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In Reply to: apparently not posted by Peter Gunn on November 10, 2004 at 05:58:58:
Wood floors will transmit vibrations, mostly from footfall, or vibes from speakers, now matter how well supported. When you place ANY TT on a floor based support you have to isolate the TT in some fashion. The walls of many houses sit on the perimeter foundation and are not directly connected to the wood floor. In these houses a wall mounted platform for the TT would be an excellent choice. Even should the walls be in contact with the floor the vibrations will be reduced by having to pass thru many different types of materiel with different vibrational modes. Of some interest to me, although I have never seen a study on it, is how much vibration passes thru the springs of a suspended TT which is not isolated in SOME manner. I think one of the reasons that John might like his TT set up without additional vibrational protection is that it needs to be able to bleed off internally created vibrations, but I would think that vibrations flow in both directions. Interestingly, I agree with him to the extent that I set my TT directly onto a hard surface to allow the TT vibes to excape, but I go one step further and I try to isolate this hard surface from incoming vibrations.Don't let John grind you down, you will note that all of his comments are negative, have very little to do with the pratical problems of TT design and use, and he offers no real world solutions. What I loved was his comment below in which he unabashedly, without any support, denegrated off the plinth motors as being the worst design possible - and at the same time he, because of some assumed engineering backgound, is an expert in the field of vibration transmission (and assummedly resonance control) which is the underlying principle for taking the motor off the plinth, i.e. to reduce vibration from the motor to the TT. Oh well......
Follow Ups:
> Even should the walls be in contact with the floor the vibrations
> will be reduced by having to pass thru many different types of
> materielA typical structural-borne vibration of 50Hz has a wavelength of about 130 feet; whether you place your turntable on the floor or the wall makes no difference to such a wave.
> Of some interest to me, although I have never seen a study on it,
> is how much vibration passes thru the springs of a suspended TT
> which is not isolated in SOME mannerIf it has a spring suspension then it is isolated. And the study you're looking for can be found in any undergraduate physics and engineering book.
> I think one of the reasons that John might like his TT set up
> without additional vibrational protection is that it needs to be
> able to bleed off internally created vibrationsWhat do you mean by "additional vibration protection"?
No, there are no internally created vibrations -- who would create these in the first place?
Lastly, there is no physical concept of "bleeding off" vibrations. As far as I can tell this term was coined within the hi-fi community by people who had no passing acquaintance with physics but wanted to give their product a sheen of scientific acceptability.
> What I loved was his comment below in which he unabashedly, without
> any support, denegrated off the plinth motors as being the worst
> design possibleNo, I was referring to the practice of using very low power motors to spin the platter, allegedly because low power motors would transmit fewer vibrations to the platter. There is essentially no scientific basis for this claim; motor vibrations are determined by the design and construction of the motor and have very little to do with its power output; in fact, the smoothest motor I have ever measured was a 10"-diameter, 50-pound jewel that required a controller bigger than my power amp. The only thing an underpowered motor can achieve is introduce speed variations, a condition that the original poster said was very sensitive to.
But this guy has chimed in on just about everyones post in this thread with no other purpose than to "correct" them about virtually everything.All the while not addressing even one of my original questions.
So I took it for what it was, but thanks.
I don't think one has to be a rocket scientist to see floors are horizontal and move in the verticle and walls are the opposite. But the real criteria is there is nothing exerting force on the wall, but people are walking on the floor. On top of that, the wall is probably load bearing in which case the weight of the entire house is damping it. Nothing is damping the floor, unless as I said it's a basement floor. I cannot see how anyone could question a wall mount not being an ideal setup unless the room has seriously faulty walls.
After that, the only vibrations reaching the table are coming from the music itself, and that is a constant regardless of where the tables is.
This reminds me of the argument about whether a dust cover should be left on or not. Some say it blocks airborn waves and should stay on and down, others say it's a reciever for waves which it transmits to the base and should be taken entirely off. mea culpa....
I think at this point I am going to do nothing. Sometime next year I will probably get a used VPI Scout, simply because they are common, well regarded and I can buy it reasonable enough. I'll pit it against my AR and see for myself.
Thanks for all your insights and kind words.
I would also like to chime in on this thread just briefly. One thing that I did while playing music on my stereo was to hold my hand against a wall and I felt a lot of vibration coming from the wall. I don’t know whether the wall was a load-bearing wall, but my house is sitting on a concrete slab so I would assume that every wall was pretty much a load-bearing wall, although I’m not an architect or civil engineer. I have my turntable on a sturdy hardwood stand spiked to the concrete slab underneath my carpet and it seems to be very stable relative to movement or vibration. I have never done a water-glass test, but I think it would pass. However, my walls definitely vibrate.
I stated the only exceptions are where a person has a poured concrete floor, as you do.I suspect your walls vibrate because the wallboard is very thin. This is an all too common problem in many homes made since the late 60's. That said, the wallboard is vibrating, the wall is not moving. Studded floors move up and down.
If you attached a plinth to the wall studs, and then attached a target wall mount to the plinth, I guarantee there would be no vibration getting to the table.
In any case, thanks for the input and kudos on the floor.
Out of curiosity, does the concrete effect the bass at all in the room? (pro or con)
> > > Out of curiosity, does the concrete effect the bass at all in the room? (pro or con)I guess I don’t know the answer to that question. I have powered subwoofers that handle the bottom octave from 30 to 60-Hz and I get what I believe to be very realistic bass on vinyl. I get some earth shaking bass on many DVD movies. However, I have no idea how the concrete floor affects the bass.
During the past ten years I’ve lived in three different houses with these same powered subwoofers. I have never had any complaints about bass, but the best house for stereo, in general, was the first of the three. It had ordinary carpeted wood floors that moved up and down quite significantly. Bass was rather exciting because you could feel your chair vibrating. The listening room in that house had other attributes that made it the most amazing listening experience that I have ever heard. I guess it was just the right size and shape to create the most holographic three-dimensional imaging that I have ever heard. Everyone who listened to my system in that house seemed to be quite amazed. I remember one person asked me where the speakers were because the sound never seemed to come directly from them. Of course, I had the speakers well out into the room with both subs in a rear corner. The ceiling was slanted such that it reached 16-feet at the rear wall. I really miss that house.
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