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Musicman 2100RD (100RD) doing 20.2VAC at speaker jack for 100W into 4 ohms. Amazing because it has only two 6L6GCs for it's output section. The output stage is unique it is a grounded grid class B design. The signal is applied at the cathode which sits about 60-70V above ground. The control grid voltage was around +22V and seems strange but it's STILL negative because the cathode is +70V or so. Screen grid is grounded. Plate voltage is extremely high, about 720V to get a huge voltage swing and lots of power. The power tubes are biased nearly at cutoff so almost no current flows at idle. This is a nice article -- http://www.linuxhorizon.ro/test/div/prj/gu50/config_GG/The%20Grounded-grid%20amplifier%20-%20Arrl.QST.-.1961-08-AUGUST.pdf

Musicman 2100RD (100RD) doing 20.2VAC at speaker jack for 100W into 4 ohms. Amazing because it has only two 6L6GCs for it’s output section.
The output stage is unique it is a grounded grid class B design. The signal is applied at the cathode which sits about 60-70V above ground. The control grid voltage was around +22V and seems strange but it’s STILL negative because the cathode is +70V or so. Plate voltage is extremely high, about 720V to get a huge voltage swing and lots of power. The power tubes are biased nearly at cutoff so almost no current flows at idle.
This is a nice article on the Grouned Grid Linear Amplifier although it is absoluely harsh and brutal to amateurs so please do not read if you are sensitive — http://www.linuxhorizon.ro/test/div/prj/gu50/config_GG/The%20Grounded-grid%20amplifier%20-%20Arrl.QST.-.1961-08-AUGUST.pdf


I had free reign to do what I wanted on this one and some of the power supply caps were bulgey so I just went ahead and recapped it throughout.

I had free reign to do what I wanted on this one and some of the power supply caps were bulgey so I just went ahead and recapped it throughout for strength and stability, in these times.