noise thru tube pre??

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.

Newbee, tubes with some microphonics (if not ridiculous) can add a sense of realism to the soundstage. They can add a slight hall or venue presence that has nothing to do with "glare, grit, grain, etc." Unless the tube is overly microphonic some of the best sounding tubes I have ever had in my system have been slightly microphonic. And speaking of "distortion", that's inherent with tubes and is the very reason many of us prefer the sound of tubes to SS to begin with :)

Fiddler, I think there is a difference between 2nd order distortion and a 'ringing' caused by tube microphonics overlaying the music.

That in minor amounts folks can enjoy an artificial reverb like distortion caused by this ringing I wouldn't deny. Studios regularily add re-verb to the mix to enhance a recording, especially dry studio recordings.

But, folks should know there is a difference and by having microphonic tubes you are allowing a distortion to exist which you have no control over. While some recordings might well sound better, and some systems might well sound better, the obverse is also true. And, if you are playing music or components that have considerable energy in the highs already, you might well find that the minor amount of microphonics added to the mix was enuf to make the sound unpleasant, but if you didn't know why you would blame the recording or your system.

Personally, I avoid microphonic tubes as I want the signal to hit the amp as clean as possible. I've always steered clear of any 'signal enhancers' because over the long haul I've always ended up taking them out of the system even though initially their effect was attractive. Thats strictly my choice. Others can tune their system as they wish.