Interesting reading:
 
http://motherboard.vice.com/read/that-time-the-navy-used-the-grateful-deads-amps-to-listen-to-soviet-subs

Dig those crazy vibrations from the man about the lowdown on the hi-fi! Those groovy Warlocks were about dropping sunshine with foxy mamas and grokking the colors, man! The captain of their vessel was called Trips, y'dig? Man? So when the Chairman of the Board told me those hep cats were like, Bogarting the power for the people and it it was time to lay some bummer on some righteous brothers, they knew just who to call.
 
You want a peace of me? Didn't think so.
 

 
I was never here, man. Dig?

Interesting article.  Thanks for posting it, David.  I know how heavy the 2300s are.  I've never seen a 3500 up close, but I suspect it's a beast.
 
Bill, tgo

According to the world wide web, a 3500 weighs 125 lbs; 57 kgs.  Heavy.

I saw several 3500's at a seismology studies lab at a UC Davis  test lab in the 1970's. They were being used to power ultra low frequency servo drivers for a shaker table design. If I remember correctly approximately 6 Hz was used to replicate the effects of liquefaction .  
 
 Wolf ( who was quite impressed and got hooked on the low frequency trip)