Foam Dampening of old keyboards?

[Jan Pospisil]

I've seen people stick foam under the PCBs of modern mechanical keyboards to dampen the sound.
Is this possible/safe on vintage boards?
I have an Ortek MCK-201FT and a Dell AT102W.
Obviously I can check if there's enough space myself, I'm just wondering if other people tried this, and what the results were.

[gianni]

Foam has a density that is too low to dampen the higher frequency sounds: to stop those you need a material with a high mass. Personally I've used foam and the difference was very noticeable, but it could have been bigger if I used different materials. You could also try some flexible panels that couple lead and foam, they're used in buildings.

Some have had with success with resins, which are flexible and thus easily removable.

https://www.reddit.com/r/MechanicalKeyb ... n_and_add/

[Findecanor]

I've seen bitumen sheets used to add heft and damping to keyboards. Those are used for sound-damping around the passenger compartment in automobiles, so you could find them in auto parts stores.
BTW. You'll probably need a car just to bring a pack home from the store also, because they are heavy and not necessarily sold in small packages. (This is the main reason I have not tried it myself.)

[gianni]

https://www.nuclead.com/soundproofing/

https://alphacoustic.com/en/product/sou ... eet-layer/

[ddrfraser1]

I use neoprene foam. It’s not as high tech as the above solutions but it does make some keyboards sound better and it is cheap and sold in small rolls.

[Coeus]

It is intersting that this should come up now. I think it has been believed that the purpose of the foam in the IBM Model F is to keep the key barrels securely in place because it was not possible to make the two metal plates and their locking tabs accuratly enough. But I have been directed form here to a YouTube video of someone using one with no foam at all and it seems to work fine.

So that does make sound deadening another possible reason to have the foam there.

Picking up on what gianni says about density, it surely depends on what frequencies you want to absorb. If you absorb the lower frequencies and not the higher ones then you will get a click without any thud, not that I have experimented with this personally.

So, gianni, is someone wanted to absorb a broad range of frequencies would a sandwich of materials of different densities be the answer?

[gianni]

So, gianni, is someone wanted to absorb a broad range of frequencies would a sandwich of materials of different densities be the answer?

Yes, that's why lead is usually sold coupled with foam. Anyway in a keyboard there aren't low frequency sounds that may be annoying. It's all about high frequency sounds. Anyway also foam alone can make a difference and make a case sound much less hollow.

[Jan Pospisil]

I bought two materials from a car shop - a thicker neoprene roll and a thinner fabric (?) like thing. Both seem to have peeling thingies, so I assume they're sticky on one side.
I'm mainly asking if it's ok to put something like this under the PCB, if that doesn't damage it, short it or be...ungood in another way.

[Wazrach]

It is intersting that this should come up now. I think it has been believed that the purpose of the foam in the IBM Model F is to keep the key barrels securely in place because it was not possible to make the two metal plates and their locking tabs accuratly enough. But I have been directed form here to a YouTube video of someone using one with no foam at all and it seems to work fine.

So that does make sound deadening another possible reason to have the foam there.

Picking up on what gianni says about density, it surely depends on what frequencies you want to absorb. If you absorb the lower frequencies and not the higher ones then you will get a click without any thud, not that I have experimented with this personally.

So, gianni, is someone wanted to absorb a broad range of frequencies would a sandwich of materials of different densities be the answer?

Some Models F stand the test of time very well, as some have tighter assemblies that give a crisp key feel even if the foam has completely disintegrated. Models F will work just fine without the foam, but will usually not feel and sound optimal. The material IBM used was always thin and extremely soft, so it's highly unlikely sound deadening was the intention.

[ddrfraser1]

This is what I did on a recent build, found some neoprene stick on strips, cut them to size and filled the space between the plate and PCB.

Then cut a roll to size and stuck it in the bottom.

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[gianni]

I bought two materials from a car shop - a thicker neoprene roll and a thinner fabric (?) like thing. Both seem to have peeling thingies, so I assume they're sticky on one side.
I'm mainly asking if it's ok to put something like this under the PCB, if that doesn't damage it, short it or be...ungood in another way.

Is a dielectric material? If it is an insulator it's ok. I have no idea how to test that. Maybe using a tester?

[Jan Pospisil]

I looked into the material - it's called Vibrofiltr Madeline, and is apparently polyester felt with an adhesive backing.
So that should be fine.

edit: Tried it, there's not enough space in the Ortek even for a thin foam slice. I also freaked out, because it looked like I bricked the keyboard somehow, it wouldn't work after I closed it up. Possibly I loosened a cable plug or something. Anyway, boo. Guess I'm stuck with the ping.

[gianni]

I looked into the material - it's called Vibrofiltr Madeline, and is apparently polyester felt with an adhesive backing.
So that should be fine.

edit: Tried it, there's not enough space in the Ortek even for a thin foam slice. I also freaked out, because it looked like I bricked the keyboard somehow, it wouldn't work after I closed it up. Possibly I loosened a cable plug or something. Anyway, boo. Guess I'm stuck with the ping.

Get some neoprene foam, it can be very compressible! I suggest you to buy it locally from some art or electronic shop to verify the compressibility.

[Jan Pospisil]

I did try the neoprene also, but it might be too thick. (6mm)

[gianni]

I did try the neoprene also, but it might be too thick. (6mm)

Yes, that's really too thick for any keyboard. I had in mind the usual thickness that we use for model f restorations, which is 2mm max.

[ddrfraser1]

When the neoprene is too thick I use drawer liner. It’s not a very high tech solution but it works for me.