The original Cello Palette looked like this.
The knobs are small on the inside but have a larger ring that is flush with the front panel. They have a very nice fell to them. I owned one of these in the mid 80's I seriously regret selling it. Beautiful piece. Also note the full width power supply.
Cello later introduced a significantly less expensive model that used op amps instead of discrete circuits. The power supply box on this unit is quite a bit smaller - not full width. Still a very nice sounding unit, but doesn't command nearly as high a price in the used market.
