Grounding of shockmount tube sockets?

[PharmRock]

Hello everyone and happy new year!
After a nearly 2 year hiatus from amp building due to medical and life issues, I'm finally back into building my next amp.
I recently picked up a few McMurdo shock-mount noval sockets, and it appears there is a wire running from the tube socket base to a center shaft of the socket.  Should I ground this shaft to the chassis?  It seems like I should since the socket is isolated from the chassis by the rubber base.
Pics are below.
Thanks!
Bruce

[kagliostro]

Connecting the center of the socket to ground it acts as shield between each pin to the other, may be it is more important to do in RF circuits instead of in AF circuits, however if you want you can do it, but use a flexible wire or the shock absorb function will be negatively afflicted


Franco

[Merlin]

You can also connect it to one of the (fully bypassed) cathodes which is usually just as good

[PharmRock]

thanks Franco and Merlin,
I'll connect the shaft to ground via a bypassed cathode. I bought a few of these and plan to use for V1 positions in combo amps. 

[trobbins]

As Franco highlights, its important for the socket to be mechanically decoupled from the chassis, so careful selection of a flexible link is worthwhile (there is no current requirement for that link).  Another aspect of suppressing microphonic output is to reduce the sprung self-resonance of the valve/socket, which can be pushed lower by adding weight to the valve (such as fitting o-rings that also may help dampen glass 'ring').

[acheld]

Personally, I would not bother trying to ground the tube base.  In the guitar amp world, extending that bit of shielding a little closer to the tubes yields -- nothing.    And introduces complexity, and a chance that you'll short out something that matters.

[PharmRock]

Thanks everyone for the feedback.  I have some dampening rings I bought from Eurotubes a while back that I can fit around the tube. 

This will be for a build using a pentode preamp (5879).  I've read that this tube isn't as susceptible to microphonics as an EF86, but figured it wouldn't hurt to to use this shock-mount socket just to be on the safe side. 

[Willabe]

This will be for a build using a pentode preamp (5879).  I've read that this tube isn't as susceptible to microphonics as an EF86, but figured it wouldn't hurt to to use this shock-mount socket just to be on the safe side.

No, it wont hurt anything.

Is it a combo amp/with speaker in same cab or just a head?

Combo amps are more susceptible to problems from tube microphonics than a separate head because of the speaker being in the same cab, more/stronger vibrations hitting the tube and chassis.

[PharmRock]

This will be for a 2x10 combo.  I'm planning on doing the HoSo56 or one of the other 5879 circuits (e.g., DMars 5879 ODS +FX).  Still in the early planning/parts gathering stages at the moment.