diy tube dampers

[pforeman]

With half a tube of black 100% silicon caulk left I decided to make some tube dampers with the rest.
I made THICK circles with an internal diameter about 30% smaller than the outer diameter of the tube. These are much thicker and robust than "store bought ".
I actually made lots, and the sizes were'nt exact so some got tossed as too large and not quite as tight on the tube as I'd like.
I made them for all my tubes EL34, KT88, KT90 KT77 12at7 and 5ar4.
Half a tube made 3 for all my tubes (+ wasted ones)
I figure the 5ar4 gets the hottest? and after about 50 hours of playing I took it off and its still as pliable and tight as when it was new.

A question about tube dampers. Would it be better to apply a ring right to the tube?
Thanks,
Paul

[trobbins]

Why did you apply it to those tubes? Have you got an amp that is microphonic, or you notice a sound when you artificially 'ding' a particular valve?

[v4lve lover]

pointless . if it dings its a shitty valve

[trobbins]

I would consider an artificial 'ding' to be a very extreme test - and often with no correlation to whether an amp sounds fine or not for many amp applications.

[pforeman]

I've read several tube amp reviews instereophile where reviewers (Dick Olsher comes to mind) claim that tube dampers improve the sonics of tubes.
I didn't apply the ring to the tube.
I made them on saran wrap when dried I stretched them onto tubes.
I was wondering if TIGHT was necessary or if it would be better, instead, to just apply the caulk to the tube and get better adhesion possibly better damping of the glass.
No, none of my tubes is microphonic.
Paul

[GloBug]

I suppose it would work fine if you just applied it directly to the tube.
I would think it just needs to be snug enough to couple with the tube.
It's the added weight that stops the glass from vibrating, or at least shifts the resonance to a different frequency.

There might be some advantage to being tight, however I don't think you can consider the tube dampers as "tight" compared to the hardness of the glass.

It's the added weight that damps the side-wall of the tube.

Much like trying to tap a crystal glass while lightly holding the rim, it won't ring, hold the base or set it on the table, tap it and it will ring.

[Zeta4]

Interesting idea. I have some 10Ys in a pre-amp Im making that are
decidedly microphonic. I get a distinct zing through the speakers
when I tap the valve with a pencil. Each of my valves is slightly different
in how microphonic they are. Flexibly mounting the valve bases helps
a bit but I was considering trying rubber rings around the valves and
your idea could be even better.

This works well with the 3A5 but I seem to remember reading somewhere
that this has caused cracking of the glass envelope on power valves.
Anyone heard of any problems like this or am I just being paranoid.
With the price of 10Ys I dont want to take any uneccesary risks

[pforeman]

About 50 hours with these on all the tubes.
About 40 hours on the KT90's.
If anything cracks, I'll be sure to post it!!
But I don't see how these would be more of a problem than store bought tube dampers or those tube coolers etc. etc.
I run the KT90's with just under 45 watts dissipation.
No problems.
I'd think the 5ar4 would get the hottest (?) as it has the most current through the heater. No problem there either.
Paul

[flatheadmurre]

Interesting with diy damping of tubes.

Wouldn´t a ring of some weight (giant washer ?) glued to the tube with say 6mm of silicon make an excellent damper ?

Usually when talking about damping you have the objekt needing damping a piece of rubber/shock absorber and a reference point/mass.

I can´t see that a o-ring adds all of above ?

[trobbins]

The mass dampening is talked about in Microphonics