Doug Sclar: "That record was cut on a Harrison board full of early VCA's (voltage controlled amplifiers). IMO, those were nasty sounding devices that allowed the volume levels of each channel to be controlled by digital voltages. This was one of the early attempts to automate consoles. You could do a mix and the moves were recorded and stored on a computer as DC levels. When you play back the automation it controlled all the VCA's which controlled many paramaters of the mix. Of course this was just for the main channel faders. The early automation systems didn't have ways to control pan pots, eq, aux sends and returns as well as other important mix paramaters.
The problem was that these VCA's didn't sound very good. They could have a hard, dry, brittle and slow sound to them which could be heard easily with some instruments, particularly cymbals which are pretty hard to process in general. They obviously have a lot of fast high frequency energy and without fast, phase coherent amplifiers their sonics are easily degraded.
Like with early digital technology and products, many people in the industry were so enamored with the things these new devices could do that they either overlooked or didn't notice the sonic degradation. I did at the time, but I my opinion was most definitely considered a minority opinion.
Btw, Neve's automation system of this era was much better sounding. Instead of using VCA's they used motorized faders which did not have the sonic cost of the VCA's. You can find similar technology on many of the hi-fi pieces that started to surface in the late 80's or 90's. Of course they were not automated, but did allow for remote control of volume adjustments."