dampening tube sockets with silicone gasket.

[g1]

Guess I missed the joke.

nosaj

Me too. But I think it may be something about Rhodes not being road worthy?

Back to microphony, if memory serves, the original boogies used grommets to mount the preamp tube sockets, or at least the first stage tube.

[Leo_Gnardo]

Back to microphony, if memory serves, the original boogies used grommets to mount the preamp tube sockets, or at least the first stage tube.

And by late 70's, Boogies were being issued with FETRON preamps, FET arrays housed in cylinders with a 9-pin header to plug into tube sockets. No microphonics there! But they never did catch on. I have a couple of them in my collection of odds n ends. Another mini trend that ran its course and went away.

[J M Fahey]

Well, Fetrons were *expensive*.
Original market was *large* Telecom companies, who paid big bucks for them to reduce servicing in bedroom sized 12A*7 baser telephone long distance repeaters.

Paying U$45 (60´s dollars, way bigger than ours) per unit was nothing compared to having to replace scores of glass tubes every Month, I read somewhere that South Africa was the last big customer they had and they had tons of NOS overstock.

Once the Phone companies went full Solid State the justification for Fetrons died.

I bet Boogie bought a batch at auction for peanuts and when they were gone, they were gone.

[SoulFetish]

Then I'm duty bound to point out your error of calling ignorance stupidity.

You know, as soon as I wrote those and hit “post” I had a terrible feeling I was going to pay for them.
I was taking a little artistic license, G1. -Dramatic interpretation, if you will-. I was hoping you would let it slide.
After I wrote that, I had a flashback of my seventh grade english teacher, who would actually make corrections in red ink on birthday and Christmas carrds she received that had any grammer or spelling errors, and send them back to the person.
When she told us she did that, even at my age back then, I remember thinking “GOOD GAWD! CLOCK OUT AND LET IT F*CKING GO, LADY!”
So, just so there’s no confusion about where to draw the line in the sand, I’ll tell you when to correct me going forward.

[SoulFetish]

I had some time away from other people's projects over the last week to make some progress on my own.
I finally finished up mounting these new sockets on their base and silicone damping gaskets. Moreover, I was able to develop a better way to execute this and am much happier with the final results (at least aesthetically).
In my initial attempt, I mounted the flat washers over the silicone sheet and then tried to cut out the center hole for the tube socket. It was difficult to achieve consistent results and wasn't happy with the quality of the cuts or presentation in the end. This is how I decided to approach the project instead.
First, what the hell was I thinking drilling out the flat washers in the first place. It was time consuming and.... took way too much damn time. I had to create a jig to clamp the washers down without warping them, while allowing me to drill through them. What I should have done was spend some time researching if there are any industry standard washers which meet my dimensional requirements. The Belton 9-pin tube sockets I'm using have an 18.5mm through-hole mounting base. An industry standard M20 machine washer has a nom. inner diameter of 21mm and outer diameter of 37mm and would have given me almost the exact dimensions I ended up with.


But, I already had the washers so I here is how I completed the rest.
I found a socket with an outer diameter as close to 18.5mm as possible to use as a template, and pre-cut the center hole in the silicone sheet.


The next step was to center the socket in the steel base and secure it with some masking tape to hold it in place


Then I could place Silicone gasket over the base and using an large diameter needle (or small diameter awl), center and pre-punch the holes for the mounting screws.


I then inserted the screws at this point which made it an easier and quicker process to align and secure the mounting base to the chassis.


After the sockets were installed and in place, I trimmed the excess silicone flush with the mounting washers. I thought this provided better results than my first attempt shown in post# 1.

[g1]

Nice work. How do you decide on final torque for the mounting screws, tight then back off some?
Or to still allow some wiggle?

[J M Fahey]

**LOVE** the practical construction threads

[SoulFetish]

Nice work. How do you decide on final torque for the mounting screws, tight then back off some?

Exactly. Really just went by what “felt” secure, but not so tight that the silicone warps under the pressure.

[nickb]

This is so much better than the grommet in each mounting hold used by Mark Sampson in Matchless / Badcat amps. One small thing I see he did was to add a jumper from chassis to the mounting screw if that tube needed a screening can.

[g1]

In this case it looks like there could still be electrical contact via the screw, but that will depend on the composition of the nylock type nut?

[SoulFetish]

In this case it looks like there could still be electrical contact via the screw, but that will depend on the composition of the nylock type nut?

Yeah, I’ve been wrestling with this part of it. Right now there is still continuity between mounting screw and chassis. But total mechanical isolation would be more effective, but that would mean I loose the convenience of continuity through the mounting screws. But it would be easy enough to hand tap 3 holes near the base and crimp some ring terminals for jumpers. I may do that.

[SoulFetish]

Here is some good technical data on the properties of silicone rubber!
https://www.shinetsusilicone-global....f/rubber_e.pdf

[The Dude]

Yeah, I’ve been wrestling with this part of it. Right now there is still continuity between mounting screw and chassis. But total mechanical isolation would be more effective, but that would mean I loose the convenience of continuity through the mounting screws. But it would be easy enough to hand tap 3 holes near the base and crimp some ring terminals for jumpers. I may do that.

I'm not sure I'd trust the mounting screws for ground anyway since you're probably not cranking them down tight. I'm assuming you're not, anyway. That would somewhat defeat the purpose of the silicone gaskets.

[Tom Phillips]

This is so much better than the grommet in each mounting hold used by Mark Sampson in Matchless / Badcat amps...

I'm not so sure. The SoulFetish method looks very nice. However, for vibration isolation, more contact area of the isolating material can actually transmit a higher level of sock and vibration between the chassis and the tube socket. Two small holding points with grommets under the screw mounting holes could actually perform the job better. One trick I've seen is to slot the screw hole to create an opening to the large clearance hole for the tube socket. Then just slid the grommets in to be held held in position by the mounting screw. That solves the problem of stuffing the grommet into a small hole. Somewhere I have a photo of the details but cannot find it at the moment.

[picturevalve]

Grommets with inserts

I've got some old parts which are grommets with metal spacer inserts, you can tighten whatever is mounted as far as the spacer allows. Vibration damping with insulation.