Hi, I'm new to this forum and pretty new to tube amps. I have an amp that has 4 6L6GC's and a bias point for each and a trim pot easily accessible from the top of the amp, but I don't see a common ground to use. I've been searching around but can't find what I need to know . I could buy/make tube socket adapters, but I figure why go through the trouble if the amp already has bias points right there .
also, am I supposed to use a banana plug into the bias point? It is not snug enough for the default probes that come with a multimeter.
from that schematic (and my assumptions), it seems like having the 4 bias points without the common ground is pretty useless. So the bias points should all just connect to pin 1 and the ground should and then through a resistor to ground.
grimm26 wrote:from that schematic (and my assumptions), it seems like having the 4 bias points without the common ground is pretty useless. So the bias points should all just connect to pin 1 and the ground should and then through a resistor to ground.
I'm assuming you could use the chassis as your ground point.
grimm26 wrote:Hi, I'm new to this forum and pretty new to tube amps. I have an amp that has 4 6L6GC's and a bias point for each and a trim pot easily accessible from the top of the amp, but I don't see a common ground to use. I've been searching around but can't find what I need to know . I could buy/make tube socket adapters, but I figure why go through the trouble if the amp already has bias points right there .
also, am I supposed to use a banana plug into the bias point? It is not snug enough for the default probes that come with a multimeter.
Thanks for any help.
Use the chassis as ground, your absent ground test point would ultimately be connected to it anyway. I just hold my probes in the bias point. Actually I usually bias from the inside so I can verify plate voltages
. I could buy/make tube socket adapters, but I figure why go through the trouble if the amp already has bias points right there 
