03-29-2015, 05:35 PM
Hi everyone
I have a Philco model 20, which uses PP 71A's and I need to replace the output transformer. I would like to use a Hammond 125C, which is rated at 8 watts. What I need to know is what should I be using for the primary impedance for PP 71A's. Voice coil impedance is: VC=1.5 X DC resistance, which, in my case, means 1.5 X 1.4 so the voice coil impedance is 2.1 ohms. What taps should I use for the correct primary impedance with the PP 71A's? I have forgotten as all I used to have to do was look up the original part number and cross it over the the replacement number and put it in! By the way, my speaker isn't the original Philco, it is a Jensen, of the same size that has been reconed and has a new field coil installed too.
Thanks,
Michael
I have a Philco model 20, which uses PP 71A's and I need to replace the output transformer. I would like to use a Hammond 125C, which is rated at 8 watts. What I need to know is what should I be using for the primary impedance for PP 71A's. Voice coil impedance is: VC=1.5 X DC resistance, which, in my case, means 1.5 X 1.4 so the voice coil impedance is 2.1 ohms. What taps should I use for the correct primary impedance with the PP 71A's? I have forgotten as all I used to have to do was look up the original part number and cross it over the the replacement number and put it in! By the way, my speaker isn't the original Philco, it is a Jensen, of the same size that has been reconed and has a new field coil installed too.
Thanks,
Michael
