noise thru tube pre??

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.

C123666
>"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"
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I still have a Sonic Frontiers Preamp same as Chadnliz has now. The board the tube socket is mounted to is isolated very well. The build quality is very good.

As far as the preamp I am using now, Sonic Frontiers Line one, I can turn the gain control up quite high and tap on the preamp case with no microphonics what so ever from the tapping heard through the speakers.

Chadnliz. Your preamp sounds great with the Mullard tube I mentioned in one of your other threads. Nice warm tubey sound....

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Jim

As pointed out, your tube is not microphonic just because you hear something when you tap on the case. If it just rings on its own or it continues to ring after you tap then it is microphonic.

Those who think tube gear is always noisy are sadly misinformed. I have an all tube system with 103dB efficient speakers. You can put your ear up to the speakers and hear very little. All components produce a certain amount of noise, even passive components such as resistors. If the equipment is properly designed then it will not be audible once you back away from the speaker a bit.