Funny noise - and finding it

[steveneddy]

So still mucking around in what turned out to be a poor build from last year.

Bassman style circuit - nothing fancy.

BUT - I was wanting to make it more sturdy for daily use by a musician who plays a lot.

So I put silicone all over the caps on the power amp side - and even did some resistors on the preamp side of things.

What I found out is that when things inside of the amp get hot and static prone - the silicone holding everything from excessive vibration caused loud noises like turning a pot with DC on it.

I simply replaced all of the resistors and the 250 pF in the tone stack that had clear silicone on them and the noise went away.

I realize that it could have been a bad resistor also - but when the amp was nice and warm and you touched some of the components with a chopstick the noise returned.

Another lesson learned.

BTW - using turret boards and flying most of the components.

[billyz]

Silicon is not the right product to use inside an amplifier. It off gases corrosive fumes which will corrode your electronics etc. there are some high temp versions that are safe but not the standard clear stuff. If it
Smells like Vinegar , don't use it.

[steveneddy]

Silicon is not the right product to use inside an amplifier. It off gases corrosive fumes which will corrode your electronics etc. there are some high temp versions that are safe but not the standard clear stuff. If it
Smells like Vinegar , don't use it.

I did not know that.

Is there a product I can purchase that I can use to sturdy up the electronic components in my tube amps besides silicone?

You stated the hi-temp versions of this stuff would work well.

Is there an electronics supplier that sells a similar product for this purpose?

[ToneMerc]

Silicon is not the right product to use inside an amplifier. It off gases corrosive fumes which will corrode your electronics etc. there are some high temp versions that are safe but not the standard clear stuff. If it
Smells like Vinegar , don't use it.

I did not know that.

Is there a product I can purchase that I can use to sturdy up the electronic components in my tube amps besides silicone?

You stated the hi-temp versions of this stuff would work well.

Is there an electronics supplier that sells a similar product for this purpose?

There's hundreds of thousands of amplfiers with not one bead of silicone in them that hold up fine for daily use. If you have to widespread plaster and coat components with silcone for additional mechanical holding strength, perhaps you should modify your construction or build technique.

If you feel the need to use silicone, there's any number of electrical grade RTV or non-corrosive gasket sealant products on the market.

TM

[Stevem]

I have used the black automotive silicone by Permatex ( its not cheap!) for 25 years and have never had a issue, and did checks to confirm no interaction from its use!
The clear stuff must make for stray capacatence to take place, if you have a cap checking meter you can probibly pin that guess of mine down.

[ToneMerc]

I have used the black automotive silicone by Permatex ( its not cheap!) for 25 years and have never had a issue, and did checks to confirm no interaction from its use!
The clear stuff must make for stray capacatence to take place, if you have a cap checking meter you can probibly pin that guess of mine down.

I ocassionally have used a small bead of either black or blue Permatex or blue Hylomar under way old NOS orange drops that are slightly microphonic to dampen them. The blue or black Permatex is what Alexander used to hide his work from us "bottleggers".

TM

[billyz]

Permatex works and the others too. Mostly , I use hot melt glue. Fast and easy to undo holds really well.

[Stevem]

A hot glue gun is just one more thing for me to burn myself with! LOL.

[Merlinb]

So I put silicone all over the caps on the power amp side - and even did some resistors on the preamp side of things.

Did the silicone touch the leads? I'm guessing it is partly conductive.

[tubeswell]

I never use any kind of goop. Its possible to build an amp without the need to.

You can use cable ties to secure big caps (as well as clusters of cables) if necessary.

For smaller components you can angle the leads so the body of the resistor/cap etc is not touching a hard surface.