Here are some related history with contact information:
The Matrix-12 owned by the Swedish band named Ace of Base in the past was brought by me to Finland Oct 6, 2007 from Göteborg, where it had been used and serviced in a music studio called Ljudlabbet, the owner of which was Daniel Saxlid. He was selling the M12 because of moving to Los Angeles. He also told me that it should be possible to speed up the envelopes, as described in the above reference link. You may find Daniel at
https://www.linkedin.com/in/daniel-saxlid-746a93a/
.
The same M12 was later (i.e., in 11.5.2015) acquired by Aake Otsala at
http://www.suneffects.fi/
. I think that he might have been in contact with e.g. Daniel regarding to the modifications etc.
Regards,
Tiitu