Knowing when to use algorithmic or convolution reverbs can be a difficult call, especially if you’re a new producer just learning this stuff. That’s why in this article we’re going to share our 8 years of music production knowledge to help you understand the differences between algorithmic and convolution reverbs and when to use them. Digital reverbs like these can open up your music production world, so buckle in and take note!
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What’s The Difference Between Algorithmic and Convolution Reverb? (TL;DR)
Here’s the difference between algorithmic and convolution reverbs (TL;DR):
- Algorithmic – less demanding on your CPU, can create otherworldly reverbs and have limitless sound design possibilities, but are worse quality and can’t re-create real spaces.
- Convolution – requires more CPU resources but sounds more authentic. They use impulse responses to simulate real-world acoustic spaces. Good for TV and Film because they can replicate real spaces.
An IR is created by recording a sine wave using microphones in a space. The idea is that the sine wave sweeps the entire frequency spectrum and records all frequencies in that space. This recording can then be read by a convolution reverb to recreate the space.
Natural reverb is created in a physical space with many sound reflections. Algorithmic reverb uses an algorithm to do this. This is computer code that uses a mathematical formula.
How Does Algorithmic Reverb Work?
Algorithmic reverb uses a mathematical equation to create reflections using multiple feedback loops and delays. The decay time makes the late reflections last longer or shorter. This gives the illusion of bigger spaces or smaller spaces.
If you’re using a pedal or some kind of hardware, digital reverb, use something called DSPs (digital signal processors) to deal with the audio signal and create reverb signals.
Pros
✅ Low CPU usage
✅ Endless possibilities for huge, small, or in-between spaces
✅ More functions for sound design like sync, reverse etc.
✅ Great for unnatural and natural-sounding spaces
Cons
❌ Don’t sound as real as convolution reverbs
❌ Difficult to emulate real spaces using them
How Does Convolution Reverb Work?
Convolution reverbs use an impulse response to re-create a real space digitally. They also use mathematical algorithms to process these impulse responses.
Impulse responses are recorded using microphones. These are made with sine waves that will sweep the entire frequency spectrum so that the impulse response software can record the entire audio spectrum of the reverb space.
This can then be read by the convolution reverb to re-create the space.
It also means you can find IRs online for virtually anything. Famous cathedrals, football pitches, and more interesting things like air hangers and more.
Pros
✅ Re-create real-life spaces for natural-sounding reverb
✅ Perfect for TV & Film sound design to match what is seen on screen
✅ Unlimited free IR presets available online for download
✅ Can record your own spaces and load them on the reverb
Cons
❌ CPU intensive & no option for unnatural reverb
❌ Limited controls compared to algorithmic
How and When To Use Algorithmic Reverb
Algorithmic reverb is great to use on multiple tracks because it doesn’t use a lot of your CPU.
You can use algorithmic reverb for:
- Natural sounding, low CPU usage, digital reverb
- Out-of-this-world sound design reverbs that couldn’t be re-created in real life
- Sound design techniques like sync, freeze, and reverse
The downside is they are not as natural sounding as analog, or convolution reverbs.
Algorithmic reverb is a top pick for most electronic, Hip Hop, and more ‘produced’ music genres, because you can use a lot more reverbs (because of the low CPU) for sound design and sculpting. They additionally give extra creative options for sound design like sync modes, freezing, reverse modes, and a lot more.
Additionally, you can create reverbs that you wouldn’t be able to re-create in real life. They are also good solutions to natural sounding reverbs without the huge CPU consumption.
Algorithmic reverbs can replicate analog reverb (usually reflection chambers recorded by mics and then fed back through the mixing desk). They are not as good at replicating these, since natural reflections will always sound better.
This is similar to analog plugins and analog synths – they generally sound better, but you can get emulations that sound almost unidentifiable to the untrained ear.
But, algorithmic reverb allows a lot more control because you can alter the settings of room, size, decay, and a whole lot more. With reverb rooms, you can’t do this, unless you rebuild the entire room.
They are also capable of replicating plate and spring reverbs, and they do this extremely well. Plate and spring reverb are huge, heavy units that made reverb extremely cumbersome.
Algorithmic reverbs are lightweight and adaptable, and on top of that – extremely cheap!
How and When To Use Convolution Reverb
Convolution reverbs can be used to copy real-world spaces in a digital plugin, but you can also morph convolution reverbs to your liking.
However, convolution reverbs are preferred in TV & Film settings due to their authenticity.
To give an example, you can re-create a scene in a cave or a church, or even a football stadium using convolution reverb. This is because you can get Impulse Responses online, and use them in your reverbs.
Using Algorithmic and Convolution Reverbs In Tandem
A combination of both algorithmic and convolution reverbs can be really useful in your productions. This is because convolution takes up a lot of CPU power, so it’s good to use algorithmic reverbs.
You should often use buses for convolution reverbs and send your instruments to the reverb bus. This allows you to have a couple of reverb buses, and send groups of instruments to each.
Another great use of algorithmic reverb is for low CPU reverb on vocals during live recordings. Live recordings can take up a lot of CPU, so you can use algorithmic reverb to splash some verb in the vocalist’s headphones so they sound better and give a better performance.
After the recording session, you can use convolution for a higher-quality reverb.
Another use of convolution reverb is, using the reverb on the master bus so that it sounds like everything was recorded together.
This can make an entire track sound cohesive and like it’s coming from the same space, but you need to be extremely careful using this technique, because you can ruin the sonics of your recordings.
What Reverb Should I Use? Algorithmic or Convolution?
Why You Need Convolution Reverbs
Convolution Reverbs are fantastic for re-creating real-life-sounding spaces. They work extremely well in TV & Film because of this. For instance, you can get a hall reverb sound for footstep foley in TV production, and match the reverb up with what is seen on screen.
This is perfect for realistic sound design.
Why You Need Algorithmic Reverbs
Algorithmic reverb gives you greater creativity and allows you to design spaces that would not be possible in reality. For example, you could have a small room size but a very long tail, which is not possible.
These are better for electronic sound design. You can use multiple reverbs and you have full control over the settings, with many options like sync and freeze, which are fantastic for creating weird and wonky sounds.
This means you can add multiple, individual reverbs for sound design and continuously add effects.
This is a little more difficult with Convolution Reverbs because they are much more CPU intensive and have less control.
