Shockmounting Valves

[spenny]

I am building a clone of my JMP 1976 SUPERBASS 100w, which i have played bass with for many seasons. one of the problems I have had is having to isolate the head from the cabinets due to vibrations rattling tubes!!

I am thinking of some sort of shockmounts for the valve sockets in the chassis....

has anyone had any experience with this type of buffoonery?

Cheers
Chris

[jaysg]

I've only done it once. In the 50's there were proper shock-mounting kits. Now I think you have to improvise. The main hole probably needs to be enlarged, then you use small o-rings or some other soft gasket material for the screw/nut connections. The tube should move easily in the axis of the mounting holes without flopping around.

Alternately, you could create a rectangular subplate that all the octals are hard-mounted to, and float that above the chassis. Individual mounts seem like a better approach, but you never know until you try.

[Structo]

jaysg is on the money.

There was a member here that ordered an exotic shock mount for a EF86 I believe it was.

But for a do it yourself type thing, I think the O rings might work OK.

As mentioned you will have to enlarge the socket hole so the socket can have good clearance from the chassis deck.

Another possible fix would be some sort of isolation feet for the amp head.
I had an old Ampeg SS Portaflex head years ago that had these rubber isolation feet on it.
Not sure if anything is commercially available now.
Or you can borrow from the Hi Fi guys, I'm sure they have stuff for this but it will cost you.

Or a piece of foam rubber on top the speaker cab then set the amp on that?

[img:425:252]http://i209.photobucket.com/albums/bb61 ... r_gmmt.gif[/img]

http://music-electronics-forum.com/t12768/

[img:265:214]http://bonanzleimages.s3.amazonaws.com/ ... umb200.jpg[/img]
http://www.bonanza.com/booths/k4_pacifi ... hock_Mount

Weber has a spring mounted socket.
http://taweber.powweb.com/store/chassis/chord2.html

A large PDF talking about shock mounts.
http://www.pearl-hifi.com/06_Lit_Archiv ... Rattle.pdf

Good luck!

[ampdork]

Seen some old tweeds with shock mounted sockets. In those they simply used a rubber grommet and glued up the nut and bolt too stay put while not being entirely clamped down.... I kinda thought it looked a bit cheesy and all but for the record the grommets were all good and the nuts and bolts were all still tightly bound. Did not look that great but it's been working well for 50+ years.

[Blind Lemon]

Wouldn't it be easier to just isolate the head from the cab? These are what I use on all my amps. I get them from CE.



BL

[Randy Magee]

Weber has a shock mount for tube sockets...

https://taweber.powweb.com/store/chassis/chord2.html

[Masco]

I've been using these for my builds: http://www.mcmaster.com/#vibration-damp ... ts/=a4og9r

I don't know the exact part# off hand since I'm now at work, but I get something like the style 3 or 4.
You have to look at the weight load of the socket and tube to determine the flexability needed for the gromet. Most are for mounting heavier objects, but there are a few under 1lb that will work. You might have to add a little mass to your tube envelope like a silicone ring or heat shrink.
I have found out that if you use a small metal cylinder that fits inside the inner mounting hole that is just shy of the height of the gromet, you won't have to worry about over tightening the mounting screw.
Since there are ribs on the surface of the gromets, you can use washers.