A Fix for Loose Tubes?

[justin_tx_16]

Hey guys, I have this great little a Sonic Adventure Reality+ headphone tube amp that has two DuMont 6922 E88CC tubes inside.

Trouble is, they sit sideways. Every one-in-a-while a channel will drop out because they lose contact and I have to either rap the side of the amp or open her up and just fully re-seat the tubes.

I have read on here of people gluing their tube base to the glass but for me this isn't the problem. The problem seems to be that gravity is simply pulling the tube ends down just to the point that the right channel is no longer fully connected. It's a tiny change, invisible to the naked eye but it's there.

Is there any sort of conductive goup people put on the metal contacts of tubes to help with maintaining a connection and maybe prevent corrosion/difficulty removing?

Here is a scan of the inside

Thanks!

[Ski Bum]

This is kind of ghetto/duct tape approach, but I'm thinking if you use some temp insensitive material to mechanically stabilize the tubes it would fix your problem. Something like small pieces of radiator tubing between the very tops of the tubes and the sides of the chassis would only contact the tubes at the very tips (thus not inhibiting convective cooling of the tube), and hold them firmly within the sockets.

[Cut-Throat]

You need to tighten the Sockets that the tube pins fit into. Usually there are separate metal contacts that the tube pins seat into. These can be bent towards the center of the socket with a tiny jewelers screwdriver. This will have the effect of gripping the tube pins tighter. That is all it will take.

[jhoak]

You need to tighten the Sockets that the tube pins fit into. Usually there are separate metal contacts that the tube pins seat into. These can be bent towards the center of the socket with a tiny jewelers screwdriver. This will have the effect of gripping the tube pins tighter. That is all it will take.

I had to do this on my first Dynaco MK IV amps. I used a fine "dental" probe to gently bend both sides of each pin connection inward. Once completed there was a bit more physical "resistance" when plugging tubes in but it completely solved the occasional channel drop outs that I was having.

The other thing I've had to do on occasion with tubes is clean the pins. I've used steel wool (major PITA) and very fine sand paper (300 - 400 grit).

A lot of older tubed hardware had a little spring wire that clipped over the tubes to hold them in to place. I've also seen them used in some modern hardware. You might investigate the possibility of retrofitting the sockets with something similar.

It should be a fairly easy fix for you. Good luck!!!

[Guest " "]

I know a lot of folks who do gig's thru out NJ , PA, NY, MD. In hauling their gear some of the amps have tubes that come loose. Not a big fan of using metal tooth pics to pry the 9 pin hole contacts.....it's easy to do on power tubes...but pre-amp tubes are a bear. If the socket can't handle clips or springs, I just tin half of the 9 pins with silver bead solder. The solder tinning adds to the width of the pins and gives the tube a tighter fit. Just don't go crazy with the rosin or flux because it could loosen the pins in the glass envelope.

[justin_tx_16]

Thanks everyone for your suggestions.

I don't feel like it's a tightness thing, pulling the tubes out or putting them back in sure isn't easy. It's already a tight fit, yet a little jiggle and they lose contact, which is why I was hoping the answer would be conductive contact grease... As you can see, it's a pretty darn tight fit in there, not sure I can do much to make any adjustments to the tube socket itself. It only has a few hundred hours on it so it's not likely a wear-and-tear sorta thing, at least I hope it isn't.

Thanks again.

[eq_shadimar]

Hey Justin -

Welcome back [] Anyway my two cents is to use some foam of the correct thickness, density, etc with a sticky side on it (or not depending on where you need to mount it) between the bottom of the case and the tube. Also put some on the top of the case so the tube is sandwiched between the foam.

Laters,

Jeff

[justin_tx_16]

Thanks Jeff, I'll open her back up and see if that'll do it. Such a finicky little thing. Perhaps I should just hit up HeadRoom for a HeadRoom Micro Amp. Then I loose the warmth of tubes but I don't lose an entire channel of sound haha.

[Marvel]

Justin,

Not sure if you can get tell, but you might want to make sure the socket is soldered to the board well. It could be a bad solder joint. Just a thought.

Bruce