Anyone use ferrite beads for input grid stopper?

[beasleybodyshop]

Hey everyone, Ive been doing some research and discovered that some amp companies use ferrite beads to block input noise. Anyone ever used them? Any thoughts on how effective it is?

[TUBEDUDE]

Yes. I use several just to help keep RF out of the chassis.

[beasleybodyshop]

Yes. I use several just to help keep RF out of the chassis.

do you use them in series right after the input jack?

[Leo_Gnardo]

Yes, in extreme cases, say when the amp's picking up radio. Sometimes just a little bead or 2 on the input lead , best placed close to the tube's grid pin (where the stopper resistor belongs despite many manufacturers putting them elsewhere). In very extreme cases (only 2 so far) I've used one of those Radio Shack clip-on ferrite block gadgets, then no more radio, just audio.

I've had a couple of RF pickup cases where beads & bypass caps did nothing, but separating the input jack from the chassis with plastic washers, plus running a short lead from the input jack ground to ground on the back of the nearby volume control did the trick. Another case where I had to re mount the volume control with plastic washers so it was floating (Seymour Duncan 400W bass amp), and others where just a two inch jumper from VC pot body to the nearest PC board ground stopped RF (SWR California Blondes). There's no cut & dry method for stopping RF interference.

[beasleybodyshop]

Thanks Leo. Will keep those methods in mind if I run into RF interference.

[Structo]

You can also run a small cap from the input to ground to shunt high RF.

[TUBEDUDE]

Ditto on the pico cap from input to ground.

[JazzGuitarGimp]

Ditto on the pico cap from input to ground.

Which is more effective if placed after the ferrite bead.

[TUBEDUDE]

I also use them on the other chassis breaks, ie the effects loop in and out, or breakout jacks. The power cord gets the big ferrite clamp on the cord at the chassis entrance and one secured on the cord inside the chassis.
There's no kill like overkill!