Convolution Reverb Questions

[Brandon203113]

Hey guys, I've avoided convolution reverbs for long enough, I'd like to know more about them and when would be a smart time to use one instead of the regular algorithmic ones. Can somebody fill me in with the differences and maybe some examples of why they'd use it in a mixing or sound designing situation instead? Also, maybe you guys could list a couple of the convolution reverbs you guys think are good plugins, thanks guys!

[lfm]

The ruler plugin of them all is probably this one
https://www.liquidsonics.com/software/reverberate-2/

You can load quad IR's(impulse response) - meaning it better represent stereo image - like leakage between left and right.
Or you can load two standard IR files and do all kinds of cool stuff with these two channels.
Most common are IR that is recorded with single microphone - so not quad. So bouncing around in a room in stereo image is not represented by these. From a mixing point of view, this can be an advantage that not too much stereo is stacked on stereo that is stacked on stereo in a mix.

If real IR it's recorded in an actual venue - and pickup more of precise reflections from a specific listening point in a room/hall etc. Some kind of "shot" rich in frequencies is fired and recorded, so how much each frequency is declining with time probably has more content than algorithmic reverbs at more customerfriendly pricetag.

There are Bricasti M7 is one algorithmic with all sorts of stuff going on - but they are at $4000 or so, and hardware. But said to be incredibly good.

Then there are fake IR generators that just as well could be made algorithmic since they are generated by algorithms. They create an IR for you - and I see no point in these.

Another good IR reverb plugin is Waves H-reverb, and probably did not hear better definition of a space ever. But maybe clinically too clean. It's some kind of hybrid of traditional IR called FIR(finite IR, if I understood ir right).

My mixing skills are not so that I "need" IR instead of algorithmic. If I find an IR I like for a mix/instrument I use it, or if finding algorithmic preset that works I use that. But this is me.

But IR are cool in that they can represent so many different things. You can run an impuls through an amp, or a speaker and things like that and then use in an IR plugin. Not only ambient room stuff.

There is a pinned thread here on KVR(effects section) that has loads of tips where to download IR.

[Brandon203113]

Thanks for the knowledge lfm

[pljones]

As far as I understand it, the reason for synthetic IRs is to enable modelling of unreal spaces and the generation of a modeled impulse response for that space. If done in detail, this is compute intensive and possibly uses a noticeable amount of time - I've neither used nor generated them, so I'm making a bit of an assumption there. But you can get the IR generation over and done with once then use it in your convolution reverb, like any other. It's not the same as simulating a reverb based on a model of an analogue hardware reverb circuit, which is what most algorithmic reverbs do. Please correct me if I've misunderstood.

[lfm]

As far as I understand it, the reason for synthetic IRs is to enable modelling of unreal spaces and the generation of a modeled impulse response for that space. If done in detail, this is compute intensive and possibly uses a noticeable amount of time - I've neither used nor generated them, so I'm making a bit of an assumption there. But you can get the IR generation over and done with once then use it in your convolution reverb, like any other. It's not the same as simulating a reverb based on a model of an analogue hardware reverb circuit, which is what most algorithmic reverbs do. Please correct me if I've misunderstood.

Your reasoning makes perfect sense.

But couldn't you just as well make those controls into a regular algorithmic reverb instead?
You have quite a bunch of controls in algorithmic reverb, near reflections, far reflections, high end detoriation/decline or what they call it to simulate other than stone walls.

Why first generate IR to be run in IR plugin?
But it could be those algos are to heavy on cpu to allow that, don't know.

Maybe there is a good reason.

[cthonophonic]

Another good IR reverb plugin is Waves H-reverb, and probably did not hear better definition of a space ever. But maybe clinically too clean. It's some kind of hybrid of traditional IR called FIR(finite IR, if I understood ir right).

All convolution reverbs are based on finite impulse responses. That's what IR recordings are: finite impulse responses to be convolved with an input signal. H-reverb is a hybrid in the sense that it generates its impulse responses algorithmically rather than using samples. This is why you can, for instance, use envelopes to control the amplitude and filter cutoff of the decay in H-Reverb, which is not something that you could do with a feedback-based (i.e. infinite impulse response) algorithmic reverb.

I wouldn't put H-Reverb in the same category as other convolution reverbs, because it's not designed to load up impulse responses from outside sources. It basically provides you with a bunch of tools to shape an impulse response, which is then used within the plugin for convolution.

[lfm]

Another good IR reverb plugin is Waves H-reverb, and probably did not hear better definition of a space ever. But maybe clinically too clean. It's some kind of hybrid of traditional IR called FIR(finite IR, if I understood ir right).

All convolution reverbs are based on finite impulse responses. That's what IR recordings are: finite impulse responses to be convolved with an input signal. H-reverb is a hybrid in the sense that it generates its impulse responses algorithmically rather than using samples. This is why you can, for instance, use envelopes to control the amplitude and filter cutoff of the decay in H-Reverb, which is not something that you could do with a feedback-based (i.e. infinite impulse response) algorithmic reverb.

I wouldn't put H-Reverb in the same category as other convolution reverbs, because it's not designed to load up impulse responses from outside sources. It basically provides you with a bunch of tools to shape an impulse response, which is then used within the plugin for convolution.

Thanks for correcting me.
I never knew about how H-reverb worked either. Just checked some demos when it was released.

Waves IR1 also has envelopes and stuff, but there you can load IRs. Just used Waves collection so far, but it is vast. IR1 also allow to reverse IR to generate reverse reverb straight up, which is cool. Even though daws usually provide reverse ability too.

[Brandon203113]

Another good IR reverb plugin is Waves H-reverb, and probably did not hear better definition of a space ever. But maybe clinically too clean. It's some kind of hybrid of traditional IR called FIR(finite IR, if I understood ir right).

All convolution reverbs are based on finite impulse responses. That's what IR recordings are: finite impulse responses to be convolved with an input signal. H-reverb is a hybrid in the sense that it generates its impulse responses algorithmically rather than using samples. This is why you can, for instance, use envelopes to control the amplitude and filter cutoff of the decay in H-Reverb, which is not something that you could do with a feedback-based (i.e. infinite impulse response) algorithmic reverb.

I wouldn't put H-Reverb in the same category as other convolution reverbs, because it's not designed to load up impulse responses from outside sources. It basically provides you with a bunch of tools to shape an impulse response, which is then used within the plugin for convolution.

Which convolution reverbs do you use?

[imrae]

I use IR1 and Reflektor for convolution with real-world impulse responses; this is great for placing a sound in a realistic space. The "studio" spaces in IR1 do a nice job of opening up DI guitar and sampled drums for me and I'll send a bit of vocal to the same space.

Synthetic impulse responses, whether drawn from a library or generated on-the-fly with H-verb, can achieve a very dense sound without prominent echos or resonances; good for thickening vocals etc.

Using unusual IR samples can be a good source of creative effects: check out the demo for Fog Convolver. For another example here's a track where I used a sample of a bell to add an eerie resonance over the main keyboard part:
https://imrae.bandcamp.com/track/marks-on-the-window

The main downside of convolution is that it doesn't really do non-linearity or variation in time. For lexicon-style modulated halls, grungy lofi or driven sounds (which often mix well) or fine-tuned special effects then algo is the way to go.

[Brandon203113]

I use IR1 and Reflektor for convolution with real-world impulse responses; this is great for placing a sound in a realistic space. The "studio" spaces in IR1 do a nice job of opening up DI guitar and sampled drums for me and I'll send a bit of vocal to the same space.

Synthetic impulse responses, whether drawn from a library or generated on-the-fly with H-verb, can achieve a very dense sound without prominent echos or resonances; good for thickening vocals etc.

Using unusual IR samples can be a good source of creative effects: check out the demo for Fog Convolver. For another example here's a track where I used a sample of a bell to add an eerie resonance over the main keyboard part:
https://imrae.bandcamp.com/track/marks-on-the-window

The main downside of convolution is that it doesn't really do non-linearity or variation in time. For lexicon-style modulated halls, grungy lofi or driven sounds (which often mix well) or fine-tuned special effects then algo is the way to go.

Cool, thankyou for the advice imrae, also cool track! I like the style