Ed used 2 Echoplexes on ATBL (hint hint VH1) and probably on Atomic Punk and might have had the 2 Echoplexes connected in his chain for the whole of VH1.
The ATBL Echoplexes are set for around 100ms and 300ms delay, see the sinas1 ATBL thread.
He could have had them hooked up in parallel (using splitter cables) with each Echoplex going to one of the two Marshall input channels.
Ed was using splitter cables and Rudy says so as well.
On the slow clean guitar just Ed and Dave section on ATBL I think the 3D effect of the Echoplex(es) is pretty easy to hear.
The JBL's are not used for VH1 according to the frequency spectrum analysis, just a Celestion cab with 2 different mic positions, one mic picking up more treble and one mic picking up more bass.
Ed and Rudy say no slaving on VH1 and running 2 Echoplexes in FRONT of the amp makes sense. Slaving without a Echoplex sort of emulates some of the 3D aspect of the Echoplex preamp so put 2 Echoplex pre's in parallel or series (probably parallel) in front of a stock Plexi and there is the 3Dish tone that slaving can emulate but there are other things as well like the Sunset Sound reverb room etc etc.
Any one JFET preamp connected in a Common Source way will give a 3Dish sound really.
Check this out for a more detailed explanation of a JFET preamp
http://runoffgroove.com/fetzervalve.html" onclick="window.open(this.href);return false;