Converting from PCB mounted preamp tubes to chassis mounted

[WORMDIRT]

My amp has PCB mounted preamp tubes, and the way it is set up sucks pretty bad. I feel like chassis mounting the tubes will be a worthwhile conversion, since I'm having trouble with the sockets already.

Any special considerations for doing this?

[Stevem]

Yes! If you have to extend any of the wires to get that done then the grid wires are the ones that could make for problems of oscillation or a very mid heavy tone!

If there is a need to extend these (grid wires) they need to be kept as short as possible.
The heater wires need to be twisted tightly and layed flat on the chassis and all the other wires need to raised up off of the socket, once again the grid wires being the most important to have that way!

[Leo_Gnardo]

My amp has PCB mounted preamp tubes, and the way it is set up sucks pretty bad. I feel like chassis mounting the tubes will be a worthwhile conversion, since I'm having trouble with the sockets already.

Any special considerations for doing this?

I've often though of doing this with Blues Juniors, even going to 6V6 output tubes.

What stevem said ^^^ and another thing to think about, it's always best to have the grid stopper resistors as close to the tube as possible - right on the socket. Same for screen grid R's on output tubes.

Lets see a snap of your completed project. I'll bet it will work a treat.

[Bob Simpson]

I think there is a picture or two of this done nicely in the TW forums.
Sockets on the chassis, wired directly vertical to pcb or turrets through a socket sized opening in the board.
One of RJ's prototypes? ( or not... )


If you can, bolt the sockets on the inside of the chassis, so the board can be removed without un-soldering and then re-soldered to put back.

And don't ask how I know this...

Bob

[DonMoose]

One option is to mount the chassis-mount sockets with screws coming UP through the chassis so you can get them out again with the board in place.
Add legs to each socket pin made of long, bare solid-core wire pointing straight up.
Use your solder sucker to clear the existing socket lead holes and check if you need to raise the standoffs a bit.
Thread the lead wires through the socket holes (frustrating!) and slide the board down on them to your standoffs.
Solder the leads in place and trim.

Now your tube-swapping stresses transfer (mostly) to the chassis, but you didn't really have to butcher your board too much.

The heater re-wire idea is still a good one - PCB heater traces can be a bit undersized.

Hope this helps!

[Gibsonman63]

The heater re-wire idea is still a good one - PCB heater traces can be a bit undersized.

Hope this helps!

I worked on a Crate vintage something or other a while back or maybe it was a Peavey. I know it was tweedish. Some of manufacturs are wiring the heaters in series. Not an issue, just be sure you know what you have before you start.

[WORMDIRT]

One option is to mount the chassis-mount sockets with screws coming UP through the chassis so you can get them out again with the board in place.
Add legs to each socket pin made of long, bare solid-core wire pointing straight up.
Use your solder sucker to clear the existing socket lead holes and check if you need to raise the standoffs a bit.
Thread the lead wires through the socket holes (frustrating!) and slide the board down on them to your standoffs.
Solder the leads in place and trim.

Now your tube-swapping stresses transfer (mostly) to the chassis, but you didn't really have to butcher your board too much.

The heater re-wire idea is still a good one - PCB heater traces can be a bit undersized.

Hope this helps!

This is an excellent idea, and what I'm going to roll with, seeing as I only need to extend the sockets 3/4 of an inch up (or down haha) to chassis mount them.

Pics by this weekend (hopefully)

[Leo_Gnardo]

The heater re-wire idea is still a good one - PCB heater traces can be a bit undersized.

Hope this helps!

I worked on a Crate vintage something or other a while back or maybe it was a Peavey. I know it was tweedish. Some of manufacturs are wiring the heaters in series. Not an issue, just be sure you know what you have before you start.

It's Peavey that does the series-filament in Classic 20, 30, 50?, Delta Blues & maybe some others. YES make sure what you have first. Parallel-wiring the filaments in one of these, it would become a smoke machine all too fast.

[WORMDIRT]

Well, no pictures, but it is done. And man, it was a pain in the ass. Thanks for the input fellas