I have pre-configured Jc Gui with the BCA EMU Casper Cathedral 00 reverb. Use the method described in the section below if you want to change the impulse response.
All of the BCA argonon dispositions require added reverb. So we will use the Jc Gui reverb. Thereefore, before you load a BCA argonon, start Jc Gui first (and make sure the 'run jconvolver' button is showing in green). Once Jc Gui is load, and the BCA argonon is loaded, look for the 'Jack Reverb' button on the BCA console. Click on the button to activate the Jack Connections script that I have written to disconnect the fluidsynth outputs from the system speakers and connect them to the Jc Gui Reverb. Wait a few seconds for the new connections to be activated.
Now play the organ, and use the sliders and knobs in Jc Gui above to get the right about of reverb for your environment.
With the Jack audio server running, start Jc-Gui (Multimedia -> Media Tools -> Jc-Gui)
Click on 'jconvolver settings' (this will open the jConv Settings window, you may need to drag the window to the center of your screen)
Click on the 'Open file' icon (the folder image)
Navigate to the impulse response reverb wav files and select one by clicking on it
Click on Open (the folder icon) [if your text is white on the light blue background, just look closely at the screen to see the text]
Wait for the wav file to be loaded. You should now see it in the preview window.
Don't worry about the other buttons and dials, those are for tweaking the reverb
Click on Ok to close the Jconv Settings window
Now click on the 'run jconvolver' button
After a few seconds (or a little longer with the older computers) the 'run jconvolver' button should turn bright green, indicating that jconvolver is loaded and running
Take note of the wet/dry slider above the four dials above the buttons that we have used
Now we need to re-connect the output of the fluidsynth soundfonts to the reverb, and connect the reverb to the jack system (speaker) outputs. Find the 'Jack Reverb' button on the BCA console and click on it to activate the script that will reset the connections.