Power Tube - Filament Rattle?

[doveman]

I've been pretty lucky with microphonic tubes ... not having problems.

One of the D'Lite 22 6V6 power tubes I have has always had this very slight oscillation noise. Like popcorn popping way off in the distance. It's consistent (always there) and you notice it when the quitar is off or you are about to turn the amp off.

If you touch the outside of the tube it stops. It's not really microphonic in that it does not seem to pick up a signal from amp vibration. It's just creating this tiny little rattle underneath the rest of the sound.

The tubes seem sound fine ... those little high temp rubber bands wrapped around it would probably stop the noise ... since touching it stops the rattle.

Other than replacing perfectly good tubes, any other ideas?

[Structo]

Could also be your body capacitance stopping the noise
Just guessing here.

[doveman]

Just by touching the glass? I could touch it with some wood to see.

[Firestorm]

If touching it by hand stops it and touching it with an insulator doesn't, it's may actually be a slight parasitic oscillation. See if there is any way to shorten the grid wire feeding the tube in question. Even half an inch can make a difference.

[doveman]

I can touch the 6V6 anywhere in the glass with a 6 inch pencil and it stops. Touch the top of the tube ... anywhere on any side of the glass ... the rattle stops.

So I guess an insulator would be in order. Any suggestions that aren't the price of a set of tubes?

[Firestorm]

The pencil probably qualifies as an insulator. So you've got a noisy tube. There's no fix I can think of cheaper than a tube. Those hi-temp rings cost more than a set of tubes (unless they're RCAs or Bendix 5992s).

[Andy Le Blanc]

go to the hardware store and get a small metal spring to wrap it
should be cheap ...around a couple bucks at most
if it works great....... if it dont thats ok too
some of my favorite tubes are microphonic and some like to rattle
and depending on the application I've had to try a few thing
off the cuff and on the cheap

[FUCHSAUDIO]

go to the hardware store and get a small metal spring to wrap it
should be cheap ...around a couple bucks at most
if it works great....... if it dont thats ok too
some of my favorite tubes are microphonic and some like to rattle
and depending on the application I've had to try a few thing
off the cuff and on the cheap

how about heatshrink tubing or a hose clamp (for a car radiator).
Maybe new tubes might be easier.

[doveman]

I wired the D'Lite as a 6V6/22w and 6L6/33w with a toggle switch. So with this problem I pulled a couple of my Boogie's 6L6 tubes and gave it a go.

Pretty nice ... had not tried the 6L6s yet ... sweet. This little D'Lite amp is just too cool. I might get another set of 6L6s in the meantime to replace the Boogie set and store the 6V6s for a bit.

EDIT: Bonus = when I put the 6V6s back in ... I swapped the sockets ... it seems to be clear of noise now. Off chance I know ... but what the hell ... it seems to have worked.