I have an Art Audio VPL MK2 preamp. I think, if I remember correctly, that Joe Fratus of Art Audio mentioned that some people place a weight on the top of the unit, which I assume is to dampen vibratory activity with weight pressure and its gravity. I have heard of this with speakers, but preamps? Is this geeky overkill, or does it really work? What are the opinions on this weighty matter ?
In some cases it can work depending on the gear involved, the type of stand used, or other factors. I used to place a VPI brick on top of my Spendor 1/2e speakers and they helped stabilize the speaker/stand interface. However, I find that I don't need to use any weight on my Audio Kinesis Stormbringer speakers.
I also used the bricks on my amp to some good effect, but it was a marginal difference compared with the speakers. Only way to know for sure is to try it out. Of course your selection of weight materials will also have an effect. Lead sacks seem to work well. Fine sand placed in plastic zip lock backs also are a good starting point and cheap to use for a test. Good luck and let us know what you find out.
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.
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).
I find this helps with my tube pre. I use a pair of two pound coated scuba weight belt weights. The coating is dead so there is no ringing and the weights (as far as audiophile prices!) are cheap.
I think you are all correct; metal to metal ringing was messing it up. I am going to figure out some rubber interface between the weight and the preamp.
I am curious if anyone has any thoughts on the shaking of my building (from surrounding traffic and such). Don't try to figure out 'why' it is happening. The question is how to treat my system so that excess vibrations can be dealt with. I have found that the very fine micro vibrations probably harm sound more than out and out floor shaking. After all, the vibrations from fairly loud music are way more profound than the shaking of my building.
I've been considering trying this "tweak" and am wondering if anyone has used a hockey puck on top of their equipment and what was the effect to the sound. If I can locate a hockey puck in my basement I might try it.
If it is safe and practical to do so you may want to try removing the cover from the preamp. I have found my preamp sounds EVEN better with the cover off. YMMV
This is all a matter of system tuning. Your finding that the sound became thin and lacked warmth is consistent with what dampening will do. If your system was overly warm, the dampening would have been positive, but, that clearly was not the case. That is why one can only tell by experimenting -- no tweak will consistently improve sound.
I have had the same experience as you reported when using vibration dampening devices on some cd players. With a lot of players, a lot of dampening is NOT a good thing.
Consider that to earthquake proof buildings the foundations are built on rollers. Symposium roller blocks, aurios, or FIM isolators perform a similar function for audio gear.
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