Loose base on vacuum tubes

[rlyach]

I have noticed that many of the large tubes (2A3's in this case) are slightly loose in their bases. Some are worse than others. Is this a problem? The tubes tend to wiggle freely and I was concerned that the vibrations would affect the sonic performance of the tube. Is there some way to secure the tube in the base?

Thanks,

Randy

 

[jrebman]

Randy, do you mean the base of the tube (usually ceramic for the larger tubes), or when they are sitting in the socket?  If it's the tube base there is some tube base cement you can get or some high temp silicone can work as well.  If you mean the socket, that is more a function of the particular sockets used, but most will allow you to move the tube a fair bit.  Just gently push down until they seat evenly and you should be good.  If the tubes are falling over on their own, then you probably need a new socket.  Some sockets have a death grip on the pins and some don't and older sockets can lose their tension after some years or repeated tube rolling.

HTH,

Jim

 

[rlyach]

It is the tube in the base not the socket. The socket seats fine. The tube wiggles in the base. Where can I get cement and how do you put it in the small gap?

 

[jrebman]

The new JJs are lose?  Did you buy them from eurotubes.com?

Antique electronics supply has tube base cement.

 

[rlyach]

I bought the JJ's from Antique electronic supply here in Phoenix. This is the second set and all four had slightly loose bases. I returned the first two because They were not matched. The test certificate in the box did not match the numbers marked on the outside. The new tubes are matched but one of the bases is a little too loose. I will purchase some cement try to find a good way to get it in the base.

 

[denti alligator]

The tubes in my Quickie are loose like this,which I notice because I have to ach between them to turn it on and off and sometimes bump them. They seem to me too easily to move. But it doesn't affect sound.

 

[Grainger49]

If you buy a high temperature RTV (silicone seal) an get it into the crack between the base and glass you won't have them wobbling anymore.

 

[rlyach]

Grainger,

Is the wobbling a problem? I looked at the tubes and it appears they are not cemented to the base. The leads from the tube are simply soldered in the pins and that is what holds the tube to the base. If this is not a problem sonically, I will just leave it be.

Randy

 

[jimiclow]

I have a few old 45's that have the same problem. Elmer's wood glue (the one I used for assembling the wood base!) worked well for me. I just put masking tape above and below the glass/base junction and put the glue. Remove the tape and put back in the socket. I use the tube for maybe 6 hours and it dries hard.

 

[Grainger49]

The wobble is not a problem in itself.  As long as you don't remove the tube by grasping the glass it should never become a problem.

 

[vetmed]

I read this one on the web a long time ago and it has stuck with me: try a few drops of acetone (nail polish remover) between the base and the glass bulb. This has worked for me with older tubes, apparently the solvent dissolves the old glue which then resets once the solvent has evaporated.
                  Best regards
                        Robert Lees

 

[Paul Birkeland]

I wouldn't worry too much about loose bases, I've used a drop of superglue in the past to tack them in place.  Also, the Steremour does not require a matched pair of 2A3's.

-PB