Hi Stephen !
I just found a link again....
Thanks again for the vote , personnaly this time.
Some info about SIR. There are two versions 1 & 2. ! is free, 2 is not.
SIR 2 in addition can read not only .wav files of impulse responces but also it's own format .sir and in true stereo (4 channels). Penguin makes some great impulses and expencive. SIR2 comes with some free Penguin files to work with. The sound is superb!!
The problem with the also very good SIR1 is it's awfull fixed latency (about8.000 !!!), witch makes it unsuitable for live playing. But you can use it after recording in remix, if you can play GrandOrgue without reverb of course.....
The best combination I found 'till now is : GrandOrgue v.2 with 4ms latency in ASIO4all, load any free set (above) add SIR2 convolver (with Jack 1.9.5 portaudio) load true stereo Cathedral impulse responce in it, close the dry level in SIR2 and raise a bit the wet level.
Play. You'll think you're in a great Cathedral playin' your favorite Pipe Organ....just from your living place(!).
Prospectum is offering as free download and in .sir format the Anloo church environtment as an impulse responce. It's a great alternative to large Cathedral if you want to play a smaller organ (i.e. new St.Stevens) with GrandOrgue in a chappel or small church.
With little search you can find some other sites offering free impulses for SIR2, like Retro ect, but these are not to my taste for VPO work (I use them in other kinds of music as SIR1.. )