Weights on a preamp

More than almost any other kind of electronic component, because they contain small signal tubes that are often microphonic, a tube linestage is prone to problems with vibration. It certainly does not hurt to try different forms of dampening. I personally like coupling the component to a good vibration dampening shelf, but, it makes sense to experiment with any and all of these choices.

Geeky overkill.

Thanks all. This afternoon I tried putting a 2.5 pound steel weight on the pre, and did not like the result. I definitely heard a difference, there was some more subtle focus. I have a theory why it didn't work: I live in a building with a lot of vibrations, shaking at times, due to proximity to the Brooklyn bridge (which is across the street). For this reason I have invested in a great stand and I put my amp on a 4'' maple block with isolation pads on the floor. This helps enormously, and I get great sound. When the building shakes I cannot hear any change, but maybe it makes a loose metal weight on the pre rattled or ring a bit. I don't know, its only a theory, but I took off the weight and it sounds like it used to. Better. Call me a geek, but I that's how it ended.

I neglected to mention what I heard that I didn't like: the tone became a bit thin and lost some warmth. I attribute this to the metal ringing atop the pre. I thought the weight in question was solid steel. It might be a cheap hollow filled composite. Either way, the sound I have come to love took a hit tone wise, despite a bit more focus to the soundstage. With things this subtle, I always question my own perception. But in the end, that's all we have to go on, and I like it better with the weight off.

Try sand bags, or as Elizabeth mentioned rubber. You can go to McMaster-Carr and order a sheet of 40 durometer rubber. Make a nice sized square or rectangle, then place it on the component. On top of the rubber you can place some additional weight like a piece or metal, stone, or wood. Take a look at the HRS isolation devices as they use similar techniques and charge quite a bit for their products. I used their damping plates for a while and liked them a lot, but they are DIYable.

I would attribute the sound you were hearing to be the result of metal to metal contact. Having an interface between the metal might help (you might get the same result with just a piece of granite on top of the component).