Tube Amps / Music Electronics
For current discussions, please visit Music Electronics Forum. New: view Recent Searches.
New: visit Schematic Hell!
The sunn still shines online!

Listen to great tunes streaming live right now!

ampage archive

Vintage threads from the first ten years

Search for:  Mode:  
previous: Jim O I noted that the MARSHALL 50w amps ... -- 11/17/1999 7:38 AM View Thread

Re: Screen Grid

11/18/1999 12:11 AM
Randy Jamz
Re: Screen Grid
I am not exactly sure if you are indeed referring to the screen grid resistors or the grid stopper resistors. Big difference. The screen grid resistor will be 1K and about a 5 watt wire wound resistor and is there to limit screen grid current, which is a bad thing to have too much of. The grid stopper resistor is a 1/2 watt regular carbon resistor there in theory to stop parasitic oscillations at the output tube. Early Marshalls didn't know any better and decided to leave the house without their screen grid resistors. They figured we would never turn the amplifier up full and we would always have a fresh supply of Brimar EL34's. The only difference you will notice without screen grid resistors is the distinct possibility of the amplifier eating tubes. Without grid stopper resistors, the amplifier may become unstable at high playing volumes. Best to have them both.  
Randy Jamz/Tone Lizard Amplifiers  

Jim O Im refering to the 1k-5watt screen ... -- 11/20/1999 7:06 AM