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Old 24th Feb 2021, 6:24 am   #5
Join Date: May 2013
Location: Deal, Kent, UK.
Posts: 118
Default Re: Adding external speaker to Wireless set 19

The output impedance at pin 4 is 100R. It was designed that way to drive multiple headsets. Most speakers are 3-8R so the impedance mismatch will result in lower audio out. By using a matching transformer you'll get best signal. Hammond type 144B is 200R CT to 3.2R so by using 1/2 of primary you'll have a perfect match.

Is the set stand alone or part of a system, ie control box or display?
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