature an excessive amount of high frequency content. If you were running at 96 kHz,

for example, you would need to make use of some deep lowpass filtering to obtain the mellow frequency response

characteristics of many reverb sounds.

A better approach would be to first reduce the high frequencies by 1/2 or even 1/4 using the “sample rate” slider,

and then apply the lowpass filter. This conserves a considerable

amount of CPU power.

Space Designer’s Envelope and EQ Parameters

Space Designer’s main interface area is used to show and edit envelope and EQ parameters.

It consists of three components: the button bar at the top, the main display, and the

parameter bar.

• The button bar is used to choose the current view/edit mode.

• The main display shows, and allows you to graphically edit, either the envelope or the

EQ curve.

• The parameter bar displays, and allows you to numerically edit, either the envelope or

the EQ curve.

• Reset button: Resets the currently displayed envelope or EQ to its default values.

Chapter

• All button: Resets all envelopes and the EQ to default values.

• Volume Env button: Displays the volume envelope in the foreground of the main display.

The other envelope curves are shown as transparencies in the background.

• Filter Env button: Displays the filter envelope in the foreground of the main display.

The other envelope curves are shown as transparencies in the background.

• Density Env button: Displays the density envelope in the foreground of the main display.

The other envelope curves are shown as transparencies in the background.

• EQ button: Displays the four-band parametric EQ in the main display.

• Reverse button: Reverses the impulse response and envelopes. When the impulse

response is reversed, you are effectively using the tail rather than the front end of the

sample. You may need to change the Pre-Dly and other parameter values when

reversing.

Volume envelope

We can edit all Volume envelope parameters numerically, and

many can also be edited graphically

Density envelope

The density envelope allows you to control the density of the synthesized impulse response

over time. You can adjust the density envelope numerically in the parameter bar, and

you can edit the Init Level, Ramp Time, and End Level parameters

Note: The density envelope is available only in Synthesized IR mode .

Thank You!

• Init Level field: Sets the initial volume level of the impulse response attack phase. It is expressed as a percentage of the full-scale volume of the impulse response file. The attack phase is generally the loudest point of the impulse response. Set Init Level to 100% to ensure maximum volume for the early reflections.

• Attack Time field: Determines the length of time before the decay phase of the volume

envelope begins.

• Decay Time field: Sets the length of the decay phase.

• Volume decay mode buttons: Set the volume decay curve type.

• Exp: The output of the volume envelope is shaped by an exponential algorithm, to generate the most natural-sounding reverb tail.

• Lin: The volume decay will be more linear (and less natural sounding).

• End Level field: Sets the end volume level. It is expressed as a percentage of the overall volume envelope.

• If set to 0%, you can fade out the tail.

• If set to 100%, you can’t fade out the tail, and the reverb stops abruptly (if the end point falls within the tail).

• If the end time falls outside the reverb tail, End Level has no effect.

• Init Level field: Sets the initial density (the average number of reflections in a given

period of time) of the reverb. Lowering the density levels will result in audible reflections

patterns and discreet echoes.

• Ramp Time field: Adjusts the length of time elapsed between the Initial and End Density

levels.

• End Level field: Sets the density of the reverb tail. If you select an End Level value that

is too low, the reverb tail will sound grainy. You may also find that the stereo spectrum

is affected by lower values.

• Reflection Shape slider: Determines the steepness (shape) of the early reflection clusters

as they bounce off the walls, ceiling, and furnishings of the virtual space. Small values

result in clusters with a sharp contour, and large values result in an exponential slope

and a smoother sound. This is handy when recreating rooms constructed of different

materials. Reflection Shape, in conjunction with suitable settings for the envelopes,

density, and early reflection will assist you in creating rooms of almost any shape and

material.

Space Designer’s EQ

Space Designer features a four-band EQ comprised of two parametric mid-bands plus

two shelving filters (one low shelving filter and one high shelving filter). You can edit the

EQ parameters numerically in the parameter bar, or graphically in the main display.

• EQ On/Off button: Enables or disables the entire EQ section.

• Individual EQ band buttons: Enable or disable individual EQ bands.

• Frequency fields: Set the frequency for the selected EQ band.

• Gain fields: Adjust the gain cut or boost for the selected EQ band.

• Q fields: Set the Q factor for the two parametric bands. The Q factor can be adjusted

from 0.1 (very narrow) to 10 (very wide).

The filter envelope:

The filter envelope is shown in the main display when the Filter Env button is active. It

provides control of the filter cutoff frequency over time. All filter envelope parameters

can be adjusted either numerically in the parameter bar or graphically in the main display

• Filter On/Off button: Switches the filter section on and off.

• Filter Mode knob: Determines the filter mode.

• 6 dB (LP): Bright, good general-purpose filter mode. It can be used to retain the top

end of most material, while still providing some filtering.

• 12 dB (LP): Useful where you want a warmer sound, without drastic filter effects. It is

handy for smoothing out bright reverbs.

• BP: 6 dB per octave design. Reduces the lower and high end of the signal, leaving

the frequencies around the cutoff frequency intact.

• HP: 12 dB per octave/two-pole design. Reduces the level of frequencies that fall

below the cutoff frequency.

• Reso(nance) knob: Emphasizes frequencies above, around, or below the cutoff frequency.

The impact of the resonance knob on the sound is highly dependent on the chosen

filter mode, with steeper filter modes resulting in more pronounced tonal changes.

Global parameters

• Init Level field: Sets the initial cutoff frequency of the filter envelope.

• Attack Time field: Determines the time required to reach the Break Level (see below).

• Break Level field: Sets the maximum filter cutoff frequency that the envelope reaches.

It also acts as the separation point between the attack and decay phases of the overall

filter envelope. In other words, when this level has been reached after the attack phase,

the decay phase will begin. You can create interesting filter sweeps by setting the Break Level to a value lower than the Init Level.

• Decay Time field: Determines the time required (after the Break Level point) to reach

the End Level value.

• End Level field: Sets the cutoff frequency at the end of the filter envelope decay phase.

GoldVerb

• Input slider: Determines how Space Designer processes a stereo or surround input

signal. For more information, see Using Space Designer’s Input Slider.

• Latency Compensation button: Switches Space Designer’s internal latency compensation

feature on or off.

• Definition area: Lets you switch to a less defined IR set, in order to emulate reverb

diffusion and save CPU resources.

• Rev Vol Compensation button: Engages Space Designer’s internal IR volume matching

function.

• Output sliders: Adjust output levels. S

GoldVerb allows you to edit both the early reflections and diffuse reverb tail separately,

making it easy to precisely emulate real rooms.

Balance ER/Reverb slider

Early Reflections parameters

Input Stereo or Surround sliders

Controls the balance between the early reflections and reverb

signal. When the slider is set to either extreme position, the other signal is not heard.

Used to emulate the original signal’s first reflections as

they bounce off the walls, ceiling, and floor of a natural room.

Mix slider and field

( Wet and Dry )

The Input slider behaves differently in stereo or surround instances. The Input slider does

not appear in mono or mono to stereo instances.

• In stereo instances, the Input slider determines how a stereo signal is processed.

• In surround instances, the Input slider determines how much LFE signal is mixed with

the surround channels routed into the reverb.

Reverb parameters

Determines the balance between the effect (wet) and direct (dry)

signals.

Control the diffuse reverberations.

• Pre-Dly knob: Sets the reverb’s predelay time, or time between the original signal and the first reflections from the reverb.

• IR Start knob: Sets the playback start point in the impulse response sample.

• Spread and Xover knobs (synthesized IRs only): Spread adjusts the perceived width of the stereo or surround field. Xover sets the crossover frequency in Hertz. Any synthesized impulse response frequency that falls below this value will be affected by the Spread parameter.

Space Designer Input Slider: Stereo Mode

• Stereo setting (top of slider): The signal is processed on both channels, retaining the

stereo balance of the original signal.

• Mono setting (middle of slider): The signal is processed in mono.

• XStereo setting (bottom of slider): The signal is inverted, with processing for the right

channel occurring on the left, and vice versa.

• In-between positions: A mixture of stereo to mono crossfeed signals is produced.

Space Designer Input Slider: Surround Mode

• Surround Max setting (top of slider): The maximum amount of LFE signal is mixed with

the other surround channels.

• Surround 0 setting (bottom of slider): The entire LFE signal is passed through the reverb

unprocessed.

• In-between positions: A mixture of LFE and surround channel information is processed.

Algorithmic reverb VS Convolution Reverb

VS

GoldVerb

Apple Logic

Space Designer Convolution

Reverb

Apple Logic