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Old 13th March 2003
  #9
Gear Head
 

EQ's and things

I don't think you fully understood what I said in the 2 previous postings. The input XLR pins 2 and 3 go to the PASSIVE network which as a total of pots, switches and components is a 3 terminal device 1 input and 1 out and common. this floats to go to the plus and minus input of the differential tube amplifier which is part of the 3 tube complete post amplifier.
Pin 1 is only a chassis ground. The common mode is about 30 dB which is sufficient for just about every case I've encountered on balanced or unbalance systems.
All my stuff these days is Pin 2 + no phase reversals.
As an aside when XLR's were invented by cannon around 1953 the American audio industry took pin 3 as + but when Studer and Neumann adopted it around '59 they thought it was like a DIN plug and got it wrong, also like mains connectors they got the sex wrong. I always remembered it as 'from a Jack to a Jill'
Then the Japanese copied the Neumann/Studer way untill it became the majority and the Americans had to cave in and recognise the defacto standard. A pity that it was not better published in the 50's.
Tim de P