Been there,done that.
Sonically, the result is a huge open stage but dynamics and timing suffer greatly.If you can't hear or don't place a high value to PRaT, you might like it, tho.
pARTicular uses it in one of their designs.
With electro mechanical devices like turntables and transports, you are adding a secondary suspension system with results largely influenced by Chaos theory.
If you hang yourself upside down instead and leave the equipment in the rack you will find very significant sonic changes but it usually takes about five or six hours of being in that position. worth the effort.
I tried it and found some beneficial effects for resolution, but essentially whatever you use to suspend the rack ends up affecting the sound significantly - a bit like the twanging of a guitar string it depends on the stretchiness, rigidity and tension it is under as to the effect you get. By funneling resonances into one region you get significant smeering of that region. At a highish frequency you will get an irritating ringing effect, and at a lower frequency then PRAT suffers to some degree, in a very similar way as bladders cause the same effect.
What you need is a stable rack that is free from vibrations. Hanging from the ceiling has two potential problems. The first is the length that you are hanging which will determine a low frequency oscillation--generally outside the audible frequency range. However it can carry harmonics from other vibrations--which is one reason you are likely to find so much variation in people's opinions of this. For example if a particular transport has an internal oscillation at say 400Hz and this excites one of the potential harmonics of the hanging stand--it could (and probably would) make things worse. The second thing is what you are hanging it from. If the ceiling is a room above and the floor is concrete--well the floor is going to be more stable and have less vibrations. In any case, predictability is on attaching to something rigid and then working with isolation or vibration tweaks--like vibrapods and tiptoes. You could get better results with hanging--but it would take quite a bit of experimentation--and if you read the thread on why do systems sound better at some times than others--you might think this level of experimentation would be difficult to say the least.
So then, what is the best possible floor for a rack to sit on? Let's say we were designing from scratch. I've always found it hard to believe that a wood floor system with it's giant diaphram is good, and concrete retains too much energy. In the perfect world, what would your set-up look like from earth up and why?
I have considered this, although it would be a huge commitment. Beyond traditional pier and beam construction, each piece of sensitive equipment would get it's own individual concrete pedestal, going deep into the earth, below the house. The rest of the living/listening area would be constructed in the normal fashion. Finishing out the pedestals and the living area floor to the same height would be tricky. Then a seal between the two individual surfaces would be needed to fill the void . With the equipment on their own individual solid concrete blocks, the entire house would be de coupled from the equipment. I know one high end manufacturer that uses this design in his home. Unfortunately I have not had the pleasure to visit and view the project myself.
Jadem6 asks a very good question. I'll give you what I've done--is it the best--no. I have a concrete slab with standard 2x4 framing. The audioroom floor is a floating (pergo) floor with an oriental rug covering 3/4 of it. All audio racks are build outward from the framing. The turntable "floats" on oak cantilevers with 150 lb granite slab on the oak. All components are in the adjacent room with the cabinet cantilevered from the wall joists. The shelving is corrian--I've found it has very little resonance (be careful here--other solid surface material does have very bad resonant signatures). There is certainly better shelving material--and I've started to experiment with a few things.
What would be better? Well a dedicated concrete slab that was separate from the audio room floor. Some people have used dedicated slabs for the speakers as well. This almost insures decoupling of the speaker vibration to the room (as well as equipment). Obviously, it's pretty impracticle--but if you were building a house and cost no object audio room--that would probably be the way to go.
This is too funny--I was writing my post while at the same time Albert posted his--when I submitted it--that's when his appeared. I like your ideas Albert--wish I had hit submit just a little faster.
I am not sure you guys are on the right path. If you sink concrete into the ground you are ensuring you get vibrations from one of the most likely sources, the planet we live on - it rumbles and grunts all the time, and transmits energy from passing vehicles. I still reckon that whatever you do you need to use a very light and rigid structure as the last step between your equipment and any supporting structure, with sharp point interfaces. I will not go further because I have already stated these opinions elsewhere and at length. If you will pardon me for a moment and hopefully accept I am not wishing to criticise, my general observation and generalisation is that Americans tend to veer towards over-building things and appear to inherently believe in using significant mass in anything they build. I could point to many American products as examples, and to the difference between reviews on either side of the Atlantic of such things as remote controls, where Americans want a remote machined from a solid piece of aluminium, and others want one that is light and easy to hold. I have often pondered that this seems to lead American audiophiles in the wrong direction a lot of the time when it comes to equipment support. Sorry for the gross generalisation - I happen to like your 60lb CD players with their half inch thick aluminium face plates.
That was exactly what I was wondering, would the school of light vs solid mass come to oppose each other. It seems to me idea one, solid mass would be very easy to achieve if your on the bottom floor with slab on grade or crawl space. I could see simply cutting out a portion of the floor, digging down a few feet and pouring concrete. I think this could be achieved in a very affordable fashion. This construction method of isolating a portion of a floor is used quite often in manufacturing. I would "being American and all" tend to see this as the proper direction, after all, everything eventually ends up sitting on the earth. The next step in this direction would be to incorporate the spring and isolation techniques used in earthquake design. In our case the spring size would be less than for a building. I would assume we could find someone who could determine the design of a spring isolation platform if anyone wanted to experiment.
I am however quite intrigued by Redkiwi line of thinking. What is the easiest way to create an extremely lightweight completely isolated system that has the most separation from the earth. Again, assuming a rack system is well spiked, what is the ultimate bearing to retain the benefits of the light weight system? Or is it adequate to simply have a rack sit anywhere as long as it's spiked? It seems to me that this is not the answer, so I'd love to hear ideas on this aproach.
Hi JD. I was being a bit provocative, albeit trying not to criticise "being American and all", by pointing out that I think "you all" (if I can use that term mate?) have a tad too much faith in throwing mass at an engineering problem. I do believe that light and rigid gets out of the way of the music better. I don't like much British equipment but their light and rigid approach seems to work. But I don't believe a floppy floor under the rack is good either. I really don't know the best way to bolster the floor as it is difficult to experiment. But I recall Caterham1700 (who knows much more about this than me) stating in another post that the biggest source of vibration energy muddying up the sound of our systems was in the ground under our houses. So direct coupling our gear to the ground does not sound right to me. If I am honest, I too have felt that a massive support must surely be less subject to vibration than something very light. But if you ponder on the physics theory you realise that the more massy support vibrates with the same energy as the light support, but holds on to that energy longer. There are times when I have been fooled into thinking a massy support sounds better, only to realise later that the music was robbed of energy and that there was smeering at low frequencies (which some like since it adds bass weight). The execution of light and rigid is also not easy - the principle problem being getting a shelf that is light and rigid, but also appropriately damped.
O.K. Red, I'm following so far. The shelf of course we've discussed at length and I believe as you do that the Nueance is as good a solution as we've found so far. If we're acceptant of that statement, then the next issue is the interface between the shelf and the support. Again I feel very confident that you have provide some excellent recommendations on that topic. The next issue is the rack or base for the shelf. I'm personally at the point of wanting to investigate racks, construction methods, and design philosophy. I have gotten some good input from Caterham 1700 off site and hope some of the products he's trying work out. In the mean time I was thinking of trying some D.I.Y. systems just to get more in tune with the issues. The first question that comes to mind for me is material. I wonder if steal is the best material to use or is it just used because that's what was used in the past? Is brass, aluminum, graphite, or whatever a better choice? I realize the difficulties of working with aluminum or graphite vs the ease of steal, but have the other options been explored? I was also wondering if welded is the best solution vs, bolting with isolation between each member. Any thought on these ideas?
I use a Billy Bags Tripod rack filled with sand. I then suspend my Dac from the rack with mon filiment fishline. I use a medium weigth spring between the fishline and the Dac to help absorb any low frequency transmission. I decouple the fsihline from the rack with a small swatch of EAR Iso-Damp. This very effectively isolates the Dac from the room/rack enviornment. Lastly I place a reasonable amount of the brown EAR damping sheets on all chassis serfuces of the Dac (I know, it looks lousy) to dampen any airborne feedback back into the Dac it self. This has produced very satifying sonics. My transport is isolated with a Nimbus air bearing platform whihc I would recommend over just about anything out there. It is exceptional and you can tune the platforms resonance almost infinitley. Good luck.
I love your post 90493m, I've copied it to my hard drive for future reference. You have some very creative approaches to isolation and I may need to play with some of them this year. Thanks for the thoughts, J.D.
Sorry JD, been away on the boat again, and just saw your post. I like 3mm thick bright steel in an L-section and welded not bolted, from the playing around that I have done. I have tried aluminium and quite like it as a support for certain types of speakers - such as those British speakers that use Birch ply rather than MDF. But I was not so keen on it as an equipment rack. I have not tried either of graphite or brass, but would be doubtful of brass. Personally, I have stopped experimenting with supports because my only objective was to get something that worked very well, and that was not letting the rest of the system down - and I believe I have achieved that.