31-10-2012, 07:51 AM
From memory I would have guessed about 5H for the 450r speaker. But I did measure one from a Ferranti Arcadia (Trader Sheet 721) that has a 1.5K field (used in series) and measures 21H. Not knowing wire gauges etc it can only be a guess that the 450r will have less turns but it seems likely. So being as L is proportional to the square of the turns then the 450r will have less inductance and 5H could be about right.
Gary
Gary
