Need your advice for tube amp case

[dontellpapa]

Hi,

For those who may have build tube amp in a wood box, I need your kind advice.

A. Painting
I found a nice unfinished wood jewlry box and decided to use for my first mono block tube amp.

I am thinking of painting with silver color and transparent lacquer for harder surface. Should I paint silver color first or transparent lacquer first?

Before I start assembling wiring and placing tube sockets, should finish painting first or do the painting after completing my tube amp?


B. Grounding inside of wood box
Could you explain to me how this shall be done? I will have a main black wire for grounding but do not know what needs to be connected.


Thanks for your kind advice.

Dontellpapa

[dontellpapa]

Hi,

Is there any one who build an tube amp in an wood box?
I need your advice for painting above?

Thanks.

Dontellpapa

[pointy]

you will need much more than a wooden box to make a valve amp as you will be using

400 VOLTS or more.

you must read more on safety before trying any high voltage work..............!


(in an odd way if you painted the inside of the box silver and then earthed the paint you may stop radio waves from hitting the wires inside.)

[tomchr]

Well... If you painted the box using silver CONDUCTIVE paint and grounded the paint, you could shield the circuit from stray electric fields.

If you are worried about shielding, you could use a metal box and cover it in wood (or put it inside the box you have). Just remember to ground the box at one point (safety/green wire ground and circuit ground meet here).

As for advice on painting of wood, I suggest asking in a woodworking forum. If you want your paint finish protected by a hard clear coat, you obviously need to apply the clear coat last.

I suggest building a prototype on a piece of plywood and getting it optimized to your liking before drilling holes in your project box.

~Tom

[SGregory]

Shielding/Grounding Aside. Clearcoat/Laq should go on top your base coat (paint). They should be compatable however.
To get a smooth surface for your paint will depend on the type of wood. Use a sanding/sealer first which is compatable with your paint.

I usually use good ole shellac thinned to 1-2lb mix. Easy to apply, drys quick, and sands easy. Takes several coats to get surface to smooth but not too much time. Should test it first with your paint on a piece of scrap wood. I have used Krylon/ and True Value epoxy paint with this method and have had no problems,but check it first to avoid suprises.

Why not leave the wood grain visable and just poly it?

[tubelab.com]

If you are worried about shielding, you could use a metal box and cover it in wood (or put it inside the box you have). Just remember to ground the box at one point (safety/green wire ground and circuit ground meet here).

Most of my PC board based designs have not needed any shielding even in the presence of nearby AM radio stations. If shielding is needed, just get some copper screen at a craft store (I got mine at Michaels) and attach it to the inside of the wooden box with a staple gun. Ground as described above.

[dontellpapa]

Thanks for all your comments above.

Dontellpapa