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Hi all.I'm thinking of a rack where each piece of equipment sits on a platform (say 19x19x1"), which then sits on a rollerball mechanism (or similar, constrained & secured by recessing it), which in turn sits on a shelf that is integral to the frame of the rack (ie non-adjustable, fused/glued/morticed into the overall frame).
My question relates to this shelf that each system of equip/platform/rollerball sits on:
I've read many saying that Baltic Birch ply (B/BB grade) is better for this application than is solid aged air/kiln dried wood. My furniture guy says that he'd rather use 2" thick solid walnut (or similar) for the shelf, as he isn't a big fan of veneering. The oustide cabinet will have to be constructed in the same manner as this shelf and he worries a little about the edge durability (he's very experienced, so I do take his advice very seriously).
He can then use Baltic Birch ply for the platform that is sandwiched b/n the equipment and the rollerball and veneer this to match the shelf. So the portion closest to the equipment is 1.5" baltic birch ply (2 bonded 3/4" sheets of 15 layer ply).
What are your thoughts? Cost should be the same, so that's not the issue. Given the flexibility would you make the shelves of baltic birch too (and then veneer) from an acoustic perspective, despite the fact that isolation is already built into the system?
Many thanks for any thoughts, experiences, references or advice. Still working through the build versus buy analysis. I've read it over a few times, but do let me know if this is unclear and I'll clarify as best I can.
Cheers
PS The entire unit will then sit on specialized feet (either air-bearing/hydraulic feet), or something like the Finite Elemente Cerabases.
Edits: 08/26/07Follow Ups:
With the help of a violin maker for the choice of wood, I made simple but effective shelves.
Each shelf has an aspect ratio according to the golden ratio (roughly speaking, if the shorter side is of length x, then the longer side is of length x * 1.6).
Each shelf is made up of two layers: the top layer is 2cm-thick tilia (lime tree basswood) and the bottom layer is 2cm-thick rigid polyurethane with paper surface (it's quite standard for preparing thermal insulation panels in the construction sector). The two layers are not glued or varnished, just the weight of the hi-end gear keep them together.
They are not expensive, just give a try and see if you like them.
Cheers
Roberto
I'd go with the solid walnut. Walnut is a GREAT sounding wood for platforms. I have tried a few and the walnut platform I have is the best so far. Also I think it's truly beautiful.
I don't know how it sounds, but walnut is a beautiful wood.
They reflect sound even if they are internally damped.
An alternative is to make beams that are just large enough to carry the roller-ball supports. Make the beams so the beams and roller-balls can be moved to fit the component. Place the component directly upon the roller-balls unless the component's bottom panel vibration requires a rigid plinth. In this case, make the plinth out of end-grain hardwood butcher block and place a sheet of Deflex rubber between the component and the plinth. Cement stainless steel sheets on the plinth bottom where it will ride on the roller-balls.
:)
Thanks Al. Unfortunately, shelves are required for other reasons. If shelves were mandatory - what would you suggest?I've learned that sandwiching between solid wood doesn't work (expansion/contraction issues). Would you sandwich a different material b/n two pieces of Baltic Birch? What would you use?
I can try and mix materials to make it the best it can be, under the constraints I have (ie has to have a shelf, look like furniture etc.).
Or, I can either go solid wood (2" thick, 1" carved out that holds the roller-balls, on which sits the platform, on which sits the piece of equipment).
Thanks
As someone who has gone shelfless for several years, made a number of constrained layer shelves of various constructions and played with them and a variety of footers, and finally gone the commercial route and bought a Grand Prix Audio Monaco 2 shelf unit with their composite shelves, I think I can make a few comments.Going shelfless does simplifiy a lot of things and can work extremely well, but you end up with the problem of what you put between the component and your support bars. I discovered that you can experiment endlessly there and spend a lot of money into the bargain.
If you have to have shelves and you're going to go DIY, my preference would probably be for one of 2 things. My first option would be a constrained layer construction with either ply or mdy outer layers and an inner layer of GatorBoard. It will support a lot of mass, it's relatively neutral, and it's reasonably effective. You can play around with a variety of footers between the component and the shelf and get some variations on the sound and effectiveness but just on its own such a construction will work well and give good results. If you want to go cheaper and not quite as effective, you can replace the GatorBoard with polystyrene but be carefull with your glues because some glues will dissolve polystyrene. White PVA woodworking glue works well and can be used without detriment to the polystyrene. If you need to dress such a construction up for appearances sake, you can make the top board slightly larger than the bottom board and GatorBoard, veneer the top and add veneer strips around the side that descent level with the bottom of the construction but don't contact the sides of the bottom 2 layers.
You can use other constructions and acrylic makes good outer layers but is expensive. My best results for an inner layer have been GatorBoard with dense polystyrene coming second.
One thing to remember about constrained layer constructions is that you don't want contact between layers anywhere but at the glue intersection between one layer and the next. Don't bolt through one, or use decorative sides that contact more than one layer.
There are now some vibration absorbing glues around that could be worth trying. They weren't available when I was experimenting with these shelves but if I were playing with them these days, I'd definitely give those glues a try.
My second option is, strangely, a shelf of balsa wood. I've only experimented briefly with this and it does seem effective. The wood is soft and probably won't support much mass unless you laminate it in several layers and you're probably going to have to do some lamination anyway because of the sizes you buy it in. You're probably going to need to consider shelves about 3/4 of an inch thick for strength, and you aren't going to be able to use cones between it and the component unless you use them point up because point down they'll simply sink into the balsa and damage it.
Regardless of which of the above options you try—if you try one—you don't want to fix it firmly to the rack frame. You need to support it on the frame somehow, whether you use cones, ball bearings, some of the footers from Herbie's Audio Lab, or whatever.
I'd strongly prefer either of the above options over solid timber but that's my personal taste and others have strong tastes for solid timber.
If you have the time and money to play a little first, I'd assemble a constrained layer shelf, perhaps a balsa shelf, and a solid timber one and try some A/B comparisons to see just what the effects of each were in my system and how they matched up to my tastes.
David Aiken
I gave up when I realized I could float my components directly upon roller-balls.
Don't mean to hijack this thread but IME, the rack/shelves have just as much influence on sound as does the component itself due to the ability and/or inability of the shelf/rack to dissipate the sound impinged upon it which can be directly correlated to the manner of the component coupling to the shelf/rack.
One way to deal with this energy transfer is to apply an energy/vibration transducer to the shelf/racks and to isolate the component from the shelf/rack via means ranging from air to lead to brass combined with lead to all manner of roller balls/cups.
The main goal here is to mitigate the vibrations of the shelf/rack before they can transfer said energy to the component(s) and the addition of vibration transducers can have a tremendous effect. In other words, float your components via air and then apply vibration transducers to the shelves on which the air isolated components rest.
Let me know if U want to know more as I have spent the last couple years exploring just how component isolation from the listening environment effects component performance and have some very interesting results.
Cheers,
~kenster
kenster,
Can't send you a PM. If you wish, please send me a note and I'll shoot you a powerpoint of my plan (very simple), but will better articulate what I'm doing. I'd certainly appreciate any wisdom you may have for me.
I'm not floating the components themselves on air, but am floating the components with a small wood platform under them... but I'd be curious to understand better what form of application of vibration transducer to the shelf on which the air-isolated components rest you'd suggest.
Again, many thanks and I'd be very happy to share some plans with you for feedback.
All the best
Contact me at: ashbybadbowtie at aol dot com.
Cheers
kenster,
Thanks - yes, I think I'm trying to accomplish what you are outlining. I'll send you a PM. Thanks
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