Amp stands- Do they work?

I think that member Mikela doesn't understand what a blind test is. In this case you would have a friend set up the system in one of two configurations 1) with stands and 2) without stands. The person evaluating the sound is not told what configuration he is listening to. If he cannot determine when the stands are in place more than 50% of the time (the value he would get by guessing) then there is no evidence that he can hear the difference. For the test to be valid it should be repeated as many times as possible and all other system variables should be held constant.

Statistical significance is not determind if the person testing is able to tell the difference more than 50%. It has been a while since I took statistics but there are a number of variables involved including how many trials were involve. Sometimes it has to occur 90% or more of the time, depending upon the trials. I'm sure those that use statistical analysis can refresh our memory, or I could dust off my 20 year old stats book. Anyhow, I don't fully buy a/b or blind testing. What I do buy is my ear. I don't care what my neighbor hears. I don't have them eat a meal or taste a wine to validate or develop my opinion. I trust my senses. Therefore, If I hear a diffence, then there is a difference. Also, quick testing doesn't always reveil what is happening. That can take time. And, yes I know you can do statistical analysis over time. As to the advantages to a stand, or an isolation device, one item that has been over-looked is resonation. If the item you are using decreases the vibration of the product, both air born and direct, it can have an affect on the sound. Note, I said can. Ultimately, I believe each indivdual should make their own conclusion about the worth of any item. That being whether or not it makes a difference or if it is worth the difference. I use an amp stand. Does it make a difference? Some, but not as much as a change in componet, source, speaker or room treatment. By the way, I made my own for $12.00.

I find interesting the comments by those who "do not see how an amp stand can make a difference with a solid state amp". These comments rank alongside those from people that could not see how competent amplifiers could sound different, or how cables with suitable electrical qualities could sound different, or how CD players could sound different. Further, the suggestions to use a concrete block, or some other stone, do not seem to be backed up by any comparisons between this and using a welded steel rack. Having tried these myself, I say get a welded steel rack. Concrete blocks and stones all "ping" to some degree and you hear it. You may not pick it up in a double-blind test but it is mighty irritating over time. The suggestion above concerning using a Vibraplane is spot on. I have tried a lot of different approaches to vibration control with my amps (and with several different amps), and have settled on using a welded steel rack, a shelf made of thick perspex bonded to thin MDF, and then a bladder product between shelf and amp. The use of a bladder product with my amp has a larger impact than using a bladder product anywhere else in my system.

I was wondering if Redkiwi could elaborate on the air bladder shelf combo. I have heard that these can make an enourmous diffrence and being a skilled craftsman want to make my own, and would like to know what materials work best.

Yes.