jet690 wrote: Worthy to note that it operates on 12v dc - centre POSITIVE connector.
This quote is from John Ashburn's message about his Blue Nebula in Guitars, Amps and Effects but I'm starting a new thread because he makes a very good point.
Suppose 12 volts centre positive has established itself as the standard, say, 40 years ago in the 1970s when low voltage transistorised gear was beginning to be common in households. Think of the saving today. Instead of houses being cluttered with umpteen out-of-date wall warts, 6v, 9v, 12v, 15v, many with centre negative, there would just be one standard, 12v centre positive. Cars have been 12v centre positive for many years. Once you'd bought one 12v transformer for the house it could be used for anything - a TV, a radio, a charger. Think of the saving in copper from those now-useless transformers that we have hanging around the house. We might even have a 12v centre positive ring main around the house - TVs, radios, chargers and all the rest wouldn't need to run from 13A plugs. Safer, too.
Sometimes one particular item creeps up to become a standard. The SD card is an example. At one time there were four or five different types of memory card. Now there is only the SD. All mobile phones now use the tiny USB socket for charging. What a shame that 12v centre positive didn't become a standard.