noise thru tube pre??

This was noticed after I rolled the stock Sylvania, with a NOS phillips tube, I dont know if it was doing it before, its not like I walk around tapping equipment (I like to tap my feet though), anyway maybe I need to re-install first tube, as of now I have no tube damper....thanks guys

YOu may not even have a microphonic tube. If you tap a tube directly, you will most likely hear a slight noise from your speakers. When tapping your chassis, depending on the tubes' isolation, you are most likely just transferring the tap to the tube. I'd be alot more worried if I were hearing noises WITHOUT things being tapped!

When I tap the chassis of my preamp it goes, "poommmmmmmmmmm".

This also shows the importance of a chassis designed to absorb resonances and not pass them to the tubes. Most units use folded sheet metal which is inadequate. Very few preamp manufacturers, except for the Very Expensive ones, use correct chassis.

Same with amplifiers. The cost of a truly high quality all aluminim chassis is quite high unless produced in truckload quantities. Even then it is much more expensive than the standard wood with aluminum top plate or folded stainless steel over cheap metal frames.

Chadnliz - this is fairly normal for a preamp. especially those with high gain. to some degree tubes are microphonic by the nature of their design. just like ice is cold by its nature. it shouldn't be a problem unless the music from your speakers creates a feedback loop through the preamp. otherwise just don't tap on the chassis while you are listening to tunes.

hal-O tube dampers may produce positive results in your system and they are inexpensive too. peronally i prefer a hint of microphonics since it adds to the airiness of the music.