6CG7 tubes with Crack & Speedball

[wmccann]

Hope this will help someone, wanted to try tube rolling and found a lot of people recommending 6CG7.  Issue is you need an adapter, with postage etc they are not cheap and worse still and they look NAF.  To get around this I decided to use a retro looking 3 pole, 2 way switch to reconfigure the heaters so I can switch between 12AU7 and 6CG7,  with Speedball you don't need any other modifications from what i could find.

12AU7 has heater power to pins 4/5 (if 6v) and pin 9
6CG7 has heater power to pin 4 and 5.  Pin 9 is grounded (though don't think this is necessary.

Switch wired/works as follows

Left                          Centre                  Right
Pin                              Pin                        Pin
1: Heater power    1: Pin 4                    1: Left Pin 1
2: Heater power    2: Pin 5                    2: Right Pin 1
3: ground                3: Pin 9                    3: Left Pin 2


When switch is left I can use 6CG7 (Raython) Valve, when Right it is 12AU7 compatible

W.

 

[Mucker]

Thanks for the info! I might give this a shot. I finally wore out one of small board board R1 positions of the old speedball by soldering it too many times while trying out 12BH7 and E80CC. ( 0V @ T1) and tried multiple tries to fix.

I just ordered a new speedball kit and now looking at messing around with switching (will go back through the forum to see what might be the best approach).