Flexy Table +
The Ultimate Hifi Equipment Rack
Introduction
After spending all my time on loudspeakers it was time for something completely different. My attention has been going towards building even better loudspeakers but of course there is more to a hi-fi system than those good old boxes. Until now my hi-fi equipment has been stacked on top of each other in two neat piles of each three components. On top of one stack stood the turntable, on top of the other stood the TG84 tube-amp. Not very audiophile!
I wanted to make an extremely rigid and solid platform to stand the equipment on, something that would also give me a neutral base to experiment on later with isolation platforms, blocks, etc. Even more importantly, I wanted the ability to make adjustments any time in the future should I acquire new or different-shaped equipment or just feel the need for a change, and being one of those Audio-Nuts this is a serious issue. Most of the pre-built equipment racks have all the shelf heights either predetermined or fixed. I also wanted to have enough extra space to be able to expand my system in the future. At this moment I need space for six components but for example I may change my integrated amp for a separate pre-amp and power-amp. I decided to make space for eight standard size components with enough height to be able to add isolation platforms under the components and some sort of weight on top.
On the Internet there are many designs to be found on this topic. One of my favourites is the TNT-Audio Flexy Table. What I like about this design is that it is beautiful because of its simplicity (I like things that are good and simple). It is also easy to make and very flexible to use (as it’s name states). The original design does lack one thing and that is mass. Taking the original Flexy Table as a starting point I decided to go a step further and build something a little more sturdy, you will read more about the total weight of my rack further on in this article. So I called it the Flexy Table + (the “+” stands for the extra mass).
A double-width rack based on the original
TNT Flexy Table design.
A
detail of my four shelved double width Flexy Table Plus. Note the counter-sunk
top washer and nut.
The construction
This rack consists of in total four double-width shelves of 1100x450mm. Each shelf is built up from three layers of 18mm mdf making the total thickness of each shelf 54mm.
The middle layer has two sections cut out which will be filled with fine dry sand. This filling procedure is a tedious job that will take a couple of hours to do properly.
The important thing is to make sure there will be no cavities in the sand later on. Therefore the sand must be compacted extremely well. I can’t stress this enough, the idea being that the top and bottom of the three mdf layers must at all times make contact with the sand inside so that vibrations are absorbed in the sand. I found the best way to fill the shelves is to drop them on their edges on the floor and then top them up again with more sand. Keep repeating this until the sand stops disappearing out of sight. It is a bit noisy and if you have downstairs neighbours you must do it when they are not at home but I found that you can get much more sand into the shelves this way than by just tapping them with a rubber hammer or something.
Filling
the shelves with sand.
To make each shelf look less massive I used a router to angle all the edges of each piece of mdf. When you glue the three pieces together you end-up with two V-shaped grooves down each side of each shelf.
If you want to build a single-width version you can build it based on the same principles but with just one middle cutout section.
The materials. The cutouts and angles have been made in the mdf sheets.
Six 890mm long M24 all-thread metal rods support the shelves. An all-thread is a long piece of round metal with a continuous thread running its entire length. They are available in standard lengths of 1000mm and 2000mm, I shortened them to 890mm to suite the proportions of the final rack (the designer eye also needs to be satisfied). The use of this continuously threaded rod makes it very easy to adjust shelf placement any way you want.
Each shelf is clamped between two M24 nuts with corresponding size washers per threaded rod making a total amount of 48 washers and 48 nuts. The standard amount available is a box of 50 pieces so this came out just right.
At the bottom of each all-thread there is a M24 capped-nut (a nut with one end closed by a round shaped cap). These give the possibility of height and level adjustment so that the Flexy Table + can be set perfectly level. The rack will also have minimal contact with the floor as it is resting on six little metal ball-shaped “spikes”.
Detail drawing of the bottom shelf with the angled edges and the adjustable capped-nut “spike”.
The mass
By now (and from reading my other articles) you have probably guessed that I like heavy constructions. There is nothing like a good sturdy and heavy construction, if it is a loudspeaker cabinet or an equipment rack. The principle is the same in both cases: I wanted something that couldn’t be brought to vibrate too easily. Each double-width sand-filled shelf weighs 22kg, the M24 washers, nuts and capped-nuts weigh 7kg and six M24 all-threads weigh 15kg. This brings the total weight of my equipment rack to 110kg. That shouldn’t move about too much!
The “sound”
Can something as basic as an equipment rack change the sound of your system? I was always a bit sceptic about this but now I know the answer is yes!
The most obvious result is more clarity in the midrange; it has become more transparent and open. The changes aren’t huge but easily audible.
To take things one-step further I immediately got out one of my other little tweaks: a piece of felt and a slab of granit of about 200x200x30mm. A piece of granit like this can be got cheaply from your local stone merchant as a left-over. Even cheaper would be a piece of concrete but that doesn’t look as cool.
Placed on top of my CD-player (first the felt and then the stone) it enforced the open sound of the rack even further. Especially the mid-bass range sounds more articulated.
A surprising bonus happened with my tuner. It gained 4dB’s in signal strength, the digital display always used to show about 59dB’s signal strength. Since it has been in my Flexy Table + the display shows 63dB’s, sometimes even 65dB’s. I guess this is a result of the components not being stacked directly on top of each other and therefore the magnetic fields from the power supply transformers, etc of each component do not influence each other as much.
The price-tag
I have split up all the costs so if you want to make a smaller rack or don’t want to paint it you can calculate roughly what your rack will cost.
Six 1-metre lengths of galvanised M24 all-thread: €56, -
One box containing 50 galvanised M24 nuts: €45, -
One box containing 50 galvanised M24 washers: €18, -
One box containing 10 galvanised M24 capped-nuts: €40, -
Two-and-a-half 2440x1220mm sheets of 18mm mdf: €67, -
One pot of white wood glue: €7, -
Two three-quarter-litre pots of paint (one ground and one top): €30, -
One bag of so called silver-sand: €3, -
Total costs for a four shelved double width Flexy Table Plus: €266, -
A fraction of an equivalent factory made equipment rack!
Happy building!
NOTE: This design is strictly for the home DIY enthusiast and not to be used professionally without my permission!
Tony Gee
The Netherlands
March 2002