Is it parallel feed on not?

[Jetbat]

The full schematic says at the bottom, referring to the output transformer, 'For 2k output strap B-C. For 500Ω output strap A-B & C-D.' This does not drive a speaker but rather another amp circuit.

The jack totally mystified me and made me read the accompanying text. I see it is a current metering test jack. (normally closed) This is an interesting circuit. The 1k to ground from the center tap of the filament supply, the 48k to ground at the bottom of the input transformer and the .5uf capacitor allow a out of phase signal to be applied to the tube through the cathode. This is a output section that has a parallel feed input? The 2uf capacitor from the output transformer to the filament supply allows a path for the output AC current loop.

Scott

[FerdinandII]

That 2uF cap from the B+ side of the OPT to the junction of the cathode bias resistor and the cathode is what later became known as "UltraPath",


http://www.tubecad.com/2008/08/blog0147.htm

This is NOT the same as parafeed, IMHO.....

The full schematic says at the bottom, referring to the output transformer, 'For 2k output strap B-C. For 500Ω output strap A-B & C-D.' This does not drive a speaker but rather another amp circuit.

The jack totally mystified me and made me read the accompanying text. I see it is a current metering test jack. (normally closed) This is an interesting circuit. The 1k to ground from the center tap of the filament supply, the 48k to ground at the bottom of the input transformer and the .5uf capacitor allow a out of phase signal to be applied to the tube through the cathode. This is a output section that has a parallel feed input? The 2uf capacitor from the output transformer to the filament supply allows a path for the output AC current loop.

Scott