Oil Damping audio tubes
This will be the most exotic of tube dampers and also one that is effective and musical, And best of all it is almost free. The immediate effect of oil damping is a darker background in the soundstage. Better inner details and tighter bass without drying out the decay.
Hardware required is minimal. Besides the tube you want to damp, you just need an O ring ( use the thicker variety), a plastic bottle and oil.
I used a discarded plastic bottle. Cut a hole in the bottom. The O ring
should be slightly smaller than the tube, so that some force is required to push
the tube through. Have the O ring near the bottom of the tube to maximize the
surface area in contact with the oil.
The neck of the bottle should also be slightly smaller than the O ring which is now around the tube. Push the tube in as far as possible into the neck of the bottle.
The tube is now ready to be plugged into your preamp or amp. Took me about 5 minutes to do this.
Of course the preamp or amp should be off before plugging in the tube. Pour in
the oil through the hole in the bottom of the bottle which is now on top. I use
olive oil, primarily because it is a non toxic, natural oil. This is so that
even if the worse happens and the oil leaks, and I get it on my hands, I can
massaged it into my skin for a healthier looking skin.
I have used these for about 3 months now with 12AX7 tubes in a Zenn phono amplifier without any leakage. This method of damping is especially effective with a phono amplifier because it is handling very small signal. Thus any microphonics or environmental noise will seriously affect the performance of the phono amplifier. Another benefit of this simple mod is it will allow you to play your audio system to a much louder level than before.
Last point to note is that oil is non conductive, thus on the chance that there is a leak into your equipment, it will not cause a short circuit and damage it. Just messy to clean up. However I will not be held liable if damage do occur due to a reader following the instructions here.
If you use this mod, it will be great if you can give me some feedback on it. Email zenn@pacific.net.sg.