I think the name comes from the surround expansion "cart" of the old Lexicon 480L
Correct. It’s the only algorithm that uses all of the 480’s processing power on a single reverb.
Casey Dowdell from Bricasti shares more info on it’s origin:
Some history on this?
Dave Griesinger had a side business outside of Lexicon. He worked with one other guy to put racks of 480s into dozens of great halls throughout the world to improve their acoustics.
Mics are placed near the stage and the 480s using the Surround Cart algorithm provided sound to hidden speakers all around the Hall. Shhhh
The Surround Cart Alg is by far the most modulated of any of the Lex algorithms. Even the early reflections are super modulated. That’s why it took the entire 480 to run.
The reason for this is that he needed to achieve as much reverb gain before feedback in the hall.
Anyone that’s ever done a live gig knows that reverb can really cause feedback headaches. The same thing was happening in the Halls due to the hidden speakers feeding back to the mics near the stage. Of course at a live rock gig feedback is a normal occurrence and can be a part of the show.
In this case, where the 480s are hidden so that no one knows that the hall is enhanced with the extra 480 verb, any feedback during a symphony, ballet or opera performance would be quite curious.
So the Surround Cart is heavily modulated, particularly the early reflections, to prevent feedback from building up.
Dave Griesinger truly dislikes the pitch artifacts of reverb modulation, but he created modulated bliss out of necessity in the Surround Cart alg.