April 14, 2010
Understanding Ableton Live’s Reverb
- File Under: Tutorials |
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Some people love it, some hate it. Some stay away from it because they don’t know how to use it. Ableton’s built in Reverb is capable of some pretty amazing things once you get to know it.
This tutorial will break down Ableton Live’s Reverb. Hopefully after reading this, you’ll be grabbing for this sometimes misunderstood plug-in more often in your productions.
What Is Reverb?
In a nutshell, reverberation (or reverb for short), is the continuation of reflected sound after the original has been removed.
Everyone has experienced some form of reverb in their life. Usually it happens in large open areas, or small areas with reflective surfaces (bathrooms, rooms with hardwood floors, etc).
When you yell, clap or talk in these rooms, there is a noticeable “tail” of quick echoes that slowly fade off. This is known as the reverb.
The millions of tiny echoes bouncing back and forth eventually dying out is known as the “decay”.
A visual representation of sound bouncing around a space.
When programming Ableton’s Reverb plug-in it helps to visualize some type of environment. Cathedrals and large rooms have a very long decay time, while a shower or small tiled room would have a very short decay time.
Listen to this example. I have a dry snare hit from a drum machine. One is treated with 400ms (milliseconds) of decay, and the other has 2 seconds of decay. Listen for the time it takes for the sound to fully die out.
400ms Decay Snare
2 Seconds Decay Snare
Different Types Of Reverb
The most primitive and natural form of reverb. Usually recording studios would have rooms with reflective surfaces (cement, tile) on the walls and floor. They would have a loud speaker playing the track, and it would be moved around the room for different colors of reverb.
Once the desired form of reverb was achieved, it would be send back into the main mix.
A speaker is attached to a piece of sheet metal (hence the name plate), and the vibrations from the metal simulate a unique version of reverb.
A pick up (small microphone) would be attached the sheet metal allowing the engineer to blend the full “wet” reverb signal, with the dry signal from the speaker (similar to the “Dry/Wet” knob on Ableton’s Reverb).
Sometime later, someone decided to add two pick ups, resulting in a stereo reverb effect.
Have you ever taken a slinky, put your ear on one end of it, and let the other end drop to the ground? It gives a very metallic space age sound.
This is the same concept behind spring reverb. Similar to plate reverb, the sound source is positioned at one end of the spring, while a pick up is positioned at the other. Sound travels through the spring and creates a “springy” sound.
With the advent of digital signal processors, reverb algorithms were created by using a large number of decaying echoes.
Equipped with the right set of tools, digital reverbs can re create many different forms of reverb ranging from the natural to the space age. Ableton’s reverb fits into this category.
Another form of digital reverb, but suited to better recreate room sounds. Convolution reverbs set out to actually “sample” room setting through a complex range of algorithms and impulse responses.
Getting To Know Ableton’s Reverb
Before diving into Ableton’s Reverb, it’s a good idea to try out some of the presets that come with it.
- Drop Ableton’s Reverb onto a track with an instrument, sample or loop.
- Click on the “Hot Swap” button located on the top right of the unit.
- In Live’s Device and File Browser, double click the orange symbol with two arrows facing up and down.
Pay close attention to the names of the presets to get a better understanding of how Ableton’s Reverb generates it’s sound. Watch which settings are turned on and off when you select a preset, some use chorus, some use hi-cut and low-cut. Some more complex than others.
The start of Ableton’s Reverb signal chain, all audio passes through here first. This is where you set the filter cut-off (with the X-Y controller) as well as the pre delay.
Lo Cut/Hi Cut – These two filters are used to cut off the highs (hi cut) or lows (lot cut). If the high end of the signal is cut off coming in, you will lose any of the “sparkle” in the reverb, making for a darker sound.
While on the other end, cutting out the lows, will only allow high frequencies to pass through, creating a thinner reverb sound. Both can but turned off to save on CPU power.
Below is an example of the reverb Dry/Wet turned to 100%, the first sound using lo cut, the other using hi cut.
Example of Reverb’s lo cut filter
Example of Reverb’s hi cut filter
Pre Delay – This is the amount of time it takes the sound to reach the first reflective surface. Obviously if the room is huge, it will take longer for the sound to reach its first wall and bounce back. Most “natural” settings use a pre delay between 1ms and 25ms.
- Place the Reverb on a Synth track.
- Turn the Dry/Wet knob up to 100%.
- Turn the Pre Delay knob up to 250ms.
- Press a note on your keyboard. Notice there is a delay before the sound plays. Since the Dry/Wet knob is turned to 100%, you’re hearing only the reverb, and since it takes 250ms for the sound to bounce back, there is a slight delay.
A bit more complex than most sections, but it’s easy to think of the early reflections as the first echoes you hear bouncing off of a surface before the onset of the reverb “tail”.
This section is more about adding character to the overall sound of the reverb.
Spin – This setting applies modulation to the early reflections with an X-Y controller. Sliding the controller to the left and right affects the depth of modulation, while sliding up and down affects the amount.
- Slide the Spin’s contoller all the way to the top right.
- This puts the spin effect at full.
- Play a note for a truly bizarre sound.
These early reflections are being modulated by a low frequency sine wave, which creates the warbly effect you’re hearing.
Shape – This control will help blend the early reflections with the onset of the reverb tail. With this setting lower there will be a “gap” between the early reflections and the onset of the reverb tail. At higher settings the two will blend together, resulting in a smoother reverb sound.
The heart of Ableton’s reverb. Use these settings to adjust the quality of the reverb, overall size, and the amount of stereo effect.
Quality – Three settings to choose from here; eco, mid, and high. The higher the quality, the bigger the toll on your processor. Some people like the “cheap” sound of the eco setting, since this is a subjective topic, you decide which quality setting you like best.
Size – This allows you to change the volume or size of the room.
- Turn the size volume all the way down.
- Play some notes, notice the thin metallic sound.
- Now turn the size knob all the way up.
- Again play something, notice the much “bigger” sound.
Stereo – With this knob turned all the way down, the reverb is mixed down to a single mono sound, when turned all the way up, the reverb effect is panned hard left and hard right, simulating a more realistic hearing experience in a room.
This is the part of the reverb unit that actually creates the reverberant tail that follows the early reflections.
Hi Shelf/Lo Shelving Filters – Adjusting the high shelf filter allows you to fine tune the frequencies of the decay model to simulate people, carpeting or other absorbent objects in a room.
The low shelf filter allows the sound of the decay to be thinned out depending on how much of the low end you are actually cutting out.
Both of these options can be turned off to save CPU consumption.
Decay – The amount of time it takes for the reflections to die down. With a setting of 2 seconds, it would take the reverb tail 2 seconds for it to reach -60dB (essentially fade out).
- Enter Hot Swap Mode to the top right of the unit.
- Select the “Sixty Seconds” preset under the “Special” folder.
- Play a note or sound.
- Since the decay knob is maxed, it takes 60 seconds for the tail to reach -60dB.
Freeze – This button will allow you to freeze the decay of a sound indefinitely. At whichever moment you initiate the freeze button, that part will be repeated until the freeze button is turned off.
The cut button stops any more signal from coming through. With this button unchecked you send as many notes or sounds as you want through, all being frozen by Live’s Reverb. Watch out for clipping!
Flat will simply bypass the high and low shelf filters while freeze is activated.
Density And Scale – These determine how many reflections will occur. With a higher density and ccale setting you are upping the amount of reflected sound bouncing around in the room.
These have a more noticeable affect with a smaller size setting.
Chorus – Similar to the spin sections, the chorus section will add modulation to the diffusion (sounds bouncing around in the room). The controls are identical to the spin section under the early reflections setting.
This section will adjust overall signal, as well as the amplification of the Reflections and Diffusions (early reflections and diffusion network, respectively).
Reflect – Changes the amplification of the early reflections section. This allows you to blend the early reflections with the rest of the reverb’s overall mix.
Diffuse – The same idea as the reflect knob, only used for the diffusion network sections.
Dry/Wet – Blends between the untreated sound and the fully treated sound. Turned down to 0% you will hear no reverb at all. Turned to 100% you will hear only the reverberated sound coming through.
When adjusting parameters on Ableton’s Reverb, it’s a good idea to have the Dry/Wet knob up to 100%. This allows you to get a better feel for the full effect of the reverb. Once you’re happy with your settings, use the knob to blend subtly (or not to subtly).