mikepukmel 8/4/2018 4:17 PM
where to buy thin cardboard with aluminum backing to shield open side of chassis.
Hi All, anyone know where I can buy a sheet of cardboard with aluminum cladding that they use in amps to shield the open side of the chassis? If I cant find that, I was thinking about going with a thin thin piece of sheet aluminum or brass, although both I think have a reaction with the steel used in Fender type amps.
Thanks
MP
 
Tom Phillips 8/4/2018 5:43 PM
I say that there is no need for the cardboard layer. For home builds, or when a customer is not concerned about period correct looking stuff, I just contact glue heavy duty aluminum foil to the wood cabinet where the open chassis rests. If done well it is unseen and very low profile with little chance of catching on the chassis and being torn up during service work. By the way, the BF Fender amps utilized a stapled in place piece of steel window screen. I once saw a really goofy mistake by wanna be cloner who used black nylon window screen.
 
mikepukmel 8/4/2018 5:56 PM
Thanks Tom. I have some fairly thick aluminum tape, pretty good quality used for heating and air conditioning. Also have some leftover aluminum windows screening. Easier to put the tape on. Thanks for the info!
 
mikepukmel 8/4/2018 5:57 PM
Oh man, black nylon window screen. Heh. I bet you got a nice laugh out of that.
 
Tom Phillips 8/4/2018 5:59 PM
Best to use one continuous piece of whatever material you end up selecting.
1) Guaranteed to be continuous electrical connection
2) Minimizes edges that could catch on the chassis
My 2 cents anyway.
Tom
 
J M Fahey 8/4/2018 6:22 PM
Quote Originally Posted by Tom Phillips View Post
I say that there is no need for the cardboard layer. For home builds, or when a customer is not concerned about period correct looking stuff, I just contact glue heavy duty aluminum foil to the wood cabinet where the open chassis rests. If done well it is unseen and very low profile with little chance of catching on the chassis and being torn up during service work. By the way, the BF Fender amps utilized a stapled in place piece of steel window screen. I once saw a really goofy mistake by wanna be cloner who used black nylon window screen.
Hey I bet no flies or mosquitoes flew through that one either, so what´s exactly your point?

As of cardboard backed aluminum, I use a lot of it, and make it myself, just contact cement kitchen type aluminum foil to business card thickness cardboard.
Overlapping aluminum glued together keeps good electrical contact, although contact rubber cement is an insulator, while relatively fresh (say, 15 minutes) it still allows aluminum wrinkles through so they touch the mating surface.

It may be glued-stapled to cabinet wood but being somewhat rigid I also build separations between preamp and power amp, small Faraday cages around input jacks, etc.
 
mikepukmel 8/4/2018 7:18 PM
Quote Originally Posted by J M Fahey View Post
Hey I bet no flies or mosquitoes flew through that one either, so what´s exactly your point?

As of cardboard backed aluminum, I use a lot of it, and make it myself, just contact cement kitchen type aluminum foil to business card thickness cardboard.
Overlapping aluminum glued together keeps good electrical contact, although contact rubber cement is an insulator, while relatively fresh (say, 15 minutes) it still allows aluminum wrinkles through so they touch the mating surface.

It may be glued-stapled to cabinet wood but being somewhat rigid I also build separations between preamp and power amp, small Faraday cages around input jacks, etc.
Thanks Juan, What do you separate your power supply sections with, and also what do you build your faraday cages with, if you don't mind me asking.
 
J M Fahey 8/4/2018 10:47 PM
Just what I said: aluminum covered (on one side only) with kitchen aluminum foil.

Way simpler than you think, I just cut needed separation walls out of it, leaving an 8 to 10mm flap which I can glue to chassis where needed, I can bend it to cover what I want to shield if I want, it´s automatically grounded when glued, for future amp servicing it can be bent out of the way or simply torn off and replaced later, cheap as dirt.

Today I am finishing a couple combos, a Guitar one and a Bass one, will post some preamp shield picture.

Adding separations in commercial amps is easy/cheap, they resistance solder them,
[img]https://classictubeaudio.com/wp-content//Sansui-1000a-upper-chassis.jpg[/img]

but on homemade stuff unless having an industrial resistance solder machine under your bed
[IMG]http://2.bp.blogspot.com/-iEe1Dana6oU/UPeJFAnYOMI/AAAAAAAABhE/iJmBPqHavkM/s1600/01-resistance-welding-machine-what-is-resistive-welding1-764707.jpg[/IMG]
you´ll have to add some kind of unsightly holes, either for riveting or plain bolting ... but since cardboard is so light, gluing becomes an option.