I asked my good friend and speaker guru Doug, if that white wall of speakers was Heil.
He responded with an emphatic 'NO'
...he thinks they were built by a carpenter/audio enthusiast Greg Boykin (sp?) who was building installations in the NW back then.
My friend ,who was working for the JBL warranty shop at the time ,
said Mike Fisher came to him for a bunch of D130 frames, cones , and dust caps .
So we gather that not all those cabs were loaded with active speakers...just an educated guess
He remembers those white PA bins catching fire at Discovery Park in Seattle.
Apparently what speakers were loaded in it weren't meant for lots of power.
(sorta makes sense since the mics are all in front of it).
He doesn't recall if it was ever rebuilt after that. I'm not sure of the date, I couldn't find a reference to the concert with a quick google search.
Doug also recalls a shortage of smaller JBLs when they were building the Wall(s) of Sound for the Dead.
One of the crew called his shop and said:
I'll take ALL you've got .
...LOL
Elwood