Tube retainer clips problematic?

[Axtman]

I have heard that the spring tube retainer clips can be problematic. According to my source metal and glass expand and contract at different rates. Plus the metal can heat up the tube.

Personally I have never seen an amp where these clips were an issue. What about you?

[Mick Bailey]

The only problem I've encountered with this type is spring rattle, cured with high-temperature silicone tubing. I've never done any checks, but the metal retainer cap always seems to run cooler than a naked glass envelope. I think the metal dissipates heat better than the glass.

[Axtman]

Mick,

Good idea about the silicone tubing. I will not name names, but the guy I heard it from runs a popluar amp repair YouTube Channel. I agree with everything else he says about amp repair. This comment made me pause. He explains the difference between the metal and glass cause thermal stress in the glass.

He did not say this but I wonder if the grounded spring clip affects the amp electrically?

I usually use "bear trap" style tube retainers. The amp I am repairing has 6550 tubes and the tubes point up from the chasis, not hand down like Fender amps. I thought I would install these retainers just to be sure the tubes don't get jossled out of place or loose from transport.

[Helmholtz]

I think nevetslab could add some own experience with those retainers.

Measuring bulb temperature requires using a thermocouple and a little heat grease for heat transfer.
An infrared thermometer is likely to give wrong results as the glass doesn't reflect like a black body. In fact it's rather transparent to heat radiation.
So one would have to paint a black spot on the bulb and focus on it.

[g1]

I think https://music-electronics-forum.com/...5293-nevetslab could add some own experience with those retainers.

Yes. If I recall, nevetslab ran into some issues with cracked glass at the dome part, which led him to using silicone tubing at the round part of the retainer as well.

[eschertron]

The only problem I've encountered with this type is spring rattle, cured with high-temperature silicone tubing. I've never done any checks, but the metal retainer cap always seems to run cooler than a naked glass envelope. I think the metal dissipates heat better than the glass.

As I see it, the metal is a better conductor of heat that air, so where the metal touches the glass, the envelope will tend to be cooler. Enough to stress the envelope? IDK

[Helmholtz]

It was my intention to mention nevetslab in a way that would make the system send him a notification mail.
Not sure if this works.

[g1]

It was my intention to mention nevetslab in a way that would make the system send him a notification mail.
Not sure if this works.

For a 'mention', you need the @ character. Not sure how you did your link. With the @ character, it will appear as it did in my post. From there, how they are notified depends how the user has their notifications set up.

[g1]

Yes. If I recall, nevetslab ran into some issues with cracked glass at the dome part, which led him to using silicone tubing at the round part of the retainer as well.

My mistake, the cracks were occurring where the spring meets the 'cap' of the retainer.
Post with pictures and solution here: https://music-electronics-forum.com/...358#post794358

[Greg Robinson]

I've also experienced both ringing/microphonics and cracked glass from the spring type retainers, and avoid them wherever possible. When unavoidable (KT88's, 6550's, etc), I do similar to nevetslab, with silicone tube on the springs. Rather than split some tubing for the top of the retainer though, I use these. The photo on their website is terrible, they're actually thin flat rings that just add a small amount of padding between the top of the retainer and the glass envelope. First time I bought them I was expecting something more like retainer rings...

Wish there was another source for these clamp type retainers, Fliptops wants a few hundred dollars to ship a dozen pieces to Australia, only other source I'm aware of is Mesa Boogie and they won't ship at all. Can find them NOS on occasion, but would be great to find a reliable/affordable source. If anyone happens to know of one, please let me know!

[Mick Bailey]

Spring retainers have been around for a good while. I saw some ex-WW2 equipment fitted with a variation where instead of the metal cap they had a woven asbestos and wire 'hat' which looked like crochet work.

[g1]

Wish there was another source for these clamp type retainers, Fliptops wants a few hundred dollars to ship a dozen pieces to Australia

These look to be around half price of the fliptops ones:
https://britishaudio.com/products/am...ies-amplifiers

[Greg Robinson]

These look to be around half price of the fliptops ones:
https://britishaudio.com/products/am...ies-amplifiers

Oooo, thanks!
They also only want about half the shipping that Fliptops do too, but they still want an arm-and-a-leg, works out to roughly $18US per clamp if I were to buy 6 at a time, ouch!

[glebert]

I had a friend who had a homebrew amp and he had some sockets that seemed to be prone to shorting out, and he had retainers with very short springs. The amp would be fine unless you put the retainer clip on and then it would blow a fuse. Neither the crappy sockets or the short springs was "right" so I can't blame the clips, but it is one issue I've seen. Then again this type of retainer can be used with coin-base tubes, which bear trap types shouldn't be used on.

[g1]

They also only want about half the shipping that Fliptops do too, but they still want an arm-and-a-leg, works out to roughly $18US per clamp if I were to buy 6 at a time, ouch!

They appear to be an official ampeg part, you might want to check with an Ampeg dealer in Aus.