Board Mounted Tube Sockets

[SerpentRuss]

During my current build it occurred to me that "next time" I might like to mount my tube sockets to my board and just make oversize holes in the chassis for the installed tubes to extend through. We're obviously talking about a front control panel construction where the pots and jacks face forward on the amp and the tubes hang down into the chassis.

There are a couple of reasons I think this might work well for me. First, I make my own boards and so I can cut them to a width that would support adding the tube sockets. Second, in the event the board has to be pulled, there are a lot less wires to unsolder.

I figure if I put enough standoffs around the sockets, inserting and removing the tubes shouldn't create any undue stress on the board.

Any thoughts?

 

[corliss1]

I mean, that's how 800 zillion amps have been built. As long as you use decent quality sockets you'll be fine.

 

[SerpentRuss]

I mean, that's how 800 zillion amps have been built. As long as you use decent quality sockets you'll be fine.

Yes, but most of those 800 zillion are the dreaded printed circuit board amps, LOL

 

[Nicko_Lps]

Any thoughts?

Yep, the first thought that came in my head!!

Personal opinion?
Wiring is much easier as you dont need to make a PCB, now if you are planning to produce multiple amps the PCB would be better.

Durability after a decade or two is not the same.. The PCB will be weak after so much heat but.. That is up to you to decide by taking account how much you use it and abuse it!

 

[2L man]

in the event the board has to be pulled, there are a lot less wires to unsolder.

When chassis mounted tube sockets and all other components and board wires are not placed under the board there should not be any reason to pull the board and all wiring, except filaments, can be as straight as possible.

 

[SerpentRuss]

I currently make my boards from the phenolic laminate taken from raised floor tiles, the type you see in data centers. It's 1/8 inch thick and has a Formica laminate on one side. On my last build I put the Formica side down (components on the non-Formica side) because for me, it's easier to see what I'm doing. It's pretty durable material as you can imagine. I pretty much have a never ending supply of this stuff and the tiles are 2ft by 2ft.

 

[SerpentRuss]

When chassis mounted tube sockets and all other components and board wires are not placed under the board there should not be any reason to pull the board and all wiring, except filaments, can be as straight as possible.

True, and I normally don't put any wires under the board anyway. I still think I'm going to try it and see what I think. I might also divide the build into a pre-amp board and a power amp board with a gap for easily passing wire from the transformer side of the chassis. I like to experiment. My current build has part of the pre-amp on a solder-able breadboard.

 

[chas.wahl]

Interesting idea. Is the entire thickness of the floor tile phenolic? Formica is basically phenolic, I think. What is the dielectric property of the floor tile? Conductivity?

My own feeling is that if there's a way to a) isolate the rest of the circuitry from the heat of the tubes in operation, b) make the mounting for the tube socket as mechanically rigid as possible (insertion and removal over years of service) and c) get stuff in the chassis separated enough that it's easy to do repair/mod work on it, then that's a better approach -- which leads me to favor the "vintage tube amp" approach.

 

[sds1]

In theory this will lead to a much quieter design. You are less restricted by an arbitrary physical layout. You can put the sockets wherever it lends to quietest operation. Grid resistors should naturally end up mounted directly on their respective pins. The most problematic signal wires tend to be the long runs to/from from panel controls and socket.

 

[schmee]

So you want to do what so many modern amps are known to have trouble with?
I guess you wont be dealing with a PCB so that helps, but also takes away any time advantage..?

 

[King Fan]

Random thoughts, not really questions. (I do like the question whether it actually eases wiring / repair.)

Tube shields, bearclaws, other retainers?

How tall are your standoffs? would it be tricky to pull or place tubes? Especially the big ones you want to pull by their base?

OTOH I’ve seen this done on *tubes-upright* amps where the tubes appear to float in space — cool. Or even inside little chromed tube cages — '30s-liner sleek.

 

[Lowerleftcoast]

Is this just the polite way to say "Get off my lawn."?

 

[SerpentRuss]

In theory this will lead to a much quieter design. You are less restricted by an arbitrary physical layout. You can put the sockets wherever it lends to quietest operation. Grid resistors should naturally end up mounted directly on their respective pins. The most problematic signal wires tend to be the long runs to/from from panel controls and socket.

In a head design this is certainly true. In a combo, there is still the speaker to contend with so putting the tubes toward the back might still be the best layout. You can always make the case tall enough so there isn't a clearance problem.

I think a few if Doug Hoffman's designs put the preamp tubes directly behind the input jacks, sort of Feng Shui style.

 

[SerpentRuss]

View attachment 997271

Is this just the polite way to say "Get off my lawn."?

He does seem a bit sensitive about the issue, LOL. My main issue with PCB amplifiers are the quick connects that make quick factory assembly possible. If the PC board and components are a really good quality the connectors are usually where the trouble starts.

 

[Lowerleftcoast]

If the PC board and components are a really good quality the connectors are usually where the trouble starts.

True.

The typical PCB with mounted tube sockets will also crack the solder or trace do to the stress from the tubes. It sounds like this area will be "beefed up" in the floor tile design.

 

[RollingBender]

Here’s how I did it…

Super Lead type build - see how many boxes I can check

First build of 2021. Heavy influence from the AX84 November, some 1959 SL, some more modern Marshall stuff. I’ve been drawing and re-drawing the board layout in DIYLC and the chassis in my CAD program for at least 6 months and after at least 5 different iterations and complete changes in...

www.tdpri.com

I can’t think of any disadvantages as long as you use a board that is robust and have the board mounts properly considering the tube sockets.