Impulse Response

How to use IR´s?

You can supply the selected IR to a digital reverb processor which is equipped with the convolution capability. When speaking about computers, this is a piece of software (plug-in) supplied by a third party, which may be inserted into the appropriate track of your audio editor: the sound without the reverberation - "dry" sound - goes in, the reverberated "wet" sound goes out into the speakers.

VST convolution reverb

The plug-ins almost universally usable in audio editors are called VST plug-ins (after the Steinberg standard for this software) We recommend using VST plugins for convolution reverberation. There are more plug-ins of this type available, just make sure that the one you choose is able to work in real-time with low latency if you want to use it for real-time performance (such as when using it in conjunction with Hauptwerk). We like to use Voxengo Pristine Space. You can supply your IR´s to this plug-in and it will do the rest of the work for you.

Hauptwerk and convolution reverb

The following section will be specific for Hauptwerk users, as our impulses are often used for the reverberation of the organ sound emulated by this software synthesizer. Until Hauptwerk has its own dedicated reverberation module, you can still find a way how to add the convolution reverb to your dry organ samples.

You have the VST plug-in, you have the IR´s, now you have to combine these with Hauptwerk to get the result. Since Hauptwerk is not - to my knowledge - currently capable of using VST effects, you have two ways:

 - Use Hauptwerk as a VSTi instrument and apply the VST convolution reverb plug-in to its track.

- Use Hauptwerk as a stand alone application but redirect its output to other software which will take care of the rest. We tested this using software called Reaper. It is an audio recording software - shareware (friendly priced). The nice thing about Reaper is, that it provides a virtual ASIO driver Rearoute with 16 channels which can be used as an audio output for Hauptwerk. The sound from Hauptwerk is thus redirected to Reaper where you can apply any VST effects to it sending the wet sound to your sound card. You may use multiple channels, so you can split your virtual organ into many divisions/stops/channels and apply different reverberation to each, if desired.

Reaper settings download

We have prepared two Reaper project files (*.rpp) which you can load directly into your Reaper and you will get most work with audio routing done. These projects are representing the surrond sound of the virtual Litomysl catherdral church (Czech Republic). We used the demo impulse responses which are available for free download on this website to allow for free experimenting. Normally, we would use high quality impulse responses which you can buy from our web pages as well.

The two Reaper projects feature essentially the same virtual church. What changes is the virtual listening position. The first file called Litomyslcathedral_surround_organist offers the possibility to hear the organ as the virtual organist does. The organist sits facing the organ which is located in one-block case on the organ loft. The nave of the church is behind the organist's back. Therefore, the dry sound of all the divisions goes to the front speakers. The wet sound goes to both, front and rear speakers with gradual predominance of the rear speakers to simulate the reverb "rolling" down the nave.

The second project (Litomyslcathedral_surround_audience) features the listening position of the audience down in the nave. Therefore the dry sound of the pipes is attenuated and the level of the reverb changes to give more "space" to the sound.

You can download both files from here and load them into Reaper. To get the expected sound, you have to check the prerequisites listed below. The screenshots will help you to go through the settings successfully.

Presuppositions:

When installing the Reaper, make sure that you select the "Rearoute" option - it is not selected by default!!!
Litomysl Dry Set has to be loaded into Hauptwerk. All ranks routed to the Main audio output which uses the ReaRoute ASIO driver as the Audio device and its channels ReaRoute Client=>Reaper 1 + 2.
You have to configure the Audio Device in the Reaper Preferences to your sound card with at least 4 channels. (In the example here, I am using the NVIDIA ASIO driver for the soundcard on the mainboard of the testing computer).
You have to have PristineSpace installed in the default directory specified in the Reaper settings.
You have to have the proper impulse resonse pairs installed in any directory of your hard drive and you have to specify this directory as the Search Path (currently set to I:\impulz\) of the PristineSpace settings - this is necessary so that Pristine Space loads the impulse response correctly. The impulse responses in question are: ChA 15 long tx (left and right) and ChA 15 long (left and right). The demo versions of these impulses are available in the IR´s section of this web site.

Understanding the LitomyslCathedral_surround Reaper project.
 

Start Reaper and load the project which you downloaded from this web page. There are 3 tracks used. All of them are receiving the Channels ReaRoute 1 and 2. (These two channels are configured to send the sound from Hauptwerk as previously explained.) The first track is used to supply the wet (reverberated) sound for the front speakers. The second track supplies the dry sound for the front speakers. The front speakers are assumed to be the speakers for the Master section of the Reaper Mixer. The third track is used to supply the wet sound for the rear pair of your speakers.
Clicking the I/O button (the green button) of the Master section of the mixer, you can check if this master is send to the Left/Right front speakers of your soundcard (it is the default setting).
Clicking the I/O button (the green button) of the track no. 3, you can check if this track is send to the rear left and rear right speakers of your soundcard.
Now, you can change the characteristics of the surround sound according to your wishes. The tracks no. 1 and 3 use two effects: Pristine Space and Equalizer. Clicking the FX button (the blue button) of the track in question, you can display the effects and their setting. Feel free to experiment with various settings of Pristine space and of the Equalizer. The track no. 2 uses two effects: Stereo enhancer and Equalizer. The farther you go virtually from the organ, the narrower the stereo space have to be and the higher frequencies have to be attenuated.