Acting On Impulse

1: Impulse response samples that you create or download can be imported to the RV7000 MkII. Also note a couple of new Rack View features: tabs for selecting devices for MIDI input, and the Browser.

The new RV7000 MkII Reverb is the star of the Reason 8.3 update.

Reason 8.3 has a handful of very welcome feature enhancements. At the time of writing 8.3 was available to all version 8 users as a public beta, so I had a chance to try out all the new goodies. Hopefully by the time you read this the full release will be available.

Reverb Revisited

The headline feature in 8.3 is a MkII rework of the RV7000 Reverb unit that’s been a standard part of Reason for many years. I’ve often thought that this is a really sweet-sounding reverb, rivalling many paid-for plug-ins on any platform. It’s always been a purely algorithmic reverb/delay, but now gains a convolution mode, with the ability to load impulse response samples and accurately recreate the sonic characteristics of real spaces.

The RV7000 front panel looks much the same as before, and is in fact backwards compatible unless you switch to Convolution mode. To access the new mode you need to expand the Remote Programmer panel and select Convolution with the Algorithm knob. As with the other reverb types, this will populate the other knobs with parameters related to that mode. The first knob selects your IR sample: there are three built-in preset samples and a User setting that allows you to load any sample.

The adjustable parameters are fairly self-explanatory, but some are worth a deeper look. Mostly they directly affect the impulse response sample, thereby changing the way the input source is affected by the convolution process. For example, Length fades out the sample. Size speeds the sample up or down, scaling the time of the reflections and reverb. Predelay shifts the IR backwards or forwards in time, and allows for both positive and negative values. A positive value produces a traditional delay between the source signal and the reverb. A negative delay is, in reality, zero delay, but effectively trims off the start of the sample, so the reverb response begins at a point further in. For example, you can remove initial echoes/reflections from a response, or shorten the natural pre-delay of a sampled response.

The Stereo Mode also warrants some explanation. The default mode is Stereo, which actually sums the input to mono, then applies the convolution in stereo with 100 percent spread/width. There are also 25, 50 and 75 percent stereo options for limiting the width, as well as mono. There are then four options that change the width over time (for example, M>S Fast, S>M Slow). Finally there is a Parallel mode which will treat the left and right inputs separately with the left and right responses (if it’s a stereo IR sample), so this is the only true stereo processing mode.

A Space Of Your Own

In addition to their realism, a big appeal of convolution reverbs is their expandability. IR samples can be dragged straight from the Browser onto the RV7000 MkII, or there’s a standard set of Reason file-loading/browsing buttons. The Props promise that a free Refill of IR samples and device patches is coming to bring many simulated spaces to RV7000. You can also load IRs from other convolution reverbs, provided they don’t protect the sample files (I dropped the library from Avid’s Space plug-in into my Browser Favourites). With a bit of web searching I also found and downloaded IR files for several cool and weird spaces like a nuclear reactor, as well as IR libraries that capture many presets from Eventide, Bricasti and Lexicon reverb/delay units.

If that’s still not enough for you, you might want to explore the world of DIY impulse response recording. This may conjure up images of earnest-looking bearded men with starter pistols and soundfield mics, but can be as simple as clapping into your laptop’s camera mic.

A bit of theory: there are two ways to create an impulse response sample. First you can record an ‘impulse’ sound played in the environment you want to capture. This impulse is supposed to be an extremely short sound that contains all frequencies within the range of hearing. A starter pistol is close, or you can use a recorded computer-generated impulse, but a sharp handclap can suffice at a push. The advantage of this method is that the recording requires no further processing; you can drop it straight into your Reverb.

2: You can record impulse responses directly into the RV7000 MkII.The second method uses a slowly swept sine wave played into the room and recorded. This recording must then be processed (‘deconvolved’), ending up as an audio sample that sounds like an impulse recording. This method creates higher-quality results, but is more difficult because you’ll need to set up a good speaker to play the sweep and keep the area quiet while it’s playing. You’ll also need to get some software that can process the file. If you happen to be a Logic user you are in luck, as it includes a utility for doing this (meant for use with Space Designer). There is also a Windows app call Deconvolver available from www.voxengo.com.

The good news is you can try creating IRs very easily as the RV7000 MkII has a direct sampling mode (the same as the other sample-based devices in Reason). Click this button and it will immediately start recording, and when you stop this will be loaded as the IR sample (see screen 2). I tried by using the very simple method of switching Reason’s input to my MacBook’s built-in mic, hitting record and clapping. Reason should automatically trim the sample start time to the transient, but you can manually adjust using the Predelay knob. Hey presto: I’ve got a rough but usable simulation of my home-studio acoustic. As an improvement I downloaded an impulse WAV file from the web, and dropped it into Reason’s sequencer.

But why go to all the trouble? Well for a start is it really cool to capture unique and unusual ambiences to use in your music and sound-design projects. But there’s also a practical use: you can capture the sound of a recording space in order to help match later overdubs recorded elsewhere. If you have a recording session in a studio, or even at someone’s house, you can grab an impulse response of that location. Then, if you need to make any changes or overdubs, you can record them as dry as possible and then apply the natural acoustic of the rest of the material.

Special Effects

Convolution is not just a great tool for reverb, you can also use it for all kinds of sonic treatments and creative effects. Impulse response recordings can be used to partially capture how a sound is affected by any environment, device or circuitry. For example, it’s great for simulating guitar/bass cabs, speakers, phones and radios, for example. They can also capture the tone of other effects devices. The test tone or impulse is simply played through the device instead of fired into a room, and the output is recorded. This doesn’t work for dynamics-based processes (compression, etc) as the IR doesn’t capture how the input level affects the sound of the system.

This gives RV7000 a whole new dimension as an effect device. Note that if you’re using things like speaker or cab samples you’ll probably want to patch RV7000 as in insert/in-line effect rather than a Send, as you won’t want the original dry sound to be blended in. But there’s no need to stop at simulating real-world environments and devices. You can load any WAV file at all into RV7000, often with dramatic and unpredictable (ie. fun) results. Used subtly this can blend ethereal layers and tones, or alien ambiences into your instruments. Used with drums it can create shifting gated pad-style effects. As an experiment, open up the Factory Sounds Refill and navigate to the Other Samples or Music Loops folders. Try dropping a few of these samples into RV7000 and enjoy the results!