'Hydraulic Hi-Fi'
was a headline 50 years ago in the edition of Electronics Weekly of September 14th 1960.
The story continues:
'A novel demonstration of a hydraulic 'loudspeaker' was an unusual feature of this year's SBAC Show at Farnborough.
The exhibit was used to accent the remarkably high speed of operation of the Dowty-Moog servo valve manufactured by Dowty-Rotol Ltd.
The operation of the valve is so fast it can drive a jack, spindle and diaphragm at frequencies up to 1,100 c/s.'
Wonderful parts the Dowty-Moog servo valves. I made a handheld controller for a load frame that used these valves to control the main hydraulic drive. Being able, literally, to crack a walnut with a machine that was capable of driving 100 tons was quite awesome. The degree of control allowed by these valves is fantastically fine.