Who makes this fitted grommet for tube hold-down clamp opening?

[nevetslab]

Anyone know who makes this nice little fitted rubber grommet for the 6550/KT88 Hold-down Tube Clamp's hat?



I just recently came across them on our newest Ampeg SVT-CL amps, while going thru them doing preventative maintenance. I've seen the white non-captive silicon rubber parts that Antique Electronics Supply sells for half a buck. This part that Ampeg has started using (presume it's from them, and not someone else that previously serviced a couple of these amps) shows someone has been thinking and properly addressed the issue. Production workers haven't yet learned to seat them though.

[tedmich]

Those sure are thin! It looks like those could stand to be a bit thicker like a std. grommet (Cracking good cheese...) whats the diameter of the hole they fit and the metal thickness?
I remember people selling "12AX7 tube dampers" for +$5 when McMaster Carr had the orings for $3 a dozen

[nevetslab]

Clamp thickness is 0.020", and the dia of the opening is 0.860". The base thickness of the grommet is 0.040", and overall thickness (not installed) is 0.100. True, I"d like a bit more meat on the plate myself. Don't know why the part mfgr decided to skimp. Not like they're saving any money for the low quantity being sold.

Not a standard hole size & plate thickness for industry grommets

[Leo_Gnardo]

Clamp thickness is 0.020", and the dia of the opening is 0.860". The base thickness of the grommet is 0.040", and overall thickness (not installed) is 0.100. True, I"d like a bit more meat on the plate myself. Don't know why the part mfgr decided to skimp. Not like they're saving any money for the low quantity being sold.

Not a standard hole size & plate thickness for industry grommets

1. Have you tried asking Ampeg? Though the company seems moribund in other ways, I still get a good response from the parts department.

B. Local industrial fastener supplier. Or rubber/silicone goods. Might try a good machine shop or auto supply. Even if they don't have it maybe one of the ol' timers could point you the right direction. Or one of the youngin's might surprise you and do the same. Standard size or not. When all else fails there's a place around here (Sarjo) that has just about everything or can order it. Some things cost a bit more than you'd like but when you gotta have it and nothing else will do...

Show 'em your grommet.

Wensleydale? mmmm, outstanding!

[nevetslab]

1. Have you tried asking Ampeg? Though the company seems moribund in other ways, I still get a good response from the parts department.

I havne't called Loud Technologies yet. Did just look up their latest post on the chassis assembly BOM, but it's dated 2007, only has their in-house P/N for the hold-down clamps. Might be a part now being supplied by that source. Unless you get someone who REALLY knows the product and isn't protected by the the front-line defense (phone operators), and you don't have a part number, it's a lost cause. I'll still shake the tree, but thought I'd throw it out for general speculation. It's a part that I'd sure buy in qty for all the gear we have in our rental inventory. If Antique's part was captive, I'd be more inclined. Yeah....RTV, other glues.......

[Leo_Gnardo]

If Antique's part was captive, I'd be more inclined. Yeah....RTV, other glues.......

Not much will stick to silicone if that's what Antique is selling. I've seen similar grommet/cushions to the ones you describe. They're not form-fit to the hole in the "hat" but are made of a spongy looking orange material. Reminds me of engine gaskets. Another good reason to run your sample past any motorhead friends you may have, small m, auto parts or machine shops. Good ol' Permatex Blue silicone adhesive works well with non silicone gasket materials, stands up to high temps. Me, I just gave up on those things but if your need is to preserve rental gear during shipping and other abuse, whatever cushioning you can put in, is all to the better.

Who knows if Ampeg's cushions are supplied new with that form fit step. They could well be flat, and get pushed into shape by heat and pressure.

[g1]

Good ol' Permatex Blue silicone adhesive works well with non silicone gasket materials, stands up to high temps.

Permatex ultra copper is their highest heat gasket maker (700deg.F) Should stick ok I would think. Why not make a bead of it on the clamp, let it dry, skip the grommet. No need for different size grommets for the various clamp sizes. Thickness as required.

[Enzo]

It would seem to me that the most likely source for that grommet is the clamp maker. I can't imagine anyone making them aftermarket. I suspect whoever supplies the clamps to Ampeg offers them padded or not padded.


A hundred zillion of those tube clamps have been used without the pad for decades, and no ill has come of it.


Peavey uses an adhesive strip of foam on the tube cover plates on amps like the 5150. I have a huge roll of it I used when I was making the tube retainers for the Classic 30. But they also sell it by the foot. If I felt the need to pad some tube clamps, I'd just cut a couple hunks of that foam strip and stick them up under the ring.

[drewl]

Yeah, I just cut down the regular electrical grommets we have at work by the thousands, to size.

[tedmich]

?

(kidding)

[Zouto]

Anyone know who makes this nice little fitted rubber grommet for the 6550/KT88 Hold-down Tube Clamp's hat?

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I just recently came across them on our newest Ampeg SVT-CL amps, while going thru them doing preventative maintenance. I've seen the white non-captive silicon rubber parts that Antique Electronics Supply sells for half a buck. This part that Ampeg has started using (presume it's from them, and not someone else that previously serviced a couple of these amps) shows someone has been thinking and properly addressed the issue. Production workers haven't yet learned to seat them though.

You can get 'em here:
Spring Tube Retainer for 6550/ KT88, nickel finish - Accessories

[jbltwin1]

Windshield washer tubing, maybe 3 or 5/32, split longwise and long enough to butt together without coming out. Maybe a little trim cement for stability till it dries? Made a lot of hole protectors that way. Mike.

[Leo_Gnardo]

A hundred zillion of those tube clamps have been used without the pad for decades, and no ill has come of it.

I've been noticing last couple of years Ampeg SVT-CL and similar come in, those without the grommet/pads on the spring clips show cracks in the glass at the top of some, not all 6550's. In most cases the cracks don't go all the way thru the glass. It gives me the willies to send 'em back out with this condition, cracked but otherwise working output tubes. In the cases the crack goes all the way thru, the usual white getter flashing on "air" not vacuum tubes.

Zouto, thanks for pointing out a source. 1.75 pounds per retainer, nearly $3, ow. Plus shipping from Germany, double ow. Well at least they have 'em. Maybe for us USAn's some source will turn up.

g-one thanks for mentioning Permatex ultra copper. I'll pick up a tube next time I'm at the auto parts store.

[TimmyP1955]

IIRC, most of our SVT-CLs lack the rubber, and I don't think I've ever replaced a 6550 that displayed visible signs of lost vacuum.

[Audiotexan]

Windshield washer tubing, maybe 3 or 5/32, split longwise and long enough to butt together without coming out. Maybe a little trim cement for stability till it dries? Made a lot of hole protectors that way. Mike.

That isn't high temp hose though is it?
How you actually tried/used this method? And if so, have you seen the results of long-term use yet (3-5 years)?? If it actually tolerates the heat...that'd be a pretty cool and cheap solution!

Either way, learned a great tip for a hole protector!! Thanks!