Grid Stopper for parallel sides of dual triode

[dsavitsk]

If one were to use both sides of something like a 6n6p or 6n30, or 6dj8 in parallel, assuming a grid stopper is necessary, is it best to use one that connects right to the pin of one side and is a tube's width form the other grid pin, or use a seperate grid stopper on each side?

 

[Tubes4e4]

Citing RDH4, p571, talking about parallel class A amplifiers:

"A grid stopper should be connected directly to one or both grids. It is usually cheaper - and just as effective - to have one grid stopper of, say, 200 ohms than two stoppers each of 100 ohms."

Tom

 

[i_should_coco]

Just my opinion: I would use one on each. Grid stoppers need to be as close to the tube as possible to be properly effective.

Cheers,
Pete

 

[Tweeker]

Dont use a wirewound here either.

 

[Brian Beck]

95% of the time, one shared grid stopper will be enough for both sections, but you might be the 5% guy. Since grid stopper resistors are dirt cheap, I would use one on each grid pin and tie the other ends together. Steve Bench went even further. He has several designs using the 417A/5842, which has four (count 'em - four) grid pins for the one section, to lower inductance. He uses four grid resistors, one for each pin. Yep, four grid stoppers for just ONE grid. Granted, the 417A is probably more of a squealer than the tubes you mentioned.

 

[ray_moth]

I agree, why skimp on grid stoppers? Alan Kimmel (of mu stage fame) has stated that he uses grid stoppers wherever there is a grid - he reckons 150 ohms is a suitable value for most stages. Maybe he uses higher values for input and output stages, like most people do, I don't know.

Yet there are people who say they prefer to avoid grid stoppers wherever possible and I have never understood why.

 

[Tubes4e4]

Hi Brian,

Yep, four grid stoppers for just ONE grid.

I bet they are required to be connected in antiparallel, too

Tom <ducking>