[Hammarlund] Audio / Filament Transformers

[James Thorusen]

Greetings to the list.

   In reading the thread about substituting a filament transformer for an 
audio transformer, the following formula comes to mind:  The impedance 
transformation ratio is the square of the turns ratio.   The voltage 
transformation ratio is the same as the turns ratio.   Therefore, a filament 
transformer with (rounding) a 12 volt secondary and a 120 volt primary has a 
turns ratio of 10.   The square of 10 is 100.   Therefore, the impedance 
transformation ratio is 100 to 1.   So... if you connect the primary to a 
600 ohm source impedance, the output impedance will be 1/100 of the input 
impedance, or 6 ohms.   Probably close enough for an 8 ohm speaker.   The 
only concern would be the quality of the core for higher frequencies.   That 
would be a function of the individual filament transformer and the ear of 
the listener.

73,
Jim T.
KB6GM
entropycat at verizon.net
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