For the past few years, a certain sound design technique has become a pretty hot topic in the dance music space. It came up so quickly and has become so prevalent that I’ve been terrified to ask the question that’s been on my mind since I’ve heard the term. But now, in 2025, I don’t have much to lose.

So, what on earth is convolution?

According to the people at Kilohearts, one of my personal favorite plug-in companies, to convolve is to “multiply a sound by another sound.” Essentially, convolution is multiplying an existing sound by an impulse response (commonly known as an IR) to dramatically affect the original sound. A great example they give is to record a short click in, let’s say, a random piano hall. You can then take that sound back to your studio, multiply a simple sound by that short clock, and that simple sound will then sound like it is playing in the very piano hall you recorded that click in. For this reason, convolution reverb is the single most common use of this technique, but you can do other cool stuff with it, too.

In order to make convolution a more easily accessible sound design technique, the team at Kilohearts recently unveiled their newest plugin: Convolver. It combines this fascinating sound design technique with the UI that Kilohearts users know and love by now, and the results are pretty awesome.

Let’s take a deep dive into Convolver.

The Interface

When opening up Convolver, you’re greeted by an interface that’ll be incredibly familiar to you if you’ve ever used a Kilohearts plugin before.

There’s a small visualizer at the top that’ll show you the IR that you’ll be convolving your sound with. It’ll look like a waveform when one is loaded in.

Then, there’s a “fade in” option, which is pretty self explanatory; it adds a fade-in to the IR. “Fade out” does the same thing, but fades the sound out at the end. You can slide the numbers left and right to increase and decrease them. Stretch is a little different: think of it as a pitch/time shift. The more the sound is stretched, the deeper its timbre will be, and the longer it will last. The smaller the stretch, the higher the pitch, and the faster the time.

Under that is the IR browser – we’ll get to that momentarily.

The last few knobs and such are pretty simple. Delay add a pre-delay before the convolution starts, and you can adjust it in milliseconds or in measures (say, 1/4). The tone adjusts the sound’s brightness, feedback brings the output back into the convolution engine, and mix allows you to determine how much of an effect you’d like the plugin to have on your sound.

The IR Browser

While you can load your own audio files into the plugin as IRs, the Kilohearts team have provided hundreds of IRs in the browser to get you started.

All of those “spaces” will give you reverb-like effects, while everything else will take your initial sound and mess with it to varying levels of insanity.

You can select chord shots and use it like a resonator. You can determine how your sound would sound played through different types of microphones. You can throw one of the glitches onto your sound and make it sound like robots are talking to you. There’s also a grains folder up there: you can get into external granular synthesis with this plugin. You just have to start clicking and playing around. Then, when you find something that’s close to what you want, you can go back to the main interface and fine-tune it.

You can also get really in depth with the shape of your IR by opening up the sample editor.

My original sample will play along this waveform.

There, you can sculpt the sound by using the select tool and literally dragging up and down on the waveform. You can be as reckless or as careful as you’d like.

Results

So, now that I’ve gone through every part of Convolver, I figured I’d give it a quick test.

I’ve taken a snare (specifically, the snare “Joe” from Basic Wavez’s “Ethereal Melodic House by Kliran.B” pack) and have run it through four different IRs: a space, a grain, a glitch, and a chord stab. The original sample plays first, followed by the convolutions in the order I’ve listed them.

I’ve also done the same thing with a melodic sample from the same pack, but this time, I omitted the chord stab, as I’ve found that the melodic IRs work a lot better on purely percussive instruments.

There is some really, really incredible stuff at work here. I’m particularly excited about the possibility of using Convolver as a granular engine; just by taking a synth loop and convolving it with one of the grains, you’re given the easiest path to granular synthesis that I’ve come across.

Pros and Cons:

Pros:

It’s incredibly easy to use.

Kilohearts plugins are among the most user-friendly I’ve ever seen, and this one is no outlier. It’s quick, sleek, and there’s no fluff at all. It does what it’s supposed to do in a no-nonsense manner, and gives you tips whenever you hover over a knob or slider. I respect that greatly.

It’s easy on the CPU.

You get mind-blowing sound design capabilities at a fraction of the RAM cost. Plus, this means you can use it in tandem with several other plugins at once. You will never have to deal with your computer freezing during a sound design session with Convolver; and, if it does, I guarantee it’s not Convolver’s fault.

It’s reasonably priced.

Convolver retails at $40 USD, which I think is a fair price for what you’re getting. It’s definitely not the cheapest thing they’ve ever offered, but in no way is the purchase not worth it. Kilohearts also offers free trials if you’d like to give it a go before making a full purchase.

Cons:

Only one tool in the sample editor.

The only major thing that irks me about this plugin is the lack of love the sample editor gets. The only real tool there is the selection tool, and all you can do with it is select part of the waveform and adjust the gain. I think adding something like a pencil tool and allowing users to draw out waveforms would be a game-changer. But, then again, there are so many IRs included that what you want to draw probably already exists.

It’s not going to replace your reverb.

This might be a personal thing, but if I want to use a reverb, I think I’m going to use a traditional room or plate reverb instead of this. I found a lot more success in my attempts to make cool sounding percussion knocks and granular atmospheres here.

Conclusion: Is this worth a buy?

If you’re only looking for a new reverb, then I wouldn’t buy it. But, if you’re looking for a easy-to-use sound design machine that can create ridiculous sounds and textures in the blink of an eye that could also function as a reverb in a pinch, then I’d definitely give it a try. It’s easy to use and fun to play with; what’s not to love?

Buy Convolver here.

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