5v333
Well-known member
Hi.
Ive been playing with active cathode load in my NYD EQ tube PP gain stage.
First i used shared leds/diodes to set bias with great results.
but when i tried a J112 with a small degenerative resistor to set bias voltage (6V about 18ma) i knew that i found the lost treasure on the secret treasure island.
so i wanted to try the same with the first tubes (12ay7) which should be set to about 1.5V-3V and about 1.5ma together.
turned out a J113 in this case just burnt out. same with a 2sk170gr...
Why is this happening? too low VDS?
can i use a Jfet that suits the task or should i use BJT ccs or back to the leds/diodes?
Ive been playing with active cathode load in my NYD EQ tube PP gain stage.
First i used shared leds/diodes to set bias with great results.
but when i tried a J112 with a small degenerative resistor to set bias voltage (6V about 18ma) i knew that i found the lost treasure on the secret treasure island.
so i wanted to try the same with the first tubes (12ay7) which should be set to about 1.5V-3V and about 1.5ma together.
turned out a J113 in this case just burnt out. same with a 2sk170gr...
Why is this happening? too low VDS?
can i use a Jfet that suits the task or should i use BJT ccs or back to the leds/diodes?